Tornado in Alabama, April 27, 2011

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOBILE AL
649 PM WED APR 27 2011

.UPDATE...EXTENDED THE HIGH SURF ADVISORY UNTIL 1 AM. WINDS CONTINUE
STRONG UNTIL FROPA LATER TONIGHT. /11

.AVIATION UPDATE... MVFR TO OCCASIONAL IFR TONIGHT IN CEILINGS AND
VISIBILITY IN AND NEAR THUNDERSTORMS. EXPECT A SQUALL LINE TO SWEEP
EAST ACROSS THE FORECAST AREA THIS EVENING WITH STRONG...DAMAGING
WINDS POSSIBLE AND ISOLATED TORNADOES. ISOLATED TORNADOES MORE
LIKELY NORTH OF THE COASTAL ZONES. WINDS WILL REMAIN STRONG
SOUTHERLY AND GUSTY UNTIL AROUND MIDNIGHT OVER THE WEST WHEN FRONT
NEARS. WEST TO NORTHWEST WINDS REMAIN A BIT GUSTY FOLLOWING FRONT.
THURSDAY SHOULD BE A BIT BREEZY EARLY BUT MOSTLY VFR FROM MID
MORNING ON. /11

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...TORNADO WATCH 235 IN EFFECT UNTIL 10 PM FOR THE NORTHERN HALF OF
THE FORECAST AREA...
...STRONG TO SEVERE THUNDERSTORMS AND TORNADOES POSSIBLE THROUGH
AROUND 2 AM TONIGHT...

.SHORT TERM [TONIGHT THROUGH FRIDAY NIGHT]...BASE OF MEDIUM
AMPLIFIED UPPER TROUGH OVER THE SOUTHERN PLAINS WILL MOVE EAST OVER
THE FORECAST AREA LATE TONIGHT AND THURSDAY MORNING. SURFACE LOW
PRESSURE CENTERED OVER THE BOOT HEEL OF MISSOURI WILL CONTINUE TO
STRENGTHEN AS IT MOVES NORTHEAST TONIGHT TOWARD THE LOWER GREAT
LAKES REGION. A STRONG MOIST SOUTHERLY WIND FLOW AHEAD OF AN
APPROACHING COLD FRONT WILL PERSIST INTO THIS EVENING CREATING WINDY
CONDITIONS ACROSS THE NORTH CENTRAL GULF COASTAL REGION. WIND GUSTS
THIS AFTERNOON HAVE BEEN AS HIGH AS 40 MPH...AND EXPECT WINDS OF 20
TO 30 MPH WINDS WITH FREQUENT GUSTS TO CONTINUE...SO THE WIND
ADVISORY WILL REMAIN IN EFFECT UNTIL 9 PM THIS EVENING.

ISOLATED TO SCATTERED COVERAGE OF SHOWERS HAVE ALREADY DEVELOP THIS
AFTERNOON...AND SCATTERED TO LIKELY COVERAGE OF SHOWERS AND
THUNDERSTORMS ARE STILL FORECAST FOR THIS EVENING. THE PRECIPITATION
WILL THEN BE ENDING FROM WEST TO EAST AS THE COLD FRONT PASSES
THROUGH THE FORECAST AREA. THE NORTHERN HALF OF FORECAST AREA WILL
REMAIN UNDER A MODERATE RISK OF SEVERE THUNDERSTORMS TONIGHT...WITH
THE SOUTHERN HALF UNDER A SLIGHT RISK. SURFACE ANALYSIS SHOWING CAPE
VALUES HAVE MANAGED TO CLIMB TO 2500 TO 3500 J/KG AS EXPECTED. KMOB
88D RADAR VAD WIND PROFILE ALSO SHOWING A 55 KNOT LOW LEVEL JET AT
3000 FEET AS EXPECTED. 18Z KBMX SPECIAL RAOB COMPUTED A SURFACE TO 3
KM STORM RELATIVE HELICITY VALUE OF 692 M2/S2. WITH ALL THE
INGREDIENTS IN PLACE WE STILL ARE EXPECTING DAMAGING WINDS...LARGE
HAIL AND DANGEROUS TORNADOES MAINLY ACROSS THE NORTHERN HALF OF THE
FORECAST AREA UNDER THE TORNADO WATCH.

