CHAPTER 5

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BBCC Aviation Meteorology

Chapter 5

5.1 SIGMET

SIGMET

  • Significant Meteorological Information
  • Disseminated to all pilots
  • Issued from the Aviation Weather Center (AWC)
  • The AWC issues for 6 regions
  • SIGMET, CONVECTIVE SIGMET and AIRMET can all be found at https://aviationweather.gov/sigmet

SIGMET

  • Sigmets are issued with a unique ID.
  • Continental US are N thru Y except for S and T
  • S and T are used for Airmets
  • Each wx event is assigned a number indicating continuation
  • Example: November 1, November 2, November 3

SIGMET

  • All heights are MSL
  • Lat and Long in whole degrees and minutes
  • Some messages may be abbreviated and or contractions may be used

SIGMET

  • In order to be issued the wx event has to cover at least 3,000 sq mi
  • May be issued if the wx event may significantly impact aircraft safety

SIGMET

  • Things that make up a SIGMET:
  • –Severe or greater turbulence (SEV TURB)
  • –Severe Icing (SEV ICE)
  • –Widespread Duststorm (WDSPR DS)
  • –Widespread Sandstorm (WDSPR SS)
  • –Volcanic Ash (VA)

SIGMET

  • Good for up to 4 hours
  • Issued whenever currently needed
  • Issued whenever conditions are forecasted in the next 4 hours

SIGMET

  • Content:
  • Series name and number
  • Beginning and ending time
  • Affected states
  • Location of phenomena
  • Phenomena description
  • Vertical extent
  • Movement
  • Intensity change
  • Indication that phenomena

SIGMET

  • (Line 1) SIGMET ROMEO series issued for the San Francisco Area at 0130 UTC on the 10th day of the month.
  • (Line 2) This is the first issuance of the SIGMET ROMEO series and is valid until the 10th day of the month at 0530 UTC.
  • (Line 3) The affected states within the SFO area are Oregon and Washington.
  • (Line 4) From Seattle, WA; to Pendleton, OR; to Eugene, OR; to Seattle, WA;
  • (Line 5) Occasional moderate or greater clear air turbulence between Flight Level 280 and Flight Level 350, expected due to jet stream. Conditions beginning after 0200Z continuing beyond 0530Z and spreading over central Idaho by 0400Z.

SIGMET

  • Cancelled when the event is over
  • Amendments not issued – a new SIGMET is issued using the next issue number
  • Corrections are indicated with a COR

CHAPTER 5

5.1.4 Convective SIGMET

CONVECTIVE SIGMET

  • What are these for?
  • Convective activity (Thunderstorms)
  • Severe or greater turbulence
  • Severe icing
  • Low level windshear

CONVECTIVE SIGMET

  • Normally issued for:
  • –Line of T-storms 60 miles long for 40% of its length
  • –Area of T-storms affecting 3,000 sq. miles covering 40%
  • –Embedded or severe T-storms lasting 30 min or more

CONVECTIVE SIGMET

  • Special issuance for:
  • –Tornado
  • –Hail ¾ inch or bigger
  • –Wind gusts 50kts or greater
  • –Rapidly changing conditions

CONVECTIVE SIGMET

  • Come out H+55
  • Valid for 2 hours

CONVECTIVE SIGMET

  • Format:
  • Series # and region letter E,W or C
  • Ending time
  • States affected
  • Location of phenomena
  • Movement
  • Cloud tops
  • Remarks

CONVECTIVE SIGMET

  • 20th SIGMET of the year
  • CONVECTIVE SIGMET
  • Can access these off ADDS or through normal briefing
  • WSUS32 KKCI 262355
  • SIGC
  • CONVECTIVE SIGMET 11C
  • VALID UNTIL 0155Z
  • LA AND CSTL WTRS
  • FROM 40SW BTR-90SE LCH-140S LCH LINE EMBD TS 30 NM WIDE MOV FROM 27030KT. TOPS TO FL290.
  • OUTLOOK VALID 270155-270555
  • FROM AEX-SJI-130ESE LEV-120SSW LCH-AEX WST ISSUANCES EXPD. REFER TO MOST RECENT ACUS01 KWNS FROM STORM PREDICTION CENTER FOR SYNOPSIS AND METEOROLOGICAL DETAILS.
  • ICAO Identifier
  • Outlook is good for 2 to 6 hours as stated

SIGMET Outside CONUS

  • Items effecting greater than 3,000 sq mi
  • Thunderstorm—of type below*
  • –Obscured (OBSC TS)
  • –Embedded (EMBD TS)
  • –Widespread (WDSPR TS)
  • –Squall line (SQL TS)
  • –Isolated severe (ISOL SEV TS)
  • Severe turbulence (SEV TURB)
  • Severe icing (SEV ICE)
  • –With freezing rain (SEV ICE (FZRA))
  • Widespread duststorm (WDSPR DS)
  • Widespread sandstorm (WDSPR SS)
  • Volcanic ash (VA)
  • Tropical cyclone (TC)
  • Radioactive cloud (RDOACT CLD)

 

CHAPTER 5

5.2 AIRMETS

AIRMET

  • These are aimed at light aircraft
  • Enroute Wx phenomena which may effect safety but at a lower intensity than a SIGMET
  • 6 separate regions

AIRMET

  • Issued for:
  • Ceilings less than 1000 & 3 miles vis
  • Mountain obscurations
  • Moderate turbulence
  • Surface winds 30kts or greater
  • Moderate icing
  • Non convective low-level wind shear below 2,000 feet AGL

AIRMET

  • Altitudes are msl
  • Normal abbreviations are used
  • Good for 6 hours
  • Unlike SIGMETS these may be amended (coded AMD)
  • Issued every 6 hours

AIRMET

  • 3 different types of AIRMETS:
  • –Sierra for IFR and mountain obscuration
  • –Tango for moderate turbulence
  • –Zulu for moderate icing

