Weather Services

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Commercial

Commercial Ground School AVF 221

WEATHER SERVICES

Be sure to check out the examples on the Chart Interpretation Test

METAR
2 Types:
METAR comes out hourly from H+45 to the top of the hour
SPECI which is non routine and comes out when special conditions exist… see table 3-1

PIREPS
The only means of getting:
1. Cloud tops
2. Icing
3. Turbulence
4. Layers
5. In-flight vis
They are available on the ADDS site
PIREP

PIREPS
All altitudes are MSL unless otherwise noted
Distance for visibility is in statute miles
Distance for everything else is in nautical miles
Time is in Zulu

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

AREA FORECAST
Known as FA
Covers a large geographical area
Useful for forecast enroute wx and for airports that do not issue a TAF
Issued 3 times a day from 6 areas
We get both the SFO and SLC
12 hour forecast with a 6 hour outlook, good for a total of 18 hours.
All heights given are MSL unless denoted as AGL or CIG

AREA FORECAST
Headers:
Synopsis
General picture of wx covering 18hrs
VFR clouds and weather
12 hrs
Sky condition in msl unless noted
Surface vis when between 3-5 miles over 3,000 sq. miles
If no vis then implied to be greater than 5
Weather precip, fog, haze dust
Included when it lowers vis below 5 mi
Wind 20kts or greater gusts 25 or greater on surface
Categorical outlook
Good for 6hrs
IFR, MVFR, VFR
WND is noted if 20kts or greater gusts 25kts or greater on surface

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

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

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

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 in the area forecast

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
All heights are MSL
Lat and Long in whole degrees and minutes
Some messages may be abbreviated and or contractions may be used (see appendix A)

SURFACE ANALYSIS CHART
Every 3 hours
Shows past wx history
Station data comes from surface observations
Commonly referred to as the weather map

SURFACE ANALYSIS CHART
Shows pressure systems and fronts
Troughs and ridges
Drylines, outflow boundaries (gust front), sea-breeze fronts, convergence lines, squall lines
Isobar lines of equal pressure are plotted usually spaced at intervals of 4 millibars

WEATHER DEPICTION CHART
Beginning at 0100z
every 3 hours
information for this chart taken from METAR
computer generated
] to the right of the station circle means automated

WEATHER DEPICTION CHART
Shows:
1. Total sky cover
2. Cloud height or ceiling
3. Wx and obstructions to vision
4. Visibility

CONSTANT PRESSURE ANALYSIS CHART
Covers a surface of equal pressure
Gives a 3 dimensional view of upper air wx
Twice daily
Valid at 12Z and 00Z
3 Contours
70-110
110-150
+150

CONSTANT PRESSURE ANALYSIS CHART
Shows observed temp
Temp dew point spread
Wind
Height of the pressure level msl in decameters (equals 10 meters)
Height changes over the previous 12 hours

SHORT RANGE SURFACE PROG
Shows:
Surface pressure systems, fronts, isobars and precip
Good out to 2 days
4 forecast periods 12,24,36,48 hours

LOW LEVEL SIG WX PROG (SIGWX)
Used for wx briefings
Covers CONUS 24,000 and below
Depicts wx categories
Less than 1,000 and 3 encircled by solid red line (IFR)
1,000-3,000 ceiling 3-5 vis blue scalloped line (MVFR)
Everything else (VFR)

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

MID LEVEL SIG WX
Tropopause heights indicate the level of the tropopause
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

 

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