National Weather Service Raw Text Product

269 
FXUS64 KMOB 251021
AFDMOB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOBILE AL
421 AM CST TUE DEC 25 2012

WISHING YOU AND YOUR FAMILY A HAPPY AND SAFE CHRISTMAS HOLIDAY FROM 
ALL OF US AT YOUR NATIONAL WEATHER SERVICE IN MOBILE AL.

...A DANGEROUS SEVERE WEATHER EPISODE IS LIKELY TO EVOLVE THROUGH 
THE DAY AND TONIGHT...INCLUDING THE POTENTIAL FOR STRONG TORNADOES 
AND WIDESPREAD DAMAGING WINDS...ACROSS PORTIONS OF THE CENTRAL GULF 
COAST REGION...

.SHORT TERM [TODAY AND TONIGHT]...WATER VAPOR IMAGERY ALONG WITH 
UPPER LEVEL GEOPOTENTIAL HEIGHT FIELD SHOWS A VIGOROUS STORM 
SYSTEM/SHARPENING SOUTHERN STREAM TROF PROGRESSING QUICKLY EASTWARD 
ACROSS TEXAS. THIS IS RESULTING IN INCREASED HIGH LEVEL DIVERGENCE 
OVER THE CENTRAL GULF COAST/SOUTHEAST. AT THE SURFACE...A STALLED 
FRONTAL ZONE WAS DRAPED FROM CENTRAL GEORGIA TO THE UPPER TEXAS 
COAST. TO THE SOUTH...A WARM FRONT WAS DRAPED OFF THE SOUTHEAST 
LOUISIANA COAST AND INTO THE ALABAMA/WESTERN FLORIDA COASTAL WATERS.

SOUTHERN STREAM STORM SYSTEM AMPLIFIES TODAY AS IT HEADS EASTWARD 
AND BECOMES INCREASINGLY NEGATIVELY TILTED AS IT PIVOTS ACROSS THE 
LOWER MISSISSIPPI RIVER DELTA. THIS WILL RESULT IN FURTHER HIGH 
LEVEL DIFFLUENCE AND APPROACH OF STRONG UPPER LEVEL JET ENERGY ASCENT
WILL INCREASE COINCIDENT WITH A NORTHWARD MOVING WARM FRONT AND
ENHANCED INSTABILITY THROUGH THE COURSE OF THE DAY. STRONG HEIGHT
FALLS ALOFT MOVING ACROSS SOUTHERN STATES FRONTAL ZONE SUPPORTS A
DEEPENING FRONTAL SURFACE LOW PRESSURE SYSTEM TO TAKE SHAPE OVER
EASTERN TEXAS THIS MORNING LIFTING QUICKLY UP INTO CENTRAL
MISSISSIPPI BY 6 PM...NE MISSISSIPPI/NW ALABAMA INTO CENTRAL
TENNESSEE BETWEEN 12 AM AND DAYBREAK WEDNESDAY. AHEAD OF AND
SOUTHEAST OF THE INTENSIFYING LOW...IMPRESSIVE WIND FIELD AND SHEAR
PROFILES ALOFT WILL RESULT IN 0-1 KM STORM RELATIVE HELICITY VALUES
LIFTING TO 150-200 M2/S2 BY NOON...TRENDING HIGHER INTO THE
AFTERNOON/EVENING TO BETWEEN 200 AND 300 M2/S2. THIS SUPPORTS THE
LIKELIHOOD OF DEEP AND PERSISTENT ROTATING UPDRAFTS AND TORNADOES IN
DISCRETE STORM CLUSTERS. IN FACT...TORNADO PARAMETER GUIDANCE IS
ELEVATED OVER THE ENTIRE FORECAST AREA. THE NUMBERS WE SEE SUPPORT
POTENTIAL OF LONG TRACK...STRONG TORNADOES. GIVEN THIS...A MODERATE
RISK OF SEVERE STORMS IS FORECAST TODAY AND TONIGHT. LARGE HAIL IS
ALSO POSSIBLE. FORECASTERS SEE THE STAGE BEING SET FOR A POTENTIAL
"DOUBLE WHAMMY". NOT ONLY IS THERE AN ELEVATED TORNADO RISK...BUT THE
PASSAGE OF A FAST MOVING...ORGANIZED SQUALL LINE TONIGHT WILL BRING
THE LIKELIHOOD OF LOCALIZED DAMAGING WIND GUSTS OF 60+ MPH IN ANY
BOWING LINE SEGMENTS. THIS FEATURE...AHEAD OF A STRONG COLD FRONT
THAT IS PROGGED TO SURGE EASTWARD BETWEEN 6 PM AND MIDNIGHT. STAY
TUNED. ADDITIONAL INFORMATION ON THIS EVENT CAN BE FOUND IN LOCAL
HAZARDOUS WEATHER OUTLOOK AND SPECIAL WEATHER STATEMENT PRODUCTS. /10

