Heat in Florida, August 5, 2010

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MIAMI FL
305 PM EDT THU AUG 5 2010

.DISCUSSION...
CURRENT WATER VAPOR IMAGERY INDICATES THAT A WEAK MID-LEVEL SHEAR
AXIS REMAINS IN PLACE ACROSS SOUTH FLORIDA AND THE ADJACENT
COASTAL WATERS THIS AFTERNOON...WITH THIS FEATURE THE REMNANTS OF
AN INVERTED TROUGH WHICH BROUGHT MORE WIDESPREAD CONVECTION TO THE
REGION ON WEDNESDAY. SHOWER AND THUNDERSTORM ACTIVITY HAS
STRUGGLED SO FAR TODAY...DUE TO THE PRESENCE OF A WEAKER SHEAR
AXIS ALOFT...CONFIRMED BY 1-3 DEGREES OF WARMING IN THE MID-
LEVELS SEEN ON MORNING RAOB FROM KMFL. EXPECT HIGHEST COVERAGE OF
PRECIPITATION THROUGH REST OF THE AFTERNOON TO BE IN THE REGION
FROM LAKE OKEECHOBEE SOUTHWESTWARD TO THE GULF COAST...AND WILL
LEAVE HIGHEST POPS IN PLACE FOR THIS PORTION OF THE FORECAST AREA.

THROUGH THE REMAINDER OF THE SHORT TERM PERIOD...MODELS CONTINUE
TO INDICATE A WARMING/DRYING TREND ACROSS SOUTH FLORIDA...AS THE
WEAK SHEAR AXIS ALOFT CURRENTLY IN PLACE OVER THE AREA IS
GRADUALLY FORCED EASTWARD TOWARD THE NORTHERN BAHAMAS. THIS WILL
OCCUR IN RESPONSE TO AN EAST-SOUTHEASTWARD EXPANSION OF MID-LEVEL
RIDGE CURRENTLY CENTERED OVER THE SOUTHERN PLAINS...AS AN UPPER-
LEVEL TROUGH PROGRESSES SLOWLY ONSHORE ALONG THE PACIFIC COAST.
POINT FORECAST SOUNDINGS FROM THE UKMET/GFS/ECMWF MODELS ALL
SUGGEST SUBSTANTIAL DRYING OF THE MID-LEVELS AS THIS OCCURS...WITH
ISOLATED TO WIDELY SCATTERED SHOWERS/STORMS AT BEST ON FRIDAY AND
SATURDAY AFTERNOONS. AT THE SURFACE...A LOW-LEVEL RIDGE AXIS WILL
DRIFT SLOWLY SOUTHWARD ACROSS THE AREA...RESULTING IN A
LIGHT/VARIABLE WIND FLOW TOMORROW. THIS SHOULD ALLOW SEA BREEZES
TO PUSH SLOWLY INLAND ALONG BOTH COASTS...WITH CONVECTIVE THREAT
CONFINED TO THE INTERIOR PENINSULA. THE LOW/MID-LEVEL RIDGE AXIS
WILL LIKELY BE LOCATED ACROSS THE FLORIDA STRAITS AND KEYS ON
SATURDAY...PERHAPS LEADING TO A SLIGHTLY MORE PRONOUNCED WESTERLY
STEERING FLOW...AND FOR THIS REASON WILL INDICATE HIGHER RAIN
CHANCES FOR EASTERN INTERIOR AND ATLANTIC COAST PORTIONS OF THE
MAINLAND. LIGHT/VARIABLE TO LIGHT SOUTHWESTERLY BOUNDARY LAYER
FLOW OVER THE ATLANTIC WILL LIMIT THE THREAT FOR NOCTURNAL SHOWER
ACTIVITY ON THE EAST COAST EACH NIGHT THROUGH THE PERIOD...
ALTHOUGH A FEW SHOWERS MAY BE POSSIBLE AT NIGHT ALONG THE GULF
COAST IN THIS REGIME. HIGH TEMPERATURES WILL BE A FEW DEGREES
WARMER ACROSS THE AREA...WITH LESS CLOUD COVER/PRECIPITATION AND
SLOWER INLAND MOTION OF SEA BREEZES. LOW TEMPERATURES WILL
CONTINUE TO RANGE FROM THE MID 70S TO AROUND 80.

RECENT VERSIONS OF THE ECMWF AND GFS ARE NOW BEGINNING TO SUGGEST
INCREASING RAIN/THUNDERSTORM CHANCES DURING THE FIRST HALF OF
THE EXTENDED FORECAST PERIOD...AS THE WEAKNESS IN THE MID-LEVEL
RIDGE OVER THE BAHAMAS IS FORECAST TO AMPLIFY INTO AN INVERTED
MID-LEVEL TROUGH AND RETROGRADE ACROSS THE AREA EARLY NEXT WEEK...
AS A MID-TROPOSPHERIC RIDGE STRENGTHENS ACROSS THE NORTH ATLANTIC.
DUE TO UNCERTAINTIES IN TIMING OF THIS FEATURE...WILL MAKE NO
MAJOR CHANGES TO THE EXTENDED FORECAST AT THIS TIME...ALTHOUGH
INCREASING RAIN/STORM CHANCES APPEAR TO BE IN ORDER...ESPECIALLY
FROM SUNDAY NIGHT THROUGH TUESDAY. THE MID-LEVEL RIDGE LOOKS TO
BECOME MORE ESTABLISHED ACROSS SOUTH FLORIDA DURING THE SECOND
HALF OF THE WEEK...WITH A RETURN TO WARMER AND DRIER CONDITIONS
ONCE AGAIN.

