Thursday Morning Tropical Weather Discussion


000
AXNT20 KNHC 201042
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT FRI JUN 20 2008

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

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS ALONG 23W S OF 12N MOVING W 10-15 KT. THE
WAVE SHOWS UP VERY WELL ON THE TPW PRODUCT AND THE HOVMOLLER
DIAGRAM THAT CLEARLY INDICATES THE WWD PROPAGATION OF THE WAVE.
LOW LEVEL SATELLITE DERIVED WINDS ALSO SUPPORTS THE POSITION OF
THE WAVE AXIS WHICH EXHIBITS SOME CYCLONIC TURNING NEAR 7N.
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS MAINLY AHEAD
OF THE WAVE AXIS FROM 5N-11N BETWEEN 23W-27W.

AN ACTIVE TROPICAL WAVE IS AFFECTING THE LESSER ANTILLES EARLY
THIS MORNING WITH SCATTERED TO NUMEROUS SHOWERS...TSTMS AND
GUSTY WINDS. ITS AXIS IS ALONG 61W/62W S OF 19N MOVING W 15-20
KT. A BROAD AREA OF CYCLONIC TURNING IS ASSOCIATED WITH THE
WAVE. SURFACE OBSERVATIONS FROM THOSE ISLANDS REVEAL THAT THE
WAVE HAS ENTERED THE E CARIBBEAN. SFC PRESSURES ARE FALLING TO
NEAR 2 MB IN THIS AREA. THE MIMIC-TPW PRODUCT SHOWS THE WAVE
VERY WELL WHERE A GOOD SURGE OF MOISTURE IS NOTED. THE WAVE IS
EXPECTED TO AFFECT THE UK/US VIRGIN ISLANDS THIS MORNING AND
PUERTO RICO THROUGHOUT THE DAY...BRINGING AN INCREASE IN
SHOWER/TSTM ACTIVITY AND GUSTY WINDS. THE WAVE SHOULD REACH
DOMINICAN REPUBLIC EARLY SATURDAY.

...ITCZ...

THE ITCZ IS PRETTY ACTIVE EARLY THIS MORNING. ITS AXIS IS
CENTERED ALONG 10N18W 6N26W 4N35W 3N45W INTO NRN BRAZIL NEAR
1N51W. CLUSTERS OF SCATTERED MODERATE TO ISOLATED STRONG
CONVECTION ARE FROM THE EQUATOR TO 5N BETWEEN 27W-40W. SIMILAR
CONVECTION IS WITHIN 100 NM N OF AXIS AND WEST OF 40W TO THE
SOUTH AMERICA COAST.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER TROUGH IS OVER THE WESTERN HALF OF THE GULF EXTENDING
FROM SE LOUISIANA TO THE BAY OF CAMPECHE. MODERATE TO STRONG
SUBSIDENCE IS NOTED ALONG THE TROUGH AXIS. AN UPPER LEVEL
RIDGE...ANCHORED ON A HIGH OVER CENTRAL AMERICA IS BUILDING OVER
THE EASTERN HALF OF THE GULF REGION. A SWATH OF UPPER LEVEL
MOISTURE IS BETWEEN THESE UPPER LEVEL FEATURES OVER THE YUCATAN
PENINSULA AND THE SE GULF. AT THE SURFACE...A STATIONARY FRONT
STRETCHES FROM SE LOUISIANA TO A 1013 MB LOW OVER S GEORGIA. A
WEAK RIDGE DOMINATES THE REMAINDER OF THE AREA WITH MOSTLY FAIR
WEATHER AND LIGHT WINDS. DIFFLUENCE ALOFT ON THE SE SIDE OF THE
ABOVE MENTIONED UPPER TROUGH IS AIDING IN SCATTERED SHOWERS AND
ISOLATED TSTMS ACROSS THE EASTERN PORTION OF THE BAY OF
CAMPECHE...THE YUCATAN PENINSULA AND THE SE GULF.

CARIBBEAN...
A RIDGE/TROUGH PATTERN IS OBSERVED OVER THE CARIBBEAN SEA. THE
RIDGE COVERS THE WEST AND CENTRAL CARIBBEAN WHILE AN UPPER-LEVEL
TROUGH FROM THE E-CENTRAL ATLC HAS ITS BASE OVER THE FAR SE
CARIBBEAN AND THE WINDWARD ISLANDS. THE TROPICAL WAVE OVER THE
LESSER ANTILLES IS INTERACTING WITH THIS UPPER-LEVEL TROUGH. AS
A RESULTS...CONVECTION HAS INCREASED ESPECIALLY NEAR THE
NORTHERN END OF THE WAVE AXIS. UPPER DIFFLUENCE BETWEEN AN
UPPER-LEVEL TROUGH OVER THE EASTERN SEABOARD AND THE RIDGE OVER
THE CARIBBEAN IS PRODUCING A BAND OF MULTILAYERED CLOUDS WITH
EMBEDDED SHOWERS EXTENDING FROM THE CENTRAL BAHAMAS NE OVER THE
W ATLC. SOME SHOWER ACTIVITY IS ALSO NOTED OVER N CENTRAL
AMERICA AND THE SW CARIBBEAN NEAR 10N80W...LIKELY DUE A
DIFFLUENT PATTERN ALOFT ASSOCIATED WITH THE AFOREMENTIONED
UPPER-LEVEL RIDGE. AT THE SURFACE...THE ATLC RIDGE WILL BUILD SW
OVER THE AREA AND STRENGTHEN THROUGH MON PRODUCING MODERATE TO
FRESH TRADE WINDS ACROSS THE BASIN WITH THE STRONGEST WINDS UP
TO 30 KT JUST OFFSHORE THE COLOMBIAN COAST.

ATLANTIC...
A BROAD UPPER TROUGH IS OVER THE EASTERN U.S. WHILE AN UPPER
RIDGE EXTENDS FROM THE CARIBBEAN ALL THE WAY NE TO BEYOND
31N58W. THIS TROUGH SUPPORTS A FRONTAL BOUNDARY THAT CLIPS THE
FAR NW PORTION OF THE AREA THEN CONTINUES NW TO A 1013 SFC LOW
OVER S GEORGIA. AN UPPER LEVEL TROUGH EXTENDS OVER THE E-CENTRAL
ATLC WITH THE BASE REACHING THE FAR SE CARIBBEAN AND THE
WINDWARD ISLANDS. AN UPPER-LEVEL RIDGE DOMINATES MOST OF THE
TROPICS AND IS ENHANCING CONVECTION ALONG THE ITCZ AXIS TODAY.
HIGH PRES IS IN CONTROL OF THE FORECAST AREA EXTENDING A RIDGE
WWD TO THE BAHAMAS AND CUBA. THIS SYSTEM IS FORECAST BY THE
COMPUTER MODELS TO STRENGTHEN THROUGH MON PRODUCING A BELT OF
MODERATE TO FRESH ELY WINDS ACROSS THE TROPICAL ATLC FROM THE
AFRICAN COAST TO THE CENTRAL CARIBBEAN.

$$
GR/CW


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