Severe Thunderstorm Warning 273, NWS Mobile, AL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOBILE AL
930 AM CST THU 27 NOV 2003

.UPDATE...WILL REMOVE A FEW NORTH AND NORTHWEST COUNTIES FROM
TORNADO WATCH 977 AND REMOVE BUTLER COUNTY FROM WATCH THAT WAS IN
ERROR. STORMS HAVE DIMINISHED A BIT BUT STILL SOME
STRONG...POTENTIALLY SEVERE STORMS MOVING EAST ACROSS SOUTHERN THIRD
OF FORECAST AREA./11

...PREVIOUS

.SHORT TERM...THE EVOLUTION OF THIS SYSTEM HAS SLOWED QUITE A BIT...
ON THE ORDER OF 12 TO 18 HR...AS IT TAKES ITS TIME TO DEEPEN OVER
ARKLATX REGION AS IT SWINGS THROUGH HERE. PROSPECTS FOR EARLY LIFTOUT
HAVE BEEN PROGRESSIVELY FADING.

345K ISENTROPIC POTENTIAL VORTICITY PATTERN SHOWS A MAXIMUM OVER
KS/MO/IL SWEEPING WITH TIME SOUTHEAST INTO OUR REGION FRIDAY MORNING.
NEGATIVE Q-VECTOR DIVERGENCE IS GREATEST JUST AHEAD OF THIS ANOMALY
INDICATING A SERIES OF SURFACE LOWS WERE EXPECTED TO SPIN ALONG THE
HYPER-BAROCLINIC ZONE...AND IT SEEMS THIS WILL STILL COME TO PASS
ALBEIT A BIT LATER THAN EXPECTED 24 HR AGO.

WE DID INDICATE TWO PROVISIONS OF PCPN...THE FIRST AFTER MIDNIGHT
WITH OVERRUNNING ADVANCING EAST AND SFC CYCLOGENESIS MOVING NORTHEAST
FROM OVER SOUTH LA. THAT WILL HAVE OCCURRED WITH ONLY MINIMAL DELAY.
AS OF MIDNIGHT THE EDGE OF THE MCS APPEARS JUST ON THE NORTHWEST CWA
AND SHOULD BE UPON US WELL BEFORE SUNRISE AND THE MESOETA CONTINUES
TO PREDICT THE SURFACE FEATURE. ONE NOTE...POSITIVE LIGHTNING HAS
BEEN INCREASING THROUGH 08Z AS THIS IS BEING WRITTEN...AND ETA
FORECAST CAPE AT 6Z WAS ABOUT 2400 J/KG JUST OFF THE WEST LA SHORE.

AS THE DAY WEARS ON...THE ETA IS INDICATING A CLOSER PHASING OF THE
OMEGA FIELD WITH THE DRY AIR OVERHANGING A DEEP MOIST LAYER. THERE
ALSO IS AN ENERGY-HELICITY INDEX MAXIMUM OF 3 OVER THE SOUTHERN AL-MS
STATE LINE. THEY BOTH PHASE CLOSELY AROUND 21Z WHICH WORRYS US SOME.
THE LOW IS NOW FCST TO DEVELOP OVER NRN MS BETWEEN 27/21Z AND 28/00Z
BUT STILL TO MOVE NE ACROSS MS-AL. IF THAT CAUSES TEMPORAL BACKING OF
THE LOCAL SFC WINDS AND THERE IS AN INCREASE OF LOW-LEVEL VERTICAL
WIND SHEAR...IT WOULD EFFECTIVELY PROVIDE FOR A WIND PROFILE SHOWING
ROTATING MINI SUPERCELLS (WITH LOW TOPS) POSSIBLE. AS STATED TODAY...
IF THERE ARE BREAKS IN THE CLOUD DECK COINCIDING WITH A HIGH SUN
ANGLE...WE COULD HEAT UP FAST AHEAD OF THAT SECOND LOW. ALTHOUGH
DYNAMICS PICTURE LOOKS PRETTY MIXED RIGHT NOW WITH AN 850 WIND MAX
FORECAST MOVING AWAY BY ETA...THE NEW DATA SET SHOULD BE EVALUATED TO
CONFIRM NO OTHERS ARE UPWIND.

