Severe Thunderstorm Warning 172, NWS Jacksonville, FL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSONVILLE FL
250 PM EDT SAT JUL 15 2000

CURRENTLY...SFC ANALYSIS SHOWS WELL DEFINED TROUGH FROM SSI-JAX-CTY.
THIS IS SERVING AS FOCUS FOR WIDELY SCT CONVECTION TO DEVELOP OVER
NE FL. AS EXPECTED HEAVIEST CONVECTION DOWN NEAR MARION COUNTY AND
PUTNAM CO. LOWER DEWPOINTS BEING OBSERVED OVER SE GA WITH AMG
REPORTING LOWER 60S NOW AND TEMPS ARE GETTING UP INTO THE SWELTERING
UPPER 90S. MAY BEING SEEING THE SIGNS OF RIVER BREEZE WHICH WILL
ALSO HELP INITIATE A FEW SHOWERS AND TSRA. ON THE LARGER
SCALE...MID/UPPER LEVEL TROUGH EXTENDS FROM NE U.S. TO THE FL E
COAST.

FORECAST...MODELS IN FAIR AGREEMENT THIS PACKAGE. ALL MODELS HAVE A
GOOD HANDLE ON THE SFC TROUGH BUT THE NGM SEEMS BETTER WITH HANDLING
PRECIP PATTERN SO FAR TODAY. THE TROUGH WILL BROADEN DURING THE PD
AND ALLOW GULF MOISTURE TO ADVECT INTO THE LOWER LEVELS OVER
SUWANNEE VALLEY AND POINTS S. AT MID/UPPER LEVELS...MODELS AMPLIFY
MID/UPPER LEVEL TROUGH OVER THE ERN U.S. THROUGH SUN AND TAKE IT
FARTHER OFFSHORE BY 00Z TUE. AVNS HANDLING OF SHORTWAVE EARLY MON
SEEMS OVERDONE AND PREFER THE ETA/NGM PROGS. SHORTWAVE COMING DOWN
DOWN INTO THE TROUGH SUN SHOULD AID IN WEAK DYNAMIC LIFT DURING THE
DAY. NOTED THAT THE NGM CAPTURED THIS SHORTWAVE FEATURE WELL TO OUR
NW WHERE WIDELY SCT PRECIP...ALBEIT WEAK...WAS FALLING AROUND AR.
MAIN LIMITING FACTOR WILL BE MOISTURE AND THINK ETA AND NGM PROGS
ARE IN LINE. SO BASICALLY PREFER NGM POPS AND TEMPS THIS PACKAGE.
THINK OVERNIGHT LOWS COULD BE A TAD HIGH WITH NGM AND WILL UNDERCUT
A DEG OR TWO. MOISTURE INCREASES FURTHER ON MON BUT NVA TAKES HOLD
OVER THE NRN HALF OF THE AREA AND MAY SUPPRESS CONVECTION. NOT
EXPECTING E COAST SEA BREEZE TO BE A PLAYER DURING THE PD DUE TO
MEAN LOW LEVEL WINDS OF ABOVE 10 KT. WILL KEEP HIGHEST POPS TO THE S
CWA WHERE DEEPER MOISTURE EXISTS IN THE PD.

MARINE...OBS INDICATING SW 10-15 KT WITH LITTLE LIGHTER WINDS NEAR
SHORE OVER GA. SFC LOW DEVELOPING IN THE VICINITY OF SW TO S CENTRAL
GA TO INCREASE PRES GRADIENT OVER THE MARINE WATERS. TREND OF
INCREASING WINDS FOR SUN LOOKS GOOD. MODELS A LITTLE INCONSISTENT
WITH REGARD TO WIND SPEEDS SUN NIGHT BUT ALL DO AGREE ON WINDS
INCREASING TO 15 TO 20 KT FOR ABOUT HALF THE SUN NIGHT PD OVER THE
WATERS...SO WILL GO WITH THIS SCENARIO.

PRELIM
AMG 70/97/69/96 -112
SSI 75/92/74/92 -212
JAX? 73/97/74/96 1323
GNV 74/95/74/94 1323 02

.JAX...
.GA...NONE
.FL...NONE

ARS

FLZ020>025-030>033-035>038-040-GAZ132>136-149>154-162>166-152200-

NORTHEAST FLORIDA/SOUTHEAST GEORGIA HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE JACKSONVILLE FL
1246 PM EDT SAT JUL 15 2000

THE COMBINATION OF LOW LEVEL MOISTURE...DAYTIME HEATING...AND AN
UPPER TROUGH WILL PRODUCE SCATTERED SHOWERS AND THUNDERSTORMS THIS
AFTERNOON OVER NORTH FLORIDA...MAINLY SOUTH OF INTERSTATE 10. THESE
THUNDERSTORMS WILL BE CAPABLE OF PRODUCING FREQUENT LIGHTNING...WIND
GUSTS OVER 40 MPH...BRIEF HEAVY RAIN...AND HAIL. ISOLATED SHOWERS AND
THUNDERSTORMS ARE EXPECTED NORTH OF INTERSTATE 10 INTO SOUTHERN
GEORGIA...PRIMARIY OCCURRING NEAR THE EAST COAST WITH THE SEABREEZE.
THE STORMS THAT DEVELOP THIS AFTERNOON WILL MOVE TOWARDS THE EAST AND
SOUTHEAST AROUND 15 MPH.

ALTHOUGH A FEW STORMS HAVE THE POTENTIAL OF BECOMING SEVERE...SPOTTER
ACTIVATION IS NOT ANTICIPATED THIS AFTERNOON.

HIGH HUMIDITY AND INLAND TEMPERATURES IN THE LOWER 90S HAVE ALREADY
PRODUCED HEAT INDICES EXCEEDING THE CENTURY MARK. USE CAUTION DURING
OUTDOOR ACTIVITIES THIS AFTERNOON AND DRINK PLENTY OF WATER.

FOR ADDITIONAL INFORMATION...VISIT THE NATIONAL WEATHER SERVICE IN
JACKSONVILLE WEBSITE ON THE INTERNET AT WWW.NWSJAX.NOAA.GOV.