HAMweather.com Area Forecast Discussion for County Warning Area MOB

Thu, 16 Feb 2012 11:25:26 GMT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOBILE AL
420 AM CST THU FEB 16 2012

...SEVERE WEATHER POTENTIAL HAS INCREASED FOR SATURDAY...

.SHORT TERM [TODAY AND TONIGHT]...WE HAVE ALREADY SEEN SOME 
IMPRESSIVE RAINFALL TOTALS ACROSS THE AREA WITH MUCH OF INLAND SE MS 
AND SW AL REPORTING 1-2 INCH RAINFALL TOTALS. SOME LOCATIONS IN SE 
MS...ESPECIALLY IN GREENE AND PERRY COUNTIES HAVE PICKED UP AS MUCH 
AS 3 INCHES. THE AREA OF HEAVY RAIN WILL SHIFT EAST THIS MORNING AS 
THE CORRESPONDING UPPER LEVEL DIVERGENCE AND LOW LEVEL CONVERGENCE 
MAX SHIFT TO EAST OF I-65 AFTER 12Z. UPPER LEVEL FORCING WILL WEAKEN 
THROUGHOUT THE DAY AS THE SHORTWAVE OVER THE MIDWEST QUICKLY SHEARS 
OUT TO THE NORTHEAST AND IS REPLACED BY SHORTWAVE RIDGING. 
HOWEVER...THE SFC COLD FRONT IS JUST CROSSING THE MS RIVER EARLY 
THIS MORNING AND WILL VERY SLOWLY MOVE EAST INTO OUR AREA TODAY. AS 
THE EARLY MORNING CONVECTION MOVES OUT...MODEL GUIDANCE SHOWS SBCAPES 
CLIMBING TO 1000-1500 J/KG THIS AFTERNOON ALONG AND EAST OF THE I-65 
CORRIDOR. THEREFORE...GIVEN THE WEAK LOW LEVEL CONVERGENCE PRESENT 
ALONG THE SFC FRONT AND AN UNCAPPED ENVIRONMENT...THE DEVELOPMENT OF 
SCATTERED SHOWERS AND THUNDERSTORMS IS LIKELY EAST OF I-65 LATE 
MORNING THROUGH THE AFTERNOON. THEREFORE...WILL KEEP POPS IN THE 
HIGH CHANCE RANGE IN THOSE LOCATIONS...BUT WILL REMOVE POPS FURTHER 
WEST THIS AFTERNOON. WE ARE NOT LOOKING AT A THREAT OF SEVERE WEATHER
TODAY AS DEEP LAYER WIND FIELDS WILL BE ON THE DECREASE THROUGH THE 
DAY. THE MAIN THREAT WILL CONTINUE TO BE LOCALLY HEAVY RAINFALL THAT 
COULD CAUSE SOME MINOR FLOODING ISSUES IN URBAN AND LOW LYING AREAS. 
STAYED CLOSE TO GUIDANCE FOR HIGHS WITH LOW TO MID 70S EXPECTED. 

THE FRONT IS FORECAST TO NEAR THE COAST BY 00Z AND VERY SLOWLY PUSH 
OFFSHORE BY THE LATE EVENING/OVERNIGHT. THE FRONT WILL LIKELY STALL 
IN THE OFFSHORE WATERS AS THE BOUNDARY BECOMES PARALLEL TO THE UPPER 
LEVEL FLOW. MAINTAINED 20-30 PERCENT RAIN CHANCES ALONG THE COAST TO 
ACCOUNT FOR THE PROXIMITY OF THE FRONT AND WEAK ISENTROPIC UPGLIDE 
TO THE NORTH OF THE BOUNDARY. THE NIGHT WILL BE MOSTLY CLOUDY ACROSS 
THE REGION (LOW CLOUDS IN THE SOUTH WITH ABUNDANT MID/HIGH LEVEL 
CLOUDS FURTHER INLAND). THIS WILL KEEP LOWS IN THE MID TO UPPER 50S 
OVER THE SOUTHERN HALF OF THE AREA WITH LOW 50S NORTH OF THE HWY 84 
CORRIDOR. 34/JFB

