Contents:
METAR; ...Hourly METAR
lists; ...Qualifiers; ...Sky
Cover; ...Forecasts; ...Special
Notes; ...METAR sequence;
...METAR sequence another way; ...ASOS/AWOS; ...Demo
Sequences; ...Terminal Area Forecasts;
...About TAFs;
...What is a TAF?;...Type
of TAF Report; ...TAF Coverage;
...Amendment Criteria of TAFs; ....TAF Samples;
--Letter K is U.S. ICAO country code that precedes location
identifier.
--Metar began in late '60 and used worldwide and by military.
--METAR means Aviation Routine Weather Report
--TAF means Terminal Aerodrome Forecast.
--METAR is a Surface Report that lists surface winds, visibility
in statute miles, weather and sky cover.
Time group starts with day followed by actual observation time
in UTC. A METAR can be either routine or SPECI(AL. METARs exclude
trend forecasts. COR is used for making a correction in a report.
Winds
Wind is five digits. Wind direction relative to true north is
first three digits. Next is wind speed in knots. 100kt+ winds
have three digits. VRB will indicate variable headings or velocity.
Calm is 0000KT. METAR winds are all 'true' except when a ASOS
or AWOS voice report. TAF winds are 'true'. Even Center winds
are 'true'.
Visibility
--Runway visual range (RVR)
--Present weather
--Sky conditon
Ceilings will not be stated as such. METAR Ceilings are based
upon whether the layer of clouds are given as broken or overcast.
Clear (CLR) exists only with ASOS and AWOS and even then only
up to l2,000'. Pilot must infer from first layer of broken or
overcast.
Temperature
All temperatures are given in Celsius.
· Dewpoint
Temp and dew point are reported in Celsius degrees using two digits.
M is prefix for below zero numbers.
· Altimeter setting (pressure)
Altimeter setting prefixed with A given in inches of mercury.
REMARKS.
Remarks begins with RMK divided into automated section and human
section.
AUTO is by Automated Surface Observing System (ASOS) or Automated
Weather Observing System (AWOS). ASOS are NWS operated often with
state financing. AWOS is airport facility required by FAA. ASOS
and AWOS reports visibility at one point. If automated visibility
is below 1/4 mile the letter M precedes the visibility
Qualifiers:
Qualifiers state intensity or describe weather
Qualifiers description
- light MI shallow
BL blowing
VC vicinity 5-10 miles PR partial
SH showers
BC patches
no-sign moderate TS thunderstorm
DR low drifting
+ heavy FZ freezing
Phenomena classified as precipitation, obscuration or other. Precipitation
described in order of dominance. Obscuration only if below seven
miles.
Phenomena
Precipitation Obscuration
DZ drizzle BR Mist 5/8 visibility
IC ice crystals DU dust
UP precipitation unknown FG fog low visibility
RA Rain SA sand
IP ice pellets FU smoke
SN snow HZ haze
GR hail VA volcanic ash
GS Small hail/snow PY spray
VV obscured
Other
PO Dust devils
DS dust storm
SQ squalls
FC funnel cloud
+FC tornado
SS Sand storm
Sky condition is gives as cloud layers according to height. Sky-cover
codes are clear, few, scattered, broken or overcast. Maximum of
six layers. AWOS only three layers. No thin or partial reported
in METAR
Sky
cover
VV vertical visibility 8/8
SKC or CLR clear 0
FEW few 0 to 2/8
SCT scattered 3/8 to 4/8
BKN broken 5/8 to 7/8
OVC overcast 8/8
Forecasts
TW.........Surface Observation 3-hour trend
TAF........Terminal forecast
FD.........Winds Aloft Forecast
UA.........Pilot Reports
SD.........Radar Summaries
FDC........FDC NOTAMS (Facilities)
NO.........NOTAMs-Distant
FA.........Area Forecasts
The Area Forecast is best considered a 'dress rehearsal' in preparation
for the big event.
WS.........SIGMETS
Warn all pilots of any weather up to 3000 square miles containing
thunderstorms, icing, turbulence, or storms. Valid for four hours
and named from November to Yankee except for Sierra and Tango
which are reserved for warnings. SIGMETS follow area Forecast
format.
WA.........AIRMETS
Conditions dangerous to small aircraft. Every six hours with six-hour
outlook for moderate icing, turbulence, winds to 30 kts, less
than 3 and ceilings below 1000'. Tango for turbulence, Zulu for
icing
WW-A.......Amended Severe Weather Forecasts
CWA........Center Weather Advisories
Conditions within two hours including real time PIREPs.
WST........Convective SIGMETS
Actual and forecast thunderstorms and level four or higher storms
covering 40% of area. Numbered and lettered in sequence and area.
NONE if no SIGMET 24,795 in 1996.
ATC........Flow Control Advisories
WH.........Hurricane and Tropical Depressions
AWW........Severe Weather Forecast Alerts
AC.........Severe Weather Convective Outlook
A 24-hour perspective on thunderstorms less than severe.
10% is 'high' probability but when? Twice daily at 700Z and 1500Z
valid for 24 hours. Goes with chart issued at 0800Z.
WW.........Severe Weather Warnings (Bulletin)
Every weather briefing must, according to the FAA, begin with
an adverse weather advisory if such weather exists. There are
several levels of such advisories. WHs are Hurricane Advisories,
A Severe Weather Watch comes as a Bulletin called WW and as an
Alert as AWW. The AWW is an advance notice for an area of severe
thunderstorms with winds of 50+ knots and 3/4 inch hail.
TSNO........At the end of a weather observation to say that the
station has no way to detect thunderstorms.
VNR.........VFR not recommended. Advisory appended to other items.
Special
Notes
PE for ice pellets is being changed to PL to avoid a word
when prefixed with RA for rain.
All VFR visibilities and cloud clearances are listed in FAR 91.155
METAR sequence
When or SPECI (special weather report) sometimes data is omitted
user must know and recognize sequence. Exceptions are RVR(runway
visibility range) and SLP (sea level pressure) SPECI remarks will
be in plain language.
1. wind information
2. prevailing visibility in statute miles
3. RVR information
4. Cloud layers and description as (FEW, SCT, BKN, OVC) with heights
in three digits.
5. temperature and dewpoint in Celsius
6. Altimeter settings are begun with A or Q plus four digits
A2992 means given in inches and hundredths of mercury
Q1013 means hecto Pascals or centimeters of mercury
--RMK begins the remarks section which will include the sea level
pressure
-- Always read in the past tense
METAR sequence
another way
----where
K first letter of all U. S. three letter identifiers making four
letters. Alaska begins with PA, Hawaii with PH
· when
First METAR time is six digits followed by Z. First two digits
are day of month, last four are time of observation. All other
times are four digits read in groups of two. From (or between)
xx to xx.
