Area Forecast Discussion
Issued by NWS Birmingham, AL

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000
FXUS64 KBMX 251948
AFDBMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BIRMINGHAM AL
248 PM CDT MON MAY 25 2015

.DISCUSSION...

WIDESPREAD SHOWERS AND STORMS CURRENTLY MOVING ACROSS CENTRAL
ALABAMA ON THIS MEMORIAL DAY. MOST OF THE THUNDERSTORM ACTIVITY NOW
LOOKS TO BE ALONG AND EAST OF I-65. SOME DRIER AIR IS MOVING IN FROM
THE WEST AND THERE COULD BE A FEW BREAKS IN THE PRECIPITATION THIS
AFTERNOON AND EVENING ACROSS PORTIONS WEST OF I-6S. CURRENT WATER
VAPOR IMAGERY AND RAP UPPER AIR ANALYSIS INDICATES A WEAK SHORTWAVE
TROUGH MOVING THROUGH THE AREA. FLOW THROUGHOUT THE COLUMN CONTINUES
TO BE FROM THE SOUTHWEST WITH A SURFACE AND UPPER LEVEL RIDGE TO THE
EAST AND SURFACE AND UPPER LEVEL LOW TO THE NORTHWEST. EXPECT
SHOWERS AND STORMS WILL CONTINUE TO MOVE TO THE EAST OVER THE NEXT
FEW HOURS AS THE TOUGH LIFTS OUT TO THE NORTHEAST. NOT EXPECTING ANY
STRONG OR SEVERE STORMS WITH 0-6KM DEEP LAYER SHEAR VALUES IN THE 20-
30 KT RANGE AND LIMITED INSTABILITY DUE TO THE EXPANSIVE CLOUD
SHIELD. EXPECT A FEW SHOWERS AND STORMS WILL CONTINUE ACROSS EASTERN
PORTIONS OF THE FORECAST AREA AFTER 00Z AS THE UPPER LEVEL TROUGH
EXITS THE AREA. IT APPEARS THERE WILL BE A BREAK IN THE ACTION
DURING THE OVERNIGHT PERIOD WITH THE FORECAST AREA IN BETWEEN
SHORTWAVE TROUGHS. THEREFORE...HAVE TAKEN POPS DOWN TO SLIGHT CHANCE
FOR MUCH OF THE OVERNIGHT PERIOD.

THE QUESTION THEN BEGINS TO FOCUS ON THE POTENTIAL FOR SEVERE
WEATHER FOR TOMORROW. A MCS WILL DEVELOP TO THE WEST TONIGHT IN
ASSOCIATED WITH THE NEXT APPROACHING SHORTWAVE TROUGH. THE MCS
SHOULD PUT OUT A DECENT AMOUNT OF CLOUD COVER ACROSS CENTRAL ALABAMA
DURING THE EARLY MORNING HOURS TOMORROW. QUESTIONS ALSO REMAIN ABOUT
HOW WELL THE COMPLEX WILL HOLD TOGETHER. LOOKING AT SOME OF THE HI-
RES MODELS...IT APPEARS THAT THE COMPLEX WILL WEAKEN AS IT MOVE
TOWARDS THE AL/MS DURING THE EARLY MORNING HOURS. SOME OF THE MORE
EXTREME MODELS INDICATE A INSTABILITY AXIS OF AROUND 2000 J/KG
ACROSS ALABAMA. AT THE SAME TIME...PW VALUES WILL BE INCREASING TO
NEAR 2 INCHES WHICH IS NEAR THE MAXIMUM AMOUNT OBSERVED FOR MID TO
LATE MAY AND EXPECT MID TO UPPER LEVEL LAPSE RATES WILL BE NEAR
MOIST ADIABATIC. MODELS ARE ADVERTISING THAT DEEP LAYER 0-6 KM SHEAR
WILL BE IN THE NEIGHBORHOOD OF 40 KTS WITH 0-1 KM SHEAR AROUND 10-20
KTS. OVERALL...IT APPEARS THAT THE THREAT IS TOO CONDITIONAL AT THIS
TIME TO ADD ANYTHING TO THE HWO. EXPECT STORMS WITH WIND GUSTS IN
THE 40-50 MPH RANGE WILL BE THE MAIN THREAT. COULD SEE A COUPLE OF
STORMS APPROACH SEVERE CRITERIA. CONDITIONS MAY BECOME A BIT CLEAR
OVER THE NEXT 12 HRS AS MORE HI-RES MODELS ARE ABLE TO GET IN RANGE
OF THE DEVELOPING MCS. REGARDLESS...HIGH RAIN CHANCES ARE EXPECTED
DURING THE DAY TOMORROW WITH ABNORMALLY HIGH PW VALUES. WIDESPREAD
SHOWERS AND STORMS ARE EXPECTED ACROSS THE AREA. HEAVY DOWNPOURS
COULD CAUSE SOME MINOR FLOODING ISSUES IN AREAS OF POOR DRAINAGE.
EXPECT WIDESPREAD SHOWERS AND STORMS WILL CONTINUE INTO THE
OVERNIGHT HOURS TUESDAY NIGHT WITH CENTRAL ALABAMA BEING IN THE
RIGHT ENTRANCE REGION OF A 70-80 KT UPPER LEVEL JET ACROSS THE OHIO
RIVER VALLEY.

