Severe Thunderstorm Warning 65, NWS Miami, FL

SOUTH FLORIDA AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MIAMI
1010 AM EDT MON AUG 18 2003

THE 12Z SOUNDING SHOWS FAIRLY LIGHT STEERING FLOW THIS MORNING...ON
THE ORDER OF 5 TO 10 KNOTS. SURFACE ANALYSIS SHOWS THE RIDGE AXIS
VERO BEACH THROUGH TAMPA...LEAVING LIGHT SOUTHEAST SURFACE FLOW IN
PLACE. CONVERGENT FLOW IS ALLOWING FOR SCATTERED SHOWERS AND
THUNDERSTORMS IN THE ATLANTIC WATERS. SLIGHTLY MORE UNSTABLE TODAY
THAN YESTERDAY AS WELL. OF NOTE...LIFTED INDEX THIS MORNING WAS
AROUND -9...ENOUGH TO SPARK DECENT CONVECTION THIS AFTERNOON WITH
MAX HEATING.

EXPECT WEAK SEA BREEZE PENETRATION LATER TODAY. ALONG WITH LIGHT
SOUTHWEST FLOW ALOFT...EXPECT CONVECTION INLAND AND CLOSE TO THE
WESTERN EDGE OF THE EAST COAST METRO AREAS. AGREE WITH MID SHIFT
THAT PALM BEACH COUNTY IS FAVORED OVER REST OF EAST COAST...WHERE
SOUTHWEST FLOW ALOFT IS A LITTLE STRONGER.

WITH PRECIPITABLE WATER VALUES UP NEAR TWO INCHES AND CONSIDERING
THE LIGHT STEERING...IT LOOKS LIKE LOCALLY HEAVY RAINFALL MAY BE IN
THE OFFING FOR THE AFTERNOON. WILL UPDATE ZONES AND WORD FOR THIS.

NO CHANGES PLANNED IN THE MARINE FORECAST MORNING UPDATE. EC.

...PREVIOUS DISCUSSION FOLLOWS...

.S FLA WILL BE IN COL BETWEEN CENTRAL PLAINS RIDGE AND BERMUDA HIGH
WITH A SUBTLE WRINKLE NEXT COUPLE OF DAYS. UPPER TROUGH ALONG E U.S.
COAST FROM NEW ENGLAND TO MID ATLC STATES DIGS NO FURTHER S AND
BEGINS TO LIFT NE AS CENTRAL PLAINS RIDGE GETS SHOVED E BY SHORT
WAVE MOVING SE FROM N ROCKYS. A VORT MAX OVER CENTRAL GULF STATES
(TAIL END OF E COAST TROUGH)...MOVES S INTO N GULF WITH A 500 MB
LOW...ALBEIT WEAK...DEVELOPING. COMBINED WITH WIND CIRCULATION
AROUND BERMUDA HIGH...A SOUTHERLY TO SW WIND FLOW DEVELOPS AS WINDS
VEER FROM A SE TO S SURFACE FLOW TO SW ALOFT WHICH PULLS DEEPER
MOISTURE FROM N CARIB N OVER S FLA.

.FOR THE SHORT TERM...TODAY THROUGH TUESDAY NIGHT...POPS INCREASE
SLIGHTLY. BUT WITH TRAJECTORY AND SEA BREEZE DEVELOPMENT EACH DAY
...N INTERIOR AND NE (PALM BEACH COUNTY)...MOST VULNERABLE WITH 50
PERCENT POPS IMPLANTED INTO AFFECTED ZONES. TEMPS SEASONABLE.

.E COAST UPPER TROUGH MOVES INTO ALTC AS RIDGE CONTINUES E TREK WITH
UPPER GULF LOW TRAPPED UNDERNEATH RIDGE. THE LATTER SYSTEM GETS
PULLED N AS ANOTHER SHORT WAVE DIVING SE OUT OF THE N ROCKYS.
RIDGING NOW DEVELOPS OVER SE U.S. AND ALONG E COAST WITH WIND FLOW
ALL LEVELS BACKING. SLIGHTLY DRIER AIR FROM THE ATLC PULLED OVER
AREA WITH A MORE NORMAL SE TO NW TRAJECTORY DEVELOPING.

.IN THE EXTENDED PERIOD...WED THROUGH SUN...SCATTERED SHOWERS AND
TSTMS EXPECTED EACH DAY WITH LATE NIGHT/EARLY MORNING E COAST
SCENARIO WITH INTERIOR AND W AFTERNOON. TEMPS SEASONABLE.

.IN THE MARINE ZONES...10 KNOTS OR LESS THROUGH THE ENTIRE PERIOD
WITH A SE TO S FLOW BECOMING MORE E TO SE TUE THROUGH FRI.

.NO HIGHLIGHTS REQUIRED FIRE WEATHER.

PBI TT 090/076 090/077 089 1552534
FLL BT 089/078 089/078 088 1542424
MIA BT 090/078 090/078 089 1542424
APF BT 089/075 089/075 090 1541425=

MIA...NONE.

FLZ063-066>075-181800-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE MIAMI FL
1120 AM EDT MON AUG 18 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTH FLORIDA.

.DAY ONE...TODAY

...LOCALLY HEAVY RAINFALL EXPECTED THIS AFTERNOON...

SEA BREEZES OFF THE EAST AND WEST COASTS WILL CONVERGE OVER INTERIOR
SECTIONS TO PRODUCE SCATTERED SHOWERS AND THUNDERSTORMS THIS
AFTERNOON. HOWEVER...LIGHT SOUTHWEST WINDS ALOFT WILL HOLD MUCH OF
THIS ACTIVITY CLOSE TO THE WESTERN EDGES OF THE METROPOLITAN AREAS
ALONG THE EAST COAST BY LATE AFTERNOON. THE INDIVIDUAL STORMS WILL
MOVE VERY SLOWLY TO THE NORTHEAST ONCE THEY FORM. WITH MOISTURE
LEVELS FAIRLY HIGH...AND THE ATMOSPHERE MODERATELY UNSTABLE...THESE
SLOW MOVING STORMS ARE CAPABLE OF PRODUCING UP TO AN INCH OF
RAINFALL PER HOUR.

ADDITIONAL INFORMATION AND DETAILED GRAPHICS CAN BE FOUND ON
THE NATIONAL WEATHER SERVICE WEB SITE AT MIAMIWEATHER.INFO.
FOR INFORMATION IN SPANISH, VISIT OUR WEB SITE AT
ELTIEMPOENMIAMI.INFO.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED.