016 FXUS64 KHUN 031130 AAA AFDHUN AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE HUNTSVILLE AL 530 AM CST SAT MAR 3 2012 .UPDATE... FOR 12Z TAFS && .DISCUSSION... /ISSUED 506 AM CST SAT MAR 3 2012/ RECENT SURFACE OBSERVATIONS CONFIRM THAT THE HIGHLY ANTICIPATED ARRIVAL OF THE STRONG COLD FRONT HAS INDEED OCCURRED ACROSS THE TENNESSEE VALLEY...WITH DEW POINT READINGS IN THE 35-40 DEGREE RANGE AND MOST OF THE REGION CURRENTLY EXPERIENCING A GUSTY NORTH WIND. TEMPERATURES HAVE BEEN SLOWER TO FALL THAN ORIGINALLY ANTICIPATED... DUE TO THE LINGERING PRESENCE OF A MID-LEVEL CLOUD DECK ACROSS ALL BUT FAR NORTHWEST ALABAMA. MODELS SUGGEST THAT THE GREAT LAKES UPPER LOW WILL CONTINUE TO DEEPEN TODAY AS IT SHIFTS NORTHEASTWARD INTO SOUTHERN QUEBEC...WITH A BROAD LONG WAVE TROUGH AXIS EXTENDING SOUTHWESTWARD INTO THE SOUTHERN PLAINS. THIS MAY ALLOW THE MID LEVEL CLOUDS TO REMAIN IN PLACE FOR THE MAJORITY OF THE DAY -- ESPECIALLY ACROSS THE SOUTHEASTERN HALF OF THE FORECAST AREA. A FEW LIGHT SHOWERS WILL ALSO BE POSSIBLE...AIDED BY THE DEVELOPMENT OF A SURFACE WAVE OF LOW PRESSURE ALONG THE PRIMARY COLD FRONT ACROSS THE CENTRAL GULF COAST -- AND BOTH THE AMPLIFICATION AND NORTHEASTWARD TRACK OF THIS FEATURE ANTICIPATED LATER TODAY/TONIGHT. ALTHOUGH ANY PRECIPITATION CHANCES WILL DIMINISH BY LATE EVENING...EXPECT AT LEAST SOME COVERAGE OF MID/HIGH-LEVEL CLOUDS TO PERSIST THROUGH TONIGHT... AS THE LONG WAVE TROUGH AXIS PUSHES EASTWARD ACROSS THE AREA. A WELL- DEFINED VORT MAX DROPPING INTO THE BASE OF THE TROUGH FROM THE NORTHWEST WILL FORCE LOW-LEVEL WINDS TO GRADUALLY BACK TO THE WEST- NORTHWEST OVERNIGHT. A BRISK WEST-NORTHWEST FLOW IS IN STORE ON SUNDAY...AS THE SURFACE LOW ASSOCIATED WITH THIS SYSTEM DROPS SOUTHEASTWARD ACROSS THE OHIO AND NORTHERN TENNESSEE VALLEYS AND EVENTUALLY CROSSES THE SOUTHERN APPALACHIANS BY MONDAY MORNING. AN INCREASE IN LOW-LEVEL CLOUD COVER IS EXPECTED SUNDAY AS THIS OCCURS...BUT WITH THE STRONGEST LARGE SCALE FORCING REMAINING TO THE NORTH IT APPEARS THAT THE GREATEST CHANCES FOR SHOWERS WILL REMAIN AWAY FROM THE LOCAL AREA AND ONLY SLIGHT CHANCE POPS ARE WARRANTED FOR THE POTENTIAL DEVELOPMENT OF A FEW SHOWER ALONG A REINFORCING COLD FRONT ATTACHED TO THIS SURFACE LOW. CLOUDS/SHOWER CHANCES WILL DIMINISH FROM MONDAY MORNING THROUGH THE END OF THE SHORT TERM PERIOD...AS STRONG MID-LEVEL SUBSIDENCE SPREADS OVERHEAD IN ADVANCE OF AN AMPLIFIED MID-LEVEL RIDGE BUILDING INTO THE REGION FROM THE WEST. TEMPERATURES DURING THE SHORT TERM PERIODS WILL BE MUCH COOLER THAN THOSE FROM RECENT DAYS...WITH HIGHS IN THE MID 50S AND LOWS GENERALLY IN THE 30S. THE EXTENDED FORECAST WILL BEGIN WITH A CONTINUATION OF VERY PLEASANT WEATHER SEEN EARLY NEXT WEEK...WITH OPTIMAL RADIATIONAL COOLING CONDITIONS APPEARING TO SET UP ACROSS THE AREA ON MONDAY NIGHT AND TUESDAY MORNING. THE GFS/ECMWF MODELS SUGGEST THAT MID-LEVEL WINDS ACROSS THE REGION WILL BACK TO THE WEST-SOUTHWEST BY TUESDAY AS ANOTHER UPSTREAM TROUGH SPREADS ONSHORE ALONG THE PACIFIC NORTHWEST COAST. HOWEVER...AFTER THIS TIME THE MODELS DISAGREE ON HOW THE TROUGH WILL EVOLVE AS IT SHIFTS EASTWARD ACROSS THE WESTERN CONUS. THE ECMWF MAINTAINS THE MORE PROGRESSIVE SOLUTION...WITH THE MOST RECENT VERSION OF THE GFS CONTINUING TO SHOW THE SOUTHERN END OF THE THROUGH BREAKING OFF INTO A LARGE CUTOFF UPPER LOW SOMEWHERE ACROSS THE CENTRAL ROCKIES. REGARDLESS OF SOLUTION...IT IS REASONABLE THAT TEMPERATURE/DEW POINT LEVELS WILL INCREASE STEADILY AS SOUTHEASTERLY WINDS RETURN AT THE SURFACE BY TUESDAY. RAIN CHANCES WILL ALSO INCREASE ONCE AGAIN BY THE VERY END OF THIS FORECAST PERIOD AS A SURFACE LOW AND COLD FRONT ASSOCIATED WITH THE UPPER TROUGH PUSH EASTWARD ACROSS THE SOUTHEASTERN U.S. TEMPERATURES WILL CONTINUE TO RUN SEVERAL DEGREES ABOVE NORMAL FOR EARLY MARCH...WITH HIGHS IN THE 60S AND LOWS IN THE MID/UPPER 30S. 70/DD && .AVIATION... FOR 12Z TAFS... VFR CONDITIONS ARE EXPECTED TO PREVAIL ACROSS N AL AND SOUTHERN MIDDLE TN OVER THE NEXT 24 HOURS. VERY ISOLATED -SHRA MAY DEVELOP DURING THE AFTERNOON HOURS...BUT HAVE NOT INCLUDED IN TAFS AT THIS TIME. 99 && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE AT WEATHER.GOV/HUNTSVILLE.