Area Forecast Discussion
Issued by NWS Birmingham, AL

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000
FXUS64 KBMX 220832
AFDBMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BIRMINGHAM AL
332 AM CDT MON SEP 22 2014

.DISCUSSION...

CURRENT WATER VAPOR IMAGERY INDICATES A POSITIVELY TILTED UPPER
LEVEL TROUGH DIVING QUICKLY SOUTH ACROSS THE MID-MISSISSIPPI RIVER
VALLEY WITH DRY AIR AND SUBSIDENCE TO THE NORTH OF THE TROUGH AXIS.
AN UPPER LEVEL RIDGE CAN BE NOTED ACROSS THE CENTRAL CONUS AND
ALTHOUGH IT IS FORECAST TO WEAKEN...THIS WILL BE THE MAIN UPPER
LEVEL FEATURE THAT WILL KEEP CONDITIONS DRY ACROSS CENTRAL ALABAMA
FOR MUCH OF THE WEEK. AT THE SURFACE...A COLD FRONT STRETCHES ACROSS
THE AREA AND IS LOCATED JUST TO THE SOUTH OF I-20/59 CORRIDOR. AT
3AM...THE DEWPOINT IS 71 DEGREES AT THE SHELBY COUNTY AIRPORT WITH A
DEWPOINT OF ONLY 61 DEGREES AT THE BIRMINGHAM AIRPORT. DEWPOINTS IN
THE 40S ARE ALREADY BEING OBSERVED IN NORTHERN TENNESSEE AND THIS
AIR WILL MOVE INTO THE STATE TONIGHT. A CURRENT LOOK AT THE RADAR
SHOWS SCATTERED SHOWER AND STORMS ALONG THIS FRONTAL BOUNDARY. MOST
MODELS EARLIER INDICATED THAT THIS ACTIVITY SHOULD HAVE WEAKENED
SIGNIFICANTLY BY NOW BUT THE LIFT FROM THE FRONT AND FAST MOVING
UPPER LEVEL TROUGH HAS KEPT CONVECTION GOING WELL INTO THE OVERNIGHT
HOURS. LOW LEVEL MOISTURE REMAINS PLENTIFUL SOUTH OF THE FRONT WITH
DEWPOINTS IN THE MID TO UPPER 60S WITH A FEW LOCATIONS IN THE LOW
70S. THEREFORE...EXPECT SCATTERED CONVECTION WILL CONTINUE TO SINK
SOUTHWARD WITH THE FRONT DURING THE EARLY MORNING HOURS. HI-RES
MODELS INDICATE SCATTERED TO NUMEROUS SHOWERS DEVELOPING LATER TODAY
AS THE FRONT APPROACHES THE I-85 CORRIDOR. SINCE COVERAGE HAS BEEN
MORE IMPRESSIVE DURING THE OVERNIGHT HOURS...WENT AHEAD AND BUMPED
UP POPS TO THE 50-60 PERCENT RANGE FOR AREAS ALONG AND SOUTH OF THE
I-85 CORRIDOR FOR LATE THIS MORNING INTO THE EARLY AFTERNOON. MODELS
INDICATE THAT THE FRONT SHOULD QUICKLY PUSH THROUGH THE FORECAST
AREA LATER IN THE AFTERNOON AND ONLY HAVE 20 POP MENTIONED AFTER 21Z
FOR LOCATIONS IN FAR SOUTHEASTERN CENTRAL ALABAMA. FURTHER TO THE
NORTH...DRY AIR WILL MOVE INTO THE AREA MAKING FOR AN EXCELLENT DAY
WEATHER WISE WITH HIGH TEMPERATURES ACROSS THE NORTH ONLY TOPPING
OUT IN THE UPPER 70S.