FRIDAY AND FRIDAY NIGHT...WAVE OF FRONTAL LOW PRESSURE BEGINS TO
TAKE SHAPE OVER SOUTHERN TEXAS ON THE TAIL END OF STALLED NORTHERN
GULF BOUNDARY. NORTH OF THE SURFACE BOUNDARY...DISTURBANCES IN THE
HIGH LEVEL WESTERLIES LOOK TO BRING ENOUGH LIFT ACROSS THE AREA FOR
HIGHER CHANCES OF RAIN OVER THE SOUTHERN HALF OF THE AREA FRIDAY.
CLOSER TO THE BOUNDARY...NUMEROUS SHOWERS AND POSSIBLY A FEW STORMS
LOOK TO POPULATE THE NORTHERN GULF WATERS. AN INCREASE IN UNSETTLED
WEATHER CONTINUES INTO FRIDAY NIGHT AS NORTHERN GULF BOUNDARY
ADVANCES SLOWLY NORTHWARD AND DEEP LAYER LIFT INCREASES WITH A CLOSED
SURFACE LOW LIFTING UP INTO THE SOUTHERN LOUISIANA COAST BY DAYBREAK
SATURDAY. DAYTIME HIGHS IN THE MID 60S FRIDAY AND MILD CONDITIONS FOR
FRIDAY NIGHT. /10

.LONG TERM [SATURDAY THROUGH WEDNESDAY]...THE LATEST (16.00Z) OPERATIONAL
GFS AND ECMWF RUNS ARE IN MUCH BETTER AGREEMENT ON THE LOW TRACK OVER
THE DEEP SOUTH ON SATURDAY. THERE ARE CHANGES THOUGH. THE MODEL
FIELDS HAVE THE LOW LIFTING NORTHEAST AND DEEPENING ACROSS LOUISIANA
INTO THE SOUTHERN HALF OF MISSISSIPPI THROUGH NOON SATURDAY...THEN
INTO CENTRAL ALABAMA BY EVENING. THE PROBLEM WITH THIS IS THAT THE
ENTIRE FORECAST AREA WILL BECOME ROOTED IN THE WARM SECTOR THROUGH
SATURDAY WITH DEEP LAYER SHEAR AND INSTABILITY BRINGING AN INCREASED
RISK OF SEVERE STORMS. WITH THE CLOSE PROXIMITY OF THE LOW...THE
SURFACE WINDS WILL BE STRONGLY BACKED FROM THE SOUTHEAST WHILE H85
LOW LEVEL JET FROM THE SOUTHWEST STRENGTHENS TO 50 TO 60 KNOTS. THERE
IS ALSO A SECONDARY WARM FRONT MOVING NORTHWARD ON SATURDAY THROUGH
THE AREA AND WILL ACT TO FOCUS DEEP STRONG TO SEVERE CONVECTIVE
UPDRAFTS. UPDRAFTS LOOK TO EXHIBIT ROTATION WITHIN AN ENVIRONMENT OF
STRONGLY CURVED HODOGRAPHS AND 0-1 KM STORM RELATIVE HELICITIES OF
300-600 M2/S2. THE STORM PREDICTION CENTER IN NORMAN OKLAHOMA HAS
PLACED A SLIGHT RISK OF SEVERE STORMS OVER THE ENTIRE FORECAST AREA
FOR SATURDAY WITH DAMAGING WINDS AND ISOLATED TORNADOES POSSIBLE IN
THE SLIGHT RISK ZONE. PERHAPS A MORE SIGNIFICANT TORNADO THREAT IN ANY
DISCRETE SUPERCELLS AHEAD OF ANY ORGANIZED STORM COMPLEX. STAY TUNED.

GIVEN RAIN EVENT PASSING THROUGH THIS MORNING ALREADY HAVING PUT
DOWN 1-3 INCH TOTALS...ADDITIONAL HEAVY RAINS ON SATURDAY COULD VERY
WELL RESULT IN SOME LOCALIZED FLOODING ISSUES.