ON WEDNESDAY INTO THE THURSDAY ...THE UPPER LEVEL JET LIFTS OUT TO
THE NORTHEAST AS THE UPPER LEVEL PATTERN ACROSS THE AREA
DE-AMPLIFIES. PW VALUES REMAIN ELEVATED AND CYCLONIC FLOW ALOFT WILL
CONTINUE ELEVATED POPS IN THE 50-70 PERCENT RANGE. THE UPPER LEVEL
FLOW AT THIS TIME IS RATHER WEAK AND NOT EXPECTING ANY SEVERE STORMS
BUT COULD SEE A STRONG STORM OR TWO WITH SBCAPE VALUES IN THE 1600-
2000 J/KG RANGE. HAVE TRENDED TOWARDS THE COOLER GUIDANCE FOR HIGH
TEMPERATURES OVER THE NEXT FEW DAYS WITH WIDESPREAD PRECIP AND CLOUD
COVER.

LATE IN THE WEEK...AN UPPER LEVEL RIDGE DEVELOPS ACROSS THE NORTHERN
GULF OF MEXICO WITH WEAK FLOW ALOFT. PW VALUES WILL REMAIN IN THE
1.4-1.6 INCH RANGE AND EXPECT POPS WILL BECOME MORE TYPICAL OF LATE
MAY EARLY JUNE. HIGH TEMPERATURES WILL ALSO WARM INTO THE MID TO
UPPER 80S AREAWIDE.

05/MA

&&

.AVIATION...
18Z TAF DISCUSSION.

MONITORING DEVELOPMENT OF CONVECTION AND PROGRESSION OF PRESENT
AREAS ACROSS C AL TO TIME TS FOR ALL BUT MAINLY RAIN FOR TCL. WILL
HOLD OFF ON INCLUDING IT FOR THEM JUST YET TO SEE HOW DEVELOPMENT
PROGRESSES THIS AFTERNOON WITH LOWER TEMPS THERE. SOME MVFR
CIGS POSSIBLE THIS AFTERNOON WITH CONVECTION. THEN SHOULD HAVE
SOME LIFTING FOR AT LEAST THE EVENING BEFORE SOME STRATUS BEHIND
THIS BATCH OF CONVECTION FOR THE EARLY MORNING. WINDS MAY STAY UP
SO FOG IS IFFY.

08/MK


&&

.PRELIMINARY POINT TEMPS/POPS...
GADSDEN     69  78  69  79  66 /  40  80  80  70  40
ANNISTON    70  78  69  78  66 /  30  80  80  70  40
BIRMINGHAM  70  79  70  80  68 /  40  80  80  70  40
TUSCALOOSA  70  78  69  82  68 /  50  90  70  70  30
CALERA      69  79  68  80  67 /  30  80  70  70  40
AUBURN      68  81  68  79  66 /  40  70  60  70  40
MONTGOMERY  71  83  70  81  68 /  30  80  60  70  30
TROY        69  82  68  81  67 /  30  70  60  70  30

&&

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

$$


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