DRIER CONDITIONS TAKE OVER ON TUESDAY AND PERSIST FOR MUCH OF THE
WORK WEEK. THE UPPER LEVEL TROUGH CLOSES OFF OVER THE SOUTH
CAROLINA/GEORGIA COAST. THE RIDGE MOVES TO THE EAST BUT BEGINS TO
FLATTEN SOME WITH NORTHWESTERLY FLOW ALOFT ACROSS CENTRAL ALABAMA.
AT THE SURFACE...HIGH PRESSURE ACROSS THE MID-ATLANTIC INTO NEW
ENGLAND WILL BE THE MAIN DRIVING FORCE WITH A COOLER AND DRIER
EASTERLY TO NORTHEASTERLY WINDS AT THE SURFACE. PW VALUES WILL BE IN
THE 0.50-0.75 INCH RANGE FOR MUCH OF THE WORK WEEK WITH MEAN RH
VALUES BELOW 40 PERCENT. FOR NOW...TUESDAY MORNING LOOKS TO BE THE
COOLEST MORNING WHERE A FEW OF THE COLDER LOCATIONS COULD DROP DOWN
INTO THE 40S.

MOISTURE BEGINS TO INCREASE OVER THE WEEKEND AS AN UPPER LEVEL
TROUGH MOVES NORTHWARD OUT OF THE NORTHWESTERN GULF. EARLIER MODELS
DIFFERED A BIT ON TIMING WITH THE ECMWF BEING MUCH SLOWER THAN THE
GFS. HOWEVER...THE LATEST RUNS HAVE COME INTO BETTER AGREEMENT WITH
THE TIMING. THEREFORE...HAVE INCREASED POPS ON SUNDAY AND MONDAY AS
TROPICAL MOISTURE INCREASE AS THE UPPER LEVEL TROUGH MOVES ACROSS
THE AREA.

05/MA

&&

.AVIATION...
06Z TAF DISCUSSION.

SHOWERS AND STORMS HAVE DEVELOPED AS EXPECTED OUT AHEAD OF THE
COLD FRONT THAT HAS MOVED INTO NORTHERN ALABAMA LATE THIS EVENING.
MOST OF THE CONVECTION HAS REMAINED SCATTERED IN NATURE...AND
LIGHTNING OUTPUT HAS DIMINISHED GREATLY OVER THE PAST FEW HOURS.
FOR THE NORTHERN SITES THROUGH 07Z...EXPECT VICINITY SHOWERS OR A
THUNDERSTORM WITH THE PASSAGE OF THE COLD FRONT. BROKEN CIGS FROM
3 TO 5 THOUSAND FEET WILL BE EXPECTED THROUGH THE MORNING HOURS
ON MONDAY THEN CLEARING THROUGH THE AFTERNOON. FOR THE SOUTHERN
SITES...HAVE NOT INCLUDED ANY MENTION OF SHOWERS OR STORMS AT THIS
TIME DUE TO LOW CONFIDENCE OF CONVECTION REACHING KMGM OR KTOI.
SKIES SHOULD CLEAR THE SOUTHERN SITES BY THE LATE AFTERNOON AND
EVENING HOURS.

PREVAILING WINDS AT THE SURFACE WILL SHIFT TO THE NORTH OVERNIGHT
TONIGHT AND BECOME GUSTY BEHIND THE INITIAL COLD FRONTAL PASSAGE.
DURING THE DAY ON MONDAY...NORTH WINDS AROUND 10-12 KNOTS WILL
PREVAIL WITH SOME HIGHER GUSTS POSSIBLE. WINDS WILL DIMINISH AFTER
SUNSET.

NOTE...THE NATIONAL WEATHER SERVICE WILL BEGIN ISSUING SEASONAL
TERMINAL FORECASTS FOR THE TALLADEGA MUNICIPAL AIRPORT (KASN) IN
TALLADEGA...ALABAMA. THE FORECAST WILL BEGIN OCTOBER 5TH AT 00Z
AND LAST THROUGH AT LEAST THE 23RD OF OCTOBER.

56/GDG


&&

.PRELIMINARY POINT TEMPS/POPS...
GADSDEN     78  51  79  53  80 /  10   0   0   0   0
ANNISTON    79  54  80  56  81 /  10   0   0   0   0
BIRMINGHAM  80  55  81  58  81 /  10   0   0   0   0
TUSCALOOSA  83  54  84  58  84 /  10   0   0   0   0
CALERA      81  55  82  58  81 /  20   0   0   0   0
AUBURN      82  58  82  58  81 /  40   0   0   0   0
MONTGOMERY  85  57  83  60  83 /  30   0   0   0   0
TROY        84  56  83  59  82 /  60  10   0   0  10

&&

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

&&

$$






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