452 FXUS64 KHUN 150827 AFDHUN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HUNTSVILLE AL 327 AM CDT FRI MAR 15 2013 .DISCUSSION... IN A PERSISTENT NW FLOW ACROSS THE EASTERN LOWER-48...A PASSING WEAK DISTURBANCE BROUGHT A BRIEF DOSE OF LIGHT PRECIPITATION ACROSS PARTS OF FAR NE ALABAMA AND ADJACENT SOUTHERN MIDDLE TENNESSEE. THERE WAS EVEN SOME SNOW REPORTED IN SOME OF THE HIGHER ELEVATED TERRAIN. DEWPOINTS IN THE TEENS PRODUCED GOOD EVAPORATIVE COOLING AND HELP TO CONTRIBUTE TO AN AT TIMES MIXED PRECIP EVENT. WHAT REMAINS OF THAT SYSTEM WAS MOVING TO THE SE ACROSS THE SAVANNAH RIVER OF SC/GA. SKIES OTHERWISE WERE GENERALLY CLEAR ACROSS THE TENNESSEE VALLEY...WITH RATHER CHILLY LOWS IN THE MID 30S TO MID 40S WITH LIGHT WINDS. IN A VERY SIMILAR PATTERN OF THE LAST 24 HOURS...BROAD MID/UPPER LEVEL TROUGHING CONTINUED ACROSS THE EASTERN NORTH AMERICAN DOMAIN. A COLD VORTEX REMAINED ACROSS SOUTHERN NUNAVUT/NORTHERN HUDSON BAY WITH A LOW MOVING ACROSS QUEBEC. THE SLOW MOVEMENT OF THIS TROUGH WAS IN PART DUE TO HIGH LATITUDE BLOCKING SITUATED OVER THE BERING STRAIT AND NORTH ATLANTIC. A FETCH OF SUBTROPICAL MOISTURE CONTINUED STREAMING TO THE ENE FROM THE EASTERN PACIFIC/MEXICO TO THE BAHAMAS. THE EAST COAST TROUGHING WAS SHOWING INDICATIONS OF FLATTENING OUT...AS UPPER RIDGING OVER THE WESTERN CONUS BUILDS TO THE EAST. SHORT RANGE FORECAST INDICATED THE AREA OF LOW PRESSURE OVER SE CANADA FADING...WITH THE UPPER FLOW BECOMING MORE ZONAL. THE MAIN COLD VORTEX IS FORECAST TO DRIFT SOUTHWARD ACROSS THE HUDSON BAY WHILE WEAKENING SOMEWHAT. THOSE CHANGES...AND A RETURN SOUTHERLY SURFACE FLOW FROM THE SW WILL HELP BOOST HIGH TEMPS RATHER SIGNIFICANTLY THIS AFTERNOON. IN FACT...AM KEEPING HIGHS WARMING INTO THE LOWER 70S MOST SPOTS...A NICE DEPARTURE FROM THE LOW/MID 50S MOST SPOTS HAD ON THU. NORMAL HIGHS TODAY ARE 65 IN HUNTSVILLE...AND 66 AT MUSCLE SHOALS. THOSE READINGS WILL RISE ABOUT A DEGREE JUST IN TIME FOR THE START OF ASTRONOMICAL SPRING...WHICH STARTS AROUND 602 AM CDT ON WED...MAR 20TH. THESE UNSEASONABLY WARM TEMPERATURES WILL CONTINUE INTO EARLY NEXT WEEK. BUT WITH LOTS OF COLD AIR TO OUR NORTH...A RISK OF COLDER CONDITIONS IS NOT OVER WITH YET. WHILE WE BASK IN THIS SHORT RESPITE OF WARMER CONDITIONS...A FRONTAL BOUNDARY TO OUR NORTH WILL APPROACH AND BECOME STATIONARY ACROSS TENNESSEE. MODEL OUTPUT FROM THE 15/0000Z NAM/GFS/ECMWF WAS IN GOOD AGREEMENT KEEPING THIS FRONT ORIENTED IN A WEST-EAST MANNER TO OUR NORTH INTO MONDAY. THE 15/0300Z SREF WAS JUST A TAD FURTHER SOUTH WITH THE FRONT IN CONTRAST TO THE ABOVE NOTED MODELS. HOWEVER...THE