AIRMET

AIRMET

  • SFOS WA 262045
  • AIRMET SIERRA UPDT 3 FOR IFR AND MTN OBSCN VALID UNTIL 270300
  • NO SGFNT IFR EXP OUTSIDE OF CNVTV ACT
  • AIRMET MTN OBSCN…WA OR CA
  • FROM 70WSW YXC TO 50NE BKE TO 60SE REO TO 40SE LKV TO 40SSW FMG TO 20SE RZS TO 40W RZS TO 30W ENI TO 90SW EUG TO ONP TO 20SSE HQM TO TOU TO HUH TO 70WSW YXC MTNS OBSC BY CLDS/PCPN/BR. CONDS CONTG BYD 03Z THRU 09Z
  • OTLK VALID 0300-0900Z AREA 1…IFR CA BOUNDED BY 20NNW FMG-40S FMG-50NE MOD-20NE CZQ-30NE EHF-40WSW EHF-RZS-40W RZS-40ESE SNS-40ESE ENI-20NNW FMG CIG BLW 010/VIS BLW 3SM PCPN/BR/FG. CONDS DVLPG 03-06Z. CONDS CONTG THRU 09Z.

CHAPTER 5

Section 5.3 Graphical Airman’s Meteorological Advisory (G-AIRMET)

G-AIRMET

  • Issuance Schedule
  • G-AIRMET snapshots are graphical forecasts of en route weather hazards valid at discrete times no more than 3 hours apart for a period of up to 12 hours into the future (00, 03, 06, 09, and 12 hours)
  • 00 hour represents the initial conditions, and the subsequent 3-hourly graphics depict the area affected by the particular hazard at that valid time.

G-AIRMET

  • Forecast of en-route weather hazards
  • Issued 4 times daily, every 6 hrs, updated as necessary
  • Valid at discrete times every 3 hrs, for a total of 12 hrs
  • 8 products available:
  • –IFR Ceiling and Visibility
  • –Mountain Obscuration
  • –Icing
  • –Freezing Level
  • –Turbulence High Level
  • –Turbulence Low Level
  • –Low Level Wind Shear
  • –Strong Surface Winds

Ceiling and Visibility

  • Bases less than 1000 AGL, Vis less than 3sm
  • Visibility causes are denoted:
  • –PCPN, FU, HZ, BR, FG, BLSN

Mountain Obscuration

  • VMC cannot be maintained
  • Obscuring phenomena:
  • –CLDS, PCPN, FU, HZ, BR, FG

Icing

  • Areas of airframe icing including bases and tops
  • Note: this is non-convective caused icing
  • Altitude variations in the bases may be denoted by more than one layer
  • E.g.: “030/010” suggests the icing layer starts at between 1000 and 3000 msl

Freezing Level

  • Lowest freezing level above the ground or at the surface
  • 4000 foot intervals in msl
  • Multiple freezing levels are denoted by base and top labels
  • Over Florida:
  • –Freezing at 7000 and again at 12,000
  • Zig zag indicates freezing level at the surface

Turbulence High Level

  • Areas of moderate turbulence
  • Bases and tops denoted
  • Non-convective

Turbulence Low Level

  • Areas of moderate turbulence
  • Bases and tops denoted
  • Non-convective

Low Level Wind Shear

  • Wind shear below 2000 AGL
  • Defined as exceeding 10kts per 100 feet
  • Non-convective

Surface Winds

  • Surface winds greater than 30 kts

G-AIRMET

  • Using the G-AIRMET
  • When using the G-AIRMET, users must keep in mind that if a 00-hour forecast shows no significant weather and a 03-hour forecast shows hazardous weather, they must assume a change is occurring during the period between the two forecasts
  • It should be taken into consideration that the hazardous weather starts immediately after the 00-hour forecast unless there is a defined initiation or ending time for the hazardous weather
  • The same would apply after the 03-hour forecast. The user should assume the hazardous weather condition is occurring between the snapshots unless informed otherwise.

CHAPTER 5

5.4 Center Weather Advisory

CENTER WEATHER ADVISORY

  • Meets the same criteria as the AIRMET, SIGMET or CONVECTIVE SIGMET
  • Useful for anticipating adverse conditions in the enroute structure
  • Is included in the Area Forecast when getting a DUAT briefing
  • May augment AIRMET/SIGMET information
  • Are usually written out in plain text

CENTER WEATHER ADVISORY

  • Valid for 2 hours
  • May be issued hourly for convective activity

CENTER WEATHER ADVISORY

  • Issued for the following reasons:
  • –There is no existing AWC or AAWU advisory in effect or
  • –Conditions meeting Convective SIGMET criteria.
  • –Icing—moderate or greater.
  • –Turbulence—moderate or greater.
  • –Heavy and extreme precipitation.
  • –Freezing precipitation.
  • –Conditions at or approaching low IFR.
  • –Surface wind gust at or above 30 kts.

CENTER WEATHER ADVISORY

  • Issued for the following reasons:
  • –LLWS (Surface—2,000 ft).
  • –Volcanic ash, duststorms, or sandstorms.
  • –When a hazard has grown significantly outside of the boundary defined by the AWC or AAWU advisory.
  • –To upgrade a thunderstorm advisory to include severe thunderstorms.
  • –To upgrade an AIRMET to include isolated severe turbulence or icing. If greater than isolated severe turbulence or icing is occurring, then a new (non-supplementary) CWA should be issued.
  • –To define a line of thunderstorms within a larger area covered by the AWC or AAWU advisory.
  • –To better define hazards expected at a major terminal already within an AWC or AAWU advisory.
  • –Anything that in the judgment of the CWSU forecaster will add value to an existing advisory.