SURFACE HIGH PRESSURE WILL BUILD IN FROM THE WEST LATE TONIGHT AND
THURSDAY...WITH SKIES BECOMING CLEAR BY NOON THURSDAY. A COOLER
DRIER WEATHER PATTERN WILL FOLLOW THROUGH FRIDAY NIGHT AS THE
SURFACE HIGH PASSES OVER THE SOUTHEAST STATES. /22

&&

.LONG TERM [SATURDAY THROUGH WEDNESDAY]...TEMPERATURES WILL WARM
INTO THE MID AND UPPER 80S OVER THE WEEKEND AS SFC HIGH PRESSURE
SLIDES EAST AND AN UPPER RIDGE BUILDS OVER THE SOUTHEAST. THE
SOUTHERLY FLOW ON THE BACK SIDE OF THE SFC HIGH WILL BRING
INCREASING LOVLV MOISTURE BACK ACROSS THE REGION DURING THE WEEKEND.
THIS WILL BE IN ADVANCE OF THE NEXT CHANCE OF SHOWERS AND
THUNDERSTORMS MONDAY INTO MONDAY NIGHT AS A COLD FRONT MOVES ACROSS
THE AREA WITH A SLIGHTLY COOLER AND DRIER AIRMASS FOLLOWING TUE-WED.
13/JC

&&

.MARINE...PASSING SYSTEM WILL PUSH A STRONG FRONT ACROSS THE AREA
TONIGHT...WITH STRONG ONSHORE FLOW IMMEDIATELY FOLLOWING. THE
OFFSHORE FLOW WILL QUICKLY SETTLE LATER THURSDAY INTO THURSDAY NIGHT
AS SURFACE HIGH PRESSURE MOVES TOWARDS...THEN OVER THE AREA. AS THE
SURFACE HIGH MOVES EAST OF THE AREA FRIDAY...ONSHORE FLOW RETURNS BY
FRIDAY NIGHT. WITH ANOTHER SYSTEM EXPECTED TO DEVELOP OVER THE
PLAINS AND MOVE EAST...THE ONSHORE FLOW IS EXPECTED TO INCREASE
SUNDAY NIGHT INTO MONDAY AS ANOTHER FRONT MOVES TOWARDS...THEN OVER
THE AREA MONDAY INTO MONDAY NIGHT. /16

&&

.AVIATION [27/18Z ISSUANCE]...NO CHANGES TO CURRENT THINKING...WITH
MVFR CIGS THROUGH THE AFTERNOON...WITH STRONG WINDS IN THE MIXING
LAYER. THE WINDS ARE CONSISTENTLY STRONG THROUGH THE LOWEST 2K' OF
THE ATMOSPHERE. WILL SEE AN INCREASE IN NNE MOVING SHOWERS THROUGH
THE AFTERNOON AHEAD OF A LINE OF STRONG TO SEVERE TSRA EXPECTED TO
MOVE OVER SE MISS BEGINNING AROUND 21Z AND EXITING S-CENTRAL AL/NW
FL PANHANDLE AROUND 06Z TONIGHT. GUIDANCE IS ADVERTISING SKIES
CLEARING OUT BY SUNRISE THURSDAY OVER THE FA. THERE IS A SMALL
POSSIBILITY OF COLD SURGE STRATUS MOVING OVER NORTHERN PARTS OF THE
AREA THURSDAY...BUT GUIDANCE IS PRETTY INCONCLUSIVE ABOUT THIS. /16

&&

.FIRE...SHOWER AND THUNDERSTORM ACTIVITY WILL APPROACH AND PASS
THROUGH THE REGION TONIGHT. COOLER DRIER CONDITIONS WILL FOLLOW ON
THURSDAY IN THE WAKE OF A COLD FRONT WITH AFTERNOON RELATIVE VALUES
DROPPING INTO THE 30S. A MODERATE NORTHWESTERLY TRANSPORT WIND WILL
RESULT IN GOOD DISPERSION VALUES ON THURSDAY. /22