.LONG TERM /WEDNESDAY THROUGH NEW YEARS/...AFTER THE PASSAGE OF THE 
COLD FRONT...BELOW AVERAGE TEMPERATURES WILL RESULT AS A CONTINENTAL 
POLAR AIR MASS SLIDES SOUTHEASTWARD. TEMPERATURES RANGING FROM THE 
UPPER 40S INLAND TO MID-50S ALONG THE COAST ARE EXPECTED. 
TEMPERATURES WILL AGAIN MODERATE TOWARD THE END OF THE WEEK AS 
MID-LEVEL HEIGHTS BEGIN TO LOWER IN RESPONSE TO A POSITIVELY TILTED 
TROUGH EJECTING FROM THE WEST. AHEAD OF IT...RETURN FLOW FROM THE 
GULF WILL ONCE AGAIN PRIME THE ATMOSPHERE FOR ADDITIONAL STORMS. 
THIS SYSTEM WILL NOT BE AS STRONG AS THE ONE AFFECTING US 
TODAY...BUT IT WILL INCREASE OUR PRECIPITATION CHANCES FOR FRIDAY 
AND SATURDAY. BY SATURDAY NIGHT AND SUNDAY...EXPECT TEMPERATURES TO 
ONCE AGAIN DROP BELOW NORMAL VALUES IN THE WAKE OF THE FRONTAL 
PASSAGE. /01

&&

.AVIATION [12Z KMOB/KBFM AND KPNS TAF ISSUANCE]...WILL POSSIBLY BE 
DEALING WITH LIFR/VLIFR CIGS/VSBYS IN FOG AND LOW STRATUS TO SHORTLY 
AFTER DAYBREAK. THE THING TO STRESS FOR THIS MORNINGS DISCUSSION IS 
THE STRENGTHENING WIND PROFILES OFF THE SURFACE THROUGH THE DAY 
WHICH CAN PROVE HAZARDOUS FOR ARRIVALS/DEPARTURES. SURFACE SOUTHERLY 
FLOW INCREASES THROUGH THE DAY WITH WINDS GUSTING TO BETWEEN 25 AND 
30 KNOTS. WINDS MUCH STRONGER IN/NEAR CONVECTION...SOME OF WHICH 
SEVERE WITH ISOLATED TORNADOES. /10

&&

.MARINE...A POWERFUL LOW PRESSURE SYSTEM IS FORECAST TO TRACK ACROSS 
NORTHERN LOUISIANA AND INTENSIFY AS IT LIFTS UP ACROSS TENNESSEE 
TONIGHT. AS THIS LOW LIFTS OUT...COLDER AIR WILL BE ALLOWED TO SURGE 
IN FROM THE WEST WITH ADVANCING COLD FRONT. AHEAD OF THIS 
BOUNDARY...THE RISK FOR STRONG TO SEVERE MARINE STORMS IS BECOMING HIGHER. 
THERE IS A RISK FOR TORNADOES OVER WATER WHICH WILL BE STRONGER THAN 
WATERSPOUTS DUE TO THE STRONGER SYNOPTIC SCALE FORCING AND DEPTH OF 
TURNING IN THE VERTICAL WIND PROFILES. WITH THE PASSAGE OF SQUALL 
LINE TONIGHT...STRONG AND POTENTIALLY DAMAGING WIND GUSTS CAN 
CAPSIZE SMALLER MARINE CRAFT. STRENGTHENING ONSHORE FLOW THROUGH THE 
DAY WILL SHIFT TO THE NORTHWEST AND BECOME EVEN STRONGER IN THE WAKE 
OF THE FRONT TONIGHT. GRIDDED WIND GUST OUTPUT CONTINUES TO SHOW 
THAT GALE CONDITIONS WILL OCCUR WITH APPROXIMATELY 40 KNOTS OVER THE
ALABAMA AND WESTERN FLORIDA OPEN GULF WATERS TONIGHT. THIS ALSO
MATCHES UP WELL WITH NEIGHBORS VIA COORDINATION. THUS...A GALE
WARNING IS ISSUED ON THIS PACKAGE FOR MARINE ZONES 650-655-670 AND
675. INCREASED WINDS RESULT IN HIGH AND DANGEROUS SEAS. TIDES COULD
ALSO BE 1 TO 2 FEET ABOVE PREDICTED LATER IN THE DAY WHEN HIGH TIDE
CYCLE IS FORECAST. OFFSHORE FLOW AND SEAS TREND LOWER BY WEDNESDAY
NIGHT INTO THURSDAY AS HIGH PRESSURE BUILDS INTO THE REGION. /10

