5-76 o Sustained surface winds of 20 kts or greater.
o 12- to 18-hour categorical outlook (IFR, MVFR, or VFR), including expected precipitation and/or obstructions to visibility.
5.11.1.8.1 FA—Hawaii Example.
FAHW31 PHFO 080940 (ICAO product header) FA0HI (NWS AWIPS Communication header) .
HNLC FA 080940 (Area forecast region, product type, issuance date/time)
SYNOPSIS AND VFR CLD/WX SYNOPSIS VALID UNTIL 090400 CLD/WX VALID UNTIL 082200...OUTLOOK VALID 082200-090400 .
SEE AIRMET SIERRA FOR IFR CLD AND MT OBSC.
TS IMPLY SEV OR GREATER TURB SEV ICE LOW LEVEL WS AND IFR COND.
NON MSL HGT DENOTED BY AGL OR CIG.
.
SYNOPSIS...SFC HIGH FAR N PHNL NEARLY STNR.
.
BIG ISLAND ABOVE 060.
SKC. 20Z SCT090. OUTLOOK...VFR.
.
BIG ISLAND LOWER SLOPES...COAST AND ADJ WATERS FROM UPOLU POINT TO CAPE KUMUKAHI TO APUA POINT.
SCT030 BKN050 TOPS 080 ISOL BKN030 VIS 3-5SM -SHRA BR. 21Z SCT030 SCT-BKN050 TOPS 080 ISOL BKN030 5SM -SHRA. OUTLOOK...VFR.
.
BIG ISLAND LOWER SLOPES…COAST AND ADJ WATERS FROM APUA POINT TO SOUTH CAPE TO UPOLU POINT. SKC. 21Z SCT-BKN060 TOPS 080. 23Z SCT030 SCT- BKN060 TOPS 080 ISOL BKN030 -SHRA. OUTLOOK...VFR.
.
BIG ISLAND LOWER SLOPES…COAST AND ADJ WATERS FROM SOUTH CAPE TO PHKO TO UPOLU POINT.
SCT050 ISOL BKN050 TOPS 080. 18Z FEW050. 23Z SCT-BKN050 TOPS 080.
OUTLOOK...VFR.
.
N AND E FACING SLOPES...COAST AND ADJ WATERS OF THE REMAINING ISLANDS.
SCT020 BKN045 TOPS 070 TEMPO BKN020 VIS 3-5SM -SHRA...FM OAHU EASTWARD ISOL CIG BLW 010 AND VIS BLW 3SM SHRA BR WITH TOPS 120. 22Z SCT025 SCT-BKN050 TOPS 070 ISOL BKN025 3-5SM -SHRA. OUTLOOK...VFR.
.
REST OF AREA.
SCT035 SCT-BKN050 TOPS 070 ISOL BKN030 -SHRA. 20Z SCT050 ISOL SCT030 BKN045 TOPS 070 -SHRA. OUTLOOK...VFR
5.11.1.9 FA—Alaska.
FAs issued for Alaska cover the airspace between the surface and 45,000 ft MSL and include the following elements:
• Synopsis: A brief description of the significant synoptic weather affecting the FA area during the first 18 hours of the forecast period.
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• Significant Clouds and Weather: A description of the significant clouds and weather for each geographical zone during the first 12 hours of the forecast period, including the following elements:
o AIRMET information for IFR ceiling and visibility, mountain obscuration, and strong surface winds.
o Cloud amount (SCT, BKN, or OVC) with bases and tops.
o Visibility below 7 sm and obstruction(s) to visibility.
o Precipitation and thunderstorms.
o Surface wind greater than 20 kts.
o Mountain pass conditions using categorical terms (for selected zones only).
o 12- to 18-hour categorical outlook (VFR, MVFR and IFR).
• Icing and Freezing Level: A description of expected icing conditions including the following elements:
o AIRMET information for icing and freezing precipitation.
o Icing not meeting SIGMET or AIRMET criteria during the 6- to 12-hour period.
o Freezing level.
o If no significant icing is forecast, NIL SIG will be entered, followed by the freezing level.
• Turbulence: A description of expected turbulence conditions, including the following elements:
o AIRMET information for turbulence or LLWS.
o Turbulence not meeting SIGMET or AIRMET criteria during the 6- to 12-hour period.
o If no significant turbulence is forecast, NIL SIG will be entered.
5.11.1.9.1 FA—Alaska Example.
FAAK47 PAWU 222010 (ICAO product header) FA7H (NWS AWIPS Communication header) JNUH FA 222015 (Area forecast region, product type, issuance date/time) EASTERN GULF COAST AND SE AK...
.
