Gale Watch 3, NWS Mobile, AL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOBILE AL
1136 PM CST SUN NOV 29 2009

.AVIATION (06Z ISSUANCE)...CEILINGS STEADILY LOWER THROUGH TOMORROW
MORNING AS THE COLD FRONT APPROACHES AND DROP TO NEAR 2.5KFT BY
MIDDAY.  INCLUDED LIGHT FOG DEVELOPING OVERNIGHT AT THE THREE TAF
SITES THEN ENDING BY 13Z.  THE FRONT MOVES THROUGH 17-20Z AND
INCLUDED A TEMPO GROUP FOR MODERATE SHOWERS AND CEILINGS NEAR
1.5KFT.  LAYER LIFTED CEILINGS NEAR 2.5KFT FOLLOW IN THE WAKE OF THE
FRONT THEN VFR CONDITIONS DEVELOP MONDAY EVENING. /29

** PREVIOUS DISCUSSION **

.SHORT TERM...(TONIGHT THROUGH TUESDAY NIGHT)...TONIGHT WE SEE WEAK
ISENTROPIC FORCING BRINGING A SMALL CHANCE OF RAIN BEFORE SUNRISE
OVER THE INTERIOR OF SOUTHEAST MISSISSIPPI AND POSSIBLY INTERIOR
SOUTHWEST ALABAMA ZONES. APPROACHING STORM SYSTEM WILL PRODUCE RAIN
AS EARLY AS TONIGHT IN NORTHWEST ZONES WITH EMBEDDED THUNDERSTORMS
MONDAY. DECREASING RAIN LATE MONDAY WILL BE FOLLOWED BY ANOTHER
ROUND TUESDAY.  HEAVIEST RAIN WILL BE TUESDAY AND TUESDAY NIGHT AND
COULD REACH 6 TO 8 INCHES ESPECIALLY WITHIN 60 TO 80 MILES OF THE
COAST.

MODERATE TO STRONG SOUTHERLY WINDS ALONG COASTAL ZONES TUESDAY AND
TUESDAY NIGHT WILL BECOMING WEST WEDNESDAY. THE PROBLEM CONTINUES TO
BE VEXING FOR LATE TUESDAY AS GFS AND ECMWF OUTPUTS ARE AT ODDS WITH
EACH OTHER. AS STATED YESTERDAY, THEY MAY BE BOTH RIGHT WITH MAIN
CENTER MAY BE WEST WITH TRIPLE POINT OF A WARM OCCLUSION NEAR MOBILE
BAY. STRONGER ONSHORE WIND IS SHOWN GUSTING TO NEAR WIND ADVISORY
CRITERIA, AND IF THE WARM FRONT MOVES ASHORE PER THE EURO IT WOULD
MIX DOWN HIGHER MOMENTUM AIR TO THE SURFACE. THAT WOULD INDEED RISK
WIND ADVISORY CRITERIA. BUT AS SEEN IN THE CALCULATIONS FOR GFS, THE
LOW WOULD BE AT A COASTAL CROSSING BETWEEN DAUPHIN ISLAND AND GULF
SHORES LATE TUESDAY BETWEEN SUNDOWN AND MIDNIGHT. HIGH TIDE IS 1.8 FT
AT 8 PM TUESDAY WITH A RANGE OF 2.3 FEET PER ASTRONOMICAL
PREDICTIONS. THERE IS A SIGNIFICANT RISK OF COASTAL FLOODING TUESDAY,
BUT WE WILL NOT KNOW MUCH MORE UNTIL CONFIDENCE BUILDS IN THE MODEL
CALCULATIONS ESPECIALLY ON WIND. AT THE POSITION INDICATED FOR
ARRIVAL ASHORE, THE SURFACE PRESSURE GRADIENT IS STEEP ENOUGH TUESDAY
AND TUESDAY EVENING TO CREATE A PROBLEM WITH ONSHORE WIND DRIVING
WATER ASHORE. THIS IS ESPECIALLY TRUE IN MOBILE BAY AND OTHER LARGE
SHALLOW BAYS. GFS CONTINUES FASTER AND EURO CONTINUES SLOWER, TO THE
WEST, STILL IN CENTRAL LOUISIANA. LATER CALCULATIONS WOULD BE ABLE TO
DEFINE THE RISK MORE CLOSELY.

AS FOR RAIN CHANCES AND AMOUNT, THE EURO AND GFS ARE STILL
SUFFICIENTLY CLOSE IN AGREEMENT WITH THEIR RESPECTIVE RAINFALL
OUTPUTS THAT HEAVY RAIN SHOULD BE CONSIDERED LIKELY TUESDAY AND
TUESDAY NIGHT, TUESDAY AND WEDNESDAY. CURRENTLY THE FORECAST IS
JOINED TO THE GFS TRACK OF THE SURFACE LOW.

