FXUS64 KMOB 292153
AFDMOB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOBILE AL
353 PM CST SUN NOV 29 2009
.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.
&&
$$