AIRMETS VALID UNTIL 230415 CB IMPLY POSSIBLE SEV OR GREATER TURB SEV ICE LLWS AND IFR CONDS.
NON MSL HEIGHTS NOTED BY AGL OR CIG.
.
5-78 SYNOPSIS VALID UNTIL 231400 989 MB LOW 275 NM SE KODIAK IS WILL MOV SE WARD TO ABOUT 350 NM S PASI BY 14Z WHILE FILLING TO 998 MB. ASSOCD OCFNT ARCING E AND SE FM LOW WILL MOV ONSHR SE AK AND DSIPT BY END OF PD.
.
LYNN CANAL AND GLACIER BAY JB...VALID UNTIL 230800 ...CLOUDS/WX...
FEW025 SCT050 BKN100 TOP 120.
OTLK VALID 230800-231400...VFR.
PASSES...WHITE...CHILKOOT...VFR.
...TURB...
NIL SIG.
...ICE AND FZLVL...
NIL SIG. FZLVL 020.
.
CNTRL SE AK JC...VALID UNTIL 230800 ...CLOUDS/WX...
FEW025 SCT050 BKN100 TOP 120.
AFT 03Z ISOL BKN050 -SHRA.
OTLK VALID 230800-231400...VFR.
...TURB...
AFT 05Z SW PAFE ISOL MOD TURB BLW 040.
...ICE AND FZLVL...
NIL SIG. FZLVL 025.
.
SRN SE AK JD...VALID UNTIL 230800 ...CLOUDS/WX...
FEW025 SCT050 BKN100 TOP 120.
AFT 00Z OCNL BKN050 -RA. ISOL BKN025 -RA.
AFT 03Z SFC WND SE 25G35KT.
OTLK VALID 230800-231400...VFR.
...TURB...
AFT 02Z CLARENCE STRAIT SW ISOL MOD TURB BLW 040.
...ICE AND FZLVL...
AFT 02Z OUTER CST PAHY S ISOL MOD ICEIC 040-100. FZLVL 025.
.
5.12 Alaskan Graphical Area Forecasts (FA).
NWS’s AAWU produces a series of graphical forecasts to complement the text-based FA for Alaska (see paragraph 5.11.1). These forecasts are available from the AAWU’s Web page under Graphical FA.
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• Flying Weather.
• Surface Forecast.
• Icing Forecast.
• Turbulence Forecast.
• Convective Outlook.
Additional products may be available. Some of these may be labeled experimental and, thus, the contents and format are subject to change.
5.12.1 Issuance.
The AAWU issues the Alaskan Graphical FAs. The flying weather, icing, and turbulence forecasts are issued three times a day, approximately at 0530, 1330, and 2130 UTC during Alaska Standard Time (AKST), and 0430, 1230, and 2030 UTC during Alaska Daylight Time (AKDT). Surface Forecasts are issued four times a day, approximately at 0315, 0915, 1530, and 2130 UTC during AKST, and 0215, 0815, 1430, and 2030 UTC during AKDT. The Convective Outlook is a seasonal product and only issued from May 1st through September 30th at 1230 UTC with updates at 0430 UTC.
All forecasts are amended as needed.
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5.12.2 Content.
5.12.2.1 Flying Weather.
The Flying Weather graphic (see Figure 5-45, Alaskan Graphical Area Forecast (FA)—Flying Weather Example) illustrates areas of prevailing Marginal VFR (MVFR) or IFR conditions, strong winds (30 kts sustained or greater), and any active volcano in Alaska. This product consists of two 6-hour forecasts valid for a total of 12 hours. Each forecast specifies where such conditions can be expected within the 6-hour valid time.
Areas of occasional or continuous MVFR/IFR are represented by shaded regions (red for IFR, blue for MVFR), whereas areas of predominately VFR weather are not shaded. MVFR/IFR conditions are possible outside these shaded regions, but only isolated in coverage. Strong surface winds are shown in a circle hatch overlay. Active volcanoes are denoted by a volcano symbol at the location of the volcano.
Note: This forecast is also referred to as IFR/MVFR graphic on their website.
Figure 5-45. Alaskan Graphical Area Forecast (FA)—Flying Weather Example
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5.12.2.2 Surface Forecast.
The Surface Forecast graphic (see Figure 5-46, Alaskan Graphical Area Forecast (FA)—Surface Chart Example) illustrates prominent surface features, including sea-level pressure, areas of high and low pressure, fronts and troughs, and precipitation. Each forecast shows the surface weather that can be expected within 1 hour of the designated time.
Areas of high pressure are depicted along with the maximum sea-level pressure. Areas of low pressure are depicted with the minimum sea-level pressure. The mean 12-hour motion of low pressure systems are also shown.