----wind
First three digits are wind direction to nearer 10°. Next
digits are wind speed usually in KT (knots) V between wind directions
that vary more than 60° and greater than 6 knots. VRB
(variable) when less than 6 knots. Peak winds in remarks section
with /time past hour of occurrence.
----Visibility
Fractions shown by /.SM (statute miles) follows.
Visual range uses R+runway/hundreds of feet. Letters other than
R may be M(below sensor ability) P (above sensor ability) V (variable).
---- Weather
Two letter descriptor followed by two character weather type.
Intensity - = light, none = moderate, + = heavy.
---- Clouds
Categorized on eights of the sky. (octas)
SKC = sky clear; FEW 1-2/8; SCT 3-4/8; BKN 5-7/8; PVC 8/8.
VV = vertical visibility; VV/// = indefinite ceiling
----Temperature/dewpoint
Listed in Celsius with / between. M = minus temperatures
---- Altimeter
A2992 if in inches. Q if metric.
ASOS/AWOS
AUTO included unless human makes remarks. Remarks tells
number of sensors. CLR means no clouds below 12K.
--Usually from airports
--Hourly at 50 minutes after hour
--Specials preceded by S
--Reports (METAR) whenever visibility is less than 6 miles.
Demo sequences
OSM FG VV000
visibility, zero statuted miles; fog; vertical visibility, zero
Demo sequence
KOAK 091720Z 1818 22020KT 4 SM -SHRA BKN020CB
Interpretation
Oakland, 9th day of month made at 1720 valid 1800 9th to 1800
10th Winds are as 220 degrees at 20KT as direction and velocity,
variable winds given as 180V220 or as VRB08 Visibility given as
4 miles prevailing. If greater than 6 miles gives as P6S(statute)
Weather given as light showers (-SH) and rain (RA)
Clouds are broken (BKN) at 2000' (020) and cumulonimbus.
KPHL 1550Z 24007KT 7SM BKN009 OVC020 18/16 A3005
Interpretation
Philadelphia, PA 1505Z observation winds 270 degrees at 7 knots,
visibility 7 statute miles, the ceiling is 900 broken with an
overcast cloud deck at 2000 feet, temperature is 18 degrees centigrade,
dew point 16 degrees centigrade, altimeter 30.05 inches
KLAX 1550Z 21008KT 1/2SM R14/3500V5500FT FG OVC 003 14/14 A3018
Interpretation
Los Angeles, CA 1550Z observation, winds 210 degrees at 8 knots,
visibility 1/2 mile (statute), runway 14 runway visual range (RVR)
is 3500 feet variable to 5500 feet in fog. The ceiling is 300
feet overcast,
temperature 14 degrees centigrade, dew point 14 degrees centigrade,
altimeter 30.18
KACY 1545Z 00000KT 11/4SM -SHSN BKNOO6 OVC010 MO3/M03 A2942 RMK
SB30
Interpretation
Atlantic City, NJ 1545Z observation, winds calm, visibility 1
and 1/4 statute miles in light snow showers, the ceiling is 600
feet broken with an overcast cloud deck at 1000 feet, temperature
is minus 3 degrees centigrade, dewpoint is minus 3 degrees centigrade,
the altimeter is 29.42, and remarks indicate that the snow began
falling at 1530Z.
KBUF 1549Z 35015G27KT 1/4SM BLSN R31/1200FT VV003 01/M01 A3OI3
Interpretation
Buffalo, NY 1549Z Observation, winds are 330 degrees at 15 knots
gusting to 27 knots with 1/4 mile )statute) visibility, runway
31 runway visual Range (RVR) is only 1200 feet, and the ceiling
is indefinite 300 feet,
temperature is 1 degree centigrade, dew point is minus 1 degree
centigrade and the altimeter is 30.13
KBOS 1549Z 15012KT6SM -RASN SCT004 BKN009 VOC015 02/M01 A2949
RMK PRESFR
Interpretation
Boston, Mass. 1549Z observation, winds from 150 degrees at 12
knots, visibility 6 statute miles in mixed light rain and snow,
scattered clouds at 400 feet, a broken ceiling at 900 feet and
an overcast deck at 1500 feet, temperature is 2 degrees centigrade,
dewpoint is minimum 1 degree centigrade, the altimeter is 29.49
and
remarks indicate that the pressure is falling rapidly.
KBWI 1550Z S09008KT 3/4SM R10/3800FT -FZDZ PE 008OVC M01/M01 A2992
Interpretation
Baltimore, MD 1550Z Observation, winds directly out of the East
(090 degrees) at 8 knots, with only 3/4's of a statute miles visibility,
runway 10 has a runway visual range (RVR) of only 3800 feet in
light freezing drizzle and ice pellets, with a ceiling of only
800 feet, temperature is minus 1 degree centigrade, a dew point
of minus 1 degree centigrade and the altimeter is 29.90
METAR HIAD 081055 A 21019G27KT 1/2SM RO4/3000FT-SN BR SCT011 OVC015
O1/O3 A2945 RMK SLP045
Interpretation
METAR - hourly report
HIAD - ICAO location indicator
081055 - Issuance time:" ALL times in UTC as a two digit
date and a four digit time.
A - ??
21019G27KT - three digit true north direction, nearest 10 degrees
or VRB (variable); gusts to 27 knots.
1/2SM prevailing visibility in statute miles
R04/3000FT - runway number and visual range in feet
-SN BR - Light snow and mist (French)
SCT 011 - Scattered clouds at 1100'
OVC015 - Overcast 1500'
temperature 1° Celsius, dewpoint 3° Celsius
A2945 - Altimeter 29.45 inches of barometric pressure
RMK - remarks SLP045 - Sea level pressure 3045
KPHL 1550z 24007KT 7SM BKN009 OVC020 18/16 A3005
Interpretation
Philadelphia, PA 1550Z observation. Winds 240 degrees at 7 knots,
visibility 7 statute miles, the ceiling is 900 feet broken with
an overcast cloud deck at 2000 feet, temperature 18 degrees centigrade,
dewpoint 16 degrees centigrade, altimeter 30.05 inches of mercury.
