000
FXUS64 KBMX 160839
AFDBMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BIRMINGHAM AL
339 AM CDT THU MAY 16 2013

.DISCUSSION...

SKIES ARE MOSTLY CLOUDY THIS MORNING WITH HIGH CLOUDS ACROSS THE
AREA AHEAD OF AN APPROACHING SHORTWAVE TROUGH. TEMPERATURES AT 3 AM
ARE STILL IN THE MID 60S THANKS TO THE WIDESPREAD CLOUD COVER.
CURRENT WATER VAPOR IMAGERY INDICATES A CLOSED LOW OVER EASTERN
OKLAHOMA WITH ANOTHER WEAK SHORTWAVE TROUGH ACROSS WESTERN COLORADO.
THESE TWO FEATURES WILL BE THE MAIN WEATHER MAKERS DURING THE
FORECAST PERIOD. AT THE SURFACE...SURFACE HIGH PRESSURE REMAINS
ENTRENCHED ACROSS THE EASTERN GULF WITH A SURFACE LOW BACK FURTHER
WEST ACROSS CENTRAL TEXAS. THE 00Z BMX SOUNDING FROM EARLIER THIS
EVEN INDICATES RATHER DRY AIR IN THE MID-LEVELS AND IT WILL TAKE
SOME TIME FOR THIS LAYER TO SATURATE OVER THE NEXT COUPLE OF DAYS.

SKIES WILL BE MOSTLY CLOUDY WITH MID TO HIGH CLOUDS EXPECTED TO
CONTINUE AHEAD OF THE APPROACHING TROUGH. THE TROUGH SHOULD
TRANSITION TO MORE OF AN OPEN WAVE AND WEAKEN. MODELS CONTINUE TO
SHOW A RELATIVE MINIMUM IN PW VALUES TODAY ACROSS CENTRAL ALABAMA
WITH PW VALUES BELOW 1 INCH. OBSERVATIONS CURRENTLY ACROSS SOUTHERN
PORTIONS OF THE FORECAST AREA INDICATE DEWPOINTS IN THE LOW TO MID
50S AND THIS IS THE DRIER AIR THE MODELS ARE PICKING UP ON. MODEL
SOUNDINGS INDICATE A RATHER SUBSTANTIAL CAP IN PLACE ACROSS THE
STATE TODAY AND THIS SHOULD ALSO HELP LIMIT ANY PRECIPITATION. THE
CAP IS THE WEAKEST ACROSS WESTERN ALABAMA AND AN ISOLATED AFTERNOON
THUNDERSTORM WILL BE POSSIBLE. WIDESPREAD CLOUD COVER AND DECREASING
HEIGHTS SHOULD KEEP TEMPERATURES A FEW DEGREES COOLER THAN YESTERDAY
AND HAVE GONE BELOW GUIDANCE BY A COUPLE OF DEGREES FOR HIGH
TEMPERATURES THIS AFTERNOON. TONIGHT SHOWERS WILL BE POSSIBLE ACROSS
THE NORTHERN THIRD OF THE FORECAST AREA AS PW VALUES INCREASE. MODEL
INDICATE A SURGE OF LOW LEVEL MOISTURE ACROSS THE SOUTH AND THERE
COULD BE SOME PATCHY FOG ACROSS THE SOUTHERN THIRD OF THE FORECAST
AREA LATE TONIGHT INTO EARLY FRIDAY MORNING.

