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000
FXUS64 KBMX 211101
AFDBMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BIRMINGHAM AL
440 AM CDT TUE MAY 21 2013

.DISCUSSION...

THE FORECAST REMAINS LARGELY UNCHANGED OVER THE NEXT 7 DAYS. UPPER
TROUGHING CONTINUES TO DOMINATE ACROSS THE CENTRAL US THIS MORNING.
LATEST WV SATELLITE IMAGERY SHOWS A LARGE UPPER LOW SPINNING OVER
THE DAKOTAS WITH A SHORTWAVE ROTATING EASTWARD THRU THE FOUR CORNERS
REGION. A LINE OF WEAKENING SHOWERS AND TSTORMS WAS ONGOING FROM
INDIANA SOUTHWESTWARD INTO THE MID MISSISSIPPI RIVER VALLEY...WHICH
IS IN ASSOCIATION WITH WHAT APPEARS TO BE A PREFRONTAL TROF WELL
AHEAD OF THE ACTUAL SFC FRONT. MEANWHILE UPPER RIDGING REMAINS IN
PLACE ACROSS THE CENTRAL GULF COAST STATES. STRATUS DECK CAN BE SEEN
SPREADING NORTHWARD ACROSS MS AND SOUTHERN AL AT THIS HOUR AND WILL
LIKELY PUSH INTO THE SOUTH AND WESTERN PORTIONS OF CENTRAL ALABAMA
OVER THE NEXT COUPLE OF HOURS. THE UPPER RIDGING WILL KEEP CENTRAL
ALABAMA DRY AGAIN TODAY WITH AFTERNOON HIGHS WARMING INTO THE UPPER
80S AND LOWER 90S.

SFC FRONT CURRENTLY IN THE CENTRAL PLAINS WILL SLOWLY PROGRESS
EASTWARD TODAY BEFORE STALLING WEST OF THE MS RIVER AS IT LOSES ITS
UPPER LEVEL PUSH. THE FOUR CORNERS SHORTWAVE WILL EVENTUALLY PICK UP
THE FRONTAL BOUNDARY TONIGHT AND BRING IT THRU THE FORECAST AREA ON
WED INTO WED NIGHT. THE SYSTEM SHOULD WEAKEN AS IT APPROACHES THE
CWA DUE TO LACK OF UPPER/LOWER JET FEATURES...RATHER WEAK LOW LEVEL
SHEAR AND MID LEVEL LAPSE RATES...AS WELL AS A LACK OF DRY AIR IN
THE MID LEVELS. THEREFORE STILL DO NOT EXPECT ANYTHING IN THE WAY OF
SEVERE WEATHER ACROSS OUR AREA. HAVE KEPT POPS THE HIGHEST AND TEMPS
A BIT LOWER IN THE NW.

INITIAL BOUNDARY MAY STILL BE LOCATED ACROSS THE SOUTHERN PART OF
THE STATE BY THURSDAY WHICH COULD LEAD TO SOME ADDITIONAL ISO/SCT
ACTIVITY. BEST CHANCES WILL BE THE SOUTH. THE MAIN UPPER TROF
FINALLY PUSHES THRU THURSDAY AFTN/EVNG BRINGING ANOTHER WEAK
BOUNDARY THRU THE CWA. MODELS AREN`T SHOWING ANY REAL QPF WITH THIS
FEATURE AS IT COMES THRU...SO POPS MAY BE A BIT OVERDONE FOR
THURSDAY IF THE FIRST BOUNDARY MANAGES TO PUSH SOUTH OF THE FORECAST
AREA.

SFC HIGH PRESSURE BUILDS IN FROM THE NORTH ON FRIDAY BRINGING A MUCH
DRIER AIR MASS INTO THE REGION. HIGHS WILL BE NEAR NORMAL WITH LOWS
IN THE 50S FRI NIGHT AND WARMING BACK INTO THE LOW 60S BY SUN NIGHT.
MODELS DIVERGE A BIT IN THE EXTENDED WITH THE ECMWF INDICATING A BIT
MORE OF A ZONAL PATTERN ACROSS THE EASTERN CONUS THAN THE GFS. THE
MORE PRONOUNCED CENTRAL US RIDGE IN THE GFS KEEPS ANY DISTURBANCES
ROTATING AROUND THE NORTHERN PERIPHERY OF THE HIGH WELL TO OUR
NORTH. WHEREAS THE ECMWF...WITH IT`S WEAKER RIDGE...TRIES TO BRING
A COUPLE IMPULSES ACROSS THE NORTHERN PORTIONS OF AL EARLY NEXT
WEEK. WILL GO WITH A DRY FORECAST FOR NOW BUT WILL KEEP AN EYE ON
FUTURE TRENDS.

19

&&

.AVIATION...
06Z TAF DISCUSSION.

THE LARGE SCALE COMMUNICATIONS FAILURE APPEARS TO HAVE BEEN
CORRECTED...AND THUS INCLUSION OF AMD NOT SKED IN THE TAFS IS NO
LONGER NECESSARY. ROUTINE AMENDMENTS HAVE RESUMED.

LITTLE CHANGE FROM PREVIOUS TAFS. VFR CONDITIONS AT PRESENT.
BOUNDARY LAYER MOISTURE IS EXPECTED TO INCREASE AS WE MOVE THROUGH
THE OVERNIGHT HOURS WITH LIGHT SOUTHERLY FLOW JUST ALOFT ABOVE THE
SURFACE. FAIRLY CONFIDENT OF MVFR VISIBILITIES BUT CONTINUE TO NOT
BE QUITE AS CONFIDENT ON THE POSSIBILITY OF IFR VISIBILITIES...SO
ONLY A FEW TEMPOS FOR NOW. WINDS ALOFT NEAR SUNRISE MAY BE TOO MUCH
FOR THE LOWER RANGE. ALL LOCALES SHOULD GO BACK TO VFR BY 14/15Z
WITH MIXING EXPECTED.

08/56

&&

.PRELIMINARY POINT TEMPS/POPS...
GADSDEN     89  66  82  66  84 /  10  10  50  40  20
ANNISTON    88  67  84  65  85 /  10  10  40  40  20
BIRMINGHAM  90  68  83  66  85 /  10  10  50  30  20
TUSCALOOSA  91  67  83  65  86 /  10  10  50  30  20
CALERA      90  66  84  66  85 /  10  10  50  40  20
AUBURN      89  67  85  65  85 /  10  10  20  40  30
MONTGOMERY  92  67  88  67  87 /  10  10  20  40  30
TROY        91  67  89  67  86 /  10  10  20  40  30

&&

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

&&

$$