KLAX 1550Z 21008KT 1/2SM R14/3500V5500FT FG OVC003 14/14 A3018
Interpretation
Los Angeles, CA 1550Z observation, winds 210 degrees at 8 knots,
visibility 1/2 statute mile, runway 14 runway visual range (RVR)
is 3500 feet variable to 5500 feet in fog, the ceiling is 300
feet overcast, temperature is 14 degrees centigrade, dewpoint
14 degrees centigrade, altimeter 30.18 inches of mercury.
KACY 1545z 00000KT 11/4SM -SHSN BKN005 OVC010 M03/MO3 A2942 RMK
SB30
Interpretation
Atlantic City, NJ 1545Z observation, winds calm, visibility 1
1/4 statute miles in light snow showers, the ceiling is 600 feet
broken with an overcast cloud deck at 1000 feet, temperature is
minus 3 degrees centigrade, dewpoint is minus 3 degrees centigrade,
the altimeter is 29.42 inches of mercury, and remarks indicate
that the snow began falling at 1530Z.
KBUF 1549z 35015G27KT 1/4SM BLSN R31/1200FT VV003 01/MO1 A3013
Interpretation
Buffalo, NY 1549Z observation, winds are 350 degrees at 15 knots
gusting to 27 knots with 1/4 statute mile visibility in blowing
snow, runway 31 runway visual range (RVR) is only 1200 feet, and
the ceiling is indefinite 300 feet, temperature is 1 edge centigrade,
dewpoint is minus 1 degree centigrade, and the altimeter is 30.13
inches of mercury.
KBOS 1549z 15012KT 6SM -RASN SCT004 BKN009 OVC015 02/M01 A29.49
RMK PRESFR
Interpretation
Boston, Mass 1549Z observation, wind from 150 degrees at 12 knots,
visibility 6 statute miles in mixed light rain and snow, scattered
clouds at 400 feet, a broken ceiling at 900 feet and an overcast
deck at 1500 feet, temperature is 2 degrees centigrade, dewpoint
is minus 1 degree centigrade, the altimeter is 29.49 inches of
mercury and remarks indicate that the pressure is falling rapidly.
KBWI 1550Z 09008KT 3/4SM R10/3800FT -FZDZ PE OO80OVC M01/M01 A2990
Interpretation
Baltimore, MD 1550Z observation, winds directly out of the east
at 8 knots, with only 3/4 statute mile visibility, runway 10 has
a runway visual range of only 3800 feet in light freezing drizzle
and ice pellets, with a ceiling of only 800 feet, temperature
is minus 1 degree centigrade, a dew point of minus one degree
centigrade and an altimeter setting of 29.90 inches of mercury.
Terminal Area
Forecasts
Using the area of a particular airport TAF predicts the next
24-hour weather beginning with where and when. The 24 hours Zulu
time is divided into periods of weather change. The first time-group
gives forecast wind, visibility, sky condition, and weather important
to aviation. A change in any one area will trigger a new time
period directed only to those areas of change. All other elements
in the first time period not changing remain the same and though
not mentioned are carried forward but not written as unchanged
into the second time period. A K as KOAK for Oakland will precede
all three-letter station identifiers. Day of the month and time-group
is followed by valid time-group. TAF format has been changed so
that each time change now begins on a new line.
First break the TAF down into specific time periods. Sequence
of wind, visibility, significant weather, cloud cover and cloud
height follows for each time block. Basically the same forecast
for a definite time period. The initial weather group and the
FM (FROM) group always include the wind, visibility and sky condition.
Cloud conditions are divided into eighths.
If no visibility or weather is mentioned it is assumed to be unrestricted
or non-existent. WS in a TAF is wind shear not part of convective
activity. Qualifiers such as TEMPO is used with two digit beginning
hour and two digit ending hour.
Get copy of NWS Federal Meteorological Handbook (FMH1A) from government
printing office. It has TAF Decoding Chart but takes some time
to learn.
About TAFs
1. Six TAFs cover U.S. SFO, (West coast), SLC, DFW, CHI, BOS
and MIA.
2. Contains written flight precautions with broad brush (crying
wolf) with nothing left to chance.
3. Times forecast for weather changes included in the text.
4. Most likely errors to be in time rather than occurrence
5. An inaccurate forecast tells you about actual as compared to
expected.
6. Serve as an alert to seek other weather information.
7. Flight precautions in airmet category of TAF and amended by
Airmets
What is a
Terminal Aerodrome Forecast?
A Terminal Aerodrome Forecast (TAF) is a concise statement
of the expected meteorological conditions at an airport during
a specified period (usually 24 hours).
The TAF code, as described here, is the one used in the
United States. TAFs use the same weather code found in METAR weather
reports.
TAF Report Elements
TAF
KOKC 051130Z 051212 14008KT 5SM BR BKN030 TEMPO 1316 1 1/2SM BR
FM1600 16010KT P6SM NSW SKC
BECMG 2224 20013G20KT 4SM SHRA OVC020 PROB40 0006 2SM TSRA OVC008CB
BECMG 0608 21015KT P6SM NSW SCT040=
TAF sequence of elements in order:
1. Type of Report
2. ICAO Station Identifier
3. Date and Time of Origin
4. Valid Period Date and Time
5. Forecast Meteorological
The U.S. has no requirement to forecast temperatures in an aerodrome
forecast and the NWS will continue to forecast icing and turbulence
in AIRMETs and SIGMETs.
The Center for this new icing forecast is located at Norman Oklahoma
Weather forecasts have been perfected to the point of showing
where icing is expected as well as its intensity. This development
includes the ability to determine were "drizzle drop"
icing is likely to occur when impacted by an aircraft. With is
ability coming into use, there is all the more reason to check
icing forecasts. WWW.awc-KC.NOAA.gov/index.html or WWW.awc-C.NOAA.gov/awe/Aviation_Weather_Center.html
Type of TAF
Report
The report type header will always appear as the first element
in the TAF forecast. There are two types of TAF reports, a routine
forecast, TAF, and an amended forecast, TAF AMD. An amended TAF
is issued when the current TAF no longer adequately describes
the ongoing weather or the forecaster feels the TAF is not representative
of the current or expected weather.
Corrected (COR) or delayed (RTD) TAFs are identified only in the
communications header which precedes the forecast text.
ICAO Station Identifier
The TAF code uses the ICAO four-letter location identifiers. In
the conterminous United States, the three-letter identifier is
prefixed with a K. For example SEA (Seattle) becomes KSEA. Elsewhere,
the first one or two letters of the ICAO identifier indicate in
which region of the world and country (or state) the station is.
