Area Forecast Discussion
Issued by NWS Birmingham, AL

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FXUS64 KBMX 240305
AFDBMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BIRMINGHAM AL
1005 PM CDT SAT MAY 23 2015

.UPDATE...
EVENING UPDATE.

&&

.DISCUSSION...

QUITE A BIT WARMER THIS EVENING THAN LAST NIGHT...BUT HIGH
TEMPERATURES WERE ALSO QUITE A BIT WARMER. GENERALLY CLEAR SKIES
BUT WE ARE EXPECTING THE PRESSURE GRADIENT TO INCREASE BETWEEN
THE HIGH TO OUR EAST AND THE LOW TO THE WEST. THEREFORE...SOME
EASTERLY WINDS SHOULD BE FELT BE MORNING. THIS EASTERLY WIND IS
ALSO BRINGING IN SOME MOISTURE FROM THE EAST. THE LATEST MODELS
ARE ADVERTISING SOME INCREASE IN LOWER CLOUDS AND THIS WILL LIKELY
OCCUR FOR FAR SOUTHERN AND EASTERN LOCATIONS AROUND OR JUST AFTER
SUNRISE.

MODIFIED THE TEMPERATURE TREND DOWN A FEW DEGREES AS THE CLEAR
SKIES WERE ALLOWING A COOL DOWN...BUT JUST STARTED AT A HIGHER
TEMP THAN LAST NIGHT. THE INCREASE IN CLOUDS SHOULD NOT HAVE A
GREAT EFFECT ON OVERNIGHT LOWS AND KEPT THEM IN THE 50S AND 60S.

75

&&

.AVIATION...
00Z TAF DISCUSSION.

VFR CONDITIONS WILL PREVAIL THRU MUCH OF THE NIGHT. A LOW CLOUD
DECK IS POSSIBLE NEAR SUNRISE SUNDAY AS MOISTURE AND SOME WEAK
ISENTROPIC LIFT MOVE IN FROM THE SOUTHEAST. WILL HINT AT SOME MVFR
CIGS AFTER 10Z FOR NOW. WILL REEVALUATE LOW STRATUS POTENTIAL AND
MAY HAVE TO ADJUST CIGS WITH NEXT ISSUANCE. SE WINDS WILL PERSIST
THRU THE PERIOD WITH SPEEDS NEAR 5 KTS OVERNIGHT INCREASING TO
10-15 KTS SUNDAY.

19


&&

.PREV DISCUSSION...
/ISSUED 248 PM CDT SAT MAY 23 2015/

DEWPOINTS ARE INCREASING ACROSS THE AREA THIS AFTERNOON. SURFACE
WINDS HAVE SHIFTED AROUND TO THE SOUTHEAST AS THE SURFACE HIGH
SHIFTS OUT OVER THE ATLANTIC. THIS SOUTHEASTERLY FLOW HAS PUSHED
DEWPOINTS UP INTO THE 50S AND 60S A GOOD 10 TO 15 DEGREES HIGHER
THAN THIS TIME YESTERDAY. EXPECT TEMPERATURES AND HUMIDITY VALUES
WILL BEGIN TO APPROACH SEASONAL CONDITIONS FOR THE START OF NEXT
WEEK. CURRENT WATER VAPOR IMAGERY AND RAP UPPER AIR ANALYSIS
INDICATES A RIDGE ACROSS THE GULF COAST STRETCHING NORTHWARD INTO
THE UPPER MISSISSIPPI RIVER VALLEY. BACK TO THE WEST...A CLOSED
UPPER LEVEL LOW IS DIGGING IN ACROSS THE FOUR CORNER REGIONS. WITH
THE RIDGE AXIS JUST TO THE WEST...SUBSIDENCE ALOFT IS KEEPING
CONDITIONS DRY FOR ANOTHER DAY ACROSS CENTRAL ALABAMA BUT THINGS
WILL BEGIN TO CHANGE EARLY NEXT WEEK AS THIS AXIS SHIFTS TO THE
EAST. FOR TONIGHT...EXPECT NEAR AVERAGE TEMPERATURES FOR THIS TIME
OF YEAR. WINDS SHOULD REMAIN UP TONIGHT WITH A GOOD PRESSURE
GRADIENT BETWEEN THE SURFACE HIGH TO THE NORTHEAST AND LEE LOW TO
THE NORTHWEST.