MODELS GENERALLY AGREE THAT FROPA WOULD BE BETWEEN 06 AND 09Z IN THE
WEST...CLEARING THE AREA BY 09 OR 12Z EARLY FRIDAY MORNING.
REMARKABLE COLD ADVECTION IS INDICATED ON A PAR WITH LAST EVENT WITH
ENSEMBLES SHOWING STANDARD DEVIATIONS RATHER CLOSELY CLUSTERED AT +/-
1 TO 2 FAHRENHEIT DEGREES FOR SAT AM MIN TEMPS...SHOWING CONFIDENCE
IN A LIGHT FREEZE THIS WEEKEND.

.EXTENDED...LITTLE CHANGE WITH A SLOW WARMING TREND THROUGH EARLY
NEXT WEEK.

.MARINE...SMALL CRAFT ADVISORY WITH GUSTS TO NEAR GALE FORCE TO BE
PROMULGATED FOR TODAY AND THIS EVENING. STEEPENING GRADIENT THROUGH
WELL AFTER FROPA FRIDAY. SEAS TO 11 FEET EXPECTED AFTER FROPA WITH
LEFTOVER SOUTHERLY FETCH AND NEW WAVE GROWTH FROM THE WIND SHIFT TO
THE NORTH AND BECOMING NEAR GALE FORCE. USED 80 NM FETCH DUE TO WEST
COMPONENT.

FIRE...NO CONCERNS AT THE MOMENT. DISPERSION INDICES COULD BE AN
ISSUE FRIDAY...BUT LOW FIRE DANGER TODAY WITH RAINFALL AND LOW MIXING
HEIGHTS.

.PRELIMINARY TEMPS / POPS...

MOBILE     77 53 60 32 / 70 90 20 00
PENSACOLA  76 57 63 35 / 60 80 40 00
DESTIN     75 59 61 37 / 50 80 60 00
EVERGREEN  75 52 55 29 / 70 90 30 00
WAYNESBORO 72 46 55 28 / 90 99 10 00
CAMDEN     73 47 55 28 / 90 90 10 00

.MOB ...
AL...NONE.
FL...NONE.
MS...NONE.

77

ALZ051>064-FLZ001>006-MSZ067-075-076-078-079-272000-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE MOBILE AL
627 AM CST THU NOV 27 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHWEST ALABAMA...INTERIOR
SOUTHEAST MISSISSIPPI AND THE WESTERN FLORIDA PANHANDLE.

.DAY ONE...(TODAY AND TONIGHT)

A STRONG UPPER LEVEL DISTURBANCE...MODERTAE INSTABILITY...AND
ABUNDANT LOW LEVEL MOISTURE WILL BRING A VARIETY OF SEVERE WEATHER TO
THE OUTLOOK AREA TODAY.  SHOWERS AND THUNDERSTORMS WILL BE LIKELY
THROUGHOUT THE DAY...WITH THE STRONGEST STORMS OCCURRING NORTHEAST OF
INTERSTATE-65.  WIND SHEAR IN THE LOW LEVELS OF THE ATMOSPHERE WILL
BE FAVORABLE FOR ROTATING UPDRAFTS AND THE FORMATION OF ISOLATED
TORNADOES WITH THE STRONGER STORMS.  HEAVY RAINS ARE ALSO EXPECTED...
LEADING TO LOCALIZED FLOODING...AS THE STORMS WILL TEND TO REDEVELOP
THROUGHOUT THE DAY OVER THE SOUTHERN PORTIONS OF LOUISIANA AND
MISSISSIPPI AND TRACK NORTHEAST OVER THE AREA.

