[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 251731
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON JUL 25 2005

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN SECTIONS
OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM
THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON
SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND
METEOROLOGICAL ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURES...

TROPICAL STORM FRANKLIN IS CENTERED NEAR 31.1N 69.6W...OR ABOUT
255 NM WSW OF BERMUDA...AT 25/1500 UTC MOVING ENE 4 KT. MAXIMUM
SUSTAINED WIND SPEED IS 35 KT WITH GUSTS TO 45 KT. ESTIMATED
MINIMUM CENTRAL PRESSURE RECENTLY REPORTED BY AIR FORCE
RECONNAISSANCE IS 999 MB. SEE LATEST NHC FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS. THE
LOW-LEVEL CENTER OF FRANKLIN IS COMPLETELY EXPOSED ABOUT 30-40
NM W/NW OF THE DEEPEST CONVECTION DUE TO THE NLY SHEAR AND
MODERATE SUBSIDENCE ASSOCIATED WITH A SHARP MID/UPPER LEVEL
TROF. WITH THIS UPPER LEVEL ORIENTATION...THE OUTFLOW IS LIMITED
PRIMARILY OVER THE ERN AND SRN SEMICIRCLES. SCATTERED MODERATE/
STRONG CONVECTION IS FROM 25N-32N BETWEEN 63W-70W. SQUALLS OF
SHOWERS/TSTMS AND STRONG GUSTY WINDS WILL CONTINUE MOVING ACROSS
BERMUDA OVER THE NEXT SEVERAL DAYS...DEPENDING ON HOW LONG
FRANKLIN DECIDES TO MEANDER W OF THE ISLAND.

TROPICAL DEPRESSION GERT IS CENTERED NEAR 22.6N 100.6W...OR
ABOUT 35 NM NE OF SAN LUIS POTOSI MEXICO...AT 25/1500 UTC MOVING
W 11 KT. MAXIMUM SUSTAINED WIND SPEED IS 25 KT WITH GUSTS TO 35
KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1008 MB. SEE LATEST
NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22
KNHC FOR MORE DETAILS. GERT HAS CLIMBED THE STEEP SLOPES OF THE
SIERRA MADRES AND IS NOW OVER THE MEXICAN PLATEAU. ALL THAT IS
LEFT OF THE DEEP CONVECTION IS SCATTERED MODERATE WITHIN A BAND
E OF MONTERREY FROM 23N-26N BETWEEN 97W-102W MOVING N TOWARDS
THE RIO GRANDE. WIDESPREAD CLOUDINESS AND SCATTERED SHOWERS
EXTEND ELSEWHERE FROM 20N-27N BETWEEN 98W-102W. THIS IS THE LAST
ADVISORY ISSUED BY THE NATIONAL HURRICANE CENTER...BUT THE
THREAT OF HEAVY RAINFALL WILL CONTINUE OVER PARTS OF N/CNTRL
MEXICO OVER THE NEXT 24 HRS.

...TROPICAL WAVES...

EAST ATLANTIC TROPICAL WAVE ALONG 30W/31W S OF 22N MOVING W 15
KT WITH A 1014 MB LOW EMBEDDED ALONG THE WAVE AND ITCZ NEAR
10.5N31W. MET-8 VISIBLE IMAGERY SHOWS A LARGE AND WELL-DEFINED
CIRCULATION CENTERED ALMOST 500 NM W OF THE CAPE VERDE ISLANDS.
ALTHOUGH THE LOW CENTER APPEARS TO BE LOCATED NEAR 14N/15N...
QUIKSCAT IMAGERY FROM 0740Z INDICATED THAT THE LOW IS FARTHER S
NEAR THE ITCZ. DRY AND STABLE AIR IN THE MID/LOW LEVELS...
INDICATED BY THE STRATOCU FIELD TO THE N...IS BEING ENTRAINED
INTO THE N AND W SIDE OF THE WAVE WHICH IS KEEPING THE BULK OF
THE DEEP CONVECTION WELL S OF THE ITCZ. OTHER WIDELY SCATTERED
SHOWERS/TSTMS ARE NEAR THE LOW FROM 12N-16N BETWEEN 30W-34W.

