721 FXUS64 KBMX 182357 AFDBMX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BIRMINGHAM AL 557 PM CST MON FEB 18 2013 .UPDATE... FOR 00Z AVIATION. && .DISCUSSION... STRONG SOUTHERLY WINDS WILL CONTINUE TO ADVECT MOISTURE IN FROM THE GULF OF MEXICO TONIGHT. DEW POINTS IN MISSISSIPPI AND LOCATIONS FARTHER WEST ARE ALREADY IN THE 40S AND LOWER 50S. WITH WINDS EXPECTED TO STAY UP OVERNIGHT AND CONTINUED MOIST AIR ADVECTION... TEMPERATURES WILL BE MUCH WARMER THAN LAST NIGHT... 40S AND 50S VERSUS 20S AND 30S. SO FAR TODAY WINDS HAVE REMAINED BELOW WIND ADVISORY CRITERIA... AND EVEN WITH THE TIGHT PRESSURE GRADIENT EXPECTED TO MOVE OVER CENTRAL ALABAMA TONIGHT AS THE SURFACE COLD FRONT APPROACHES FROM THE WEST... IT STILL APPEARS THAT WE WILL PROBABLY REMAIN JUST BELOW WIND ADVISORY CRITERIA FOR OUR NORTHERN TIER OF COUNTIES. SHOWERS AND THUNDERSTORMS HAVE FORMED ALONG AND AHEAD OF THE SURFACE COLD FRONT THIS AFTERNOON ACROSS ARKANSAS... LOUISIANA... AND EASTERN TEXAS. EXPECT A PRETTY DECENT SOAKING FOR US OVERNIGHT AS THE FRONT PUSHES THROUGH CENTRAL ALABAMA. WITH THE MAIN UPPER TROUGH REMAINING TO OUR NORTH AND SURFACE DEW POINTS STRUGGLING TO GET INTO THE LOWER 50S IN CENTRAL ALABAMA AHEAD OF THE COLD FRONT... NOT EXPECTING ANY SEVERE WEATHER WITH THE FRONT TONIGHT. BUT... THERE COULD BE SOME EMBEDDED THUNDERSTORMS ALONG THE FRONT... MAINLY BEFORE MIDNIGHT. EXPECT ALMOST ALL RAIN ACTIVITY TO BE DONE BY NOON TUESDAY AS THE UPPER TROUGH USHERING THE SURFACE FRONT THROUGH THE SOUTHEAST REMAINS PROGRESSIVE AND MOVES OVER THE NORTHEAST CONUS. MUCH DRIER AIR WILL FILTER INTO THE STATE BEHIND THE FRONT WEDNESDAY... WHICH COULD LEAD TO SOME FIRE WEATHER CONCERNS WEDNESDAY AFTERNOON. FOR MORE DETAILS... SEE THE FIRE WEATHER SECTION BELOW. THE BREAK FROM THE RAIN WILL BE SHORT-LIVED HOWEVER... AS PROGRESSIVE FLOW ALOFT BRINGS MULTIPLE SHORTWAVE TROUGHS THROUGH THE BASE OF A LONGWAVE TROUGH FORECAST TO SET UP OVER THE WESTERN HALF OF THE CONUS. RAIN CHANCES WILL INCREASE QUICKLY THURSDAY AFTERNOON AND EVENING AS MOISTURE RETURNS FROM THE GULF OF MEXICO... AND WILL CONTINUE THROUGH AT LEAST SATURDAY AFTERNOON FOR MOST OF CENTRAL ALABAMA... AND POSSIBLY LONGER THAN THAT. A COLD FRONT IS FORECAST TO ENTER THE REGION FRIDAY... AND THEN STALL OVER THE AREA UNTIL IT IS PUSHED OUT LATER IN THE WEEKEND. STAYED AWAY FROM MOS DEW POINTS IN THE EXTENDED AS THEY WILL MOST LIKELY BE FAR TOO LOW BASED OFF THE FORECAST MOISTURE RETURN SUGGESTED BY BOTH THE GFS AND ECMWF. STRUGGLED TO FIND A SUFFICIENT COMBINATION OF FORECAST INSTABILITY AND WIND SHEAR TO SUPPORT SEVERE STORMS DURING THIS WET TIME FRAME. THERE WILL CERTAINLY BE THUNDERSTORMS WITH DEW POINTS EXPECTED TO REACH INTO THE UPPER 50S AND LOWER 60S FRIDAY AND SATURDAY. THE BEST CHANCE FOR STRONG TO POSSIBLY SEVERE STORMS LOOKS TO BE FRIDAY AFTERNOON INTO SATURDAY MORNING SOUTH OF THE COLD FRONT. THERE IS ABOUT 50 KTS OF 0-6 KM BULK SHEAR ALONG WITH SOME SBCAPE IN THE AREA. WITH THAT SAID... THERE IS NO SHORTWAVE TROUGH IN THE VICINITY TO HELP ENHANCE UPWARD MOTION... 