[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 250530
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT WED 25 MAY 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0445 UTC.

...TROPICAL WAVES...

TROPICAL WAVE OVER THE FAR E ATLC JUST OFF THE AFRICAN COAST
ALONG 19W S OF 14N MOVING W 10-15 KT. WIDESPREAD CLOUDINESS AND
AREAS OF DEEP CONVECTION WITHIN THE ITCZ ACCOMPANIES THE WAVE
WITH SCATTERED MODERATE/STRONG CONVECTION WITHIN 90 NM OF THE
ITCZ AXIS BETWEEN 16W AND THE WAVE AXIS. UPPER LEVEL SW FLOW IS
ADVECTING HIGH LEVEL MOISTURE AND CLOUDINESS FROM THIS ACTIVITY
INTO W PORTIONS OF AFRICA.

CENTRAL ATLC TROPICAL WAVE EXTENDS FROM 12N51W INLAND OVER SOUTH
AMERICA BEYOND 5N54W MOVING W 10-15 KT. WEAK LOW LEVEL ROTATION
IS NOTED IN SATELLITE IMAGERY BUT THERE IS ONLY WIDELY SCATTERED
SHALLOW TOPPED SHOWERS WITHIN 120 NM OF THE WAVE AXIS.

CENTRAL CARIBBEAN TROPICAL WAVE IS LOCATED ALONG 71W S OF 14N
MOVING W 10-15 KT. THE WAVE DOES NOT EXHIBIT A GOOD SATELLITE
SIGNATURE AND THE PRESENT POSITION IS BASED UPON CONTINUITY.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS NOTED OVER
COLOMBIA AND NW VENEZUELA INCLUDING LAKE MARACAIBO.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 10N11W 7N17W 6N28W 2N40W 1N52W.
CLUSTERS OF SCATTERED MODERATE/STRONG CONVECTION IS FROM 3N-9N
BETWEEN 10W-16W. CLUSTERS OF SCATTERED MODERATE CONVECTION ARE
WITHIN 120/150 NM EITHER SIDE OF AXIS FROM 20W-38W.

...DISCUSSION...

GULF OF MEXICO...
MID/UPPER TROUGH EXTENDS FROM NW FLORIDA SW TO THE MEXICAN COAST
JUST S OF BROWNSVILLE TEXAS AND CONTINUES TO BE THE MAIN PLAYER
IN THE WEATHER OF THE GULF AS IT PRODUCES CONFLUENT FLOW ALOFT
AND STRONG SUBSIDENCE ACROSS THE AREA. RESULTING AIRMASS IS
QUITE DRY THROUGH ALL LEVELS. THIS PATTERN IS PRODUCING CLEAR
SKIES AND TRANQUIL WEATHER OVER THE ENTIRE AREA. NUMERICAL
GUIDANCE INDICATES THAT THIS UPPER LEVEL TROUGH WILL CONTINUE TO
SLIDE SLOWLY E KEEPING THE GULF AND FLORIDA ON THE CONFLUENT/DRY
SIDE. AT THE SAME TIME...A WEAK COLD FRONT...CURRENTLY OVER THE
N GULF COAST AREA...WILL MOVE S ACROSS N FLORIDA THIS MORNING
THEN BECOME INCREASINGLY DIFFUSE AS IT PUSHES THROUGH NE FLORIDA
EXTENDING FROM THE W ATLC TO OVER CENTRAL FLORIDA NEAR LAKE
OKEECHOBEE BY TONIGHT. DEEP-LAYERED MOISTURE WILL BE ABSENT
COURTESY OF THE UPPER TROUGH BUT LOW LEVEL MOISTURE POOLING
ALONG THE BOUNDARY MAY BE SUFFICIENT TO ALLOW A FEW ISOLATED
SHOWERS/THUNDERSTORMS TO GENERATE. EXPECT WHAT LITTLE ACTIVITY
TO BE PRIMARILY FOCUSED ALONG AND IN ADVANCE OF THE FRONTAL
BOUNDARY. ANY ACTIVITY THAT DOES FORM HAS THE POTENTIAL TO BE
STRONG GIVEN THE CAP AND MID-LEVEL DRY AIR IN PLACE.