CENTRAL ATLANTIC TROPICAL ANALYZED FROM FRENCH GUIANA TO 14N53W
22N50W MOVING W 10-15 KT WITH A WEAK 1015 MB LOW NEAR 15N53W.
THE LOW IS BASED ON SLIGHTLY LOWER PRESSURES NEAR BUOY 41040 AND
A WEAK CIRCULATION NOTED IN THE LOW-LEVEL CLOUD FIELD. THE WAVE
HAS BEEN SHARPLY TILTED OVER THE PAST FEW DAYS...AND UPPER AIR
SOUNDING DATA FROM SEVERAL OF THE STATIONS IN THE LESSER
ANTILLES INDICATE THAT THE SRN PORTION OF THE WAVE MAY HAVE
BROKEN AWAY FROM THE MORE WELL-DEFINED NRN PART. THE 18Z
ANALYSIS WILL REFLECT THIS BY PLACING A TRPCL WAVE JUST E OF THE
ABC ISLANDS...AND MAKING THE FEATURE STILL E OF THE ISLANDS A
SFC TROF/LOW. SCATTERED MODERATE CONVECTION IS NEAR THE LOW FROM
15N-17N BETWEEN 51W-54W. SCATTERED SHOWERS/TSTMS ALSO N OF THE
ABC ISLANDS FROM 12N-14N BETWEEN 66W-70W. THE WAVE IS SURROUNDED
BY A LARGE AREA OF DRY AIR...WHICH IS LIMITING CONVECTION...AND
THE LOW IS NOT EXPECTED TO LAST AS IT NEARS THE LESSER ANTILLES.
MOISTURE VALUES WILL RISE A BIT BEHIND THE WAVE BUT THE OVERALL
ENVIRONMENT WILL CONTINUE TO LIMIT WIDESPREAD DEEP CONVECTION.

WEST CARIBBEAN TROPICAL WAVE ALONG 86W/87W S OF 20N MOVING W
15-20 KT. 12Z UPPER AIR DATA FROM SAN JOSE COSTA RICA AND BELIZE
INDICATES THAT THE WAVE IS CURRENTLY BETWEEN THESE TWO
STATIONS...SO THE CURRENT POSITION IS QUITE REASONABLE.
SCATTERED MODERATE CONVECTION IS LAGGING THE WAVE ALONG THE
COAST OF HONDURAS AND NICARAGUA SWD TO NRN COSTA RICA FROM
9N-16N BETWEEN 82W-86W.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 10N14W 13N25W 6N38W 15N50W 12N62W.
SCATTERED MODERATE CONVECTION FROM 10N-16N BETWEEN 19W-25W.
SCATTERED MODERATE WITHIN 200 NM OF THE AXIS BETWEEN 33W-42W.

...DISCUSSION...

GULF OF MEXICO...
WITH T.D. GERT MOVING FARTHER INLAND OVER CNTRL MEXICO...THE
GULF WATERS HAVE CLEARED OUT QUITE NICELY WITH AN ABUNDANCE OF
FAIR SKIES. A SUBTLE SFC TROF EXTENDING AWAY FROM T.S. FRANKLIN
STRETCHES ACROSS FAR S FLORIDA AND THEN OVER THE E GULF WATERS
TO 27N88W WITH WEAK 1015 MB LOW PRES NEAR 26.5N84.5W. THIS
FEATURE HAS CAUSED EXTREMELY WEAK FLOW OVER THE NE GULF AND
WIDELY SCATTERED SHOWERS/TSTMS HAVE DEVELOPED FROM 26N-29N
BETWEEN 87W-92W. THE UPPER LEVEL FLOW IS DOMINATED BY A BROAD
UPPER TROF STRETCHING FROM THE YUCATAN PENINSULA NWD...MOVING W
INTO THE W GULF WATERS BEHIND GERT. THE ATMOSPHERE WILL REMAIN
RELATIVELY DRY OVER THE NEXT FEW DAYS WITH A LOW CHANCE OF
SHOWERS/TSTMS OVER THE WATER. THE BULK OF THE MUCH-HERALDED
AFRICAN DUST IS REMAINING EITHER TO THE S OVER THE CARIBBEAN OR
IS GETTING SUCKED INTO THE CIRCULATION OF FRANKLIN...SO LITTLE
EFFECTS ARE EXPECTED OVER THE GULF REGION.

