FXUS64 KHUN 081153 AFDHUN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HUNTSVILLE AL 553 AM CST MON DEC 8 2014 .UPDATE... FOR 12Z TAFS && .DISCUSSION... /ISSUED 315 AM CST MON DEC 8 2014/ AS OF 09Z...SURFACE OBSERVATIONS ARE SHOWING THE BACKDOOR FRONT THROUGH THE FORECAST AREA. DEW POINTS HAVE DROPPED INTO THE UPPER 20S TO MIDDLE 30S FOR THE AREA AND PARTS OF NW GEORGIA. THAT...AND WINDS SHIFTING AROUND FROM THE SE ARE THE ONLY REAL IMPACTS EXPECTED WITH THIS FRONT. AN UPPER LEVEL SOUTHERN STREAM JET STREAK WILL CONTINUE TO PUSH MID LEVEL CLOUDS TO THE EAST TODAY WITH DRY AIR ALREADY MOVING WEST TO EAST INTO LOUISIANA AS OF 09Z. OTHERWISE... AN UPPER TROUGH AND SURFACE LOW ARE DEVELOPING NICELY IN NORTHERN MINNESOTA WITH A WEAK AREA OF HIGH PRESSURE BUILDING IN FROM THE WEST. ALTHOUGH DEW POINTS DID DROP SLIGHTLY WITH THE BACKDOOR FRONT NOSING IN...MID LEVEL MOISTURE IS ALSO STREAMING IN WITH IT AND THE QUESTION WILL BE HOW FAR WEST DOES THAT MOISTURE/MID LEVEL CLOUD DECK MAKE IT. GUIDANCE SEEMS TO BE HINTING AT WARMER HIGH TEMPS IN THE WESTERN COUNTIES TODAY BECAUSE OF THIS AND WILL CONTINUE THAT IDEA. THE PREVIOUSLY MENTIONED TROUGH WILL DEEPEN AND DIVE SOUTHEASTWARD TONIGHT INTO TUESDAY MORNING. THIS WILL DRAG A COLD FRONT THROUGH THE REGION SOMEWHERE BETWEEN 9-12Z TUESDAY. MOISTURE IS LACKING THROUGH THE COLUMN WITH JUST A 850-900MB MOISTURE PUSH WITH THE UPPER VORT MAX AS IT SINKS TO THE SOUTHEAST OF THE REGION. EVEN SO...WITH A DEEP NW FLOW...EXPECT SOME UPSLOPE ALONG HIGHER TERRAIN IN THE TN VALLEY TO AID IN THE LIFT AND TAP INTO SOME OF THE MID-LOW LEVEL MOISTURE. THEREFORE WILL INCLUDE SPRINKLES IN THE FORECAST FOR OUR TN COUNTIES TUES AFTERNOON. EVEN IF THE SURFACE DOES COOL DOWN...DO NOT THINK THERE IS ENOUGH MOISTURE IN THE SNOW GROWTH REGION TO EVEN WARRANT THE THOUGHT OF SNOW. THE UPPER TROUGH THEN PROGRESSES EAST AND CUTS OFF INTO A STRONG UPPER SYSTEM OVER THE NORTHEAST AND ROTATES THERE FOR THE REMAINDER OF THE LONG TERM PERIOD LEAVING DRY NORTHWEST FLOW ACROSS OUR REGION. A PIECE OF ENERGY IS FORECAST TO ROTATE AROUND THE BASE OF THIS UPPER LOW FOR THURSDAY BUT WITH SUCH A DRY AIR MASS IN PLACE...NOT EXPECTING ANY PRECIP FROM THIS. THIS COULD ACTUALLY MIX OUT THE INVERSION/LOW CLOUDS AND AID IN MOSTLY SUNNY SKIES FOR THU- SAT. OTHERWISE...HIGH PRESSURE OVER MUCH OF THE CENTRAL U.S. WILL BUILD IN AND REMAIN AS AN UPPER RIDGE AMPLIFIES IN RESPONSE TO THE CUT OFF UPPER LOW. TEMPERATURES THROUGH THE PERIOD WILL BE LARGELY INFLUENCED BY THE RESULTING CLOUD COVER. WITH SUCH A THIN LAYER OF MOISTURE PRESENT UNDER THE INVERSION FOR THE NEXT FEW DAYS...THIS IS EASIER SAID THAN DONE IN TERMS OF FORECASTING THE COVERAGE OF THE CLOUDS. FOR NOW...THE FORECAST IS PROBABLY SLIGHTLY TOO OPTIMISTIC TUE/WED FOR SKY COVER AND THEREFORE DID NOT LOWER TEMPS AS MUCH AS THEY COULD BE. BUT WITH THE COOLER NW FLOW...TEMPS WILL DROP TO NEAR TO JUST BELOW NORMAL VALUES FOR HIGHS THROUGH AT LEAST FRIDAY. WITH THE RIDGE BUILDING FOR THE WEEKEND...LIKELY WILL SEE TEMPS IN THE UPPER 50S. LOWS WILL ALSO BE BELOW NORMAL FOR MUCH OF THE PERIOD. ALL OF THIS WILL DEPEND ON SHORTER TERM UPDATES IN REGARDS TO SKY COVER FOR EACH DAY. LN && .AVIATION... FOR 12Z TAFS...VFR CONDITIONS WILL CONTINUE AT HSV/MSL THRU THIS AFTERNOON...WITH BKN/OVC ALTOSTRATUS DECK LOWERING TO ARND 10 KFT. SOME VIRGA WILL BE PSBL THIS MORNING...BUT NO PRECIPITATION IS EXPECTED AT EITHER TERMINAL. LIGHT SE FLOW WILL GRADUALLY VEER AROUND TO THE SW EARLY THIS EVENING AS A PREFRONTAL TROUGH MOVES EWD ACROSS THE REGION...FOLLOWED BY A LOWER STRATUS DECK ARND 3500 FT. THE NEXT COLD FRONT WILL ARRIVE BTWN 09/05-08Z ACCOMPANIED BY OVERCAST MVFR STRATUS AND WIND SHIFT TO THE NW AT 7G15 KTS. THREAT FOR -SHRA WILL REMAIN TO THE N/E OF BOTH TERMINALS THRU 12Z. 70/DD && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE AT WEATHER.GOV/HUNTSVILLE.
Posted on: Mon, 08 Dec 2014 11:54:20 +0000
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