CENTER WEATHER ADVISORY

CENTER WEATHER ADVISORY

  • ZME1 CWA 081300
  • ZME CWA 101 VALID TIL 081500
  • FROM MEM TO JAN TO LIT TO MEM
  • OCNL TS MOV FM 26025KT. TOPS TO FL450.
  • Center Weather Advisory issued for the Memphis, Tennessee ARTCC on the 8th day of the month at 1300 UTC. The 1 after the ZME in the first line denotes this CWA has been issued for the first weather phenomenon to occur for the local calendar day. The 101 in the second line denotes the phenomenon number again (1) and the issuance number (01) for this phenomenon. The CWA is valid until the 8th of the month at 1500 UTC. From Memphis, Tennessee to Jackson, Mississippi to Little Rock, Arkansas to Memphis, Tennessee. Occasional thunderstorms moving from 260 degrees at 25 knots. Tops to flight level 450

CHAPTER 5

5.5 Meteorological Impact Statement

METEOROLOGICAL IMPACT STATEMENT (MIS)

  • Unscheduled planning forecast tool for ARTCC
  • Helps ATC with flow control when the wx may impact flight ops
  • Good for up to 48hrs
  • Content includes any event that might effect the traffic flow
  • Includes the cause, area, altitudes and movement

MIS

  • Page Loaded (UTC): Sunday, 28-Feb-2010 02:01:14 GMT
  • Minneapolis ARTCC (KZMP) Center Weather Advisory (CWA) No Current CWAs Meteorological Impact Statement (MIS)
  • ZMP MIS 02 VALID 280130-281200
    …FOR ATC PLANNING PURPOSES ONLY…
    ZMP AREA WITHIN A LN FM 45N MOT-PIR-50WSW PIR…LIFR CONDS WITH
    CIG/VIS AS LOW AS 004 AND 1/4SM IN FG/BR. ZMP AREA E OF A LN FM 40SE
    YQT-35N DLL…LGT TO MOD ICG BLO 120.
  • If you look at the metars for this area you can see why they wanted one

CHAPTER 5

5.6 Convective Outlooks

CONVECTIVE OUTLOOKS

  • Known as AC
  • Covers severe and non-severe convective activity
  • Tornadoes, winds 50kts or greater, hail 1 inch or greater
  • 5 levels of threat:
  • Marginal risk (MRGL)
  • Slight risk (SLGT)
  • Enhanced risk (ENH)
  • Moderate risk (MDT)
  • High risk (HIGH)

CONVECTIVE OUTLOOKS

  • Issued for a 24 hr period
  • These are very general in nature
  • Days 1-3 depict general T-storm risk
  • The day 1, day 2 and day 3 use descriptive text to indicate the convective activity
  • Days 4-8 depict two probabilistic thresholds

CONVECTIVE OUTLOOKS

  • The area affected is read to the right of the arrow

Chapter 5

5.6.2 Watch Notification Messages

Watch Notification Messages

  • The Storm Prediction Center (SPC) issues three watches:
  • – Aviation Watch Notification Messages (SAW)
  • –Public Severe Thunderstorm Watch Notification Message
  • –Public Tornado Watch Notification Message
  • http://www.spc.noaa.gov/
  • Watch
  • –Severe weather is possible
  • Warning
  • –Severe weather has been observed or is expected within the hour

Aviation Watch Notification (SAW)

  • Includes
  • –Severe thunderstorm threats
  • –Tornadoes
  • –Hail
  • –Convective damaging winds

Aviation Watch Notification (SAW)

  • Issuance
  • –These are nonscheduled
  • –Only are issued when there is a need
  • –Good for the time on the chart

Public Severe Thunderstorm Watch

  • Includes
  • –Hail 1 inch or greater
  • –Winds of 50kts or greater
  • –Must impact at least 8,000 square miles for 2 hours or more
  • 3 blocks of information
  • –Geographical location
  • –Valid time
  • –Description of the threats
  • Issued
  • –When 6 or more hail events are forecasted
  • –Can be issued for smaller areas if SPC determines a need

Public Tornado Watch Notification

  • Issued when
  • –2 or more tornadoes or any F2 tornado is possible
  • –Must include the 8,000 square mile threshold for 2 or more hours
  • –Can be issued for smaller areas if SPC determines a need
  • Includes
  • –Area description
  • –Expiration time
  • –Largest hail size
  • –Strongest wind gusts expected
  • –Definition of the watch
  • –Call to action statement
  • –List of other valid watches
  • –Meteorological discussion
  • –Technical information for the aviation community

Public Tornado Watch Notification

  • 3 blocks of information
  • –Geographical location
  • –Valid time
  • –Description of the threats

COLLABORATIVE CONVECTIVE FORECAST PRODUCT (CCFP)

  • Graphical representation of forecast convective activity
  • ATC uses this thing to plan for delays and reroutes
  • Computer generated at 2,4,6 & 8 hrs
  • Issued year round
  • Not used for pilot wx briefings
  • Uses polygons
  • What the hell are polygons?
  • Polygons are a multi sided figure
  • A pentagon is a polygon with 5 sides
  • A nonagon is a 9 sided polygon
  • A decagon is a 10 sided polygon
  • A icosagon is a 20 sided polygon
  • A chiliagon is a 1,000 sided polygon
  • I’d like to see them draw one of these

EXTENDED CONVECTIVE FORECAST
PRODUCT (ECFP)

  • This is the Collaborative Convective Forecast extended out to 72 hours (3days)
  • Intended to enhance the CCFP which is good out to only 8 hours
  • Same format as the CCFP
  • Used by ATC and airline dispatchers

NATIONAL CONVECTIVE WX FORECAST (NCWF)

  • Near real time high res
  • Supplements convective SIGMET info
  • Updated every 5 minutes
  • Shows
  • –current convective hazards
  • –1 hr forecast polygons
  • –Forecast speed and direction
  • –Echo tops

NCWF

  • Uses data from the WSR-88D
  • Echo tops less than 17,000 are not shown
  • Uses CTG info
  • 6 hazard levels
  • First number is speed
  • Second is echo tops

NCWF

  • Limitations:
  • Initiation, growth and decay of precip not forecast
  • Short lived or embedded convection may not be accurate
  • Low topped convection with no lightning may not be depicted
  • Erroneous motion vectors
  • Convective hazard field scales are not identified
  • Use this thing to see where the worst T-storms are

Chapter 5

5.7 Tropical Cyclones

  • AVIATION TROPICAL CYCLONE ADVISORY (TCA)
  • Provides short term tropical cyclone forecast guidance
  • National Hurricane Center NHC takes care of the Atlantic and Eastern Pacific
  • Central Pacific Hurricane Center takes care of the Central Pacific
  • TCAs are issued at 0300, 0900, 1500, and 2100
  • Gives:
  • –Current position
  • –Motion and intensity
  • –12, 18 and 24 hr forecast positions