CARIBBEAN...
WITH THE W CARIBBEAN TRPCL WAVE NOW MOVING ACROSS CNTRL
AMERICA...THE SAHARAN DUST SURGE HAS JUST ABOUT SPREAD ACROSS
THE ENTIRE CARIBBEAN BASIN. THE PLUME CONCENTRATIONS HAVE
THINNED OUT CONSIDERABLY OVER THE PAST FEW DAYS...AND NOW
VISIBLE IMAGERY SUGGESTS ONLY HAZY SKIES OVER THE AREA.
VISIBILITY ACROSS THE CARIBBEAN ISLANDS HAS OCCASIONALLY FALLEN
BELOW 10 MILES...AND THE LOWEST VISIBILITY I CAN FIND IS 3 MILES
AT LA ROMANA DOMINICAN REPUBLIC. CONVECTION IS STRANGELY ABSENT
FOR THIS TIME OF YEAR DUE TO THE WIDESPREAD DRY AIR...ALTHOUGH
SCATTERED MODERATE CONVECTION STILL LIES S OF 14N W OF 80W NEAR
NICARAGUA AND COSTA RICA. THE ATMOSPHERE IS BEING CAPPED BY AN
UPPER LOW SITTING OVER THE DOMINICAN REPUBLIC AND THE ASSOCIATED
SUBSIDENCE EXTENDING OVER MOST OF THE AREA N OF 12N.

ATLANTIC...
A SHARP MID/UPPER LEVEL TROF IS ALIGNED OVER T.S. FRANKLIN AND
IS DRAWING BROAD NLY UPPER LEVEL FLOW TOWARDS THE BAHAMAS AND
CUBA. AN UPPER RIDGE AXIS EXTENDS FROM THE SRN BAHAMAS NEWD TO
28N60W WITH THE ASSOCIATED DIFFLUENCE ALONG ITS NRN PERIPHERY
INITIATING THE CONVECTION TO THE SE OF FRANKLIN'S CENTER.
FARTHER E...ANOTHER SHARP UPPER TROF IS ALONG 29N52W 20N56W BUT
APPEARS TO BE LIFTING TO THE N IN WATER VAPOR IMAGERY. AN
EXTENSION OF THE TROF STRETCHES WELL INTO THE TROPICS ALONG
55W. STRONG UPPER RIDGING LIES ACROSS THE E/CNTRL ATLC ALONG 16N
WHICH IS SUPPORTING DEEP EASTERLY FLOW OVER A LARGE AREA TO ITS
S. HOWEVER...MOISTURE IS MOSTLY LIMITED AND STABLE CONDITIONS N
OF THE ITCZ ARE LIMITING CONVECTION TO TWO MAIN AREAS...S OF THE
TRPCL WAVE ALONG 32W AND BETWEEN SENEGAL AND THE CAPE VERDE
ISLANDS. FARTHER N...A SHEARED UPPER TROF LIES FROM MADEIRA
ISLAND SW TO 23N40W WITH A 40 KT SWLY JET EXTENDING TOWARDS THE
CANARY ISLANDS.

$$
BERG


WWWW
This weather bulletin was brought to you by:
www.nashvilleweather.net