CARIBBEAN...
BROAD AREA OF LOW PRESSURE REMAINS LOCATED OVER THE N CENTRAL
CARIBBEAN WITH 1009 MB LOW ANALYZED IN THE VICINITY OF JAMAICA
DRIFTING NE. THE LOW IS LOCATED ALONG THE TAIL END OF A
PERSISTENT SURFACE TROUGH EXTENDING FROM THE CENTRAL ATLC
ACROSS THE N LEEWARD ISLANDS...PUERTO RICO AND HISPANIOLA.
STRONG LOW LEVEL CONVERGENCE ALONG THIS BOUNDARY CONTINUES TO
PRODUCE SCATTERED STRONG THUNDERSTORMS OVER HISPANIOLA AND
PUERTO RICO WITH MORE WIDELY SCATTERED ACTIVITY OVER THE N
LEEWARD AND VIRGIN ISLANDS. THIS LOW AND TROUGH COULD CONTINUE
TO GENERATE SHOWERS/THUNDERSTORMS ACROSS THIS AREA THROUGH
TODAY. THEREFORE...THE POTENTIAL EXIST FOR LOCALIZED HEAVY
RAINFALL AND FLOODING ESPECIALLY IN MOUNTAINOUS AREAS THROUGH
TODAY UNTIL THE TROUGH AND ASSOCIATED AXIS OF SHOWERS/
THUNDERSTORMS LIFTS SLOWLY N INTO THE ATLC. DIURNAL CONVECTION
CONTINUES OVER INTERIOR SECTIONS OF CENTRAL AMERICA AND WILL BE
DISSIPATING THROUGH THE EARLY MORNING HOURS. SIMILARLY...
ACTIVITY OVER THE YUCATAN PENINSULA IS LESS WIDESPREAD BUT
EXPECT INCREASING ACTIVITY AS AN UPPER JET OVER THE W ATLC
STRENGTHENS PRODUCING INCREASING UPPER LEVEL DIVERGENCE OVER THE
NW CARIBBEAN. LOW LEVEL MOISTURE SHOULD ALSO BE ON THE INCREASE
AS A WEAK TROPICAL WAVE...CURRENTLY ALONG 71W...GETS PULLED N
AROUND THE W PERIPHERY OF THE SUBTROPICAL RIDGE.

ATLANTIC...
LARGE MID/UPPER LEVEL CLOSED LOW OVER THE NE UNITED STATES
CONTINUES TO AMPLIFY S PUSHING A WEAK COLD FRONT OFF THE SE
UNITED STATES COAST. THIS BOUNDARY HAS MOVED TO ALONG THE N
PERIPHERY OF THE DISCUSSION AREA AND WILL EXTEND FROM ROUGHLY
32N72W TO CENTRAL FLORIDA BY THIS AFTERNOON/EVENING. UPPER
DYNAMICS ARE IMPROVING THIS MORNING AND WILL CONTINUE THROUGH
TODAY AS THE SHORTWAVE TROUGH IN THE W ATLC ROUNDS THE BASE OF
THE LARGE SCALE TROUGH. INCREASING CLOUDINESS WITH DEVELOPING
SHOWERS/THUNDERSTORMS ALONG AND AHEAD OF THE FRONT. BEST
DYNAMICS AND MOISTURE WILL BE FROM THE N BAHAMAS NE. OVER THE
CENTRAL ATLC...ZONAL FLOW ALOFT PREVAILS N OF 20N WITH A RATHER
WEAK RIDGING ALONG 54W N OF 30N. LARGE AREA OF SUBSIDENCE AND
DRY AIR ARE OVER THE CENTRAL ATLC FROM 20N-32N BETWEEN 35W-52W.
FURTHER E...A SHARP SHORTWAVE TROUGH EXTENDS THROUGH 32N36W
27N44W WITH ATTENDANT 1002 MB SURFACE LOW NEAR 33N36W. A SURFACE
TROUGH TRAILS S ALONG 26N39W THEN SW ALONG 22N51W TO THE N
LEEWARD ISLANDS. WIDESPREAD CLOUDINESS AND SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS ARE WITHIN 500 NM E OF THE LOW/TROUGH N
OF 20N E OF 40W AND WITHIN 250 NM S OF THE TROUGH BETWEEN
40W-57W. THE SURFACE LOW IS EXPECTED TO RAPIDLY LIFT NE OUT OF
THE AREA TAKING WITH IT THE HEAVIEST SHOWERS/THUNDERSTORMS.
HOWEVER...WIDELY SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WILL
LINGER ALONG THE TRAILING TROUGH WHICH WILL SLIDE E EXTENDING
FROM 32N32W TO 20N55W BY THIS AFTERNOON. OVER THE E ATLC...A
SECOND EVEN SHARPER UPPER TROUGH EXTENDS FROM THE CANARY ISLANDS
INTO THE DEEP TROPICAL ATLC NEAR 10N37W. UPPER DIFFLUENCE TO THE
E IS SUPPORTING ENHANCED ITCZ ACTIVITY E OF 35W. AFRICAN DUST
REMAINS OVER THE AREA S OF 20N TO THE ITCZ AXIS E OF 57W AS WELL
AS BEING DRAWN NE OVER THE CANARY AND MADEIRA ISLANDS.

$$
WALLACE


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