LATEST FROM NWS BMX
.SHORT TERM...
TODAY AND TONIGHT.
* A SIGNIFICANT THREAT FOR SEVERE WEATHER EXISTS FOR THE
NORTHWESTERN HALF OF CENTRAL ALABAMA THIS AFTERNOON & OVERNIGHT
PERIOD. THREATS INCLUDE STRONG TORNADOES, DAMAGING WIND GUSTS
UP TO 60 MPH, AND QUARTER-SIZE HAIL.
* GREATEST POTENTIAL FOR ALL MODES OF SEVERE WEATHER WILL PRIMARILY
RESIDE IN AREAS CURRENTLY OUTLINED BY THE ENHANCED RISK (3/5) &
MODERATE (4/5) RISK AREAS NORTHWEST OF INTERSTATE 59.
* A FLOOD WATCH REMAINS IN EFFECT FOR THE NORTHERN HALF OF CENTRAL
ALABAMA THROUGH 6 AM SUNDAY MORNING.
SYNOPSIS...
GOES-EAST WATER VAPOR IMAGERY & RAP MESOANALYSIS DEPICT A DYNAMIC &
STRENGTHENING MID/UPPER-LEVEL DISTURBANCE NEAR THE SOUTHERN ROCKIES.
THIS UPPER TROUGH IS EXHIBITING A NEUTRAL TILT WITH 500MB HEIGHTS
~544 DECAMETERS. RIDGING TO OUR SOUTHWEST HAS ESTABLISHED A BROAD
SWATH OF SOUTHWESTERLY 700-300MB FLOW WITH SOUTHEAST TO SOUTHERLY
SURFACE WINDS (DEPENDING ON LOCATION RELATIVE TO THE SURFACE FRONT).
SOUTH OF THE FRONT, SOUTHERLY SURFACE WINDS ALONG WITH A 30-40 KT
850MB LOW-LEVEL JET HAVE ADVECTED TROPICAL AIR OF CARIBBEAN ORIGINS
(PWS 1.5-1.6" PER 06Z VORTEXSE SOUNDINGS) INTO THE SOUTHERN GULF
COAST STATES. THE WARM FRONT IS NOW APPROACHING TUSCALOOSA
SOUTHEASTWARD TOWARDS EUFAULA AS OF 09Z. SURFACE DEWPOINTS SOUTH
OF THE FRONT HAVE GENERALLY RANGED IN THE MID TO UPPER 60S
OVERNIGHT, THOUGH OBSERVATION STATIONS ACROSS SOUTHERN MS &
SOUTHWESTERN AL HAVE SHOWN DEWPOINTS ~70-72 DEGREES (F) SUPPORTIVE
OF SBCAPE ALREADY UP TO ~1,500 J/KG. AREAS OF MODERATE TO HEAVY
RAINFALL WITH EMBEDDED THUNDERSTORMS HAVE LINGERED TO OUR
NORTHWEST OVERNIGHT ACROSS NORTHERN MS, NORTHERN AL, & SOUTHERN TN
WHERE A DANGEROUS FLOODING EVENT IS ONGOING.
DISCUSSION...
THE PRIMARY UPPER-LEVEL FEATURE TO OUR WEST IS PROGGED TO EJECT
NORTHEASTWARD INTO THE GREAT PLAINS TODAY & PHASE WITH THE SUB-
TROPICAL JET. A STRONG H5 JET STREAK WITH WINDS IN EXCESS OF 100 KTS
IS EXPECTED TO DEVELOP AT THE BASE OF THE TROUGH NORTH OF THE
ARKLATEX REGION. DESPITE NOT HAVING THE BEST JET STREAK ORIENTATION,
HEIGHT FALLS & DEEP-LAYER FORCING ALONG WITH AN EASTWARD MOVING
SURFACE FRONT/DRY LINE FEATURE WILL PROVIDE FOCUS FOR DOWNSTREAM
CONVECTIVE INITIATION ACROSS THE LOWER MISSISSIPPI RIVER VALLEY
(MRV). SEVERE CONVECTIVE WEATHER IS EXPECTED ACROSS THIS REGION UP
TO AN AREA GENERALLY WHERE THE WARM FRONT/TRIPLE POINT SETS UP NEAR
WESTERN KY/TN. AFTERNOON BOUNDARY LAYER DESTABILIZATION WITH SURFACE
DEWPOINTS IN THE UPPER 60S TO NEAR 70 IS EXPECTED TO INCREASE SBCAPE
VALUES TO ~750-1,500 J/KG, ESPECIALLY ACROSS THE WESTERN & SOUTHERN
PORTIONS OF OUR FORECAST AREA WHERE TEMPERATURES IN THE UPPER 70S &
LOWER 80S ARE POSSIBLE GIVEN SUFFICIENT INSOLATION & MIXING. WITH
DEEP-LAYER SHEAR VALUES (50-60 KTS 0-6KM BULK SHEAR, 400-500 0-3KM
SRH) & THEIR ORIENTATION TO THE FRONT/TROUGH, ANY STRONGER
STORMS/UPDRAFTS WILL LIKELY BECOME SUPERCELLULAR ACROSS MISSISSIPPI
& EVENTUALLY INTO OUR WESTERN & NORTHWESTERN COUNTIES IN THE LATE
AFTERNOON/EVENING. LOW LCL HEIGHTS (400-700 METERS) & LOW-LEVEL WIND
SHEAR (300-400 0-1KM SRH) W/ BROAD HODOGRAPH CURVATURE SUGGEST ANY
ORGANIZED THUNDERSTORMS/SUPERCELLS WILL CARRY A SIGNIFICANT TORNADO
THREAT WHETHER THEY REMAIN DISCRETE CELLS OR MANAGE TO CONGEAL INTO
A SQUALL LINE OR QLCS. FORECAST SOUNDINGS ALSO SUGGEST MORE ROBUST
CAPE IN THE HAIL GROWTH ZONE, SO STRONGER STORMS WILL ALSO CARRY AN
ISOLATED SEVERE HAIL THREAT.
