Severe Thunderstorm Warning 10, NWS Melbourne, FL

EAST CENTRAL FLORIDA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MELBOURNE FL
300 PM EST THU MAR 13 2003

...ENHANCED RAIN CHANCES INTO THE WEEKEND WITH POTENTIAL FOR STRONG
STORMS...

16Z CAPE SOUNDING SHOWS OFFSHORE FLOW STRONGER THAN MODELS FORECAST.
AS EXPECTED SEA BREEZE HAS DEVELOPED IN MARTIN COUNTY FIRST BUT THE
ONSET MAY BE LATER THAN EXPECTED ELSEWHERE. CU REMAINS QUITE
SUPPRESSED WITH WEST COAST SEA BREEZE NOT PRODUCING ANY CONVECTION.
SEE PREVIOUS AFD ISSUED AT 1 PM REGARDING CONVECTIVE THREAT THIS
AFTN/EVE FOR EC FL.

MODELS AGREE IN DEVELOPING A CUT-OFF LOW OVER THE LOWER MS VALLEY
EARLY FRI AND CONTINUING THROUGH SAT. THIS WILL ADD DIFFLUENCE ALOFT
TO THE ALREADY LOADED ATM. STEEP LAPSE RATES AND COLD AIR ALOFT WILL
COMBINE WITH SUFFICIENT MOISTURE...AND SOON UPPER LEVEL DYNAMICS...
TO PRODUCE HIGHER COVERAGE OF STORMS FRI AND SAT WITH POTENTIAL OF
SEVERE STORMS. AS A RESULT...ONCE CONVECTION GETS GOING FRI AFTN IT
WILL NOT STOP...CONTINUING OVERNIGHT FRI. WE WILL NOT BE AS
SUPPRESSED FRI...SO EXPECT EARLIER CONVECTIVE INITIATION THAN TODAY.
PLUS...WITH FRONTAL ZONE ACROSS THE AREA GRADIENT WILL BE WEAKER SO
SEA BREEZE WILL DEVELOP EARLIER AND MAKE IT FARTHER INLAND. THIS
WILL KEEP MLB/VRB/FPR TEMPS COOLER THAN TODAY.

NOT SURE WHY AVN POPS ARE LOWER SOUTH THAN NORTH FRI...AND THINK
OVERALL POPS ARE A LITTLE LOW. SO WILL RAISE EVERYONE TO 40%. WILL
FOLLOW HIGH AVN MOS POPS FRI NIGHT AND SAT.

UPPER LOW WEAKENS BY SUN AND LIFTS NE. SHOULD SEE A RESPITE FROM THE
HIGH POPS BUT SCATTERED CONVECTION STILL EXPECTED SUN. PASSAGE OF
UPPER TROUGH SHOULD BRING IN SOME DRIER AIR MON SO WILL LEAVE RAIN
CHANCES OUT. EXTENDED AVN BRINGS THE NEXT FRONT THROUGH WED NIGHT
WITH A BAND OF CONVECTION. BUT SFC HIGH BEHIND IT IS VERY WEAK (1019
MB). STRONGLY SUSPECT TIMING OF THIS IS TOO FAST. WILL HOLD OFF ON
RAIN CHANCES WITH THIS NEXT FRONT AND KEEP WED/THU DRY FOR NOW.

PRELIM CCF NUMBERS...
DAB BT 063/080 065/078 063 3477
MCO BT 064/085 065/083 064 1477
MLB BT 065/081 067/082 063 3477

.MLB...NONE.

PUBLIC/MARINE...KELLY
AVIATION/FIRE WX...GITTINGER

AMZ550-555-570-575-FLZ041-044>047-053-054-058-059-064-141-144-147-
132200-

EAST CENTRAL FLORIDA HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE MELBOURNE FL
1115 AM EST THU MAR 13 2003

.DAY ONE...THIS AFTERNOON:

...SCATTERED STRONG TO SEVERE THUNDERSTORMS POSSIBLE TODAY...

SLOWLY INCREASING MOISTURE AND UPPER LEVEL IMPULSES MOVING OVERHEAD
WILL PRODUCE A VERY UNSTABLE ATMOSPHERE ACROSS CENTRAL FLORIDA THIS
AFTERNOON. DAYTIME HEATING WILL INCREASE THE INSTABILITY AND ALLOW
LAKE AND SEA BREEZE DEVELOPMENT AS WELL. THESE LAKE AND SEE BREEZE
BOUNDARIES...AS WELL AS THUNDERSTORM OUTFLOW BOUNDARIES APPROACHING
FROM THE NORTH WILL PROVIDE A FOCUS FOR SCATTERED THUNDERSTORM
DEVELOPMENT THIS AFTERNOON AND EVENING.