/ 77

.LONG TERM...(WEDNESDAY THROUGH SUNDAY)...NO CHANGES. RESIDUAL RAIN
ENDING WEDNESDAY NIGHT OR EARLY THURSDAY MORNING WITH COOLER AIR
RETURNING.

&&

.MARINE...HIGH PRESSURE OVER THE SOUTHEAST STATES RESULTS IN A
CONTINUED LIGHT ONSHORE FLOW THROUGH TONIGHT. A COLD FRONT WILL
APPROACH FROM THE NORTHWEST AND MOVE ACROSS THE MARINE AREA MONDAY
AFTERNOON...WITH A MODERATE TO STRONG OFFSHORE FLOW DEVELOPING MONDAY
NIGHT. WINDS WILL GENERALLY BE IN THE 15-20 KT RANGE MONDAY NIGHT...
BUT THERE IS CERTAINLY A POSSIBILITY OF A PERIOD OF SUSTAINED WINDS
OF 20 KT AND SMALL CRAFT ADVISORIES MAY BECOME NECESSARY. NOT ENOUGH
CONFIDENCE ON THIS SHIFT TO ISSUE ONE AT THIS TIME.

THE FRONT THEN STALLS OVER THE NORTH CENTRAL GULF BY TUESDAY WITH A
LOW PRESSURE SYSTEM DEVELOPING ALONG THE BOUNDARY OVER THE WESTERN
GULF. WHILE GUIDANCE STILL DIFFERS SOMEWHAT ON TIMING AND TRACK OF
THE LOW...WE ARE CONFIDENT IN THE GENERAL IDEA OF A DEEPENING LOW
MOVING ACROSS THE NORTHERN GULF COAST LATE TUESDAY NIGHT INTO
WEDNESDAY MORNING. WITH A 1020+ MB HIGH POSITIONED OFF THE CAROLINA
COAST...A FAIRLY SIGNIFICANT PRESSURE GRADIENT WILL EXIST OVER THE
MARINE AREA. CONDITIONS ARE EXPECTED TO DETERIORATE TUESDAY AFTN
INTO EARLY WEDNESDAY. A SIGNIFICANT AMOUNT OF THE MODEL GUIDANCE IS
POINTING AT THE POTENTIAL FOR GALE CONDITIONS TUESDAY NIGHT AND HAVE
WORDED THE POSSIBILITY IN THE COASTAL WATERS FORECAST. HAVE ALSO
BUMPED UP THE SEAS FORECAST TO A RANGE OF 8-13 FEET OFFSHORE. SOME
GUIDANCE HAS SEAS AS HIGH AS 15-17 FT...AND WE WILL HAVE TO MONITOR
THIS POTENTIAL. TIDES ALSO EXPECTED TO RUN 1 TO 2 FEET ABOVE NORMAL
TUESDAY NIGHT AS THE FLOW BECOMES INCREASINGLY ONSHORE AND WITH THE
SPRING TIDE CYCLE AT ITS PEAK...COASTAL FLOODING WILL BE A CONCERN.
ONE OTHER HAZARD WILL BE THE POTENTIAL FOR A FEW STRONG TO SEVERE
STORMS OVER THE OPEN WATERS.

A STRONG OFFSHORE FLOW DEVELOPS BY WEDNESDAY NIGHT AS THE LOW AND
ITS ATTENDANT COLD FRONT PULL OFF WELL TO THE NORTHEAST. SMALL CRAFT
ADVISORY LEVELS WILL LIKELY BE MAINTAINED THROUGH THURSDAY. 34/JFB

&&

.AVIATION...
18Z TAF CYCLE.
LIGHT SOUTHERLY FLOW WITH VFR CONDITIONS EXPECTED THROUGH THE REST
OF TODAY WITH ONLY PASSING MID AND HIGH LEVEL CLOUDS. MID LEVEL
CLOUDS INCREASE OVERNIGHT...WHICH MAKES FOG POTENTIAL UNCERTAIN. KEPT
AN MVFR VSBY MENTION AT THE TERMINALS FOR THE EARLY MORNING. A COLD
FRONT WILL APPROACH FORM THE NORTHWEST TOMORROW...NEARING MOB/BFM BY
18Z AND PNS A FEW HOURS AFTER. A FEW SHOWERS ALONG WITH BROKEN CIGS
OF 3-5 KFT EXPECTED WITH THE FRONTAL PASSAGE. 34/JFB &&

.FIRE WEATHER...APPROACHING STORM SYSTEM WILL PRODUCE RAIN AS EARLY
AS TONIGHT IN NORTHWEST ZONES WITH EMBEDDED THUNDERSTORMS MONDAY.
DECREASING RAIN LATE MONDAY WILL BE FOLLOWED BY ANOTHER ROUND
TUESDAY. HEAVIEST RAIN WILL BE TUESDAY AND TUESDAY NIGHT AND COULD
REACH 6 TO 8 INCHES ESPECIALLY WITHIN 60 TO 80 MILES OF THE COAST.
MODERATE TO STRONG SOUTHERLY WINDS ALONG COASTAL ZONES TUESDAY AND
TUESDAY NIGHT WILL BECOMING WEST WEDNESDAY. MINIMUM HUMIDITY IN THE
40S AND 50S MOST OF THE WEEK. RH UNLIKELY TO DESCEND TO LESS THAN 35
PERCENT UNTIL FRIDAY.