0-1 KM SHEAR IS RATHER WEAK...AND EXPECT WIDESPREAD CLOUDINESS FROM ONGOING SHOWERS AND STORMS TO LIMIT SURFACE HEATING ALONG THE FRONT AS IT ENTERS CENTRAL ALABAMA FRIDAY. BASICALLY... THE OVERALL SETUP SIMPLY LOOKS TOO MARGINAL TO INCLUDE ANY MENTION OF SEVERE WEATHER IN THE HAZARDOUS WEATHER OUTLOOK FOR NOW. THERE COULD BE SOME FLOODING CONCERNS ACROSS PORTIONS OF CENTRAL ALABAMA GIVEN THE SOUTHWESTERLY FLOW ALOFT RUNNING PARALLEL TO THE SURFACE COLD FRONT. BUT ANY AREAS OF POSSIBLE FLOODING WILL NOT BE ABLE TO BE DETERMINED UNTIL WE GET LATER IN THE WEEK AND HAVE HIGHER CONFIDENCE ON WHERE THESE POSSIBLE MULTIPLE BANDS OF HEAVY RAIN WILL SET UP. THANKFULLY WE HAVE A WHILE YET TO LOOK AT THIS LATE WEEK SYSTEM. BY LATE IN THE WEEKEND BOTH THE GFS AND ECMWF ARE SUGGESTING THAT RAIN CHANCES WILL BE DECREASING AS AN UPPER TROUGH FINALLY PUSHES THE SURFACE COLD FRONT SOUTH OF THE AREA. BUT BY SUNDAY EVENING... YOU GUESSED IT... RAIN CHANCES LOOK TO RETURN AS YET ANOTHER UPPER LEVEL TROUGH DIGS INTO THE SOUTHERN PLAINS AND HELPS BRING MOISTURE INTO THE SOUTHEAST AHEAD OF IT. THE GFS AND ECMWF DIFFER ON HOW MUCH MOISTURE TO RETURN AHEAD OF AND THE STRENGTH OF THIS FINAL SYSTEM FOR THE FORECAST PERIOD. SO WILL MAINTAIN CHANCE POPS FROM SUNDAY NIGHT INTO NEXT MONDAY UNTIL THE MODELS CONVERGE ON A SOLUTION OF THE SYNOPTIC SCALE UPPER PATTERN. ALSO... FAR TOO SOON TO DETERMINE ANY POSSIBILITY OF SEVERE WEATHER WITH THIS SYSTEM GIVEN MODEL DIFFERENCES. 77/GLEASON && .AVIATION... 00Z TAF DISCUSSION. VFR CONDITIONS WILL SLOWLY DROP TO MVFR THRU THE NIGHT THANKS TO INCREASING MOISTURE AND ISENTROPIC LIFT AHEAD OF THE FRONT. RAIN SHOWERS...AND PERHAPS A FEW EMBEDDED TSTORMS...WILL SPREAD FROM W/NW TO E/SE ACROSS THE FORECAST AREA LATE THIS EVENING AND OVERNIGHT AS THE FRONT APPROACHES. BRIEF IFR VIS ARE POSSIBLE IN ANY HEAVIER SHOWERS. THE FRONT WILL BE QUICK TO EXIT THE AREA...WITH RAIN ENDING AND SKIES CLEARING BEGINNING SHORTLY AFTER 12Z IN THE WEST THRU 18Z OR SO IN THE EAST. BREEZY SE WINDS WILL CONTINUE AHEAD OF THE FRONT WITH SUSTAINED WINDS OF GENERALLY 12-17 KTS AND GUSTS UP TO 25 KTS. SEEING A FEW OBSERVATIONS TO OUR WEST ACROSS PARTS OF MS WHICH ARE INDICATING GUSTS UPWARDS OF 30-35 KTS. WILL MONITOR TRENDS CLOSELY AS THE SYSTEM MOVES CLOSER TO SEE IF HIGHER GUSTS ARE WARRANTED FOR OUR AREA. HAVE DECIDED TO GO AHEAD AND INCLUDE WS FOR MOST OF THE NORTHERN SITES LATER THIS EVENING AS A STRONG SOUTHWESTERLY LOW-LEVEL JET OF APPROXIMATELY 45-50 KTS PASSES OVERHEAD. WINDS WILL QUICKLY SHIFT TO THE WNW BEHIND THE FRONT. 19 && .FIRE WEATHER... A COLD FRONT WILL SWEEP THROUGH CENTRAL ALABAMA TUESDAY AFTERNOON USHERING IN A VERY DRY AIRMASS FROM THE NORTHWEST. RELATIVE HUMIDITIES ARE EXPECTED TO DROP UNDER 25 PERCENT BY WEDNESDAY AFTERNOON FOR MULTIPLE HOURS ACROSS ALL OF CENTRAL ALABAMA. THEREFORE...OUTDOOR BURNING WILL BE HIGHLY DISCOURAGED DURING THIS TIME. 56/GDG && .PRELIMINARY POINT TEMPS/POPS... GADSDEN 42 54 26 51 29 / 100 50 0 10 10 ANNISTON 43 56 27 52 31 / 100 60 0 10 10 BIRMINGHAM 46 55 30 51 33 / 100 30 0 10 10 TUSCALOOSA 48 58 30 54 35 / 100 20 0 10 10 CALERA 47 57 30 52 33 / 100 40 0 10 10 AUBURN 44 58 30 55 34 / 80 90 0 10 10 MONTGOMERY 47 61 31 57 35 / 100 70 0 10 10 TROY 46 62 31 57 37 / 90 100 0 10 10 && .BMX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 77/19/56