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000
FXUS64 KBMX 150211
AFDBMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BIRMINGHAM AL
911 PM CDT TUE MAY 14 2013

.UPDATE...
FOR THIS EVENING`S WEATHER.

&&

.DISCUSSION...

CRYSTAL CLEAR SKIES ARE PRESENT ACROSS ALL OF CENTRAL ALABAMA THIS
EVENING...WITH TEMPERATURES NOTICEABLY WARMER THAN THEY WERE AT
THIS TIME YESTERDAY. THE KBMX 00Z RAOB ALSO INDICATED MOISTURE
LEVELS ARE A BIT HIGHER AS WELL...WITH PWATS AROUND 0.70 INCHES.
SOUTHWESTERLY TO SOUTHERLY SURFACE FLOW WILL CONTINUE OVER THE
NEXT SEVERAL DAYS THAT WILL HELP TO INCREASE MOISTURE GRADUALLY
ACROSS THE SOUTHEAST. THE FORECAST TONIGHT LOOKS TO BE IN PRETTY
GOOD SHAPE...AND ONLY MINOR ADJUSTMENTS TO OVERNIGHT LOW
TEMPERATURES AND DEWPOINTS WERE MADE. UPDATES ARE ALREADY OUT.

56/GDG

&&

.AVIATION...
00Z TAF DISCUSSION.

VFR THROUGH THE PERIOD. WINDS CALM DOWN ONCE AGAIN OVER THE NEXT
FEW HOURS AND PICK BACK UP AFTER 15Z ON WEDNESDAY. MAY SEE SOME
MORE IN SCATTERED HIGH CLOUDS ACROSS THE SOUTH...BUT NO IMPACTS
EXPECTED.

NOTE: THERE IS A VISIBILITY ISSUE WITH KEET THIS AFTERNOON.
LOOKING OUT THE WINDOW...THERE IS ZERO RESTRICTIONS. WILL INCLUDE
AMD LTD TO CLD...WIND AND WX THROUGH 0515/18Z. SHOULD BE RESOLVED
BY THAT TIME AS THE EQUIPMENT IS STILL WORKING.

16


&&

.PREV DISCUSSION...
/ISSUED 257 PM CDT TUE MAY 14 2013/

THIS AFTERNOON THE SENSIBLE WEATHER ACROSS THE SOUTHEAST WAS BEING
DOMINATED BY AN EXPANSIVE AREA OF HIGH PRESSURE AT THE SURFACE
CENTERED OVER LOUISIANA... SOUTHERN MISSISSIPPI AND ALABAMA...  AND
GEORGIA. ALOFT AN AREA OF SUBSIDENCE IN THE FORM AN APPROACHING
UPPER RIDGE WAS SUPPRESSING CLOUD DEVELOPMENT ACROSS MOST OF THE
REGION. OVER NORTHWESTERN MEXICO A CLOSED UPPER LOW WAS NEARLY
STATIONARY PER LATEST WATER VAPOR SATELLITE IMAGERY.

OVERALL... NOT MANY CHANGES NEEDED TO THE FORECAST PACKAGE. THE UPPER
RIDGE NOTED ABOVE WILL BECOME CENTERED OVER THE SOUTHEAST TOMORROW...
WHICH WILL HELP WARM TEMPERATURES A DEGREE OR TWO ABOVE HIGH TEMPS
FOR TODAY. BY THURSDAY THE CLOSED LOW MENTIONED ABOVE WILL HAVE
EJECTED FROM THE SOUTHWEST CONUS... AND WILL BE ADVANCING AS A
SHORTWAVE TROUGH OVER THE SOUTHEAST. WITH SOME LOW LEVEL MOISTURE IN
PLACE COMBINED WITH THE WEAK SHORTWAVE TROUGH... ISOLATED TO
SCATTERED SHOWERS AND THUNDERSTORMS APPEAR POSSIBLE THURSDAY AND
FRIDAY. BUT WITH THE LACK OF AN OBVIOUS LOW LEVEL FORCING
MECHANISM... HAVE MAINTAINED ONLY 20-30 PERCENT POPS FOR THIS TIME
FRAME. FOR TEMPS THURSDAY AND FRIDAY HAVE KEPT THEM LOWER THEN MOS
GUIDANCE DUE TO THE EXPECTED CLOUD COVER AND PRECIP.

THIS WEEKEND THE 12Z GFS KEEPS CENTRAL ALABAMA PRETTY MUCH DRY
WITH ANOTHER SHORTWAVE RIDGE MOVING OVER THE REGION. BUT THE 12Z
ECMWF SHOWS SOME LIGHT PRECIP IN THE AREA FOR BOTH SATURDAY AND
SUNDAY. THIS APPEARS TO BE DUE A SLIGHT DIFFERENCE IN HOW EACH
MODEL HANDLES A SUBTLE WEAKNESS (SHORTWAVE TROUGH/VORTICITY
MAXIMUM) THAT IS FORECAST TO ROUND THE TOP OF THE RIDGE THAT WILL
BE OVER US. THE GFS KEEPS THIS FEATURE A BIT FURTHER NORTH THAN
THE ECMWF... AND DUE TO THE UNCERTAINTY WITH THE LOCATION OF THIS
FEATURE 4-5 DAYS OUT AND FOR THE SAKE OF CONTINUITY WITH THE
PREVIOUS FORECAST... WILL NOT MENTION ANY POPS FOR THIS WEEKEND.
BUT IF THE ECMWF IS CORRECT... THEN SOME SLIGHT CHANCE TO CHANCE
POPS MAY BE NEEDED BOTH SATURDAY AND SUNDAY AFTERNOON. REGARDLESS
OF WHICH SOLUTION VERIFIES... TEMPS FOR THIS WEEKEND LOOK WARM...
GENERALLY IN THE MID TO UPPER 80S.

NEAR THE END OF THE CURRENT FORECAST PERIOD... NEXT MONDAY AND
TUESDAY... A LONGWAVE TROUGH WILL BE ADVANCING OUT OF THE GREAT
PLAINS AND INTO THE OHIO VALLEY. THERE ARE SOME LARGE DISCREPANCIES
BETWEEN THE GFS AND ECMWF IN THE HANDLING OF THE SYNOPTIC SCALE
FEATURES FOR THIS SYSTEM THIS FAR OUT... BUT IT DOES APPEAR THAT A
COLD FRONT WILL BE APPROACHING THE REGION FROM THE NORTHWEST
SOMETIME AROUND NEXT TUESDAY AFTERNOON/EVENING.

77/GLEASON

&&

.PRELIMINARY POINT TEMPS/POPS...
GADSDEN     51  83  57  80  57 /   0   0  10  30  20
ANNISTON    55  83  60  82  59 /   0   0  10  30  20
BIRMINGHAM  60  83  63  81  62 /   0   0  10  30  20
TUSCALOOSA  57  85  62  83  62 /   0   0  10  30  20
CALERA      57  83  61  81  61 /   0   0  10  30  20
AUBURN      58  84  65  81  63 /   0   0  10  20  20
MONTGOMERY  57  86  62  84  62 /   0   0  10  20  20
TROY        52  85  59  83  61 /   0   0  10  20  20

&&

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

&&

$$