SOUTHERLY FLOW WILL KICK INTO FULL FORCE TOMORROW AS THE SURFACE
HIGH SHIFTS FURTHER TO THE EAST AND A WEAK WARM FRONT LIFTS
NORTHWARD ACROSS THE FORECAST AREA. PW VALUES WILL INCREASE TO OVER
1.5 INCHES BY THE END OF THE DAY. MODELS DIFFER GREATLY ON
PRECIPITATION AMOUNTS. THE NAM IS FAIRLY AGGRESSIVE WITH CONVECTION
DEVELOPING ALONG THE LIFTING WARM FRONT WHILE THE GFS AND ECMWF ARE
MUCH MORE CONSERVATIVE WITH ACTIVITY LIMITED TO SOUTHWESTERN
PORTIONS OF CENTRAL ALABAMA. FOR NOW...HAVE CONTINUED WITH 30-50 POP
FOR LOCATIONS WEST OF I-65 LATE IN THE AFTERNOON. IF THE NAM IS
CORRECT...POPS WILL NEED TO BE INCREASED LATE SUNDAY AFTERNOON.
SOUTHWESTERLY FLOW ALOFT WILL TAKE OVER FOR MUCH OF THE WEEK WITH
THE UPPER LEVEL RIDGE TO THE EAST AND TROUGH TO THE WEST BEING SEMI-
PERMANENT FEATURES. PW VALUES WILL INCREASE TO AROUND 1.7-1.9 INCHES
ON MONDAY AFTERNOON AS A SHORTWAVE TROUGH MOVES THROUGH THE
SOUTHEAST. HAVE GONE WITH 50-70 POP MONDAY AFTERNOON WITH NUMEROUS
TO WIDESPREAD SHOWERS AND STORMS EXPECTED. EXPECT THERE COULD BE A
FEW STRONG STORMS MONDAY AFTERNOON WITH 0-6 KM SHEAR VALUES AROUND
30 KTS AND SBCAPE VALUES AROUND 1000-2000 J/KG.

MUCH OF THE SAME CONTINUES INTO TUESDAY AND WEDNESDAY WITH LITTLE
CHANGE IN THE OVERALL SYNOPTIC SETUP. SHORTWAVE TROUGHS CONTINUE TO
MOVE THROUGH THE SOUTHWESTERLY FLOW ALOFT WITH THE ATMOSPHERE
REMAINING SATURATED WITH PW VALUES NEAR MAXIMUM VALUES OBSERVED FOR
MID TO LATE MAY KEEPING POPS ELEVATED DURING THIS TIMEFRAME. EXPECT
HEAVY DOWNPOURS WILL BE POSSIBLE BUT WITH THE DRY START TO THE MONTH
OF MAY...NOT EXPECTING ANY FLOODING ISSUES AT THIS TIME. WITH THE
INCREASED CLOUD COVER AND PRECIPITATION DURING THIS TIME...HAVE CUT
HIGH TEMPERATURES BY A FEW DEGREES EACH AFTERNOON.

THE UPPER LEVEL TROUGH WILL FINALLY MOVE THROUGH THE AREA LATE
WEDNESDAY INTO THURSDAY.  WEAK UPPER LEVEL RIDGING IN THE GULF OF
MEXICO WILL BRING POPS BACK DOWN NEAR CLIMATOLOGY WITH 20-40% EACH
AFTERNOON WITH HIGHS IN THE MID TO UPPER 80S.

05/MA

&&

.PRELIMINARY POINT TEMPS/POPS...
GADSDEN     59  84  68  82  68 /   0  10  20  50  50
ANNISTON    62  83  70  83  69 /   0  10  20  50  50
BIRMINGHAM  66  84  70  83  70 /   0  20  20  50  50
TUSCALOOSA  67  87  70  83  70 /   0  50  30  60  50
CALERA      65  85  70  83  69 /   0  30  20  60  50
AUBURN      62  84  67  83  68 /   0  10  20  50  30
MONTGOMERY  66  88  71  86  71 /   0  30  20  50  30
TROY        66  87  69  85  69 /   0  20  20  50  30

&&

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

$$


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