Date and Time of Origin
This element is the UTC date and time the forecast is actually
prepared. The format is a two-digit date and four-digit time followed,
without a space, by the letter Z. Routine TAFs are prepared and
filed approximately one-half hour prior to scheduled issuance
times. TAFs are scheduled for issuance foure times daily at 0000Z,
0600Z, 1200Z, and 1800Z.
Example:
091050Z - Forecast prepared on the ninth day of the month at 1050Z.
Valid Period Date and Time
The UTC valid period of the forecast is a two-digit date followed
by the two-digit beginning hour and two-digit ending hour. Routine
TAFs are valid for 24-hours. Valid periods beginning at 0000Z
shall be indicated as 00. Valid periods ending at 0000Z shall
be indicated as 24. The 24 indication applies to all time group
ending
times.
In the case of an amended forecast, or a forecast which is corrected
or delayed, the valid period may be for less than 24 hours. Where
an airport or terminal operates on a part-time basis (less than
24 hours/day) the TAFs issued for those locations will have the
abbreviated statement NIL AMD SKED AFT (closing time)Z, added
to the end of the forecast. For the TAFS issued while thes elocations
are closed, the word NIL will appear in place of the forecast
text. A delayed (RTD) forecast will then be issued for these locations
after two complete observations are received.
Examples:
091212 - Forecast valid from the ninth at 1200Z til the tenth
at 1200Z.
110023 - Forecast valid from the eleventh at 0000Z till the twelfth
at 0000Z.
010524 - Amended forecast valid from the first at 0500Z till the
second at 0000Z.
Forecast Meteorological Conditions
This is the body of the TAF. The basic format is:
Wind - Visibility - Weather - Sky Condition - Optional Data (Wind
Shear)
The wind, visibility, and sky condition elements are always included
in the initial time group of the forecast. Weather is included
in the initial time group only if significant to aviation. If
a significant, lasting change in any of the elements is expected
during the valid period, a new time period with changes is included.
It should be noted that, with the exception of a FM group, the
new time period will include only those elements which are expected
to change; i.e., if a lowering of the visibility is expected but
the wind is expected to remain the same, the new time period reflecting
the lower visibility would not include a forecast wind. The forecast
wind would remain the same as in the previous time period.
Any temporary conditions expected during a specific time period
are included with that time period.
Wind
The wind group includes forecast surface winds. The surface wind
is the expected wind direction (first three digits) and speed
(last two or three digits if 100 knots or greater). The contraction
KT follows to denote the units of wind speed in knots. Wind gusts
are noted by the letter G appended to the wind speed followed
by the highest expected gust (two or three digits if 100 knots
or greater).
Calm winds (three knots or less) are encoded as 00000KT.
Variable winds are encoded when it is impossible to forecast a
wind direction due to winds associated with convective activity
or low wind speeds. A variable wind direction is noted by VRB
where the three digit direction usually appears.
Examples:
18010KT - Wind one eight zero at one zero knots
35012G20KT - Wind three five zero at one two gust two zero knots
00000KT - Wind calm
VRB16G28KT - Wind variable at one six gust two eight knots
Visibility
The expected prevailing visibility is forecast in statute miles
and fractions of statute miles followed by SM to note the units
of measure. Statute miles followed by fractions of statute miles
are separated with a space, for example, 1 1/2SM. Forecast visibility
greater than 6 statute miles is indicated by coding P6SM. Directional
or variable visibility is not forecasted and the visibility group
is omitted if missing.
Examples:
1/2SM - Visibility one-half statute mile
2 1/4SM - Visibility two and one-quarter statute miles
5SM - Visibility five statute miles
P6SM - Visibility more than six statute miles.
Weather
The expected weather phenomenon or phenomena is coded in TAF reports
using the same format, qualifiers, and phenomena contractions
as METAR reports (except UP).
Qualifiers of Intensity or Proximity
- Light
Moderate (no qualifier)
+ Heavy or well-developed
VC in the Vicinity
Qualifier Descriptor
MI Shallow
BC Patches
DR Low Drifting
BL Blowing
SH Showers
TS Thunderstorm
FZ Freezing
PR Partial
Precipitation
DZ Drizzle
RA Rain
SN Snow
SG Snow Grains
IC Ice Crystals
PE Ice Pellets
GR Hail
GS Small Hail or Snow Pellets (less than 1/4 inch in diameter)
UP Unknown precipitation (automated stations only)
Obscuration
BR Mist (Foggy conditions with visibilities greater than 5/8 statute
mile)
FG Fog (visibility 5/8 statute mile or less)
FU Smoke
DU Dust
SA Sand
HZ Haze
PY Spray
VA Volcanic Ash
Other
PO Well-Developed Dust/Sand Whirls
SQ Squalls
FC Funnel Cloud
+FC Well-Developed Funnel Cloud, Tornado or Waterspout
SS Sandstorm
DS Duststorm
Obscurations to vision will be forecast whenever the prevailing
visibility is forecast to be 6 statute miles or less.
If no significant weather is expected to occur during a specific
time period in the forecast, the weather group is omitted for
that time period. If, after a time period in which significant
weather has been forecast, a change to a forecast of no significant
weather occurs, the contraction NSW (No Significant Weather) will
apear as the weatehr group in the new time period. However, NSW
is only included in the BECMG or TEMPO groups.
Sky Condition
TAF sky condition forecasts use the METAR format. Cumulonimbus
clouds (CB) are the only cloud type forecast in TAFs.
When the sky is obscured due to a surface-based phenomenon, vertical
visibility (VV) into the obscuration is forecast. The format for
vertical visibility is VV followed by a three-digit height in
hundreds of feet.
Note: Ceiling layers are not designated in the TAF code. For aviation
purposes, the ceiling is the lowest broken or overcast layer or
vertical visibility into a complete obscuration.
Examples:
SKC - Sky clear
SCT005 BKN025CB BKN250 - Five hundred scattered, ceiling two thousand
five hundred broken cumulonimbus clouds, two five thousand broken.
VV008 - Indefinite ceiling eight hundred
Optional Data (Wind Shear)
Wind shear is the forecast of non-convective low level winds (up
to 2000 feet) and is entered after the sky conditions when wind
shear is epxected. The forecast includes the height of the wind
shear followed by the wind direction and wind speed at the indicated
height. Height is given in hundreds of feet AGL up to and including
2,000 feet. Wind shear is encoded with the contraction WS followed
by a three-digit height, slant character, and winds at the height
indicated in the same format as surface winds. The wind shear
element is omitted if not expected to occur.
