457 
FXUS64 KBMX 031133
AFDBMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BIRMINGHAM AL
633 AM CDT THU OCT 3 2013

.UPDATE...
FOR 12Z AVIATION.

&&

.DISCUSSION...

TWO MORE DAYS OF RELATIVELY QUIET CONDITIONS ACROSS CENTRAL ALABAMA 
BEFORE A MORE ACTIVE PATTERN NOW TAKING SHAPE TO OUR WEST AND SOUTH 
AFFECTS THE AREA OVER THE WEEKEND. TO OUR WEST...A CLOSED LOW IS 
DROPPING INTO THE CENTRAL ROCKIES AND WILL SHIFT INTO THE NORTH 
CENTRAL PLAINS BY THE WEEKEND. AS THIS SYSTEM OCCLUDES...A SURFACE 
FRONT WILL PUSH TOWARD CENTRAL ALABAMA LATE THIS WEEKEND. 
MEANWHILE...A TROPICAL WAVE NEAR THE YUCATAN WILL PUSH NORTHWARD 
INTO THE SOUTHERN GULF OF MEXICO TODAY AND TRACK NORTHWARD TOWARD 
THE NORTH CENTRAL GULF COAST...AFFECTING THE SOUTHEASTERN CONUS THIS 
WEEKEND. THESE TWO FEATURES WILL COME TOGETHER...BRINGING RAIN TO 
THE AREA FOR AT LEAST PART OF THE WEEKEND. 

AS THE TROPICAL WAVE PUSHES NORTHWARD...AN INITIAL SURGE OF MOISTURE 
ON FRIDAY COULD BRING A SLIGHTLY BETTER CHANCE OF ISOLATED SHOWERS 
OR A THUNDERSTORM TO SOUTHWESTERN PORTIONS OF THE AREA...AND WILL 
CARRY LOW POPS DURING THE AFTERNOON. SIMILAR SET UP ON SATURDAY AS 
CONVECTION DEVELOPS ALONG THE COAST AND PUSHES INLAND THROUGH THE 
AFTERNOON. AIRMASS ACROSS CENTRAL ALABAMA WILL STILL BE RELATIVELY 
DRY WITH EASTERLY FLOW AROUND THE TROPICAL SYSTEM DOMINATING LOCAL 
WIND FIELDS. EXPECT MOST OF THE AREA TO REMAIN DRY THROUGH MOST OF 
THE DAY. RAIN CHANCES BEGIN TO INCREASE SATURDAY NIGHT AS THE 
TROPICAL SYSTEM NEARS THE COAST LINE AND BETTER TROPICAL MOISTURE 
SURGES ACROSS THE AREA. MOISTURE WILL FILTER NORTHEASTWARD AS THE 
TROPICAL SYSTEM TURNS TO THE NORTHEAST AHEAD OF THE PREVIOUSLY 
MENTIONED COLD FRONT APPROACHING FROM THE WEST.

THERE REMAINS QUITE A BIT OF UNCERTAINTY WITH THE FORECAST THROUGH 
THE WEEKEND. THE EXACT TRACK OF THE CURRENT TROPICAL WAVE WILL 
GREATLY AFFECT CONDITIONS ACROSS CENTRAL ALABAMA. THE OPERATIONAL 
GFS REMAINS A EAST OUTLIER...WITH ENSEMBLE MEMBERS...CMC...AND ECMWF 
GUIDANCE ALL FAVORING A WESTWARD TRACK...BRING THE TROPICAL WAVE 
NEAR BILOXI AND MERGING WITH THE APPROACHING COLD FRONT OVER 
ALABAMA. THIS WOULD RESULT IN THE GREATEST RAINFALL TOTALS FOR THE 
AREA. MODELS ARE IN GOOD AGREEMENT THAT THIS SYSTEM WILL REMAIN 
RELATIVELY WEAK AND COMPACT. EVEN WITH A MORE WESTWARD 
TRACK...RAINFALL TOTALS COULD VARY GREATLY ACROSS THE AREA DEPENDING 
ON WHERE A HEAVIER RAIN BAND SETS UP AND WHERE THE CENTER OF THE LOW 
TRACKS. WILL CONTINUE TO MENTION A LOW END FLOODING THREAT IN THE 
HWO. THE SYSTEM MOVES THROUGH RATHER QUICKLY WHICH WOULD LIMIT 
WIDESPREAD FLOODING CONCERNS. GIVEN THE CURRENT TIMING...THE 
GREATEST IMPACT TO CENTRAL ALABAMA WILL BE SATURDAY NIGHT AND 
SUNDAY. 

AS THE FRONT PUSHES THROUGH THE AREA...MOISTURE LIFTS TO THE 
NORTHEAST AS DRIER AIR FILTERS INTO THE AREA. WITH HIGH PRESSURE 
BUILDING ACROSS THE EASTERN CONUS...THE REMAINDER OF THE FORECAST 
PERIOD LOOKS DRY. 

14


&&

.AVIATION...
12Z TAF DISCUSSION.

VFR CONDITIONS WILL PREVAIL ONCE AGAIN TODAY WITH WINDS GENERALLY
OUT OF THE SE AROUND 5 KTS. THE LOW STRATUS DECK THAT DEVELOPED
ACROSS THE LOWER MISSISSIPPI RIVER VALLEY LAST NIGHT WILL LIKELY
REDEVELOP TONIGHT...BUT SHOULD REMAIN JUST TO THE WEST OF CENTRAL
ALABAMA. WILL MONITOR FOR POTENTIAL PATCHY FOG OVERNIGHT.

19

&&

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

&&

$$