GMZ013 Zone Forecast

GMZ013-040315- N CENTRAL GULF INCLUDING FLOWER GARDEN BANKS MARINE SANCTUARY- 1012 AM EST TUE MAR 3 2015 …GALE CONDITIONS POSSIBLE THU… .TODAY…SE WINDS 10 TO 15 KT. SEAS 3 TO 5 FT. .TONIGHT…SE TO S WINDS 10 TO 15 KT. SEAS 4 TO 5 FT. .WED…SE TO S WINDS 10 TO 15 KT. SEAS 4 TO 5 FT. .WED NIGHT…S WINDS 10 TO 15 KT. SEAS 4 TO 5 FT. .THU…N OF 27N W OF 92W NE WINDS 30 TO 35 KT DIMINISHING TO 25 TO 30 KT. SEAS 8 TO 10 FT BUILDING TO 11 TO 13 FT. ELSEWHERE W OF FRONT N TO NE WINDS 26 TO 30 KT. SEAS 6 TO 9 FT BUILDING TO 8 TO 10 FT. E OF FRONT SW WINDS 5 TO 10 FT BECOMING N TO NE WINDS 25 TO 30 KT. SEAS 3 TO 5 FT BUILDING TO 8 TO 10 FT. .THU NIGHT…N TO NE WINDS 25 TO 30 KT…BECOMING NE 20 TO 25 KT LATE. SEAS 9 TO 13 FT. .FRI…NE WINDS 20 TO 25 KT. SEAS 7 TO 10 FT. .FRI NIGHT…NE TO E WINDS 15 TO 20 KT. SEAS 6 TO 8 FT. .SAT…NE TO E WINDS 15 TO 20 KT. SEAS 4 TO 6 FT. .SAT NIGHT…NE WINDS 20 TO 25 KT…DIMINISHING TO 15 TO 20 KT LATE. SEAS 3 TO 5 FT.

TROPICAL CYCLONE PUBLIC ADVISORY (TCP)

  • Issuance of warnings and watches when needed
  • Tropical depression up to 33 kts
  • Tropical storm 34-63 kts
  • Hurricane/Typhoon in excess of 64 kts

Chapter 5

5.8 Volcanic Ash Forecasts

VOLCANIC ASH ADVISORY

  • Comes from the Volcanic Ash Advisory Center (VAAC)
  • Predict the lateral and vertical extent of eruption clouds
  • Issued within 6hrs of an eruption and every 6hrs after
  • Location, height of volcano, height of ash plume, lat and long of ash dispersion cloud, and a forecast of where it’s going

VOLCANIC ASH ADVISORY

  • FVXX23 KNES 031808
  • VA ADVISORY
  • DTG: 20150303/1808Z
  • VAAC: WASHINGTON
  • VOLCANO: COLIMA 341040
  • PSN: N1930 W10337
  • AREA: MEXICO
  • SUMMIT ELEV: 12631 FT (3850 M)
  • ADVISORY NR: 2015/135
  • INFO SOURCE: GOES-EAST. GFS WINDS. VOLCANO WEB
  • CAMERA.
  • ERUPTION DETAILS: EMISSION AT 03/1448Z
  • OBS VA DTG: 03/1745Z
  • OBS VA CLD: SFC/FL200 N2120 W10236 – N2120 W10216
  • – N2056 W10216 – N2056 W10237 – N2120 W10236 MOV
  • NE 30KT
  • FCST VA CLD +6HR: 04/0000Z SFC/FL200 NO ASH EXP
  • FCST VA CLD +12HR: 04/0600Z SFC/FL NO ASH EXP
  • FCST VA CLD +18HR: 04/1200Z NO ASH EXP
  • RMK: VA FROM THIS EMISSION IS 105 NMI NNE FROM
  • THE SUMMIT. WEBCAMERA AND IMAGERY HAS NOT SHOWN
  • ANY ADDITIONAL VA EMISSIONS BUT EMISSIONS OF
  • GASES WITH POSSIBLE LIGHT VA CONTINUE …SCHWARTZ

Chapter 5

SECTION 5.11 TERMINAL AERODROME FORECAST

TAF

  • Issued 4 times a day:
  • 0000z
  • 0600z
  • 1200z
  • 1800z
  • Good for 24 hours
  • Some are good for 30 hours
  • Covers an area out to 5sm
  • May be AMD or COR

TAF

  • 1. Type
  • 2. Location
  • 3. Date / time
  • 4. Valid period
  • 5. Forecast
  • 6. Probability forecast
  • 7. Temporary conditions
  • 8. Forecast change groups

TAF

TAF  KMWH 301135Z 3012/3112 33006KT P6SM SCT150

        TEMPO 3012/3014 BKN150

         FM302000 VRB03KT P6SM SCT060 OVC120 TEMPO 3021/3101 5SM        BR

         FM310500 22013G17KT 3SM BR OVC080 PROB30 3105/3109 1SM –  SHSN OVC005

  • 3 types: TAF, TAF AMD, & TAF COR

TAF

TAF  KMWH 301135Z 3012/3112 33006KT P6SM SCT150

   TEMPO 3012/3014 BKN150

FM302000 VRB03KT P6SM SCT060 OVC120 TEMPO 3021/3101 5SM BR

FM310500 22013G17KT 3SM BR OVC080 PROB30 3105/3109 1SM -SHSN OVC005

  • ICAO identifier

TAF

TAF  KMWH 301135Z 3012/3112 33006KT P6SM SCT150

   TEMPO 3012/3014 BKN150

FM302000 VRB03KT P6SM SCT060 OVC120 TEMPO 3021/3101 5SM BR

FM310500 22013G17KT 3SM BR OVC080 PROB30 3105/3109 1SM -SHSN OVC005

  • Date time block = 30 day of the month, 1135Z time of issuance.