&&

.PRELIMINARY POINT TEMPS/POPS...
MOBILE      59  77  50  83 /  60  05  00  00
PENSACOLA   66  80  55  82 /  60  10  00  00
DESTIN      66  80  58  80 /  70  10  00  00
EVERGREEN   60  76  45  83 /  70  10  00  00
WAYNESBORO  55  76  46  83 /  60  05  00  00
CAMDEN      57  75  45  83 /  70  10  00  00
CRESTVIEW   68  80  45  84 /  70  10  00  00

&&

.MOB WATCHES/WARNINGS/ADVISORIES...
AL...HIGH SURF ADVISORY UNTIL 1 AM THURSDAY FOR THE FOLLOWING ZONES:
     LOWER BALDWIN...AND LOWER MOBILE.

     WIND ADVISORY UNTIL 9 PM WEDNESDAY FOR THE FOLLOWING ZONES:
     BUTLER...CHOCTAW...CLARKE...CONECUH...COVINGTON...
     CRENSHAW...ESCAMBIA...LOWER BALDWIN...LOWER MOBILE...
     MONROE...UPPER BALDWIN...UPPER MOBILE...WASHINGTON...AND
     WILCOX.

FL...WIND ADVISORY UNTIL 9 PM WEDNESDAY FOR THE FOLLOWING ZONES:
     COASTAL ESCAMBIA...COASTAL OKALOOSA...COASTAL SANTA ROSA...
     INLAND ESCAMBIA...INLAND OKALOOSA...AND INLAND SANTA ROSA.

     HIGH SURF ADVISORY UNTIL 1 AM THURSDAY FOR THE FOLLOWING ZONES:
     COASTAL ESCAMBIA...COASTAL OKALOOSA...AND COASTAL SANTA
     ROSA.

MS...WIND ADVISORY UNTIL 9 PM WEDNESDAY FOR THE FOLLOWING ZONES:
     GEORGE...GREENE...PERRY...STONE...AND WAYNE.

GM...SMALL CRAFT ADVISORY UNTIL 1 PM THURSDAY FOR THE FOLLOWING
     ZONES: COASTAL WATERS FROM DESTIN TO PENSACOLA FL OUT 20
     NM...COASTAL WATERS FROM PENSACOLA FL TO PASCAGOULA MS OUT
     20 NM...MOBILE BAY...WATERS FROM DESTIN TO PENSACOLA FL
     FROM 20 TO 60 NM...AND WATERS FROM PENSACOLA FL TO
     PASCAGOULA MS FROM 20 TO 60 NM.

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE MOBILE AL
502 AM CDT WED APR 27 2011

ALZ051>064-FLZ001>006-GMZ630-650-655-670-675-MSZ067-075-076-078-
079-281200-
CHOCTAW-WASHINGTON-CLARKE-WILCOX-MONROE-CONECUH-BUTLER-CRENSHAW-
ESCAMBIA-COVINGTON-UPPER MOBILE-UPPER BALDWIN-LOWER MOBILE-
LOWER BALDWIN-INLAND ESCAMBIA-COASTAL ESCAMBIA-INLAND SANTA ROSA-
COASTAL SANTA ROSA-INLAND OKALOOSA-COASTAL OKALOOSA-MOBILE BAY-
COASTAL WATERS FROM PENSACOLA FL TO PASCAGOULA MS OUT 20 NM-
COASTAL WATERS FROM DESTIN TO PENSACOLA FL OUT 20 NM-
WATERS FROM PENSACOLA FL TO PASCAGOULA MS FROM 20 TO 60 NM-
WATERS FROM DESTIN TO PENSACOLA FL FROM 20 TO 60 NM-WAYNE-PERRY-
GREENE-STONE-GEORGE-
502 AM CDT WED APR 27 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF INTERIOR SOUTHEAST
MISSISSIPPI...SOUTHWEST AND SOUTH CENTRAL ALABAMA...THE WESTERN
FLORIDA PANHANDLE...AND THE COASTAL WATERS OF ALABAMA AND NORTHWEST
FLORIDA.