&&

.PRELIMINARY POINT TEMPS/POPS...
MOBILE      57  67  46  60 /  10  70  20  70
PENSACOLA   57  69  49  61 /  05  60  20  60
DESTIN      57  69  51  60 /  05  50  20  60
EVERGREEN   49  64  39  59 /  10  70  05  50
WAYNESBORO  51  62  39  56 /  30  80  05  60
CAMDEN      51  63  36  57 /  20  80  05  40
CRESTVIEW   49  69  44  63 /  05  50  10  50

&&

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

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE MOBILE AL
355 PM CST SUN NOV 29 2009

ALZ051>064-FLZ001>006-GMZ630-650-655-670-675-MSZ067-075-076-078-
079-302200-
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-
355 PM CST SUN NOV 29 2009

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

.DAY ONE...TONIGHT AND MONDAY.

HAZARDOUS WEATHER IS NOT EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...MONDAY NIGHT THROUGH SATURDAY.

A MODERATE TO STRONG OFFSHORE FLOW AND BUILDING SEAS IS EXPECTED
OVER THE COASTAL WATERS MONDAY NIGHT IN THE WAKE OF A FRONTAL
PASSAGE. SMALL CRAFT ARE ADVISED TO EXERCISE CAUTION.

A SURFACE LOW WILL DEVELOP OVER THE WESTERN GULF ON TUESDAY AND
DEEPEN AS IT TRACKS TOWARD THE NORTHERN GULF COAST TUESDAY NIGHT
INTO EARLY WEDNESDAY. RAIN CHANCES WILL CONTINUE TO INCREASE WITH
EMBEDDED THUNDERSTORMS NEAR THE COAST AND OFFSHORE LATE TUESDAY INTO
WEDNESDAY. SOME OF THE RAIN COULD BE HEAVY AND SEVERAL INCHES OF
RAIN IS POSSIBLE ESPECIALLY CLOSER TO THE COAST. THIS HEAVY RAIN
COULD PRODUCE LOCALIZED FLOODING IN POOR DRAINAGE AREAS. OVER THE
MARINE AREA...CONDITIONS ARE FORECAST TO WORSEN WITH WINDS
INCREASING CLOSE TO GALE FORCE BY TUESDAY NIGHT. THE DURATION OF A
STRONG EASTERLY AND THEN SOUTHERLY FETCH RESULTS IN SEAS BUILDING TO
AROUND 8 FEET NEAR SHORE...UPWARDS TO AROUND 13 FEET WELL OFFSHORE.
THERE IS A SLIGHT RISK THAT SOME OF THE STORMS OFFSHORE AND ALONG
THE IMMEDIATE COAST COULD BECOME SEVERE WITH ISOLATED TORNADOES
TUESDAY NIGHT INTO WEDNESDAY MORNING.

ASTRONOMICAL HIGH TIDES ARE FORECAST AS WINDS INCREASE AND TAKE ON A
SOUTHERLY COMPONENT TUESDAY NIGHT. THERE IS AN INCREASED RISK OF
MINOR COASTAL FLOODING LATE TUESDAY...ESPECIALLY OVER THE WEST END
OF DAUPHIN ISLAND...AROUND THE WESTERN SHORES OF MOBILE BAY...AND
ALONG THE IMMEDIATE COAST FROM FORT MORGAN TO FORT PICKENS.

STAY TUNED FOR ADDITIONAL FORECASTS AND UPDATES FROM THE NATIONAL
WEATHER SERVICE ON THIS DEVELOPING LOW PRESSURE SYSTEM.

IN THE WAKE OF THE LOW...HAZARDOUS CONDITIONS OVER THE COASTAL
WATERS LOOK TO CONTINUE THROUGH THURSDAY...WITH A MODERATE OFFSHORE
FLOW AND MODERATE SEAS THURSDAY THROUGH SATURDAY.

.SPOTTER INFORMATION STATEMENT...

ACTIVATION OF STORM SPOTTERS AND EMERGENCY MANAGEMENT FOR SEVERE
WEATHER WILL NOT BE REQUIRED THROUGH MONDAY.