TAF

TAF  KMWH 301135Z 3012/3112 33006KT P6SM SCT150

   TEMPO 3012/3014 BKN150

FM302000 VRB03KT P6SM SCT060 OVC120 TEMPO 3021/3101 5SM BR

FM310500 22013G17KT 3SM BR OVC080 PROB30 3105/3109 1SM -SHSN OVC005

  • Valid time = 30 day of the month, 1200Z to 1200Z the next day, NIL = no TAF issued. Forecast time period 1200Z to 2000Z to 0500Z

TAF

TAF  KMWH 301135Z 3012/3112 33006KT P6SM SCT150

   TEMPO 3012/3014 BKN150

FM302000 VRB03KT P6SM SCT060 OVC120 TEMPO 3021/3101 5SM BR

FM310500 22013G17KT 3SM BR OVC080 PROB30 3105/3109 1SM -SHSN OVC005

  • Wind group 330° (true) at 6 knots
  • Variable direction at 3 kts,
  • 220° at 13 gusting to 17 kts

TAF

TAF  KMWH 301135Z 3012/3112 13012KT WS020/27055KT P6SM SCT150

    TEMPO 3012/3014 BKN150

FM302000 VRB03KT P6SM SCT060 OVC120 TEMPO 3021/3101 5SM BR

FM310500 22013G25KT 3SM BR OVC080 PROB30 3105/3109 1SM -SHSN OVC005

  • Non convective wind shear is forecast from the surface to 2000 AGL surface winds 130@12 winds at 2000 are 270@55
  • Variable wind at 3 kts
  • G=gusts with 10 kts or more between peaks and lulls  220@13 Gusting 17

TAF

TAF  KMWH 301135Z 3012/3112 33006KT P6SM SCT150

   TEMPO 3012/3014 BKN150

FM302000 VRB03KT P6SM SCT060 OVC120 TEMPO 3021/3101 5SM BR

FM310500 22013G17KT 3SM BR OVC080 PROB30 3105/3109 1SM -SHSN OVC005

  • Visibility = Plus 6 statute miles, 5sm, 3sm and 1sm.

TAF

TAF  KMWH 301135Z 3012/3112 33006KT P6SM SCT150

   TEMPO 3012/3014 BKN150

FM302000 VRB03KT P6SM SCT060 OVC120 TEMPO 3021/3101 5SM VCFG

FM310500 22013G17KT 3SM BR OVC080 PROB30 3105/3109 1SM -SHSN OVC005

  • Significant wx is given when vis is 6 or less, like Mist or light Snow Showers. If VC is used then it covers an area from 5-10sm

TAF

TAF

TAF  KMWH 301135Z 3012/3112 33006KT P6SM 1/2SM TSRA OVC010CB

   TEMPO 3012/3014 BKN150

FM302000 VRB03KT P6SM SCT060 OVC120 TEMPO 3021/3101 5SM VCFG

FM310500 22013G17KT 3SM BR OVC080 PROB30 3105/3109 1SM -SHSN OVC005

  • CB is the only cloud type in the TAF

TAF

TAF  KMWH 301135Z 3012/3112 33006KT P6SM SCT150

   TEMPO 3012/3014 BKN150

FM302000 VRB03KT P6SM SCT060 OVC120

    TEMPO 3021/3001 5SM BR

FM310500 22013G17KT 3SM BR OVC080 PROB30 3105/3109 1SM -SHSN OVC005

  • TEMPO = Temporary fluctuations of 1hr or less.  On the 30th day from 2100Z to 0100Z, 5SM in Mist is predicted. Wind, visibility and clouds are unchanged.

TAF

TAF  KMWH 301135Z 3012/3112 33006KT P6SM SCT150

   TEMPO 3012/3014 BKN150

FM302000 VRB03KT P6SM SCT060 OVC120 TEMPO 3021/3101 5SM BR

FM310500 22013G17KT 3SM BR OVC080 PROB30 3105/3109 1SM -SHSN OVC005

PROB30 = about a 30% chance

  • On the 31st day from 0500Z to the 31st day at 0900Z 1sm vis, light snow showers and 500 OVC will exist.

TAF

  • TAF writer guys use the METAR obs to generate these puppies
  • If the METAR is missing they can use other sources to generate one
  • AMD NOT SKED (amendments not scheduled) at the end of the TAF indicates they had to use other sources
  • Expanded statements use AFT 120200 and then TIL to show resumption
  • If the wx source is part time then AMD NOT SKED 3005-3018Z=
  • If the wx source requires part time augmentation then AMD LTD TO CLD VIS AND WIND 1505-1518=
  • For non-augmented automated sites then AMD NOT SKED
  • The only cloud type forecasted in a TAF is CB

TAF

  • Issuance

CHAPTER 5

SECTION 5.12 INTERNATIONAL AVIATION ROUTE FORECASTS (ROFOR)

  • Prepared by the WFO Honolulu
  • Text based
  • Twice a day for 2 routes
  • KSFO (San Francisco) to PHNL (Honolulu)
  • KSBA (Santa Barbara) to PHNL (Honolulu)
  • They contain:
  • Winds and temps aloft
  • Significant enroute wx
  • Zone wx
  • Overall wind factor component
  • Weather synopsis

CHAPTER 5

5.13 Wind and Temperature Aloft

WIND AND TEMP ALOFT

  • Based on the North American Mesoscale (NAM) model
  • Remember there are 12 models
  • Altitudes in msl:
  • 3000
  • 6000
  • 9000
  • 12000
  • 18000
  • 24000
  • 30000
  • 39000
  • Temps above 24,000 feet are negative
  • They come out 4 times a day every 6 hours
  • Good for the time on the chart

WIND AND TEMP ALOFT

  • Winds not issued for stations within 1,500
  • GEG’s elevation is 2,376
  • Since it is 624 feet from the 3,000 foot level no forecast is issued
  • Temps not issued for stations within 2,500 feet
  • YKM’s elevation is 1,099
  • Since it is 1,901 feet from the 3,000 foot level no temp is issued