Example:
WS010/18040KT - Low level wind shear at one thousand, wind one
eight zero at four zero.
Probability Forecast
The probability or chance of thunderstorms or other precipitation
events occuring, along with associated weather conditions (wind,
visibility, and sky conditions).
The PROB40 group is used when the occurrence of thunderstorms
or precipitation is in the 30% to less than 50% range, thus the
probability value 40 is appended to the PROB contraction. This
is followed by a four-digit group giving the beginning hour and
ending hour of the time period during which the thunderstorms
or precipitation is expected.
Note: PROB40 will not be shown during the first six hours of a
forecast.
Examples:
PROB40 2102 1/2SM +TSRA - Chance between 2100Z and 0200Z of visibility
one-half thunderstorm, heavy rain.
PROB40 1014 1SM RASN - Chance between 1000Z and 1400Z of visibility
one rain and snow.
PROB40 2024 2SM FZRA - Chance between 2000Z and 0000Z of visibility
two freezing rain.
Forecast Change Indicators
The following change indicators are used when either a rapid,
gradual, or temporary change is expected in some or all of the
forecast meteorological conditions. Each change indicator marks
a time group within the TAF report.
FROM Group
The FM group is used when a rapid change, usually occuring in
less than one hour, in prevailing conditions is expected. Typically,
a rapid change of prevailing conditions to more or less a completely
new set of prevailing conditions is associated with a synoptic
feature passing through the terminal area (cold or warm frontal
passage). Appended to the FM indicator is the four-digit hour
and minute the change is expected to begin and continues until
the next change group or until the end of the current forecast.
A FM group will mark the beginning of a new line in a TAF report.
Each FM group contains all the required elements -- wind, visibility,
weather, and sky condition. Weather will be omitted in FM groups
when it is not significant to aviation. FM groups will not include
the contraction NSW.
Examples:
FM0100 SKC - After 0100Z sky clear
FM1430 OVC020 - After 1430Z ceiling two thousand overcast
BECOMING Group
The BECMG group is used when a gradual change in conditions is
expected over a longer time period, usually two hours. The time
period when the change is expected is a four-digit group with
the beginning hour and ending hour of the change period which
follows the BECMG indicator. The gradual change will occur at
an unspecified time within this time period. Only the conditions
are carried over from the previous time group.
Example:
OVC012 BECMG 1416 BKN020 - Ceiling one thousand two hundred overcast.
Then a gradual change to ceiling two thousand broken between 1400Z
and 1600Z.
TEMPORARY Group
The TEMPO group is used for any conditions in wind, visibility,
weather, or sky condition which are expected to last for generally
less than an hour at a time (occasional), and are expected to
occur during less than half the time period. The TEMPO indicator
is followed by a four-digit group giving the beginning hour and
ending hour of the time period during which the temporary conditions
are expected. Only the changing forecast meteorological conditions
are included in TEMPO groups. The omitted conditions are carried
over from the previous time group.
Examples:
SCT030 TEMPO 1923 BKN030 - Three thousand scattered with occasional
ceilings three thousand broken between 1900Z and 2300Z.
4SM HZ TEMPO 0006 2SM BR HZ - Visibility four in haze with occasional
visibility two in mist and haze between 0000Z and 0600Z.
TAF Coverage:
--IFR conditions
--Mountain obscurations
--Moderate turbulence, icing, 30 kt winds
--Coincides with Airmet information
--Three times a day. A 12 hour forecast with 6 hour outlook that
is `printed 15 minutes before an hour to all stations
--Hazards/flight precautions
--IFR conditions/thunderstorms
--Icing, turbulence, obscurations
--Visibility when below 5 miles
--Winds over 30 kts.
--Synopsis is a Total overview that is good for six hours
--Clouds and Weather good for 12 hours referenced to mean sea
level
--Ceilings referenced to ground level
--Outlook good for 18 hours
--TAF excludes temperature, turbulence and icing forecasts.
--Ceiling is not designated: defined as lowest broken or overcast
layer or the vertical visibility.
Amendment
Criteria of TAFs
Visibility
9000 meters = 56. miles
8000 meters = 5 miles (File IFR)
7000 meters = 4.3 miles
6000 meters = 3.7 miles
4800 meters = 3 miles
1600 meters = 1 mile Don't fly)
9999 means more than 6 miles visibility
Shortcut is to subtract 3 from the thousands place and call it
miles.
Ceiling
If the forecast is Amend if...
No ceiling or ceiling above 3000' Forecast is not representative
or ceiling is 3000' or less.
3000' to 2000' Ceiling = or < 3000' or below 2000'
Less than 2000' to 1000' = or < 2000' or below 1000'
Less than 1000' to 600' = or < 1000' or below 600'
Less than 600' to 200' = or < 600' or below 200'
Less than 200' = or < 200'
Visibility
Forecast Amend if:
< 5 miles Decreases to 5 miles or less
3 to 5 miles < than 5 or below 3 miles
2 to > 3 miles = or < 3 or below 2 miles
1 to > 2 miles = or < 2 or below 2 miles
1/2 to > 1 mile = or < 1 or below 1/2 mile
> 1/2 mile = or < 1/2 mile
Qualifing terms of TAFs
LIFR (Low IFR)
Ceiling below 500' visibility below 1 mile
IFR
Ceiling 1000 to 500, visibility 1 to 3 miles
MVFR (Marginal VFR)
Ceiling 1000 to 3000, visibility 3-5 miles
VFR
Ceiling over 3,000, visibility over 5 miles
Intensity/proximity
- light, +heavy, no sign = moderate
VC: Vicinity 5-10 sm from runway center
Description
MI shallow, BC patches, DR drifting, TS Thunderstorm, PR Partial
BL blowing, SH showers, FZ freezing PO dust devil
Weather
DZ drizzle, RA rain, SN snow, SG snow grains
IC diamond dust, PE ice pellets, GR hail (French), GS small hail
Obscuration
BR mist (French), FG fog, FU smoke(French), VA volcanic ash
SA sand, HZ haze, SY blowing spray, DU dust PY spray
Other
SK sky clear CLR clear TCU towering cumulus
SQ squall, SS sand storm, DS dust storm, PO dust whirls
FC funnel cloud MI shallow SA sand
CAVOK = CAVU = WX NIL or SKC
CIG010 = ceiling 1000
SKY-X = sky partially obscured
9//005 Sky obscured(9), clouds not visible (//) 500' vertical
visibility Octas (eights)
2CU030 = 2/8 scattered cumulus at 3000'
Prognostic TAF qualifiers
Permanent shifts
GRADU = gradual change over 1/2 hour as with fog burning off
RAPID = with time a quick (less than 1/2 hour) turnabout
FRONT = rarely used
Short term variations
TEMPO = CHC less than 1 hour of variation
INTER = OCNL quick changes in ceilings/visibility
PROB = VRBL less certain of changes.
