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