CURRENTLY FORECAST TIMING PROGS THE THREAT FOR SEVERE WEATHER TO
ENTER THE NORTHWEST AROUND 5 PM AT WHICH TIME SEVERE PARAMETERS WILL
BE HIGH. TRENDS AFTER SUNSET POINT TO A GENERAL WEAKENING OF
INSTABILITY AS WE LOSE DIABATIC HEATING, THOUGH THE TROPICAL AIRMASS
WILL STILL SUPPORT STRONG UPDRAFTS WITH SUFFICIENT SBCAPE VALUES
~500-1,000 J/KG. AS THIS SYSTEM MOVES EASTWARD/SOUTHEASTWARD
TOWARDS THE I-59 CORRIDOR (TRANSITION TO SLIGHT RISK AREA) ITS
ORIENTATION WILL BECOME MORE PARALLEL TO SHEAR VECTORS. THIS
EVENTUALLY FAVORS A DIMINISHING TORNADO THREAT, THOUGH EXPECT A
TORNADO THREAT THROUGH MIDNIGHT & EARLY MORNING. DAMAGING WINDS WILL
ALSO CARRY A THREAT INTO THIS REGION IF ANY STRONGER DOWNDRAFTS CAN
TRANSPORT LLJ ENERGY TO THE SURFACE. LOSS OF DEEP-LAYER FORCING &
INSTABILITY SIGNAL MORE WEAKENING AS THE SYSTEM APPROACHES THE I-85
CORRIDOR ~3 AM SUNDAY WHERE A TRANSITION TO SUB-SEVERE CONDITIONS IS
EXPECTED. SCATTERED PRE-FRONTAL SHOWERS & THUNDERSTORMS ARE ALSO
EXPECTED THROUGHOUT THE MORNING & EARLY AFTERNOON, THOUGH LATEST
FORECAST SOUNDINGS SUGGEST AN ELEVATED MIXED LAYER & ASSOCIATED
INVERSION ALOFT WHICH WOULD HELP TO LIMIT THIS ACTIVITY.
HERE IS THE HWO FROM BMX
THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE COUNTIES SERVED BY THE
NATIONAL WEATHER SERVICE OFFICE IN BIRMINGHAM.
.DAY ONE...THROUGH TONIGHT.
SEVERE THUNDERSTORMS ARE LIKELY TODAY. HAZARDOUS THREATS INCLUDE
STRONG TORNADOES, DAMAGING WINDS, AND HAIL. AT THIS TIME, THE THREAT
APPEARS TO BEGIN AROUND 5 PM IN THE WEST AND MAY CONTINUE THROUGH 3
AM IN THE EAST. THESE THREATS ARE GREATEST NEAR AND NORTH OF A LINE
FROM DEMOPOLIS TO CALERA TO CENTRE. OUTSIDE THESE AREAS, SOME
THUNDERSTORMS CAN BE EXPECTED BUT SHOULD BE WEAKER IN INTENSITY.
AREAS OF LOCALLY HEAVY RAINFALL WILL REMAIN POSSIBLE TODAY AND
TONIGHT. THEREFORE, THE FLOOD POTENTIAL REMAINS HIGH. ANY HEAVY RAIN
ON ALREADY SATURATED GROUNDS WILL ONLY ENHANCE THE FLOOD POTENTIAL.
THE MAIN FLOOD THREAT AREA WILL BE NEAR AND NORTH OF AN ALICEVILLE
TO CALERA TO WEDOWEE LINE. ELSEWHERE, MINOR FLOODING IS POSSIBLE IF
SHOWERS AND STORMS MOVE OVER THE SAME AREAS MORE THAN ONCE.
CENTRAL ALABAMA RIVERS WILL EXPERIENCE HEFTY RISES THE NEXT SEVERAL
DAYS. RIVER STAGES WILL REACH INTO THE MINOR AND MODERATE FLOOD
LEVELS. CHECK THE LATEST RIVER FLOOD PRODUCTS FOR SPECIFIC
INFORMATION.
.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY.
CENTRAL ALABAMA RIVERS WILL CONTINUE TO EXPERIENCE HEFTY RISES THE
NEXT SEVERAL DAYS. RIVER STAGES WILL REACH INTO THE MINOR AND
MODERATE FLOOD LEVELS. CHECK THE LATEST RIVER FLOOD PRODUCTS FOR
SPECIFIC INFORMATION.
.SPOTTER INFORMATION STATEMENT...
ACTIVATION OF STORM SPOTTERS AND EMERGENCY MANAGEMENT MAY BE NEEDED
THROUGH SUNDAY.