Others:
00000 = calm winds
VRB means variable direction of winds
1920 from 1900Z to 2000Z
OCNL, OCNLY = Occasional, occasionally means greater than 50%
chance for less than half of the forecast period.
OTLK = outlook covers six hours following forecast period.
CHC = chance means 30 to 50% probability during forecast period.
SLGT CHC = 10 to 20% chance
ISOLD = isolated is lowest thunderstorm/precipitation alert level
WDLY SCT = widely scattered is less than 25% chance
SCT = scattered 25 to 54%
CHC means that there is a 30 to 50% likelihood of an event. Chance
tests your appraisal of what is believable compared to what you
would rather believe. Any flight into a chance of icing or thunderstorms
is considered by the NTSB as an FAR violation.
NMRS = numerous is more than 54% chance
VCNTY = vicinity between 5 and 25 miles
VC-SHRA = rain showers in vicinity
NSW = no significant weather
9999 = visibility over 6 miles
BR = mist (baby rain)
T16/11 = temperature 16°C at 1100Z
6CU030 = 6/8th cumulus at 3000'
FEW = 1/8 to 2/8 sky coverage
COR = correction
SPECI = special or Special Report)
KPIT U.S. station identifiers begin with K followed by three letters.
201955Z 20th day 1955Z time of issue. It is always 6 digits and
"Z"
COR for correction to observation) ...follows the time field (when
present)?
RMK SLP013 remarks, sea level pressure 30.13
FM1930 FroM and 2-digit hour and 2-digit minutes indicates significant
change in weather. Each FM group has a separate line which is
indented five spaces.
PROB40 2022 PROBability and 2-digit percent; probable condition
during 2-digit beginning and 2-digit ending time period.
Intensity or proximity
>> - = light no sign = moderate + = heavy
>> VC = vicinity This covers only weather in vicinity of
airport up to ten miles.
>> TAFs tend to be more accurate than FAs.
>> Three FTs a day, valid for 24 hours
>> 18 hour forecast with additional 6 a categorical outlook
>> Expected ceilings, clouds/coverage, visibility, weather,
vision, surface winds
>> Outlook of last 6 hours is VFR, MVFR, IFR, and low IFR
>> Ceilings as C in 100s of feet above ground
>> Clouds in ascending order
>> Visibility in miles and fractions up to 2 miles. Over
6 not reported.
>> Winds reported to neared 10 degrees from true north in
knots.
>> Extends only 5 miles from airport center
>> VCTNY in forecast means within 25 miles
>> Never use an FT after the station has closed for the
day.
>> If the surface report and FT are not available at destination
have alternate.
>> 2/10 of weather coverage (rain) means that 80% of area
is rain free.
When METAR data is missing from the body of the report (e.g. dew point), it is simply omitted and the user must know the sequence to recognize this. Some exceptions apply in remarks such as RVRNO, or SLPNO when RVR or SLP are normally reported but not currently available. METARs exclude trend forecast.
Uncommon TAF Terms
9M04/// means temperature -4 degC, dewpoint not available.
FM1930 = FroM gives a two digit hour and two digit minute as time
of
significant change. Each FM begins a new line indented five spaces.
PROB = PROBability
PROB40 2022 Has a two digit percent during time between two digit
beginning and end.
TEMPO = TEMPOrary
TEMPO0407 Changes less than an hour duration and less than half
of time between two digit beginning and two digit end.
BECOMING = BECoMinG
BECMG 1315 Change expected from beginning two digit and ending
two digit time period.
BINOVC breaks in overcast
BRKS N breaks in layer below 1000' covers 6/10+ of sky
ACCAS ALQDS Altocumulus castellanus all quadrants
CUFRA W cumulus factus clouds west
IC4 ice crystals 4/10 of sky
PRESSRR pressure rising rapidly
RADAT 87120 87 is relative humidity of freezing level, 120(00)
is altitude
RADAT ZERO freezing level at ground
F5 fog covering 5/10 of sky
RWU E Rain showers of unknown intensity east
OCNL LTGIC occasional lightning in clouds
FQT LTGCCCA Frequent lightning cloud to cloud and cloud to atmosphere
SB50 PRESSFR Snow began 50 minutes after the hour pressure falling
rapidly
KOCTY smoke over the city
CLDS APCHG STN clouds approaching station
PRJMP 8/1012/18 pressure jump .8inch at 10:12 stopped at 18 after
10:00
TWRINUN control tower in unknown
AB13E20 HLSTO1/2 Hail began 13 after and ended 20 after 1/2"
hailstones
SU N snow of unknown intensity north
SHLW GFDEP 4 Shallow ground fog 4 feet deep
SNOINCR 1/4/8 snow depth increase 1inch per hour/4 inches last
six 8" deep
PCPN 103 1.03 precipitation in past hour
ACSL altocumulus standing lenticular clouds
CCSL Cirrocumulus standing lenticular
CBMAMcumulonimbus mama
P (Plus)as a letter imposed before visibility means 'greater than'
otherwise means +. (Plus)
NSC means no significant clouds apparently differs from SKC (sky
clear).
NSW means no significant weather
VC means vicinity...at or within five miles
DSNT means distant...at or beyond ten miles
SKC means sky clear
FEW means cloud coverage 1 to 2 eights sky coverage
TEMPO (Means "conditions temporary about half of time) Weather
and visibility from another time period carries forward through
TEMPO unless mentioned.
PROB40 (40% chance of...),
BECMG (becoming...) After qualifiers components omitted are expected
to remain the same. Weather not expected to continue into BECMG
or TEMPO time periods is written as NSW (no significant weather)
TAF Samples
KRNO
141624Z 1818 28010KT P6SM SCT035 SCT100 BKN250 BECMG 1920 25012KT
SCT075 BKN100 TEMPO 1901 VRB12G40KT 11/2SM +TSRA OVC015CB BECMG
OOO1 26006KT SCT730 SCT100 BKN250 BECMG 0909 00000KT 5SM BR SCT250
BECMG 1213 25007KT NSW SCT025=
Interpretation
First six digits give (14th) day of month, (1624Z)time of
issue. Four digits (1818) give valid time of forecast from 1800Z
the 14th to 1800Z the 15th.
