A Pilot's Guide to Inflight Icing
Module I - Before You Fly
Check the Weather
Section: Area Forecasts
Start This SectionArea Forecasts Check the Weather
Step 1. Check the Area Forecast.
Begin your examination of the standard weather briefing with the Area Forecast.
The Area Forecast provides a synopsis of the weather over a large area from the surface to approximately 63,000 feet. The synopsis describes the location and movement of pressure systems, fronts, and other weather patterns, usually as brief, generalized statements.
Area Forecasts are issued three times a day, valid for 12 hours with an additional 6-hour categorical outlook.
In addition to providing a general overview of the weather, the Area Forecast is the primary source of cloud type (cumulus or stratus) and height information for the en route part of the flight. Visibility, surface winds, and cloud heights, coverage, and tops are included in the Area Forecast. Altitudes are normally given above MSL but are sometimes given in AGL within 4,000 feet of the surface. Obstructions to vision are forecast when the visibility is expected to be 5 miles or less. Widespread areas of strong surface winds (more than 20 knots) are also forecast here.
From the Area Forecast, you can determine where the fronts are and where there is likely to be visible moisture in the form of clouds or precipitation. The risk of an icing encounter is greatest if you are planning to fly in the vicinity of relatively cold moist air and you will approach a front or other source of lifting (e.g. mountain range).
Area Forecast Regions
Related Information
CHIC FA 120145
SYNOPSIS AND VFR CLDS/WX
SYNOPSIS VALID UNTIL 122000
CLDS/WX VALID UNTIL 121400...OTLK VALID 121400-122000
ND SD NE KS MN IA MO WI LM LS MI LH IL IN KY
SYNOPSIS...WRMFNT PLB-LOW NR RHI. CDFNT RHI-DSM-GAG-TCC. STNR FNT
TCC-AKO. CDFNT W CNTRL MB-SRN SK-SRN AB. 20Z CDFNT WRN QB-MBS-FAM-FSM-LOW NR ABI-NERN NM. CDFNT NWRN ON-YWG-SRN SK. HIGH NR
MKC. ...HIRT...
LM LWR MI LH
NW LWR MI/N HLF LM...OVC150 TOP FL300. 08Z CIG BKN040. SCT VIS 3-5SM -SHRA. 10-12Z CIG OVC020. VIS 3SM -RA BR. OTLK...IFR CIG.
S HLF LM/SW LWR MI...BKN CI. 06Z AGL SCT050 BKN150 TOP FL300. 10-12Z CIG OVC020. VIS 3SM -RA BR. OTLK...MVFR CIG.
NE LWR MI/N HLF LH...BKN150 TOP FL300. 11-13Z CIG BKN030 OVC090.
SCT VIS 4SM -SHRA. OTLK...IFR CIG.
RMNDR...SCT150. 08Z AGL SCT045 BKN120 TOP FL250. OTLK...VFR TSRA.
Chicago area forecast:
prepared on the 11th at 9:45pm EDT (0145Z).
Synopsis and VFR clouds / weather.
Synopsis valid until the 12th at 4:00pm EDT (2000Z).
Clouds / weather valid until the 12th at 10:00am EDT (1400Z)
Outlook valid the 12th at 10:00am EDT (1400Z) - the 12th at 4:00pm EDT (2000Z).
For: North Dakota, South Dakota, Nebraska, Kansas, Minnesota, Iowa, Missouri, Wisconsin, Lake Michigan, Lake Superior, Michigan, Lake Huron, Illinois, Indiana, Kentucky
Synopsis
Warm front Plattsburgh [PLB] - low near Rhinelander [RHI]. Cold front along a line defined by Rhinelander [RHI] - Des Moines [DSM] - Gage [GAG] - Tucumcari [TCC]. Stationary front from Tucumcari [TCC] to Akron [AKO]. Cold front from west central Manitoba through southern Saskatchewan to southern Alberta.
At 4pm EDT (20Z) cold front western Quebec - Saginaw [MBS] - Farmington [FAM] - Fort Smith [FSM]. Low near Abilene [ABI] - northeastern New Mexico. Cold front northwestern Ontario - Winnipeg [YWG] - southern Saskatchewan. High near Kansas City [MKC].
Lake Michigan, Lower Michigan, Lake Huron
Northwest lower Michigan / north half Lake Michigan
15,000 feet overcast, tops Flight Level 300.
By 4am EDT (08Z) ceiling 4,000 feet broken. Scattered clouds, visibility 3 to 5 statute miles in light rain showers.
Between 6am EDT (10Z) to 8am EDT (12Z) ceiling 2,000 feet overcast; visibility 3 statute miles in light rain, mist.
Outlook: IFR due to ceilings.