[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 280007
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT FRI MAY 27 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 OVER THE FAR E ATLC ALONG 25W/26W S OF 14N MOVING
W AT AN ESTIMATED SPEED OF 15 KT.  THERE IS LITTLE OR NO
SATELLITE SIGNATURE FOR THIS WAVE AND THE CURRENT POSITION IS
BASED PRIMARILY UPON EXTRAPOLATION.  THE SPEED IS BASED UPON
ESTIMATED PASSAGE THROUGH W AFRICA UPPER AIR STATIONS INDICATING
6-7 DEGREES OF MOVEMENT PER DAY.

TROPICAL WAVE OVER THE CENTRAL ATLC ALONG 46W/47W SOUTH OF 13N
MOVING W AT AN ESTIMATED SPEED OF 15 KT. THIS WAVE IS ALSO
POORLY DEFINED IN SATELLITE IMAGERY WITH CURRENT POSITION BASED
MAINLY UPON EXTRAPOLATION AND PAST WAVE PROPAGATION SPEED.
INSPECTION OF SATELLITE IMAGERY INDICATES A RATHER BELLIGERENT
ENVIRONMENT COURTESY OF A LARGE AFRICAN DUST SURGE.  AS
SUCH...ANY CONVECTION IN THE VICINITY OF THE WAVE AXIS IS
PRIMARILY WITHIN THE ITCZ.

TROPICAL WAVE OVER THE E CARIBBEAN ALONG 67W S OF 16N MOVING
WEST NEAR 15 KT. THERE IS SOME CYCLONIC ROTATION NOTED WITHIN
THE LOW CLOUD FIELD NEAR THE WAVE. SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS FROM 13N-17N BETWEEN 65W-70W.

TROPICAL WAVE OVER THE W CARIBBEAN ALONG 82W S OF 15N MOVING W
NEAR 15 KT.  THE WAVE HAS BECOME POORLY DEFINED IN SATELLITE
IMAGERY AND IS BASED UPON EXTRAPOLATION FROM APPARENT PASSAGE
THROUGH KINGSTON UPPER AIR SOUNDING AROUND 0000 UTC MAY 26. ALL
ASSOCIATED CONVECTION IS CONFINED TO THE ITCZ WITH SCATTERED
MODERATE/ISOLATED STRONG ACTIVITY S OF 11.5N BETWEEN 79W-83W
INCLUDING THE N COAST OF PANAMA AND PORTIONS OF COSTA RICA.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 8N10W 4N30W 6N40W 8N60W.  WIDELY
SCATTERED MODERATE/ISOLATED STRONG CONVECTION WITHIN 150 NM
EITHER SIDE OF ITCZ FROM 20W-43W.  ISOLATED ACTIVITY ELSEWHERE
ALONG ITCZ.

...DISCUSSION...

GULF OF MEXICO...
MIDDLE TO UPPER LEVEL TROUGH OVER THE AREA YESTERDAY MOVED
ACROSS FLORIDA LAST NIGHT AND INTO THE W ATLC TODAY.  THE FLOW
IS NOW CONFLUENT WITH A MORE DRY/STABLE ENVIRONMENT NOW
PREVAILING IN THE WAKE OF THE TROUGH. UPPER AIR DATA FROM THE
MIAMI SOUNDING INDICATES SIGNIFICANT DRYING THROUGH ALL BUT THE
LOWEST LEVEL DURING THE LAST 24 HOURS WITH PRECIPITABLE WATER
VALUES FALLING OVER 1.00 INCH. ACCORDINGLY...THERE WAS FAR LESS
CONVECTIVE ACTIVITY ACROSS FLORIDA TODAY.  BOTH THE GFS AND
UKMET SHOW THIS DEEP LAYERED DRY AIRMASS REMAINING ACROSS THE
AREA THROUGH THE WEEKEND WITH APPRECIABLE MOISTURE NOT MAKING IT
BACK UNTIL THE MON/TUE TIME FRAME.  THIS ENVIRONMENT SHOULD
PRODUCE BELOW NORMAL COVERAGE OF AFTERNOON SHOWERS/TSTMS ACROSS
FLORIDA THIS WEEKEND.  HOWEVER...WITH A CAPPING ENVIRONMENT IN
PLACE...ANY AFTERNOON ACTIVITY THAT DOES FORM HAS THE POTENTIAL
TO BE STRONG. AT THE SURFACE...OLD REMNANT FRONTAL TROUGH
LINGERS ACROSS THE AREA FROM CENTRAL FLORIDA JUST N OF LAKE
OKEECHOBEE TO THE CENTRAL GLFMEX NEAR 27N92W.  THIS BOUNDARY
SHOULD REMAIN STATIONARY OR DRIFT NWD AND BECOME INCREASINGLY
DIFFUSE DURING THE WEEKEND.  MEANWHILE...A WEAK COLD FRONT
CURRENTLY MOVING SWD OVER THE S UNITED STATES WILL MOVE INTO N
FLORIDA SAT NIGHT BECOMING STATIONARY ON SUN AND LIFTING BACK N
OF AREA MONDAY.  THE FRONT LOOKS TO BE MOISTURE STARVED BUT MAY
BE ENOUGH TO BREAK THE CAP AND PRODUCE WIDELY SCATTERED
AFTERNOON SHOWERS/THUNDERSTORMS ACROSS N FLORIDA SUN.

