Severe Thunderstorm Warning 117, NWS Mobile, AL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOBILE AL
340 PM CDT WED JUN 13 2001

DIURNAL TEMPERATURE FORECAST AND PLACEMENT OF PRECIPITATION WILL BE
A MAJOR FACTOR IN THE FORECAST PROCESS THROUGH DAY ONE.  VIS SAT IMG
SHOWING THE LEADING EDGE OF A MODERATE SEA BREEZE FROM HATTIESBURG,
MS TO JUST SOUTH OF EVERGREEN, AL CREEPING NORTHWARD AND INTERACTING
WITH NUMEROUS OUTFLOW BOUNDARIES FROM PREVIOUS CONVECTION.  ONE
DISCERNIBLE PATTERN IN THE DEVELOPMENT OF THE CONVECTION IS THAT ITS
MAIN TRIGGER IS THE SEA BREEZE.  HOWEVER CONFIDENCE REMAINS LOW AS
TO HOW LONG AND WHERE THE CONVECTION WILL REMAIN THROUGH THIS
EVENING...PARTICULARLY SINCE A FEW CELLS SOUTH OF THE SEA BREEZE HAD
PERSISTED ON OUTFLOW BOUNDARIES AND DUMPED UP TO FOUR INCHES OF RAIN
IN THE PAST THREE HOURS. FORECASTING HIGH TEMPERATURES THIS
AFTERNOON WAS LESS PREDICTABLE WITH RANGES FROM THE MID 70S IN RAIN
COOLED AREAS TO AROUND 90 FAR NORTHERN ZONES.

I EXPECT MUCH THE SAME FOR TOMORROW UNDER SIMILAR CONDITIONS WITH
ADEQUATE BOUNDARY LAYER MOISTURE REMAINING (PRECIPITABLE WATER
VALUES AROUND 1.75)...INCREASING INSTABILITY (LIS -5/SBCAPES
2500-3000 J/KG)...AFTERNOON HIGHS 85 TO 90 AND WEAK SURFACE
BOUNDARY  CONVERGENCE.  ONCE AGAIN EXPECT INITIAL DEVELOPMENT OF
CONVECTION
IN THE AM JUST OFF THE COAST (A FEW WATERSPOUTS POSSIBLE) THEN
GRADUALLY MOVING INLAND.  WILL NEED TO RELY ON SURFACE CONVERGENCE
AS PRIMARY TRIGGER...HOWEVER UPPER SUPPORT FOR SUSTAINED CONVECTION
WILL WEAKEN THROUGHOUT THE DAY AS RIDGING BUILDS SLIGHTLY...ALSO
SURFACE PRESSURES ARE EXPECTED TO RISE A FEW MB.  THIS SHOULD RESULT
IN WEAKER UPDRAFT AND HENCE LOWER POTENTIAL FOR COVERAGE AND
INTENSITY OF HEAVY RAINFALL.

EXPECT ONLY SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS FRIDAY AS
UPPER RIDGE BUILDS...TEMPERATURES MATCHING GUID (AROUND 90).  BASE
OF BROAD UPPER TROUGH MOVING THROUGH THE NORTHERN MISSISSIPPI RIVER
VALLEY THIS WEEKEND WILL FLATTEN UPPER RIDGING BRINGING A CHANCE OF
AFTERNOON SHOWERS AND THUNDERSTORMS TO THE NORTHERN ZONES...MAINLY
SLIGHT CHANCE SOUTHERN ZONES.  FAIRLY DRY INTO MID WEEK WITH
TEMPERATURE HEAR CLIMATE NORMS.

FIRE...NO CONCERNS DUE TO HIGH HUMIDITY AND MODERATE DISPERSION.

MARINE...SOUTH WINDS THROUGH FRIDAY 10 TO 15 KNOTS BECOMING WEST AND
NORTH THROUGH THE WEEKEND WITH TROUGH PASSAGE.  SEAS AROUND 3 FEET.

22

PRELIM NUMBERS...
MOB BB 074/088 073/090 072 22141
PNS BB 074/087 075/089 073 22141
DTS BB 075/085 075/087 076 22141
GZH BB 072/089 072/091 070 22042
2R0 BB 072/089 072/090 068 22142
61A BB 071/090 070/090 068 22142

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