FRIDAY...SHOWERS AND THUNDERSTORMS SHOULD BECOME MORE WIDESPREAD AS
THE UPPER LEVEL TROUGH MOVES ACROSS THE MISSISSIPPI RIVER. A CAP
DURING THE MORNING SHOULD KEEP CONDITIONS MOSTLY DRY THROUGH THE
MORNING HOURS. CONVECTIVE TEMPERATURES WILL BE IN THE LOW TO MID 80S
AND THESE TEMPERATURE SHOULD BE REACHED BY MID-AFTERNOON. AGAIN
THE CAP WILL BE THE WEAKEST OVER WESTERN PORTIONS OF THE STATE. THE
GFS IS SHOWING SBCAPE VALUES IN EXCESS OF 2000 J/KG ACROSS EXTREME
WESTERN PORTIONS OF CENTRAL ALABAMA. THE UPPER LEVEL WAVE IS RATHER
WEAK AND THE 0-6 KM BULK SHEAR IS AROUND 30 KTS.
ADDITIONALLY...THERE IS NO SURFACE FEATURE TO LIFT PARCELS TO THEIR
LFC. THEREFORE...EXPECT SHOWERS AND THUNDERSTORMS WILL BE SCATTERED
IN NATURE. DUE TO THE INSTABILITY A COUPLE OF STRONG STORMS WILL BE
POSSIBLE FRIDAY AFTERNOON AND EVENING ACROSS WESTERN ALABAMA AND
COULD PRODUCE GUSTY WINDS. PW VALUES WILL INCREASE TO NEAR 1.75
INCHES FRIDAY NIGHT AND INTO SATURDAY MORNING AS THE TROUGH MOVES
OVERHEAD. EXPECT SHOWERS AND THUNDERSTORMS WILL CONTINUE INTO THE
OVERNIGHT WITH MID-LEVEL LAPSE RATES STEEPENING SLIGHTLY AS THE WAVE
MOVES ACROSS THE AREA.

SATURDAY THE BEST CHANCE FOR SHOWERS AND THUNDERSTORMS WILL BE OVER
NORTHEASTERN PORTIONS OF CENTRAL ALABAMA AS THE SHORTWAVE
TRANSITIONS ACROSS THE STATE. THE FORCING WILL BE EXITING DURING THE
DAY ON SATURDAY BUT THE MOISTURE AND INSTABILITY REMAIN RATHER
IMPRESSIVE. PW VALUES OF OVER 1.5 INCHES WILL CONTINUE WITH SBCAPE
VALUES OVER 1500 J/KG ACCORDING TO THE GFS. THE SHEAR WILL BE EVEN
LESS IMPRESSIVE WITH 0-6 KM BULK SHEAR AROUND 20 KTS. THEREFORE...A
BRIEF STRONG STORM OR TWO WILL BE POSSIBLE GENERALLY ACROSS
NORTHEASTERN PORTIONS OF THE FORECAST AREA. MODELS INDICATE THAT
ANOTHER WEAK SHORTWAVE WILL MOVE THROUGH THE NORTHWESTERLY FLOW ON
SUNDAY WITH CHANCES FOR SHOWERS AND THUNDERSTORMS CONTINUING ACROSS
NORTHEASTERN ALABAMA INTO THE DAY SUNDAY.

THE RIDGE WILL AMPLIFY EARLY IN THE WEEK WITH RAIN CHANCES COMING TO
AN END ON MONDAY. WITH UPPER LEVEL HEIGHTS INCREASING AND MOSTLY
SUNNY SKIES...HIGH TEMPERATURES ON MONDAY WILL PUSH UP INTO THE MID
TO UPPER 80S TO NEAR 90. RAIN CHANCES WILL RETURN TO THE FORECAST BY
THE MIDDLE OF THE WEEK AS MOISTURE INCREASES AHEAD OF THE NEXT
APPROACHING TROUGH.

05/MA

&&

.AVIATION...
06Z TAF DISCUSSION.

VFR CONDS EXPECTED THRU THE PERIOD. BKN-OVC CIRRUS WILL PREVAIL
ACROSS ALL OF ALABAMA THRU 12Z AS A SHORT WAVE TROF OVER THE
SOUTHERN PLAINS STATES ADVANCES EASTWARD. FEW TO SCT CUMULUS CLOUDS
MAY DEVELOP AFTER 17Z AS LOW LEVEL MOISTURE INCREASES IN SOUTHERLY
FLOW.

58/ROSE


&&

.PRELIMINARY POINT TEMPS/POPS...
GADSDEN     83  59  81  61  80 /  10  20  40  40  50
ANNISTON    82  61  81  62  81 /  10  20  30  30  50
BIRMINGHAM  83  65  81  67  83 /  10  20  30  40  40
TUSCALOOSA  83  66  82  68  84 /  10  20  40  20  20
CALERA      82  63  81  65  82 /  10  20  30  20  30
AUBURN      82  63  82  66  83 /  10  10  20  20  30
MONTGOMERY  85  62  84  65  87 /  10  10  20  20  20
TROY        83  61  84  64  87 /  10  10  20  20  20

&&

.BMX WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$