CARIBBEAN SEA...
LARGE MIDDLE TO UPPER LEVEL RIDGE PREVAILS OVER THE AREA WITH A
WEAK SHORTWAVE TROUGH SPLITTING THE RIDGE FROM PUERTO RICO TO NW
VENEZUELA NEAR LAKE MARACAIBO.  THIS SMALL TROUGH IS PRODUCING
ANTICYCLONES TO EITHER SIDE WITH WESTERNMOST FEATURE OVER THE SW
CARIBBEAN NEAR 11N80W AND EASTERNMOST FEATURE OVER THE CENTRAL
ATLC NEAR 18N55W.  INSPECTION OF UPPER AIR SOUNDINGS OVER THE
AREA SHOWS DEEP LAYERED MOISTURE REMAINS LARGELY IN PLACE WITH
AFTERNOON SHOWERS/THUNDERSTORMS OVER JUST ABOUT ALL LAND
MASSES.  THE EXCEPTION IS THE LESSER ANTILLES WHERE LOW LEVEL
DRY AIR ASSOCIATED WITH AN AFRICAN DUST SURGE IS ENTERING THE
AREA.  THE LEADING EDGE IS CURRENTLY ESTIMATED ALONG 64W AND IS
MOVING WEST BETWEEN 20-25 KT.  THE AIRMASS WILL CONTINUE TO
SPREAD WESTWARD ACROSS THE AREA WITH AREAS OF DUST...LOW LEVEL
DRYING...AND DECREASED CHANCES OF AFTERNOON SHOWERS/TSTMS IN ITS
WAKE.

ATLANTIC OCEAN...
A TROUGH-RIDGE-TROUGH PATTERN PREVAILS IN THE UPPER LEVELS WITH
A BROAD/FLAT TROUGH OVER THE W ATLC W OF 60W...RIDGE OVER THE
CENTRAL ATLC FROM THE LESSER ANTILLES TO BEYOND 32N45W...AND
TROUGH OVER THE E ATLC FROM THE AZORES TO 10N40W. CONFLUENCE AND
DRY AIR IN THE WAKE OF THE W ATLC TROUGH IS SPREADING RAPIDLY
EWD NOW POLEWARD OF A LINE FROM 32N55W TO W CUBA.  THIS
ENVIRONMENT IS PRODUCING TRANQUIL CONDITIONS WITH LIMITED
SHOWER/TSTMS ACTIVITY.  SE OF THE TROUGH...DIFFLUENCE ALOFT
COUPLED WITH DEEP LAYERED MOISTURE IS PRODUCING CLOUDINESS AND
WIDELY SCATTERED SHOWERS/TSTMS UP TO 600 NM S AND E OF A REMNANT
FRONTAL TROUGH FROM 30N60W TO THE TURKS/CAICOS.  EXPECT THE W
EXTENT OF THE FRONTAL TROUGH TO LIFT SLOWLY NWD AT THE SAME TIME
A SHORTWAVE TROUGH IN THE UPPER LEVELS MOVES ACROSS W CUBA AND
THE BAHAMAS TONIGHT.  THIS SHOULD PRODUCE INCREASING
SHOWERS/TSTMS NE OF THE BAHAMAS SAT INTO SUN. SHORTWAVE WILL
ALSO FLATTEN RIDGE PATTERN OVER THE CENTRAL ATLC DURING THE
WEEKEND.  OVER THE E ATLC...SHARP TROUGH DIPS WELL INTO THE
TROPICAL ATLC FROM THE AZORES THROUGH 25N30W TO 10N40W
CONTINUING AS A CYCLONIC SHEAR AXIS TO 10N60W.  DIFFLUENT FLOW S
AND E OF THE TROUGH AXIS IS FAVORING ITCZ ACTIVITY OVER THE
CENTRAL ATLC.  THE UPPER TROUGH IS EXPECTED TO CONTINUE
AMPLIFYING SEWD WITH MAIN ITCZ ACTIVITY SHIFTING EWD.
ELSEWHERE...EARLIER VISIBLE SATELLITE IMAGERY SHOWED AN
EXPANSIVE AREA OF AFRICA DUST COVERING THE ENTIRE AREA S OF 23N
TO THE ITCZ E OF THE LESSER ANTILLES.

$$
RHOME



WWWW
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