******** FD Winds Aloft Forecast ******** DATA BASED ON 140000Z

VALID 141200Z FOR USE 0900-1800Z. TEMPS NEG ABV 24000

 FT    3000      6000       9000     12000     18000    24000    30000   34000   39000

GEG            3332-06 3130-13 3046-19 3079-26 8129-31 827141 826952 813157

YKM 3112 3131-03  3142-07 3151-12 3191-18 8108-25 812740 823751 823363

LWS 2922 2932-04   3138-12 2952-17 3094-24 8027-31 826941 827452 813858

WIND AND TEMP ALOFT

  • Winds are true and in knots
  • 9900 codes calm winds
  • 100 to 199 kts is coded by subtracting 100 from the speed and adding 50 to the direction
  • To decode subtract 50 and add a 100

WIND AND TEMP ALOFT

******** FD Winds Aloft Forecast ******** DATA BASED ON 140000Z

VALID 141200Z FOR USE 0900-1800Z. TEMPS NEG ABV 24000

 FT    3000      6000       9000     12000     18000    24000    30000   34000   39000

GEG            3332-06 3130-13 3046-19 3079-26 8129-31 827141 826952 813157

YKM 3112 3131-03  3142-07 3151-12 3191-18 8108-25 812740 823751 823363

LWS 2922 2932-04   3138-12 2952-17 3094-24 8027-31 826941 827452 813858

  • 82 – 50 = 320
  • 71 + 100 = 171
  • Temp is -41

WIND AND TEMP ALOFT

******** FD Winds Aloft Forecast ******** DATA BASED ON 140000Z

VALID 141200Z FOR USE 0900-1800Z. TEMPS NEG ABV 24000

 FT    3000      6000       9000     12000     18000    24000    30000   34000   39000

GEG            3332-06 3130-13 3046-19 3079-26 8129-31 827141 826952 813157

YKM 3112 3131-03  3142-07 3151-12 3191-18 8108-25 812740 823751 823363

LWS 9900 2932-04   3138-12 2952-17 3094-24 8027-31 826941 827452 813858

  • 81 – 50 = 310
  • 08 + 100 = 108
  • Temp -25
  • LWS at 3000 is light and variable

Graphical Winds and Temps

 

Chapter 5

5.14 Freezing Level Graphics

FREEZING LEVEL GRAPHICS

  • This chart shows current freezing level
  • 3 hour forecast comes out hourly
  • Forecasts for 6, 9, and 12 hours into the future come out every 3 hours
  • Keep in mind inversions may create more than 1 freezing level

FREEZING LEVEL GRAPHICS

  • Where does the data come from?
  • 4 different sources
  • Commercial aircraft
  • Profiler related:
  • Wind profilers (404 and boundary layer 915 MHz)
  • VAD (Velocity Azimuth Display) winds from WSR-88D radars
  • RASS (Radio Acoustic Sounding System)
  • Rawinsondes and special dropwinsondes
  • (a rawinsonde is a radiosonde that can measure wind)
  • Surface:
  • GPS total precipitable water estimates
  • GOES cloud-top data (pressure and temperature)
  • GOES total precipitable water estimates
  • SSM/I total precipitable water estimates
  • GOES high-density visible and infrared (IR) cloud drift winds
  • Experimental:
  • Radar reflectivity (3-d)
  • Lightning
  • Regional aircraft data with moisture (TAMDAR)

 

FREEZING LEVEL GRAPHICS

  • Colors are 100s of feet above sea level
  • White regions are below freezing
  • Hatched areas indicate surface below freezing and multiple freezing layers aloft
  • When the scale jumps by more than 1 color, the surface is above freezing with multiple freezing layers aloft

FREEZING LEVEL GRAPHICS

  • Case 1 represents the condition where temperature is below freezing at the surface and all levels above the surface (represented in the graphic above by white-colored pixels).

FREEZING LEVEL GRAPHICS

  • Case 2 represents the condition where the temperature goes above and below freezing two or more times vertically through the atmosphere while the surface temperature is less than 0°C.
  • These regions are hatched with white.
  • The underlying color represents the lowest height where the temperature crosses the 0°C line as shown by the blue arrow on the vertical temperature graphic.

FREEZING LEVEL GRAPHICS

  • Case 3 represents the condition where the temperature goes above and below freezing three or more times vertically through the atmosphere while the surface temperature is higher than 0°C.
  • These regions are located in areas where adjacent pixels change by more than one color when compared against the color scale.

FREEZING LEVEL GRAPHICS

  • Case 4 is relatively simple and represents the condition where the temperature at the surface is above freezing and the air generally cools with height crossing the 0°C line once.

FREEZING LEVEL GRAPHICS

Chapter 5

5.15 Upper Air Forecasts

Upper Air Forecasts

  • Upper air forecasts are generated using computer models so complex they are run on the NWS Cray super computer
  • These are intended to be used for guidance for Meteorologists
  • You may find more information on the NCEP Central Operations Model Analyses and Guidance Web Site

Chapter 5

5.15.1 Constant Pressure Levels Forecasts

  • Constant Pressure Levels Forecast
  • Computer modeled forecast for a specified pressure level
  • Handy for forming a 3D picture of the weather
  • Shading indicates winds greater than 70kts
  • Issuance
  • The Global Forecast System(GFS) model and the North American Model (NAM) come out 4 times a day
  • The High Resolution Rapid Refresh (HRRR) comes out hourly

Constant Pressure Levels Forecast

  • Most of these provide a winds forecast
  • They may also show
  • Temperature
  • Relative Humidity
  • Vorticity
  • Other derived parameters
  • Used to provide an overview of weather patterns
  • The Jet Stream shows up on the 300mb, 250mb and 200mb levels

 

Chapter 5

5.16 Short-Range Surface Prognostic Chart

SHORT RANGE SURFACE PROG

  • Shows:
  • Surface pressure systems, fronts, isobars and precip
  • Good out to 2.5 days
  • 4 forecast periods 12, 18, 24, 48 and 60 hours

SHORT RANGE SURFACE PROG

  • Precipitation symbology
  • NDFD Rain (Chance)–(light green)–There is a 25 to less than 55 percent probability of measurable rain (≥0.01”) at the valid time.
  • NDFD Rain (Likely)–(dark green)–There is a greater than or equal to 55 percent probability for measurable rain (≥0.01”) at the valid time.
  • NDFD Snow (Chance)–(light blue)–There is a 25 to less than 55 percent probability of measurable snowfall (≥0.01” liquid equivalent) at the valid time.
  • NDFD Snow (likely)–(dark blue)–There is a greater than or equal to 55 percent probability of measurable snow (≥0.01” liquid equivalent) at the valid time.
  • NDFD Mix (Chance)–(light purple)–There is a 25 to less than 55 percent probability of measurable mixed precipitation (≥0.01” liquid equivalent) at the valid time. “Mixed” can refer to precipitation where a combination of rain and snow, rain and sleet, or snow and sleet are forecast.