Areas of occasional or continuous precipitation and/or fog are represented by shaded regions (green for precipitation, yellow for fog), whereas isolated or scattered precipitation is not shaded. This product is issued every 6 hours with forecasts valid for 00Z, 06Z, 12Z, and 18Z.
Figure 5-46. Alaskan Graphical Area Forecast (FA)—Surface Chart Example
5.12.2.3 Ici ng Forecast.
The Icing Forecast graphic (see Figure 5-47, Alaskan Graphical Area Forecast (FA)—Icing For ecast Example) provides information about freezing levels and the potential for significant icing at specified valid times.
5-82 Freezing level heights are blue-filled contours (every 2,000 ft). Areas of isolated (ISOL) moderate (MOD) icing are shaded yellow, occasional (OCNL) or continuous (CONS) moderate icing are shaded orange, and red is used for moderate with isolated severe (SEV) icing (refer to SIGMETs for occasional or greater severe icing). These forecasts are issued every 8 hours and amended as needed.
Figure 5-47. Alaskan Graphical Area Forecast (FA)—Icing Forecast Example
5.12.2.4 Turb ulence Forecast.
The Turbulence Forecast graphic (see Figure 5-48, Alaskan Graphical Area Forecast (FA)—Tur bulence Forecast Example) depicts areas of significant turbulence at specified valid times.
Areas of isolated (ISOL) moderate (MOD) turbulence are shaded yellow, occasional (OCNL) or continuous (CONS) moderate turbulence are shaded orange, and red is used for moderate with isolated severe (SEV) turbulence (refer to SIGMETs for occasional or greater severe turbulence).
Separate graphics are provided for low-level (defined for this product as FL180 and below) and high-level (defined for this product as above FL180) turbulence.
Figure 5-48. Alaskan Graphical Area Forecast (FA)-Turbulence Forecast Example VALID 07 Apr 2015 0300 AKDT LEGEND (SFC / 040 FL180 & BELOW
JISOL MOD Jocn to cons moD _MOD ISOL SEV FC / 080
BASE / TOP in 100s of Feet MSL ABOVE FL180 SFC / 080 COCNL TO CONS MOD
SOL SEV WI 020 AGL SFC / 040 FC / 060) LLWS SFC / 040 (SFC / 040 (SFC / 040)
LOW LEVEL
VALID TURBULENCE FORECAST ISSUED 07 Apr 2015 06 Apr 2015 1100 UTC NOAA - NWS ALASKA AVIATION WEATHER UNIT 08 PM AKDT
5.12.2.5 Convective Outlook.
The Convective Outlook graphic (see Figure 5-49, Alaskan Graphical Area Forecast (FA)-Convective Outlook) is a seasonal product that provides information about Convective activity at specific valid times. Each forecast indicates where conditions are favorable for the development of towering cumulus and thunderstorms.
Locations of towering cumulus are depicted in yellow. Locations of isolated (ISOL), scattered (SCT), and widespread (WDSPRD) thunderstorms (TS) are depicted in orange, red, and dark red, respectively. Cloud bases and tops are also depicted.
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Figure 5-49. Alaskan Graphical Area Forecast (FA)-Convective Outlook VALID 30 Jul 2013 01 PM to 31 Jul 2013 01 AM AKDT LEGEND TCU 060 / FL280 060 / FL200 ISOL TS SCT TS
WDSPRD TS (BASE / TOP in 100s of Feet 040 / FL1
VALID CONVECTIVE OUTLOOK ISSUED 30 Jul 2013 2100 to 30 Jul 2013 31 Jul 2013 0900 UTC NOAA - NWS ALASKA AVIATION WEATHER UNIT 04 AM AKDT
5.12.3 Use.
The Alaska Graphical FAs are a series of forecasts intended to complement, not replace, the text-based FA for Alaska.
5.13 Terminal Aerodrome Forecast (TAF).
A TAF is a concise statement of the expected meteorological conditions significant to aviation for a specified time period within 5 sm of the center of the airport's runway complex (terminal). The TAFs use the same weather codes found in METAR weather reports (see paragraph 3.1) and can be viewed on https://www.aviationweather.gov.
5.13.1 Responsibility.
TAFs are issued by NWS WFOs.
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5.13.2 Generic Format of the Forecast Text of an NWS-Prepared TAF.
Table 5-15. Generic Format of NWS TAFs TAF or
TAF AMD or
TAF COR Type of report
CCCC YYGGggZ Y1Y1G1G1/Y2Y2G2G2 dddffGfmfmKT Location identifier Date/time of forecast origin group Valid period Wind group
VVVV w'w' or NSW NsNsNshshshs or VVhshshs or SKC WShwshwshws/dddftKT Visibility group Significant weather group Cloud and vertical obscuration groups Non-Convective Low-Level Wind Shear (LLWS) group
TTGGgg Forecast change indicator groups
FMY1Y1GGgg TEMPO Y1Y1GG/YeYeGeGe PROB30 Y1Y1GG/YeYeGeGe From group Temporary group Probability group
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5.13.2.1 Type of Report (TAF or TAF AMD or TAF COR).
