000 FXUS64 KBMX 202056 AFDBMX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BIRMINGHAM AL 256 PM CST TUE JAN 20 2009 .DISCUSSION... BIG CHILL CONTINUES ACROSS AREA WITH AFTERNOON TEMPERATURES ABOUT 20 DEGREES BELOW AVERAGE. COMBINATION OF STEEP LAPSE RATES BELOW 5000 FEET AGL AND MINIMAL MOISTURE HAVE PRODUCED JUST ENOUGH LIFT TO PRODUCE CUMULUS CLOUDS AND SNOW FLURRIES. CLOUDS SHOULD DISSIPATE QUICKLY AFTER SUNSET WITH ANOTHER DEEP FREEZE ACROSS AREA TONIGHT. LOWS WILL BE IN THE UPPER TEENS TO LOWER 20S. BRISK NORTH WINDS WILL ALSO DIMINISH AFTER SUNSET. WEAK WARM AIR ADVECTION WILL KICK IN WEDNESDAY AND TEMPERATURES WILL WARM QUICKLY THROUGH THE 20S AND 30S BEFORE LEVELING OFF BY NOONTIME. WEAKER WINDS ON WEDNESDAY WILL ALSO MAKE IT FEEL WARMER. A NICE WARM-UP ON THURSDAY AND FRIDAY AS SOUTHERLY FLOW PREVAILS AHEAD OF NEXT COLD FRONT. GFS SEEMS A LITTLE AGGRESSIVE WITH SOUTHWARD EXTENT OF SHOWERS ON FRIDAY WHILE NAM KEEPS IT MAINLY TO OUR NORTHWEST...AND DECREASED POPS SLIGHTLY OVER SOUTHERN COUNTIES. BETTER RAIN CHANCES COME FRIDAY NIGHT AS FRONT MOVES ACROSS AREA. WITH SURFACE DEWPOINTS IN THE 40S...AIR MASS SHOULD REMAIN STABLE ENOUGH TO KEEP THUNDERSTORMS FROM DEVELOPING. A SIGNIFICANT SHIFT IN THE UPPER LEVEL FLOW ACROSS THE UNITED STATES WILL TAKE PLACE OVER THE WEEKEND AS UPPER TROF DEVELOPS OVER THE WESTERN UNITED STATES AND ZONAL FLOW EAST OF ROCKIES. THIS PATTERN SHIFT WILL BRING MUCH WARMER TEMPERATURES TO THE GULF COAST REGION. 12Z GFS MODEL RUN STALLING OUT FRONT SOONER AND DEVELOPS A SURFACE WAVE ON THE FRONT SATURDAY NIGHT. THIS IS NOT SUPPORTED BY 12Z ECMWF OR 00Z DGEX AND WILL CONTINUE WITH DRY FORECAST SATURDAY NIGHT AND SUNDAY. SURFACE FRONT WILL EVENTUALLY PULL BACK NORTHWARD AS A WARM FRONT AND SET UP A NICE BAROCLINIC ZONE ACROSS TENNESSEE MONDAY AND TUESDAY. BEST RAIN CHANCES WILL BE ACROSS AREAS NORTH OF I-20 MONDAY AND TUESDAY. 58/ROSE && .AVIATION...18Z TAF DISCUSSION. GUSTY WINDS WILL BE THE MAIN PROBLEM THIS AFTERNOON. HOWEVER...THEY ARE EXPECTED TO SLOWLY SUBSIDE SHORTLY AFTER SUNSET. ALSO...SOME LOCATIONS COULD BRIEFLY SEE SOME BKN OR OVC SKIES...BUT THEY THEY SHOULD REMAIN AROUND 4000 FEET. 10/ARM && .FIRE WEATHER... AFTERNOON RELATIVE HUMIDITIES WILL DIP TO 25 PERCENT OR LESS WEDNESDAY AFTERNOON BUT WILL NOT LIKELY MEET THE 4 HOUR DURATION CRITERIA NECESSARY FOR A RED FLAG WARNING. && .PRELIMINARY POINT TEMPS/POPS... GADSDEN 17 45 20 56 33 / 0 0 0 0 0 ANNISTON 20 47 24 58 35 / 0 0 0 0 0 BIRMINGHAM 21 48 27 58 43 / 0 0 0 0 0 TUSCALOOSA 21 49 25 60 42 / 0 0 0 0 0 CALERA 23 48 27 59 39 / 0 0 0 0 0 AUBURN 20 48 24 56 40 / 0 0 0 0 0 MONTGOMERY 21 50 26 61 37 / 0 0 0 0 0 TROY 18 50 23 61 37 / 0 0 0 0 0 && .BMX WATCHES/WARNINGS/ADVISORIES...LAKE WIND ADVISORY UNTIL 6 PM TODAY. && $$