PROXIMITY OF THIS BOUNDARY AND INCREASING MOISTURE/INSTABILITY MOVING INLAND FROM THE GULF BRINGS WITH IT A RISK FOR SHOWERS AND SOME THUNDERSTORMS. HAVE KEPT A SIMILAR AREAL COVERAGE...WITH JUST A SLIGHT CHANCE OF CONVECTION BEGINNING OVERNIGHT SATURDAY. WILL DEFER TO A DRIER MODEL TREND...AND LOWER RAIN CHANCES TO A SLIGHT CHANCE FOR SUNDAY. THE FRONT WILL EVENTUALLY MAKE A MOVE TO THE SE DURING MONDAY...WITH A GOOD CHANCE FOR SHOWERS/STORMS. BUFR SOUNDINGS FROM THE GFS MONDAY AFTERNOON/EVENING DOES INCREASE SOME OF THE CONVECTIVE PARAMETERS...THUS CANNOT RULE OUT A STRONG TO MARGINALLY SEVERE STORM OR TWO. WILL MAINTAIN LIKELY PRECIP CHANCES FOR MON AFTERNOON/ EVENING...COINCIDING WITH THE FRONT PASSAGE. SHOWER ACTIVITY SHOULD WIND DOWN MON NIGHT...WITH DRIER AND COOLER CONDITIONS EXPECTED ON TUE. THERE IS STILL PLENTY OF COLD AIR TO OUR NORTH...AND MORE OF IT WILL FILTER ACROSS THIS REGION DURING THE MIDDLE OF THE NEXT WORK WEEK. HIGH TEMPERATURES WILL ONLY WARM INTO MID/UPPER 50S ON TUE...COMPARED TO LOW 70S THE DAY BEFORE. DESPITE SPRING STARTING WED MORNING...IT MAY NOT FEEL LIKE IT. IN FACT... CANNOT RULE OUT A LIGHT FREEZE WITH LOWS IN THE LOWER 30S. HIGHS ON WED SHOULD RECOVER INTO THE LOW 60S...ONLY 3-5 DEGREES BELOW SEASONAL NORMS. UNLIKE THIS PAST WEEK...THIS NEXT COOL SNAP SHOULD BE WEAKER AND SHORTER LIVED...AS HIGHS RECOVER BACK INTO THE MID 60S BY THU/FRI. THERE IS A LOW CONFIDENCE IN THE FORECAST BEYOND MIDWEEK REGARDING RAIN CHANCES...GIVEN VARIOUS SOLUTIONS THE MEDIUM RANGE MODELS ARE DISPLAYING. THE 00Z GFS AND ITS ENSEMBLE WERE DEVELOPING LOW PRESSURE EAST OF THE ROCKIES...WHICH COULD TURN INTO A MAJOR SPRING STORM (BREEZY TO WINDY...WITH SNOW IN ITS COLD SECTOR AND STRONG CONVECTION IN ITS WARMER SECTOR) IN A WEEK OR SO FROM NOW. THE ECMWF WAS WEAKER AND FURTHER NORTH WITH THE FORMATION OF A LEE-SIDE CYCLONE. HOWEVER...BOTH MODELS WERE INDICATIVE OF MORE CLOUDS AND RAIN CHANCES FOR THE LAST FEW DAYS OF THIS FORECAST...WHICH WE WILL KEEP IN THE FORECAST. RSB && .AVIATION... /ISSUED 1220 AM CDT FRI MAR 15 2013/ FOR 06Z TAFS...VFR CONDITIONS ARE EXPECTED TO CONTINUE ACROSS N AL/S MIDDLE TN FOR THE NEXT 24 HOURS, WITH A WIND DIRECTION CHANGE TO SW AND AN INCREASE IN WIND SPEED AFTER 14-15Z. SL.77 && .PRELIMINARY POINT TEMPS/POPS... HUNTSVILLE 73 49 74 51 / 0 0 10 20 SHOALS 74 50 75 51 / 0 0 10 20 VINEMONT 70 48 71 51 / 0 0 10 10 FAYETTEVILLE 70 48 71 49 / 0 0 10 30 ALBERTVILLE 68 47 71 50 / 0 0 10 10 FORT PAYNE 69 45 73 51 / 0 0 10 10 && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE AT WEATHER.GOV/HUNTSVILLE.