Aviation Weather Services

Area Forecasts (FA) and implies there may be occurrences of severe or greater The FA gives a picture of clouds, general weather conditions, turbulence, severe icing, low-level wind shear, and IFR and visual meteorological conditions (VMC) expected over conditions. The final line of the precautionary statement alerts a large area encompassing several states. There are six areas the user that heights, for the most part, are MSL. Those that for which area forecasts are published in the contiguous 48 are not MSL will state AGL or CIG. states. Area forecasts are issued three times a day and are 3. Synopsis—gives a brief summary identifying the valid for 18 hours. This type of forecast gives information location and movement of pressure systems, fronts, vital to en route operations, as well as forecast information and circulation patterns. for smaller airports that do not have terminal forecasts. Example: Area forecasts are typically disseminated in four sections and SYNOPSIS…LOW PRES TROF 10Z OK/TX PNHDL AREA include the following information: FCST MOV EWD INTO CNTRL-SWRN OK BY 04Z. 1. Header—gives the location identifier of the source of WRMFNT 10Z CNTRL OK-SRN AR-NRN MS FCST LIFT the FA, the date and time of issuance, the valid forecast NWD INTO NERN OK-NRN AR EXTRM NRN MS BY 04Z. time, and the area of coverage. Explanation: Example: As of 1000Z, there is a low pressure trough over the Oklahoma DFWC FA 120945 and Texas panhandle area, which is forecast to move eastward SYNOPSIS AND VFR CLDS/WX into central to southwestern Oklahoma by 0400Z. A warm SYNOPSIS VALID UNTIL 130400 front located over central Oklahoma, southern Arkansas, and CLDS/WX VALID UNTIL 122200…OTLK VALID northern Mississippi at 1000Z is forecast to lift northwestward 122200-130400 into northeastern Oklahoma, northern Arkansas, and extreme OK TX AR LA MS AL AND CSTL WTRS northern Mississippi by 0400Z. 4. VFR Clouds and Weather—This section lists expected Explanation: sky conditions, visibility, and weather for the next 12 The area forecast shows information given by Dallas Fort hours and an outlook for the following 6 hours. Worth, for the region of Oklahoma, Texas, Arkansas, Louisiana, Mississippi, and Alabama, as well as a portion Example: of the Gulf coastal waters. It was issued on the 12th day S CNTRL AND SERN TX of the month at 0945. The synopsis is valid from the time AGL SCT-BKN010. TOPS 030. VIS 3-5SM BR. 14-16Z of issuance until 0400 hours on the 13th. VFR clouds and BECMG AGL SCT030. 19Z AGL SCT050. weather information on this area forecast are valid until 2200 OTLK…VFR hours on the 12th and the outlook is valid from 2200Z on the OK 12th to 0400Z on the 13th. PNDLAND NW…AGL SCT030 SCT-BKN100. 2. Precautionary statements—IFR conditions, mountain TOPS FL200. obscurations, and thunderstorm hazards are described 15Z AGL SCT040 SCT100. AFT 20Z SCT TSRA DVLPG.. in this section. Statements made here regarding height FEW POSS SEV. CB TOPS FL450. are given in MSL, and if given otherwise, AGL or OTLK…VFR ceiling (CIG) is noted. Explanation: In south central and southeastern Texas, there is a scattered Example: to broken layer of clouds from 1,000 feet AGL with tops at SEE AIRMET SIERRA FOR IFR CONDS AND MTN 3,000 feet, visibility is 3 to 5 SM in mist. Between 1400Z and OBSCN. 1600Z, the cloud bases are expected to increase to 3,000 feet TS IMPLY SEV OR GTR TURB SEV ICE LLWS AND AGL. After 1900Z, the cloud bases are expected to continue IFR CONDS. to increase to 5,000 feet AGL and the outlook is VFR. NON MSL HGTS DENOTED BYAGL OR CIG. In northwestern Oklahoma and panhandle, the clouds are Explanation: scattered at 3,000 feet with another scattered to broken layer The area forecast covers VFR clouds and weather, so the at 10,000 feet AGL, with the tops at 20,000 feet. At 1500 precautionary statement warns that AIRMET Sierra should Z, the lowest cloud base is expected to increase to 4,000 be referenced for IFR conditions and mountain obscuration. feet AGL with a scattered layer at 10,000 feet AGL. After The code TS indicates the possibility of thunderstorms 13-10