[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 302356
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT JUL 30 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2330 UTC.

...TROPICAL WAVES...

TROPICAL WAVE ALONG 42W SOUTH OF 18N MOVING WEST 15-20 KT.
CONVECTION REMAINS LIMITED AND DISORGANIZED AS WAVE IS EMBEDDED
IN VERY DRY AIR AND SUBSIDENCE.

TROPICAL WAVE ALONG 55W SOUTH OF 18N MOVING WEST 20 KT WITH A
1012 MB LOW NEAR 11N/12N. CONVECTION ASSOCIATED WITH THIS WAVE
IS QUITE ACTIVE...WITH SCATTERED MODERATE/ISOLATED STRONG
CONVECTION EXTENDING FROM 10N-17N ALONG AND W OF THE WAVE AXIS
TO 58W. SURFACE OBSERVATIONS SHOW THAT THE WAVE IS AT THE
LEADING EDGE OF A WIND/AFRICAN DUST SURGE...WITH WINDS OF 20-25
KT BEHIND THE WAVE.  WHILE LITTLE IN THE WAY OF ORGANIZATION IS
CURRENTLY NOTED...CONDITIONS MAY BECOME SOMEWHAT MORE FAVORABLE
FOR DEVELOPMENT DURING THE NEXT 24-36 HOURS AS THE WAVE MOVES
AROUND THE SW PERIPHERY OF THE MID/UPPER LEVEL HIGH OVER THE
CENTRAL ATLC. ON ITS CURRENT MOTION...SHOWERS AND TSTMS WILL
BEGIN TO AFFECT THE WINDWARD ISLANDS LATE TONIGHT OR EARLY SUN
WITH GUSTY WINDS AND LOCALLY HEAVY RAINS.

A WELL-DEFINED TROPICAL WAVE IS LOCATED OVER THE CENTRAL
CARIBBEAN AND SW ATLANTIC ALONG FROM 12N72W TO 23N68W MOVING
WEST 15-20 KT. SATELLITE IMAGERY...SURFACE OBSERVATIONS...AND
QUIKSCAT DATA SHOW THE WAVE AXIS CONTINUES TO BE QUITE SHARP BUT
LACKS A DISCERNIBLE LOW LEVEL CIRCULATION.  NONETHELESS...THE
WAVE CONTINUES TO BE VERY ACTIVE WITH SCATTERED MODERATE TO
STRONG CONVECTION FROM 17N-22N BETWEEN 65W-73W INCLUDING MUCH OF
HISPANIOLA WHERE SATELLITE RAINFALL ESTIMATES INDICATE AMOUNTS
OF 4 INCHES ARE POSSIBLE.  THE MIDDLE TO UPPER LOW TO THE NW OF
THE WAVE HAS YET TO PULL AWAY PRODUCING S-SW UPPER LEVEL FLOW
AND A MARGINALLY UNFAVORABLE ENVIRONMENT FOR DEVELOPMENT.
ADDITIONALLY...THE PROXIMITY OF THE SYSTEM TO HISPANIOLA IS
LIKELY INHIBITED SIGNIFICANT DEVELOPMENT AT THIS TIME.
REGARDLESS...HEAVY RAINS ...FLOODING...AND POSSIBLE MUDSLIDES
WILL CONTINUE TO AFFECT HISPANIOLA THIS EVENING AND TONIGHT.
THIS ACTIVITY WILL ALSO BEGIN AFFECTING THE S BAHAMAS AND E CUBA
LATER TONIGHT THEN SPREAD ACROSS THE REMAINDER OF THE BAHAMAS
AND W CUBA ON SUNDAY.

...ITCZ...

ITCZ AXIS EMERGES OFF THE COAST OF AFRICA NEAR GUINEA EXTENDING
WESTWARD ALONG 9N30W 13N40W 11N50W 9N61W CONTINUING ACROSS N
PORTIONS OF S AMERICA. A SMALL CLUSTER OF SCATTERED STRONG
CONVECTION IS LOCATED FROM 8N-10N BETWEEN 19W-21W.
ELSEWHERE...WIDELY SCATTERED SHOWERS AND ISOLATED MODERATE
CONVECTION WITHIN 400 NM S OF ITCZ.

...DISCUSSION...
GULF OF MEXICO...
MID/UPPER LEVEL LONGWAVE TROUGH EXTENDS OVER THE LOWER
MISSISSIPPI VALLEY TO THE EXTREME NW GULF ALONG THE TEXAS COAST.
WATER VAPOR IMAGERY INDICATES DRY AIR AND SUBSIDENCE RIGHT ALONG
THE IMMEDIATE COASTAL WATERS OF W LOUISIANA AND TEXAS...LIMITING
CONVECTION IN THESE AREAS. E OF THE UPPER TROUGH...BROAD
DIFFLUENCE COUPLED WITH A WEAK SURFACE LOW...1015...OVER SE
LOUISIANA CONTINUES TO TRIGGER CLOUDINESS AND WIDELY SCATTERED
SHOWERS/TSTMS OVER THE N GULF N OF ABOUT 24N. THE MOST NUMEROUS
AND STRONGEST OF THIS ACTIVITY CURRENTLY RESIDES OVER THE NE
GULF FROM THE WITHIN 100-200 NM EITHER SIDE OF A LINE FROM THE
FLORIDA BIG BEND AREA SW TO 24N90W.  FARTHER S...STORMINESS
CONTINUES OVER MUCH OF FLORIDA COURTESY OF A MID/UPPER LOW OVER
THE SE GULF AND A SURFACE TROUGH FROM W CUBA TO CENTRAL
FLORIDA.  BOTH FEATURES WILL TRANSITION SLOWLY WESTWARD DURING
THE NEXT 24 HOURS ALLOWING UNSETTLED/STORMY CONDITIONS TO
CONTINUE OVER THE E GULF AND FLORIDA THROUGH SUNDAY.
FINALLY...AN UPPER LEVEL LOW OVER THE SW GULF CENTERED 21N94W IS
DRIFTING W TOWARDS THE MEXICO COAST...WITH LITTLE CONVECTION
MAINLY DUE TO DRY AIR ALOFT.