Forecast wind (28010KT) is from 280 at 10 kts.
Visibility expected is (P)over (6SM) six statute miles.
(SCT055) Scattered clouds at 5,500'. Next layer is scattered at
10,000' (Only CU or CB cloud types are ever mentioned.) Broken
clouds are at 25,000'.
Becoming a change (BECMG) between (1920) 1900Z and 2000Z wind
(2512KT) from 250 at 12 kts a layer of (SCT075) scattered clouds
at 7,500' and a layer (BKN100) of broken clouds at 10,000'.
Visibility when not given is unlimited.
(TEMPO) Temporarily (up to half of the time) between 1900Z and
0100Z a variable (VBL12G40) direction wind with velocities between
12 and 40 knots.
Visibility is one and one-half (11/2SM) statute miles with heavy
(+TSRA) thunder showers with temporary ceiling (OVC015CB) at 1,500
and cumulus buildups.
Between midnight and 0100Z (BECMG 0001)wind becoming from 260
degrees at six knots with cloud layers of Scattered at 7,300,
another scattered layer at 10,000', and broken clouds at 25,000'.
Becoming (BECMG) between 0900Z and 0900 calm wind conditions (000000KT)
with five ((5SM) statute mile visibility in mist (BR) was a scattered
layer at 25,000'.
By the period between (1213)1200Z and 1300Z becoming a wind from
250 at seven knots, (NSW) no significant weather other than scattered
clouds a 25,000'.
TAF
TAF KIAD 271725Z 271818 21006KT P6SM VCSH SCT050 BKN090 TEMPO
1802 BKN050 BECMG 0002 23006KT KP6SM SCT060 TEMPO
0413 4SM BR SCDT010 BKN060
FM1300 28012G20KT P6SM BKN045 OVC080 PROB30 1318 5SM
-SHRA=
Interpretation
KIAD Location: Dulles International airport (K is the USA)
271725 Issued on the 27th day at 1725 Zulu
271818 Forecast 24-hour period from 1800Z the 27th to 1800Z the
28th
21006KT Wind forecast from 210 (TAF uses 3-digit wind) degrees
at 6 knots
P6SM Visibility P stands for 'plus' greater than six statute miles.
Where weather is not given none relates to aviation.
SCT050 Sky conditions have scattered clouds at 5000' AGL (U.S.
uses feet)
Scattered means 3 to 4 eights cloud coverage.
BKN090 Broken clouds at 9000' covering 5 to 7 octas of the sky.
This is a
ceiling but must be a factor known to the pilot.
TEMPO 1802 Says a temporary change is forecast between 1800 Zulu
and 0200 Zulu.
BKN050 Says the temporary change is a ceiling of 5000' over a
period of eight hours only.
BECMG Means a gradual permanent change between 0002 and 0000 Zulu
and 0200
Zulu there will be...
23006kt a Wind shift to 230 at 6 knots
P6SM visibility will be better than 6 statude miles along with
SCT060 Scattered clouds at 6000'
TEMPO 0413 Between 0400 Zulu and 1300 Zulu a temporary change
will occur in which (4SM BR)
visibility will decrease to four statute miles in misty conditions.
BR means that you can see more than 5/8th of a mile. Fog has visibility
less than 5/8th of a mile.
SCT010 a scattered layer of clouds will be at 1000'
BKN060 forecasts a broken layer of 5 to 7 octa at 6000'
FM begins a new line and indicates a change will take less than
an hour.
1300 is the time the change begins
28012G20 knots winds will be from 280 at 12 knots gusting to 20
knots.
P6SM visibility over six statute miles
BKN045 cloud layer at 4500' AGL
OVC080 overcast layer at 8000' AGL
PROB30 is a 30% chance of a significant change between ...
1300 Z and 1800Z to
5SM visibility of five statute miles
-SHRA The weather visibility is reduced due to rain showers.
TAF KCRP 2371730z 271818 14020G29KT P6SM VCSH BKN020
OVC030 TEMPO 1822 5SM-SHRA BKN017
FM0100 15015G21KT P6SM SCT015 BKN025 WS020/17035KT
Interpretation
Issued on the 27th at 1730 and valid from 1800Z to 1800Z the 28th.
Wind will be from 140 at 20 knots gusting to 29 knots.
Visibility will be greater than 6 miles
Weather will consist of showers in the (VCSH) vicinity (within
five miles)of the airport.
Broken clouds (ceiling) will be at 2000' and overcast at 3000'
There will be a temporary change from 1800Z to 2200Z with visibility
of five statute miles due to light rain showers with broken (ceiling)
at 1700'
From 0100Z winds will be 150 at 15 knots gusting to21 knots.
Visibility will be more than six statute miles. with scattered
clouds (3 to 5 eights) at1500' and a broken cloud (ceiling) covering
six to eight octas at 2500'.
Winds at 2000' will cause wind shear while blowing from 170 at
35 knots.
TAF (Terminal Aerodrome (Aviation) Forecast)
TAFKLIZ0606 31022/39 O700 71SN 9//008 QNH2990INSCIG008 INTER 0714
0000
39BLSN 9//000 620003 CIG000 GRADU 1415 33025 38 BLSN 8SC020 QNH
2993INS CIG 020 TEMP 1517 85SNSH ...GRADU 2021 32010 WXNIL 3S020
RAPID 22 VRB04 9999 SKC;
Interpretation
TAF = Terminal aerodrome forecast
KLIZ = K is the United States, LIX is station identifier
0606 TAS every six hours, 0000, 0500, 1200, 1800. = 0600 one day
to 0600 the next.
31022/39 = Wind from 310 at 22 knots gusts to 39 knots.
0700 = meters of visibility, 3/8s of a mile
71SN = Uses code lattice 71 to indicate SN snow. No apparent reason
for
the numbers since SN = snow.
9//008 = obscured sky with 800 feet vertical visibility
QNH2990INS = Altimeter MSL is 29.90 inches. May be lowest of forecast
period.
CIG008 = Ceiling of 800 feet
INTER0714 = Says from 0700 to 1400 conditions will occur frequently
for less than an hour.
0000 = zero-zero visibility
39BLSN = Uses code lattice 39 to indicate blowing snow. No reason
for numbers.
9//000 = Sky obscured with zero-zero visibility vertically
620003CIG000 = 6 = icing group symbol , 2 = light rime icing in
cloud,
000 = lowest height AGL, 3 = 300 feet, CIG = ceiling, 000 = height
above AGL (zero)
GRADU 1415 = A gradual change from 1400 to 1500
33025 = wind from 330 degrees at 25 knots
38 BLSN = 38 uses code lattice to indicate blowing snow, BLSN
means blowing snow.