SHORT RANGE SURFACE PROG

  • NDFD Mix (Likely)–(dark purple)–There is a greater than or equal to 55 percent probability of measurable mixed precipitation (≥0.01” liquid equivalent) at the valid time. “Mixed” can refer to precipitation where a combination of rain and snow, rain and sleet, or snow and sleet are forecast.
  • NDFD Ice (Chance)–(light brown)–There is a 25 to less than 55 percent probability of measurable freezing rain (≥0.01”) at the valid time.
  • NDFD Ice (Likely)–(brown)–There is a greater than or equal to 55 percent probability of measurable freezing rain (≥0.01”) at the valid time.
  • NDFD T-Storm (Chance)–(red hatching)–There is a 25 to less than 55 percent probability of thunderstorms at the valid time. Areas are displayed with diagonal red hatching enclosed in red border.
  • NDFD T-Storm (Likely and/or Severe)–(dark red)–There is a greater than or equal to 55 percent probability of thunderstorms and/or the potential exists for some storms to reach severe levels at the valid time.

SHORT RANGE SURFACE PROG

  • Uses the standard symbology for pressure systems and fronts
  • Pressure systems are depicted by pressure centers, troughs, isobars, drylines, tropical waves, tropical storms, and hurricanes using standard symbols
  • Isobars are denoted by solid thin black lines and labeled with the appropriate pressure in millibars.
  • The central pressure is plotted near the respective pressure center
  • Good for seeing the progression over 60 hrs

SHORT RANGE SURFACE PROG

  • Issuance
  • These are mainly good for seeing the progression over a 2.5 day period

Chapter 5

5.17 Significant Weather Forecast

LOW LEVEL SIG WX PROG (SIGWX)

  • Used for wx briefings
  • Covers CONUS 24,000 and below
  • 12hr and 24 hr panels
  • Snapshot of the weather in the future

LOW LEVEL SIG WX PROG

  • Flying Categories
  • IFR outlined with solid red
  • Marginal VFR outlined with a scalloped blue
  • Everything else is VFR

LOW LEVEL SIG WX PROG

  • Turbulence
  • Brown dashed line
  • 1 witch hat mod turb
  • 2 witch hats sev turb
  • 3 witch hats extreme turb
  • Tops and bases separated by a /
  • Absence of lower number indicates to the surface

LOW LEVEL SIG WX PROG

  • Freezing level at surface blue zigzag
  • Freezing level aloft green dashed line
  • Spaced at 4,000 foot intervals
  • Usually everything north of the zigzag is below freezing
  • Lines are drawn for the highest freezing level if multiple layers exist
  • Multiple layers may be drawn see example at right

LOW LEVEL SIG WX PROG

  • Issuance
  • Comes out 4 times a day
  • 2 charts 12 and 24hrs

Chapter 5

Mid-Level Significant Weather Chart

MID LEVEL SIG WX

  • Covers altitude from 10,000msl to FL450
  • Issuance
  • 24hr forecast issued 4 times a day

MID LEVEL SIG WX

  • Coverage of CBs are indicated by a box appended to area enclosed by a red scalloped line
  • xxx means bases are below the lower limit of the chart
  • ISOL – less than 4/8ths coverage
  • OCNL – 4/8ths to 6/8ths
  • FRQ – more than 6/8ths
  • EMBD – used when thunderstorms are embeded

MID LEVEL SIG WX

  • Tropopause heights indicate the level of the tropopause
  • The L is for low pressure
  • The H is for High pressure
  • Tropical storms and hurricanes are also on this puppy
  • Moderate or severe icing is enclosed by the red scalloped lines
  • Moderate or severe turbulence may also be indicated by yellow dashed line
  • Non cumulus cloud coverage indicated using standard oktas scale
  • Volcanic eruptions and my personal favorite radioactive materials release

MID LEVEL SIG WX

  • Fronts have an arrow showing speed of movement
  • Jet streams are green
  • Standard wind pennants indicate core speed
  • Altitude separated by a / indicate top and bottom of 80kt jet field
  • Double hash marks indicate change in speed in 20kt intervals

HIGH LEVEL SIG WX

  • Covers altitudes from FL250 to FL630
  • U2 and SR71 pilots use these
  • Pretty much the same symbology is used here with a few additions
  • Oh look there’s a volcano in Guatemala

HIGH LEVEL SIG WX

  • Smokes on a daily basis but last eruption was 2/8/15
  • Also known as the volcano of fire, De Fuego is about 10,000 feet high
  • Is one of the most active volcanoes in the Americas
  • Has erupted on a regular basis since 1524

HIGH LEVEL SIG WX

  • Like the mid level sig wx these are mostly for international flights
  • Used by airline dispatchers
  • Issuance

Chapter 5

5.18 World Area Forecast System

World Area Forecast System

  • Global forecasts of:
  • Upper wind and temperature (i.e., wind and temperature aloft, which is also issued in chart form for select areas);
  • Upper-air humidity;
  • Geopotential altitude of flight levels;
  • Flight level and temperature of tropopause (i.e., tropopause forecast);
  • Direction, speed, and flight level of maximum wind;
  • Cumulonimbus clouds;
  • Icing; and
  • Turbulence.
  • Global forecasts of Significant Weather (SIGWX), i.e., High-Level Significant Weather (SIGWX) forecasts (see paragraph 5.17.3).
  • Select regional areas of Medium-Level Significant Weather (SIGWX) forecasts