CARIBBEAN SEA...
ISOLATED SHOWERS/TSTMS ARE CURRENTLY NOTED THROUGHOUT CENTRAL
AMERICA...ALBEIT FAR LESS NUMEROUS THAN YESTERDAY AS THE VERY
ACTIVE TROPICAL WAVE PULLS AWAY. THE STRONGEST AND MOST NUMEROUS
OF THIS ACTIVITY IS CURRENTLY OVER N GUATEMALA AND THE YUCATAN
PENINSULA.  ADDITIONAL ACTIVITY IS NOTED OVER PANAMA WHERE THE
ITCZ HAS BEEN PULLED NWD. EXPECT AFTERNOON SHOWERS/TSTMS TO
RETURN TO MORE NORMAL COVERAGE AS A ANTICYCLONE CURRENTLY
POSITIONED OVER HONDURAS SHIFTS WESTWARD ALLOWING DRIER AIR
ALOFT TO MOVE OVER THE AREA. SHIFTING EWD...A WEAK MID/UPPER
LEVEL LOW S OF HAITI NEAR 17N74W CONTINUES TO INTERACT WITH A
STRONG TROPICAL WAVE OVER HISPANIOLA TO PRODUCE VERY HEAVY
RAINFALL.  SEE TROPICAL WAVES ABOVE. ELSEWHERE...THE E CARIBBEAN
IS EXPERIENCING AN INFLUX OF DEEP TROPICAL MOISTURE AS SLY FLOW
E OF THE AFOREMENTIONED WAVE EXTENDS NWD FROM SOUTH AMERICA
THROUGH HISPANIOLA AND PUERTO RICO. AS A RESULT...SHOWERS AND
TSTMS WILL CONTINUE TO INCREASE OVER THE E CARIBBEAN ESPECIALLY
AS A STRONG TROPICAL WAVE NEAR 55W ENTERS THE AREA LATER TONIGHT
AND SUNDAY.

ATLANTIC OCEAN...
SUBTROPICAL RIDGE IS CONFINED TO NW CORNER OF AREA AS THE
MID-OCEANIC TROUGH...COMPRISED OF A STRONG UPPER LOW NEAR
31N40W...CONTINUES ITS DOMINANCE OF THE E HALF OF THE ATLC.
SCATTERED SHOWERS/TSTMS HAVE BECOME MORE NUMEROUS NEAR THE COLD
CORE LOW WITH SCATTERED TO LOCALLY NUMEROUS ACTIVITY FROM
24N-32N BETWEEN 35W-47W.  OVER THE W ATLC...THE W EXTENT OF THE
MID-OCEANIC TROUGH HAS FRACTURED FORMING TWO RETROGRADING UPPER
LOWS...THE STRONGEST NEAR 26N68W...AND THE SECOND MOVING INTO
THE SE GLFMEX.  THESE TWO UPPER LOWS COMBINED WITH AMPLE
TROPICAL MOISTURE ASSOCIATED WITH TROPICAL WAVES HAVE PRODUCED
VERY STORMY CONDITIONS OVER MUCH OF THE W ATLC WATERS AND THE
BAHAMAS.  THE STRONGEST AND MOST NUMEROUS ACTIVITY IS CURRENTLY
LOCATED FROM PUERTO RICO AND HISPANIOLA NWD TO 25N BETWEEN 58W
AND THE TURKS/CAICOS.  THIS ACTIVITY WILL CONTINUE TO SPREAD
WEST-NORTHWESTWARD AROUND THE SW PERIPHERY OF THE W ATLC
SUBTROPICAL RIDGE SPREADING LOCALLY HEAVY RAINFALL AND GUSTY
WINDS OVER THE S BAHAMAS TONIGHT AND THE REMAINDER OF THE
BAHAMAS ON SUNDAY.  OVER THE REMAINDER OF THE ATLANTIC...A LARGE
AREA OF SAHARAN DUST CONTINUES TO MARCH WESTWARD FROM THE ITCZ
NWD T0 25N E OF A TROPICAL WAVE ALONG 55W. EARLIER VISIBLE
SATELLITE IMAGERY INDICATES THE HIGHEST CONCENTRATION OF DUST IS
E OF 30W.

$$
RHOME



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