8SC020 = 8/10 stratocumulus sky cover. 0 temperature group symbol.
20 degrees Celsius.
QNH2993ins = Altimeter setting 29.93 inches of mercury
CIG 020 = Ceilings (?), 020 = 2000 feet (?)
TEMP 1517 = For less than 1/2 hour periods between 1500 and 1700
85SNSH = snow showers
...GRADU 2021 = gradual change from 2000 to 2100 zulu
32010 = wind at 320 degrees at 10 knots
WXNIL = no significant weather
3SC020 = 3/10 sky covered with stratocumulus, at 2000 feet
RAPID 22VRB04 = Rapid change of wind from 22 knots to 4 knots
9999 = Visibility greater than six miles
SKC = sky clear
WS015/30045KT wind shear field direction(s) and velocity
TAF KJKF 251720Z 1818 21007KT 5SM -SHRA BKN030 OVC 080
FM 22Z 33015G25KT P6SM 030BKN BKN080 PROB40 2301 1SM TSRA
FM05 32005 P6SM 050SCT 100SCT TEMPO 0709 00000KT 1SM FG
FM12 33010 4SM FGHZ BECMG 1416 30010 P6SM NSW SKC
Interpretation
This is the terminal forecast for John F. Kennedy airport
for the 25th day of the month, prepared at 1720Z for
the period from 1800Z of the 25th until 1800Z on the 26th.
-The TAF calls for, from the beginning of the forecast period
(1800Z) until 2200Z, winds out of the southwest (210°)
at 7 knots, with the visibility to be 5 statute miles in light
rain showers, with a (broken) ceiling of 3000 feet and an overcast
deck at 8000 feet. Note use of term deck instead of overcast)
After FM) 2200Z, it calls for winds out of the northwest (wind
shift to 330°) at 15 to 25 knots, with visibility improving
to more than (P) 6 statute miles with just broken clouds, one
deck (ceiling) at 3000 feet and an overcast deck at 8000 feet
with a probability of (occasionally) Between 2300Z and 0100Z,
visibility dropping to 1 statute mile in thunderstorms and rain
showers.
-After 0500Z the winds are expected to be out of the Northwest
(320°)at only 5 knots, visibility more than (P)6 statute
miles with just scattered clouds at 5000 and 10000 feet, but temporarily
(chance of), Between 0700Z and 0900Z, the winds becoming calm
and visibility dropping to 1 statute mile in fog.
-After 1200, the forecast calls for winds out of the northwest
330° at 10 knots with visibility 4 statute miles in fog
and haze becoming between (or by) 1400-1600Z winds out of the
Northwest (300°) at 10 knots, visibility more than 6 statute
miles with no significant weather and clear skies.
TAF KMCI 011725Z 011818 24020KT 2SM FZRA OVC 010
MCI
Interpretaton
Eleventh day of the month at 1725 Zulu
Eleventh day of the month from 1800 zulu to 1800 zulu next day
wind 240 at 20 knots
2 statute miles visibility
freezing rain and overcast ceiling at 1000 feet.
TAF 131530Z KABC 0716 27015KT 10SCT015 TEMPO 1116 4000 +SHRA PROB30
TEMPO 1416 TSRA BKN010CB
Interpretation
131530z Thirteenth day of month at 1530 zulu
KABC K is U. S. code and three letter station identifier
0716 Date and time of forecast elements 0600 Z to 1600 Z
27015KT wind 270 at 15kts
10SCT015 sky 10,000' scattered visibility 15 miles
TEMPO temporary
1116 between 1100 and 1600 zulu always 4 digits separated.
4000 4000' ceiling with
+SHRA heavy rain showers
PROB30 30% chance
TEMPO 1416 Between 1400 and 1600Z
TSRA moderate chance of thunderstorm
BKN101CB Sky going to 1000' broken with cumulonimbus clouds
TAFs
ABC 1410 AMD VRB05KT 9000 BR SCT020 BKN050 OVCO80 QNH3020 CIG050
BCMG 1314 VRB05KT 1600 BR SCT020 BKN040 OVC100 QNH3018INS CIG040
VC-RA
Interpretation
Amended forecast 1400Z to tomorrows 1000Z"wind"
variable to five knots 9000 meters visibility (5.6 miles) mist
scattered clouds at 2000 feet broken at 5000 and overcast at 8000
feet altimeter 30.2 ceiling is 5000 feet becoming "between"
1300Z and 1400Z ind" variable at 5 knots 1600 meters visibility
(1-mile) with misty (French word) 2000 scattered 4000 broken overcast
at 10,000 altimeter 30.18 inches ceiling at 4000 rain in vicinity.
KJKF 251720Z 1818 21007KT 5SM-SHRA BKN030 OVC080
FM 22Z 33015G25KT P6SM BKN030 BKN080 PROB40 2301 1SM TSRA
FM05 32005 P6SM 050SCT 100SCT TEMPO 0709 00000KT 1SM FG
FM12 33010 4SM FGHZ BECMG 1416 300010 P6SM NSW SKC
Interpretation
This is the terminal forecast for John f. Kennedy airport
for the 25th day of the month, prepared at 1720Z , for the period
from 1800Z of the 25th day until 1800Z on the 26th. The TAF calls
for, from the beginning of the forecast period (1800Z) until 2200Z,
winds out of the southwest at 7 knots, with the visibility to
be 5 statute miles in light rain showers, with a ceiling of 3000
feet and an overcast deck at 8000. After 2200Z, it calls for winds
out of the northwest (note wind shift) at 15 to 25 knots, with
visibility improving to more than 6 statute miles with just broken
clouds, one deck at 3000 feet and the other at 8000 feet with
a probability of (occasionally) between 2300Z and 0100Z, visibility
dropping to 1 statute mile in thunderstorms and rain showers.
After 0500Z, the winds are expected to be out of the northwest
at only 5 knots, visibility more than 6 statute miles with just
scattered clouds at 5000 and 10,000 feet, but temporally (chance
of) between 0700Z and 0900Z, the winds becoming calm and visibility
dropping to 1 statute mile in fog. After 1200Z, the forecast calls
for winds out of the northwest at 10 knots with visibility 4 statute
mines in fog and haze becoming between (or by) 1400-1600Z, winds
out of the northwest at 10 knots, visibility more than 6 statute
miles with no significant weather and clear skies.