Chapter 5

5.18 WAFS Wind and Temperature

5.18.1.3 Humidity, Max Wind, Tropopause Forecasts

5.18.1.4 WAFS Turbulence, Icing and Cumulonimbus Cloud Forecast

WAFS Wind and Temps

  • Used by ICAO
  • Grid point format

WAFS Potpourri

  • Humidity, Max Wind, Tropopause Forecast
  • Grid point for flight planning systems
  • Turbulence, Icing and Cumulonimbus Cloud Forecast
  • Check it out at https://www.aviationweather.gov/wafs

Chapter 5

5.19 Additional Products for Icing and Turbulence

CURRENT ICING PRODUCT (CIP)

  • Ready for this? 10 graphics provide a 3 dimensional picture of icing
  • Uses sensor and numerical data from:
  • –WSR-88D
  • –Satellite
  • –PIREPS
  • –Surface Wx reports
  • –Lightning and computer models
  • This product should be used in conjunction with AIRMETs and SIGMETs

CIP

  • Included in the suite are:
  • Icing probability
  • Icing probability max
  • Icing severity
  • Icing severity max
  • Icing severity probability >25%
  • Icing severity probability >25% max
  • Icing severity probability >50%
  • Icing severity probability >50% max
  • Icing severity plus supercooled large droplets
  • Icing severity plus supercooled large droplets max

CIP

  • Generated every 2,000 feet from 1,000 to FL300
  • Max products cover all altitudes
  • PIREPs up to 75 minutes old are included
  • Probabilities range from 0% to 85% (nearly certain icing)
  • Probabilities indicate % chance (either 26% or 51%) to 100%
  • Let’s take a look at them

CIP

  • Max covers probability for all altitudes

CIP

  • Icing severity
  • Icing intensity categories are
  • –Trace
  • –Light
  • –Moderate
  • –Heavy
  • –Note severe is used instead of heavy when giving a PIREP
  • Brown indicates terrain above the selected altitude

CIP

  • Icing severity max

CIP

  • Icing severity probability >25%
  • This means your probability for ice is greater than 25% up to 100%
  • Gray color is used to denote areas less than 25%

CIP

  • Icing severity probability >50%
  • This means your probability for ice is greater than 50% up to 100%

CIP

  • Icing severity probability >50% max

CIP

  • Icing severity plus supercooled large droplets
  • Supercooled water droplets are defined as being larger than 50 micrometers
  • A micrometer or micron is 1 millionth of a meter
  • The average human hair is 80 microns in diameter
  • Freezing drizzle is down in the small micron range

CIP

  • Icing severity plus supercooled large droplets max

CIP

  • Issuance
  • –Updated hourly + 15
  • –0,1,2,3,6,9,12 and 18 hours
  • Some aircraft are ice magnets others are not
  • Icing experienced by a Cessna will be different than for a 787
  • Pilot perceptions of icing differ as well
  • Assessing the size of supercooled water is difficult your results may vary
  • This product assesses the meteorological environment not the resultant icing that may occur
  • –Results not typical, your mileage may vary
  • –Does not include any exclusions, exemptions or innuendos
  • –Not meant to address your level of macho or sexual orientation

FORECAST ICING POTENTIAL (FIP)

  • The FIP provides the same suite of products
  • The CIP is the latest analysis of icing data
  • The FIP is the forecast of anticipated icing
  • The FIP uses National Weather Prediction (NWP) data only whereas the CIP combines sensor data with the NWP
  • The CIP/FIP are shown as a conjunctive product on the AWC site

FIP

  • Displays the relative potential for icing

FIP

  • Good for determining the likelihood of icing

GRAPHICAL TURBULENCE GUIDANCE (GTG)

  • 4 dimensional diagnosis and forecast of CAT
  • Comes out hourly, however
  • 0,1,2,3,6,9,12 and 18hr forecasts comes out every hour
  • Depicts the location and intensity potential of CAT and mountain wave turbulence
  • Issued every 1000 feet between 10,000 and FL450
  • Should be used in conjunction with AIRMET and SIGMET
  • Accuracy is dependent on the computer models
  • Turbulence PIREPS are overlayed
  • Only displays info for upper level fronts and the jet stream, no convective info

GTG

  • Just like the CIP has a max setting which covers all the altitudes

CTG

  • Here are 4 examples

Chapter 5

5.20 Additional Products for Clouds, Visibility, Weather and Surface Winds

Aviation Forecast Discussion

  • Weather conditions as related to the TAF
  • Provides further details as to the reasoning behind the TAF
  • Issuance
  • –Roughly every 6 hours
  • Plain language

National Digital Forecast Database Graphic

  • Designed to complement the Short Range Surface Progs
  • Charts available
  • –Maximum and minimum temperature;
  • –Temperature
  • –Dewpoint
  • –Relative humidity
  • –Sky cover
  • –Weather
  • –Hazards
  • –Probability of precipitation
  • –Amount of precipitation
  • –Snow amount
  • –Snow level
  • –Ice accumulation
  • –Sky cover
  • –Surface wind direction, speed, and gusts.
  • https://graphical.weather.gov/sectors/conus.php?element=Sky

Airport Weather Warning

  • Addresses weather affecting ground ops at airports like
  • –strong surface winds
  • –freezing rain
  • –heavy snow
  • –lightning within 5 miles of the airport
  • Plain language, not for in flight use

Space Weather

  • Space Wx scales for 3 events
  • –Geomagnetic storms
  • –Solar radiation storms
  • –Radio blackouts
  • Space Wx messages include
  • Watch messages are issued with long lead times for the majority of all space weather activity predictions.
  • Warning messages are issued when some condition is expected. The messages contain a warning period and other information of interest.
  • Alert messages are issued when an event threshold is crossed and contain information that is available at the time of issue.
  • Summary messages are issued after the event ends and contains additional information that was not available at the time of issue.

Space Weather

  • Forecast Discussion is issued every 12 hours
  • –Has a summary and a forecast
  • 3 day forecast issued every 12 hours
  • –Looks at the observed and forecast space wx
  • There are others…

Soaring Forecast

  • The soaring forecast is out there, somewhere

 

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