&&

.MARINE...
THERE ARE NO MARINE WEATHER CONCERNS THROUGH THE PERIOD...WITH
SOUTHEAST TO SOUTH-SOUTHEAST FLOW OF 5-10 KNOTS EXPECTED TO
PERSIST THROUGH THE END OF THE WEEK. WINDS WILL LIKELY VEER TO
SOUTHWEST OVER THE LOCAL WATERS THIS WEEKEND...AS A LOW-LEVEL
RIDGE AXIS PUSHES SOUTHWARD ACROSS THE FLORIDA STRAITS AND KEYS.
THIS RIDGE AXIS IS EXPECTED TO LIFT NORTHWARD EARLY NEXT WEEK...
WITH STRONGER EAST-SOUTHEASTERLY FLOW OF 10-15 KNOTS ANTICIPATED
FOR REMAINDER OF THE FORECAST PERIOD. SEAS WILL RANGE FROM 1-3
FEET IN THE GULF STREAM...TO AROUND 1 FOOT ON REST OF THE COASTAL
WATERS.

&&

.FIRE WEATHER...
THERE ARE NO FIRE WEATHER CONCERNS...WITH MINIMUM AFTERNOON RH
VALUES EXPECTED TO REMAIN SUFFICIENTLY HIGH ACROSS THE ENTIRE
REGION.

&&

.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH  78  91  75  91 / 20 20 20 40
FORT LAUDERDALE  81  91  79  91 / 20 20 20 30
MIAMI            80  92  79  92 / 20 20 20 30
NAPLES           77  92  77  92 / 20 20 20 30

&&

.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.

&&

LONG TERM...70/DD
SHORT TERM/AVIATION...30/KOB

HAZARDOUS WEATHER OUTLOOK FOR SOUTH FLORIDA
NATIONAL WEATHER SERVICE MIAMI FL
506 AM EDT THU AUG 5 2010

FLZ063-066>075-168-172>174-060015-
GLADES-HENDRY-INLAND PALM BEACH-METRO PALM BEACH-COASTAL COLLIER-
INLAND COLLIER-INLAND BROWARD-METRO BROWARD-INLAND MIAMI DADE-
METRO MIAMI DADE-MAINLAND MONROE-COASTAL PALM BEACH-
COASTAL BROWARD-COASTAL MIAMI DADE-FAR SOUTH MIAMI DADE-
506 AM EDT THU AUG 5 2010

...SCATTERED TO NUMEROUS AFTERNOON THUNDERSTORMS INTERIOR AND WEST...
...HEAT INDEX READINGS AROUND 105 OR HIGHER INLAND...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTH FLORIDA.

.DAY ONE...TODAY AND TONIGHT

THUNDERSTORMS: SCATTERED TO NUMEROUS THUNDERSTORMS ARE EXPECTED
TO DEVELOP THIS AFTERNOON ACROSS INTERIOR SECTIONS AND THE WEST
COAST. ISOLATED THUNDERSTORMS ARE EXPECTED OVER THE REST OF THE
AREA. A FEW STORMS COULD BECOME STRONG, CONTAINING GUSTY WINDS,
FREQUENT LIGHTNING, AND HEAVY DOWNPOURS.

WIND: THE STRONGEST THUNDERSTORMS THIS AFTERNOON MAY PRODUCE WIND GUSTS
OF 40 TO 50 MPH.

FLOODING: SLOW MOVING STORMS WILL RESULT IN THE POTENTIAL FOR
MINOR FLOODING OF STREET AND POORLY DRAINED AREAS THIS AFTERNOON.

TEMPERATURES: HEAT INDEX READINGS BETWEEN 105 AND 109 DEGREES WILL
BE FELT ACROSS MUCH OF THE INTERIOR SECTIONS THIS AFTERNOON, WITH
HEAT INDICES UP TO 105 OVER COASTAL AREAS.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

SCATTERED THUNDERSTORMS WILL CONTINUE EACH AFTERNOON THROUGH THE
PERIOD, MOST FAVORED ACROSS THE INTERIOR.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED, HOWEVER INDIVIDUAL SPOTTERS
ARE ENCOURAGED TO REPORT HIGH WIND, HAIL AND FLOODING TO THE
NATIONAL WEATHER SERVICE FORECAST OFFICE IN MIAMI.

FOR MORE INFORMATION...VISIT THE NATIONAL WEATHER SERVICE IN
MIAMI WEBSITE AT WWW.WEATHER.GOV/MIAMI.