&&

.FIRE WEATHER...A VERY UNSTABLE ATMOSPHERE WILL DOMINATE CHRISTMAS 
DAY...WHICH WILL RESULT IN PERIODS OF WET WEATHER WITH A HIGH 
LIKELIHOOD OF SEVERE WEATHER.  WITH THE FRONTAL PASSAGE LATE 
CHRISTMAS DAY AND INTO THE EVENING HOURS...EXPECT COLDER...DRIER 
TEMPERATURES IN ITS WAKE.  STRONG NORTHWEST TO NORTHERLY FLOW WILL 
THEN DOMINATE THROUGH THE PERIOD...ACCOMPANIED BY HIGH DISPERSIONS 
AND LOWER RELATIVE HUMIDITY VALUES. WIND AND LOW LEVEL MOISTURE 
VALUES SHOULD REMAIN BELOW CRITICAL THRESHOLDS THROUGH THE PERIOD.

FOG POTENTIAL WILL DIMINISH AS THE SURFACE WINDS INCREASE LATER THIS 
MORNING. EXPECT DRIER CONDITIONS TO PREVAIL BY WEDNESDAY. /01

&&

.PRELIMINARY POINT TEMPS/POPS...
MOBILE      72  44  55  31  50 / 100  60  10  00  05 
PENSACOLA   72  48  57  33  50 / 100  80  10  00  05 
DESTIN      71  51  60  37  50 / 100  80  20  00  05 
EVERGREEN   70  45  53  29  50 / 100  80  10  00  05 
WAYNESBORO  69  38  48  26  49 / 100  60  10  00  05 
CAMDEN      67  42  49  29  48 / 100  80  10  00  05 
CRESTVIEW   72  50  58  30  51 / 100  80  20  00  05 

&&

.MOB WATCHES/WARNINGS/ADVISORIES...
AL...DENSE FOG ADVISORY UNTIL 6 AM TUESDAY FOR THE FOLLOWING ZONES: 
     CLARKE...CONECUH...COVINGTON...ESCAMBIA...LOWER BALDWIN...
     LOWER MOBILE...MONROE...UPPER BALDWIN...UPPER MOBILE...
     WASHINGTON... 

FL...DENSE FOG ADVISORY UNTIL 6 AM TUESDAY FOR THE FOLLOWING ZONES: 
     COASTAL ESCAMBIA...COASTAL OKALOOSA...COASTAL SANTA ROSA...
     INLAND ESCAMBIA...INLAND OKALOOSA...INLAND SANTA ROSA... 

MS...DENSE FOG ADVISORY UNTIL 6 AM TUESDAY FOR THE FOLLOWING ZONES: 
     GEORGE...GREENE...PERRY...STONE... 

GM...SMALL CRAFT ADVISORY FROM NOON TUESDAY TO 6 PM WEDNESDAY FOR THE 
     FOLLOWING ZONES: CHOCTAWHATCHEE BAY...MISSISSIPPI SOUND...
     NORTHERN MOBILE BAY...PENSACOLA BAY SYSTEM...PERDIDO BAY...
     SOUTHERN MOBILE BAY... 

     GALE WARNING FROM 6 PM TUESDAY TO NOON WEDNESDAY 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...WATERS FROM DESTIN TO PENSACOLA FL FROM 20 
     TO 60 NM...WATERS FROM PENSACOLA FL TO PASCAGOULA MS FROM 
     20 TO 60 NM... 

     SMALL CRAFT ADVISORY FROM 9 AM TUESDAY TO 6 PM TUESDAY 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...WATERS FROM DESTIN TO PENSACOLA FL FROM 20 
     TO 60 NM...WATERS FROM PENSACOLA FL TO PASCAGOULA MS FROM 
     20 TO 60 NM... 

     SMALL CRAFT ADVISORY FROM NOON WEDNESDAY TO 6 PM WEDNESDAY 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...WATERS FROM DESTIN TO 
     PENSACOLA FL FROM 20 TO 60 NM...WATERS FROM PENSACOLA FL TO 
     PASCAGOULA MS FROM 20 TO 60 NM... 

&&

$$