SEVERE WEATHER THREAT ENDS SATURDAY EVENING AS THE LOW LIFTS
NORTHEAST UP INTO GEORGIA AND THE CAROLINAS. TEMPERATURES COOLER.
SUNDAY AND MONDAY RAINFREE AS HIGH PRESSURE BUILDS EASTWARD ACROSS
THE SOUTHERN STATES. DAILY HIGHS A FEW DEGREES SHORT OF
CLIMATOLOGY...IN THE LOWER/MID 60S SUNDAY/MONDAY. NIGHTTIME LOWS
COOL. AN UPTICK IN RAIN CHANCES BY THE MIDDLE OF NEXT WEEK WITH
APPROACH OF NEXT SYSTEM. TEMPERATURES MODERATING. /10

.AVIATION [12Z ISSUANCE]...IFR CIGS AND PERIODS OF LGT/MDT RAIN TO
CONTINUE ACROSS THE REGION THROUGH MID MORNING...ESPECIALLY EAST OF
I-65. THE AXIS OF THE HEAVIEST RAINFALL WILL CONTINUE TO SHIFT EAST
THIS MORNING WITH CIGS GRADUALLY RISING TO MVFR LEVELS BY MIDDAY. A
WEAK COLD FRONT WILL SLOWLY MOVE THROUGH THE AREA TODAY...WITH
SCATTERED THUNDERSTORMS DEVELOPING ALONG THE BOUNDARY. PNS HAS THE
BEST CHANCE OF HAVING THUNDER IN THE VICINITY OF THE TERMINAL THIS
AFTERNOON. THE FRONT WILL PUSH SOUTH OF THE COAST TONIGHT...WITH THE
POTENTIAL OF CIGS RISING TO VFR LEVELS. UNCERTAIN AS TO HOW LONG VFR
CONDITIONS WILL LAST AS WEAK NE WINDS COMBINED WITH ABUNDANT GROUND
MOISTURE MAY RESULT IN THE DEVELOPMENT OF IFR CIGS/VSBYS OVERNIGHT.
34/JFB

.MARINE...A LIGHT ONSHORE FLOW WILL CONTINUE TODAY AS A WEAK COLD 
FRONT SLOWLY APPROACHES FROM THE WEST. THE FRONT IS FORECAST TO VERY 
SLOWLY MOVE INTO THE COASTAL WATERS TONIGHT...STALLING IN OR JUST 
SOUTH OF THE COASTAL WATERS. A SURFACE LOW IS FORECAST TO DEVELOP 
OVER THE WESTERN GULF ON FRIDAY AND TRACK INTO CENTRAL ALABAMA BY 
SATURDAY NIGHT. ONSHORE WINDS ARE FORECAST TO BECOME VERY STRONG
ACROSS THE COASTAL WATERS ON SATURDAY...INCREASING AS THE DAY
PROGRESSES. GIVEN THE STRENGTH OF THE LOW AND ITS CURRENT FORECAST
TRACK...OCCASIONAL GUSTS TO GALE FORCE ARE POSSIBLE. THIS WILL AID IN
SEAS BUILDING TO 8-11 FT SAT AFTN/EVE. STRONG STORMS WILL BE POSSIBLE
OVER THE COASTAL WATERS SATURDAY THROUGH SATURDAY EVENING. THE SFC
LOW WILL QUICKLY PULL OFF TO THE NORTHEAST LATE SATURDAY NIGHT WITH
ITS ATTENDANT COLD FRONT PUSHING THROUGH THE MARINE AREA. STRONG WEST
TO NORTHWEST WINDS ARE EXPECTED IN THE WAKE OF THE FRONT...WHICH WILL
PERSIST THROUGH SUNDAY. A SMALL CRAFT ADVISORY WILL LIKELY BECOME
NECESSARY FOR THE WEEKEND. OFFSHORE WINDS WILL GRADUALLY DECREASE
LATE SUNDAY INTO EARLY MONDAY WITH SEAS SUBSIDING. HOWEVER...A
DEVELOPING SOUTHEAST FLOW MONDAY NIGHT WILL BUILD SEAS BACK TO 3-5
FT. 34/JFB

.FIRE WEATHER...NO HEADLINES. DAYTIME HUMIDITY REMAINS ABOVE CRITICAL
LEVELS. /10

.PRELIMINARY POINT TEMPS/POPS...
MOBILE      75  57  66  57 /  50  20  50  50 
PENSACOLA   74  60  67  58 /  70  30  50  50 
DESTIN      68  61  67  58 /  80  30  60  40 
EVERGREEN   74  54  67  52 /  70  10  30  30 
WAYNESBORO  73  50  67  51 /  20  10  40  40 
CAMDEN      73  51  67  52 /  50  10  20  30 
CRESTVIEW   73  58  67  55 /  80  20  40  40 

.MOB WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
FL...NONE.
MS...NONE.
GM...NONE.