078 FXUS64 KHUN 200858 AFDHUN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HUNTSVILLE AL 358 AM CDT WED MAR 20 2013 .DISCUSSION... QUIET AND CALM CONDITIONS ACROSS THE TENNESSEE VALLEY THIS MORNING GIVE NO HINT ABOUT THE ACTIVE WEATHER EXPECTED OVER THE NEXT WEEK. UNDER A DECK OF HIGH LEVEL CLOUDS...TEMPERATURES ACROSS THE CWA HAVE DROPPED INTO THE LOWER 40S/UPPER 30S THIS MORNING. FURTHER TO OUR NORTHWEST...A MASS OF MUCH COLDER AIR IS POISED OVER THE CENTRAL/NORTHERN PLAINS AND WILL DIVE TOWARD THE SOUTHEAST TODAY. THE LEADING EDGE OF THE COLD AIR WILL BE A WEAK FRONT...NOT IN TERMS OF THE COLD TEMPERATURES IT WILL BRING BUT RATHER IN TERMS OF PRECIP. MOISTURE AND LIFT REMAIN LIMITED WITH THIS FRONT...BUT AM STILL ANTICIPATING OUR TERRAIN TO HELP FORCE AT LEAST A LITTLE LIGHT PRECIP OVER OUR FAR NE COUNTIES LATE THIS AFTERNOON. OTHERWISE THE FRONT WILL BRING A PERIOD OF GREATER MID LEVEL CLOUD COVER...INCREASING SFC WINDS AND STRONGER COLD ADVECTION. THIS COLD ADVECTION WILL LEAD TO A SIGNIFICANT DROP IN TEMPS OVERNIGHT...WITH LOWS EXPECTED TO FALL INTO THE MID 20S ACROSS THE CWA. WHILE OUR FREEZE WARNING PROGRAM DOES NOT OFFICIALLY BEGIN UNTIL APRIL 1ST (DUE TO DATES OF OUR AVERAGE LAST FREEZE)...WE WILL LIKELY ISSUE A PNS TO HIGHLIGHT THESE ESPECIALLY COLD TEMPERATURES CONSIDERING THAT VEGETATION AROUND THE CWA HAS RECENTLY STARTED TO BLOOM. THE COLD ADVECTION WILL CONTINUE INTO TOMORROW AND INCREASING CLOUD COVER AHEAD OF OUR NEXT SYSTEM SHOULD HELP HOLD DOWN DAYTIME TEMPS ON THURSDAY. THESE COLD TEMPS COULD SET THE STAGE FOR SOME INTERESTING WEATHER ON THURSDAY NIGHT. OUR NEXT ROUND OF PRECIP WILL ARRIVE LATER ON THURSDAY...COMBATING SOME VERY DRY AIR. WITH AFTERNOON/EVENING DEWPOINT VALUES FALLING INTO THE TEENS...SFC WETBULB TEMPERATURES WILL BE BELOW FREEZING OVERNIGHT. AS A SHORTWAVE PASSES ACROSS THE REGION IN THE STRONG NW FLOW...BROAD ISENTROPIC LIFT WILL ACCOMPANY A SURGE OF MID LEVEL MOISTURE. THERMAL PROFILES FROM THE ECMWF AND NAM INDICATE A STRONG POTENTIAL FOR SNOW/SLEET MIX DURING THE OVERNIGHT HOURS...WHILE THE GFS REMAINS BULLISHLY WARMER. THINGS THAT WILL WORK IN FAVOR FOR WINTRY PRECIP ACCUMULATION ACROSS THE CWA INCLUDE...TIMING OF THE HEAVIEST PRECIP BEING BTWN 06-12Z (THE COOLEST PART OF THE DAY) AND OUR SHOT OF COLD AIR FOR THURSDAY LOWERING GROUND SFC TEMPS. BUT WE COULD MISS OUT IF WARM ADVECTION WINS OVER (AS INDICATED IN THE GFS) AND IF DRY AIR HOLDS ON LONG ENOUGH TO REDUCE PRECIP RATES. ATTM HAVE HELD WITH THE ECWMF/NAM SOLN IN LEAVING OUT ANY MENTION OF LIQUID PRECIP OVERNIGHT...BUT HAVE TAILORED BACK ON THE ACCUMULATIONS TO START AFTER MIDNIGHT AND TO BE AROUND ONE HALF INCH. ANTICIPATE FURTHER REFINEMENTS IN THIS FORECAST OVER THE NEXT 24-36 HOURS. THE GOOD NEWS IS THAT TEMPERATURES SHOULD WARM ENOUGH BY LATE MORNING/EARLY AFTERNOON ACROSS THE CWA TO CONVERT ALL PRECIP BACK TO LIQUID. WE SHOULD THEN SEE OFF AND ON PRECIP THROUGH SUNDAY. ANOTHER MID LEVEL SYSTEM THAT DEEPENS OFF THE LEE OF THE ROCKIES OVER THE WEEKEND COULD EVEN BRING ANOTHER ROUND OF THUNDERSTORMS TO THE SOUTHEAST. DISCREPANCIES BTWN THE ECMWF AND GFS REMAIN IN THE PLACEMENT OF THIS NEXT SYSTEM...WITH THE GFS DEVELOPING A STRONGER SFC LOW FURTHER TO OUR NORTHWEST...INCREASING OUR WARM ADVECTION. ON THE OTHER HAND...THE ECWMF TRACKS A LITTLE WEAKER AND FURTHER SOUTH. EITHER WAY...THIS SYSTEM WILL NEED TO BE WATCHED FOR THE POTENTIAL OF ANY DEEPER CONVECTION DRAWING STRONGER WINDS DOWN TO THE SFC. BELOW SEASONABLE TEMPERATURES CAN THEN BE EXPECTED TO CONTINUE BEHIND THIS SYSTEM INTO THE MIDDLE OF NEXT WEEK WITH A STRONG TROF ALONG THE EASTERN SEABOARD AND STRONG RIDGING OFF THE WEST COAST DOMINATING THE CONUS PATTERN. CCC && .AVIATION... /ISSUED 1152 PM CDT TUE MAR 19 2013/ FOR 06Z TAFS...HIGH PRESSURE BUILDING ACROSS THE AREA WILL KEEP VFR CONDITIONS THRU THE FCST PERIOD. 07 && .PRELIMINARY POINT TEMPS/POPS... HUNTSVILLE 60 25 47 34 / 0 0 10 60 SHOALS 61 25 48 34 / 0 0 20 70 VINEMONT 57 24 44 33 / 0 0 10 60 FAYETTEVILLE 56 23 43 32 / 20 10 0 60 ALBERTVILLE 59 25 44 33 / 0 0 0 60 FORT PAYNE 57 23 47 32 / 10 0 0 60 && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE AT WEATHER.GOV/HUNTSVILLE.