The report-type header always appears as the first element in the TAF and is produced in three forms: a routine forecast, TAF, an amended forecast, TAF AMD, or a corrected forecast, TAF COR.
TAFs are amended whenever they become, in the forecaster’s judgment, unrepresentative of existing or expected conditions, particularly regarding those elements and events significant to aircraft and airports. An amended forecast is identified by TAF AMD (in place of TAF) on the first line of the forecast text.
5.13.2.2 Location Identifier (CCCC).
After the line containing either TAF, TAF AMD, or TAF COR, each TAF begins with its four-letter ICAO location identifier.
Examples:
KDFW Dallas-Fort Worth PANC Anchorage, Alaska PHNL Honolulu, Hawaii
5.13.2.3 Date/Time of Forecast Origin Group (YYGGggZ).
The date/time of forecast origin group (YYGGggZ) follows the terminal’s location identifier. It contains the day of the month in two 2 digits (YY) and the time in four digits (GGgg in hours and minutes) in which the forecast is completed and ready for transmission, with a Z appended to denote UTC. This time is entered by the forecaster. A routine forecast, TAF, is issued 20 to 40 minutes before the beginning of its valid period.
Examples:
061737Z The TAF was issued on the 6th day of the month at 1737 UTC.
121123Z The TAF was issued on the 12th day of the month at 1123 UTC.
5.13.2.4 Valid Period (Y1Y1G1G1/Y2Y2G2G2).
The TAF valid period (Y1Y1G1G1/Y2Y2G2G2) follows the date/time of forecast origin group. Scheduled 24- and 30-hour TAFs are issued four times per day, at 0000, 0600, 1200, and 1800Z. The first two digits (Y1Y1) are the day of the month for the start of the TAF. The next two digits (G1G1) are the starting hour (UTC). Y2Y2 is the day of the month for the end of the TAF, and the last two digits (G2G2) are the ending hour (UTC) of the valid period.
A forecast period that begins at midnight UTC is annotated as 00. If the end time of a valid period is at midnight UTC, it is annotated as 24. For example,
5-87 a 00Z TAF issued on the 9th of the month and valid for 24 hours would have a valid period of 0900/0924.
Whenever an amended TAF (TAF AMD) is issued, it supersedes and cancels the previous TAF. That is, users should not wait until the start of the valid period indicated within the TAF AMD to begin using it.
Examples:
1512/1612 The TAF is valid from the 15th day of the month at 1200 UTC until the 16th day of the month at 1200 UTC.
2306/2412 This is a 30-hour TAF valid from the 23rd day of the month at 0600 UTC until the 24th day of the month at 1200 UTC.
0121/0218 This is an amended TAF valid from the 1st day of the month at 2100 UTC until the 2nd day of the month at 1800 UTC.
0600/0624 This TAF is valid from the 6th day of the month at 0000 UTC until the 6th day of the month at 2400 UTC (or 7th day of the month at 0000 UTC).
5.13.2.5 Wind Group (dddffGfmfmKT).
The initial time period and any subsequent FM groups begin with a mean surface wind forecast (dddffGfmfmKT) for that period. Wind forecasts are expressed as the mean three-digit direction (ddd—relative to true north) from which the wind is blowing, rounded to the nearest 10 degrees, and the mean wind speed in knots (ff) for the time period. If wind gusts are forecast (gusts are defined as rapid fluctuations in wind speeds with a variation of 10 kts or more between peaks and lulls), they are indicated immediately after the mean wind speed by the letter G, followed by the peak gust speed expected. KT is appended to the end of the wind forecast group. Any wind speed of 100 kts or more will be encoded in three digits. Calm winds are encoded as 00000KT.
The prevailing wind direction is forecast for any speed greater than or equal to 7 kts. When the prevailing surface wind direction is variable (variations in wind direction of 30 degrees or more), the forecast wind direction is encoded as VRBffKT. Two conditions where this can occur are very light winds and Convective activity. Variable wind direction for very light winds must have a wind speed of 1 to 6 kts inclusive. For Convective activity, the wind group may be encoded as VRBffGfmfmKT, where Gfmfm is the maximum expected wind gusts. VRB is not used in the Non-Convective LLWS group.
Squalls are forecast in the wind group as gusts (G) but must be identified in the significant weather group with the code SQ.