.DAY ONE...TODAY AND TONIGHT

A POWERFUL LOW PRESSURE SYSTEM WILL BRING A RISK FOR SEVERE STORMS
AND TORNADOES TO THE AREA TODAY INTO MUCH OF TONIGHT.  ATMOSPHERIC
CONDITIONS WILL BECOME ESPECIALLY CONDUCIVE FOR SEVERE THUNDERSTORM
AND TORNADO DEVELOPMENT DURING THE DAY WITH THE MOST FAVORABLE
CONDITIONS SHIFTING EASTWARD ACROSS THE AREA OVERNIGHT AS A COLD
FRONT MOVES THROUGH THE AREA.  THERE IS THE POTENTIAL THAT A FEW
LONG TRACK VERY DAMAGING TORNADOES MAY OCCUR...MAINLY OVER INTERIOR
AREAS.

FOR TODAY...THE GREATEST RISK FOR SEVERE STORMS AND TORNADOES WILL
BE OVER INTERIOR SOUTHEAST MISSISSIPPI AND INTERIOR SOUTHWEST
ALABAMA...OR ROUGHLY NORTH OF A LINE FROM WIGGINS MISSISSIPPI TO
LUVERNE ALABAMA.  FOR TONIGHT THE GREATEST RISK AREA WILL BE OVER
INTERIOR SOUTHWEST AND SOUTH CENTRAL ALABAMA AND ALSO OVER MUCH OF
THE NORTHWEST FLORIDA PANHANDLE...OR ROUGHLY WEST OF A LINE FROM
GROVE HILL ALABAMA TO MILTON FLORIDA.  WHILE THESE AREAS DELINEATE
THE MOST FAVORABLE CONDITIONS FOR SEVERE WEATHER...SEVERE STORM
DEVELOPMENT WILL BE POSSIBLE ACROSS THE REMAINDER OF THE AREA AS
WELL.

A HIGH SURF ADVISORY IS IN EFFECT THROUGH THE EARLY EVENING HOURS
FOR THE BEACHES OF ALABAMA AND THE NORTHWEST FLORIDA PANHANDLE.
BREAKING WAVES OF 6 TO 8 FEET WILL BE POSSIBLE IN THE SURF ZONE.
THERE IS ALSO A HIGH RISK OF DANGEROUS RIP CURRENTS ALONG AREA
BEACHES.

STRONG SOUTHERLY WINDS OF 20 TO 30 MPH WITH HIGHER GUSTS WILL BE
PRESENT ACROSS THE AREA THROUGH THE EARLY EVENING HOURS.  MUCH
STRONGER WINDS ARE LIKELY IN AND NEAR THUNDERSTORMS.

STRONG WINDS OVER THE MARINE AREA WILL CREATE HAZARDOUS BOATING
CONDITIONS FOR SMALL CRAFT THROUGH TONIGHT.

MINOR RIVER FLOODING CONTINUES ALONG PORTIONS OF THE TOMBIGBEE
RIVER.  SEE THE LATEST RIVER PRODUCTS FOR ADDITIONAL UPDATES.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH MONDAY

STRONG WINDS CONTINUE TO POSE A HAZARD TO SMALL CRAFT UNTIL THE
WINDS DIMINISH DURING THE DAY ON THURSDAY.  MODERATE TO STRONG WINDS
MAY POSE A RISK TO SMALL CRAFT LATER IN THE PERIOD FROM FRIDAY NIGHT
THROUGH SUNDAY.

.SPOTTER INFORMATION STATEMENT...

ACTIVATION OF SKYWARN SPOTTER NETWORKS AND EMERGENCY MANAGEMENT FOR
SEVERE STORMS IS REQUESTED THROUGH TONIGHT.

SEVERE WEATHER REPORTS CAN MADE DIRECTLY TO THE NWS IN MOBILE AT
251-633-6443.