THE SEVERE WEATHER RISK WILL WEAKEN DURING THE EVENING HOURS AS THE
LOW LEVEL WINDS BECOME LESS FAVORABLE FOR SUSTAINED ROTATING UPDRAFTS
AND TORNADOES...BUT ISOLATED DAMAGING WINDS AND HEAVY RAINS WITH
LOCALIZED FLOODING WILL CONTINUE.  THE LINE OF THUNDERSTORMS WILL
SHIFT EASTWARD THROUGHOUT THE NIGHT...ENDING NORTHEAST OF INTERSTATE-
65 AFTER MIDNIGHT.  WHILE AREAS ALONG AND SOUTHEAST OF INTERSTATE-
65 CONTINUE TO RECEIVE HEAVY RAINS THROUGH DAYBREAK.  STRONG NORTH
WINDS WILL DEVELOP BEHIND A COLD FRONT LATE TONIGHT INTO EARLY
FRIDAY MORNING.

THE RIP CURRENT RISK IS HIGH TODAY AS STRONG ONSHORE WINDS PERSIST
AHEAD OF A COLD FRONT MOVING THROUGH THE SOUTHERN PLAINS.

.DAYS TWO THROUGH SEVEN (FRIDAY THROUGH WEDNESDAY)

NO SEVERE OR HAZARDOUS WEATHER IS EXPECTED.

.SPOTTER CALL TO ACTION STATEMENT...

ACTIVATION OF EMERGENCY MANAGERS AND STORM SPOTTERS FOR SEVERE STORM
OPERATIONS WILL LIKELY BE REQUIRED THROUGHOUT THE DAY...MAINLY ALONG
AND NORTHEAST OF INTERSTATE-65.

ALZ051>056-059-061>064-MSZ067-075-076-078-079-271700-

SPECIAL WEATHER STATEMENT...CORRECT PREVIOUS SPS
NATIONAL WEATHER SERVICE MOBILE AL
952 AM CST THU NOV 27 2003

TORNADO WATCH NUMBER 977 HAS BEEN CANCELLED FOR THE FOLLOWING
COUNTY IN SOUTHWEST ALABAMA...CHOCTAW

TORNADO WATCH NUMBER 977 HAS BEEN CANCELLED FOR THE FOLLOWING
COUNTY IN SOUTHEAST MISSISSIPPI...WAYNE

THE TORNADO WATCH REMAINS IN EFFECT UNTIL 11 AM FOR THE FOLLOWING
COUNTIES...

SOUTHWEST ALABAMA...MOBILE...BALDWIN...WASHINGTON...CLARKE...WILCOX
MONROE...CONECUH AND ESCAMBIA.

SOUTHEAST MISSISSIPPI...PERRY...STONE...GREENE...GEORGE

A LINE OF THUNDERSTORMS...SOME POTENTIALLY SEVERE WILL MOVE FROM
WEST TO EAST ACROSS THE WATCH AREA THROUGH THIS AFTERNOON.

ALZ052-053-061-MSZ076-079-271700-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOBILE AL
1001 AM CST THU NOV 27 2003

NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A LINE OF STRONG
THUNDERSTORMS FROM JUST WEST OF GROVE HILL TO 10 MILES SOUTHWEST
OF BASIN OR ABOUT 15 MILES WEST OF MOBILE...MOVING EAST AT 20 MPH.

THE LINE OF STORMS WILL AFFECT AREAS IN AND NEAR...
EVANSTON...VINEGAR BEND...TIBBIE...DEER
PARK...SHIPMAN...AGRICOLA...MOVELLA AND LEROY THROUGH 1030 AM CST
AND BE NEAR INTERSTATE 65 BY 11 AM.

ANOTHER STRONG STORM WAS MOVING EAST ACROSS THE NORTHERN TIP OF
WILCOX COUNTY...MOVE WAS EAST AT 35 MPH.

THE PRIMARY THREATS FROM THESE STORMS ARE STRONG WINDS AND DANGEROUS
LIGHTNING. WIND GUSTS OF 35 TO 45 MPH COULD DOWN SMALL TREE LIMBS OR
BRANCHES AND BLOW AROUND UNSECURED SMALL OBJECTS. FREQUENT CLOUD TO
GROUND LIGHTNING STRIKES ARE LIKELY. SEEK SHELTER IN A SAFE HOME OR
BUILDING UNTIL THESE STORMS HAVE PASSED.

A TORNADO WATCH REMAINS IN EFFECT UNTIL 1100 AM CST THURSDAY MORNING
FOR SOUTHWESTERN ALABAMA AND SOUTHEAST MISSISSIPPI.