WITH ATMOSPHERIC MOISTURE REMAINING SLIGHTLY LIMITED...THUNDERSTORM
COVERAGE IS EXPECTED TO REMAIN SCATTERED. HOWEVER...SMALL UPPER LEVEL
DISTURBANCES AND COLDER THAN NORMAL AIR IN THE UPPER LEVELS OF THE
ATMOSPHERE WILL PROVIDE AN ENVIRONMENT THAT IS FAVORABLE FOR STRONG
TO SEVERE THUNDERSTORM DEVELOPMENT. THEREFORE...ANY THUNDERSTORMS
THAT DO FORM TODAY WILL HAVE THE POTENTIAL TO PRODUCE EXCESSIVE
LIGHTNING STRIKES...DAMAGING WIND GUSTS IN EXCESS OF 60 MPH AND COIN
SIZE HAIL. THUNDERSTORMS WILL GENERALLY MOVE EAST TO NORTHEAST AT 20
TO 30 MPH...WITH THE STORMS EVENTUALLY PUSHING ACROSS THE
INTRACOASTAL WATERWAYS AND OFFSHORE INTO THE ATLANTIC OCEAN.

PERSONS IN EAST CENTRAL FLORIDA...INCLUDING MARINE INTERESTS...
SHOULD KEEP ALERT FOR APPROACHING STORMS. OPEN PLACES SUCH AS BEACHES
AND GOLF COURSES ARE NOT SAFE FROM THE LIGHTNING DANGER DURING
STORMS...NOR ARE THE OPEN AIR SHELTERS AT MANY OUTDOOR RECREATION
AREAS. CONTINUE TO MONITOR NOAA WEATHER RADIO OR LOCAL MEDIA
OUTLETS FOR STATEMENTS OR WARNINGS REGARDING THIS WEATHER SITUATION
AND BE PREPARED TO TAKE SHELTER IN A STURDY BUILDING BEFORE STORMS
ARE OVERHEAD.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY:

A PERSISTENT MOIST AND UNSTABLE AIR MASS ALONG WITH AN UPPER LEVEL
LOW PRESSURE AREA MOVING ACROSS THE GULF COAST STATES WILL CONTINUE
STORM CHANCES FRIDAY AND INTO THE WEEKEND.

.SPOTTER CALL TO ACTION STATEMENT...

SPOTTERS SHOULD SELF ACTIVATE IF A WARNING IS ISSUED FOR THEIR
COUNTY TODAY.

MJG

FLZ064-140015-

EXCESSIVE LIGHTNING ALERT
NATIONAL WEATHER SERVICE MELBOURNE FL
629 PM EST THU MAR 13 2003

...STORMS WITH EXCESSIVE LIGHTNING OVER SOUTHEASTERN MARTIN COUNTY...
...URBAN AND SMALL STREAM FLOOD ADVISORY EFFECTIVE FOR SOUTHEASTERN
MARTIN COUNTY UNTIL 745 PM EST...

AT 630 PM EST...NATIONAL WEATHER SERVICE LIGHTNING DETECTION
EQUIPMENT INDICATED A STORM WITH EXCESSIVE LIGHTNING OVER JOHNATHAN
DICKINSON STATE PARK...MOVING EAST AT 5 MPH.

THIS STORM IS ALSO CAPABLE OF PRODUCING WIND GUSTS TO 55 MPH AND PEA
TO MARBLE SIZE HAIL. RADAR RAINFALL ESTIMATES OF 2 TO 3 INCHES AN
HOUR OVER SOUTHEAST MARTIN COUNTY WILL CAUSE PONDING OF WATER ON
ROADWAYS AND LOCALIZED FLOODING. MOTORISTS SHOULD EXERCISE CAUTION.

IF YOU ARE OUTDOORS...TAKE SHELTER IN A BUILDING OR ENCLOSED
AUTOMOBILE. TREES AND OPEN SHELTERS FOUND ON A BEACH OR GOLF COURSE
OFFER NO PROTECTION.

BOATERS BETWEEN HOBE SOUND AND JUPITER INLET ARE ESPECIALLY
VULNERABLE TO THE DANGERS OF LIGHTNING. GET TO SAFE HARBOR AT THE
FIRST SIGN OF A LIGHTNING STORM THEN SEEK SHELTER IN A BUILDING OR
ENCLOSED VEHICLE AS QUICKLY AS POSSIBLE.

FLZ059-140100-

SPECIAL WEATHER STATEMENT FOR STRONG WINDS AND SMALL HAIL
NATIONAL WEATHER SERVICE MELBOURNE FL
705 PM EST THU MAR 13 2003

...STRONG STORM CAPABLE OF PRODUCING WINDS UP TO 55 MPH AND SMALL
HAIL DEVELOPING IN CENTRAL ST. LUCIE COUNTY...

AT 703 PM EST...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STORM CAPABLE OF PRODUCING STRONG WINDS AND SMALL HAIL 6 MILES WEST
OF SAINT LUCIE WEST...MOVING EAST AT 15 MPH.

LOCATIONS IN THE PATH OF THE STORM WHICH MAY EXPERIENCE STRONG WINDS
AND SMALL HAIL INCLUDE INDIAN RIVER ESTATES AND PORT SAINT LUCIE
RIVER PARK.

IF THE STORM BECOMES SEVERE...A WARNING WILL BE ISSUED.