[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 182352
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT THU JUN 18 2009

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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS ALONG 42W S OF 8N MOVING W NEAR 10 KT. THIS WAVE
REMAINS RELATIVELY LOW AMPLITUDE AND EMBEDDED WITHIN THE ITCZ. A
MAXIMUM IN DEEP LAYER MOISTURE IS EVIDENT ON TOTAL PRECIPITABLE
WATER IMAGERY FROM CIMSS AS WELL. SCATTERED MODERATE CONVECTION IS
FROM 4N-8N BETWEEN 37W-42W.

A TROPICAL WAVE IS IN THE BAY OF CAMPECHE ALONG 95W S OF 20N INTO
THE E PACIFIC MOVING W NEAR 10-15 KT. COINCIDING WITH A MAXIMUM IN
DEEP LAYER MOISTURE THIS WAVE EXHIBITS SLIGHT LOW-LEVEL CYCLONIC
CURVATURE ACROSS THE WRN BAY OF CAMPECHE AND SRN MEXICO. THIS
LOW-LEVEL LIFT ALONG WITH AN UPPER DIFFLUENT PATTERN OVER THE REGION
IS SUPPORTING SCATTERED MODERATE/ISOLATED STRONG CONVECTION S OF 22N
W OF 95W OVER THE BAY OF CAMPECHE AND SIMILAR CONVECTION OVER
PORTIONS OF SRN MEXICO BETWEEN 92W-100W.

...THE ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 9N13W 6N24W 4N40W 2N44W AND INTO NE
BRAZIL NEAR 1N50W. SCATTERED MODERATE CONVECTION/ISOLATED STRONG
CONVECTION IS FROM 8N-14N BETWEEN 12W-20W. SCATTERED MODERATE
CONVECTION IS FROM 6N-9N BETWEEN 20W-29W. SIMILAR CONVECTION IS
ASSOCIATED WITH THE TROPICAL WAVE ALONG 42W FROM 4N-8N BETWEEN
37W-42W.

...DISCUSSION...

GULF OF MEXICO...
AN AMPLIFIED UPPER RIDGE EXTENDS ACROSS THE WRN GULF WITH AXIS ALONG
95W. ANTICYCLONIC FLOW DOMINATES THE REGION WITH THE ONLY EXCEPTION
BEING THE FAR PORTIONS OF THE SE GULF...THE EXTREME SRN FLORIDA
PENINSULA AND STRAITS OF FLORIDA...WHERE UPPER LEVEL TROUGHING
EXTENDS FROM THE W ATLC TO ACROSS CUBA. THE UPPER LEVEL TROUGHING
SUPPORTS A WEAK SURFACE TROUGH ACROSS SRN FLORIDA AND THE FLORIDA
KEYS WITH SCATTERED SHOWERS AND TSTMS OVER THE FLORIDA PENINSULA AND
NEARBY COASTAL WATERS N OF 26N E OF 84W. THE REMAINDER OF THE GULF
REMAINS RATHER TRANQUIL UNDER THE UPPER LEVEL RIDGE WITH A 1017 MB
SURFACE HIGH CENTERED NEAR 28N88W. ALSO OF NOTE...THE TROPICAL WAVE
ALONG 95W S OF 20N IN THE BAY OF CAMPECHE ALONG WITH THE UPPER LEVEL
RIDGE ACROSS THE WRN GULF IS GENERATING SCATTERED SHOWERS AND
ISOLATED TSTMS SW OF A LINE FROM 18N93W TO 24N98W.

CARIBBEAN SEA...
AN UPPER LEVEL DIFFLUENT ATMOSPHERE IS EVIDENT ON WATER VAPOR
IMAGERY ACROSS CENTRAL AMERICA AND THE SW CARIBBEAN AS SCATTERED
SHOWERS AND TSTMS ARE OCCURRING MAINLY W OF A LINE FROM NRN COLOMBIA
NEAR 11N73W TO FAR ERN HONDURAS NEAR 15N83W CONTINUING TO THE NE TIP
OF THE YUCATAN PENINSULA. UPPER LEVEL TROUGHING DOMINATES THE
REMAINDER OF THE NW AND CENTRAL CARIBBEAN W OF 70W AS MODERATELY DRY
AIR ON NWLY FLOW ALOFT IS IN PLACE. HOWEVER...LOW-LEVEL INSTABILITY
AND MIDDLE TO UPPER LEVEL LIFT DUE TO THE UPPER TROUGH IS GENERATING
SCATTERED SHOWERS AND TSTMS ACROSS MUCH OF CUBA...JAMAICA...AND
HISPANIOLA. E OF 70W...MOIST SWLY UPPER LEVEL FLOW IS GENERATING
SCATTERED HIGH CLOUDS AND ISOLATED SHOWERS ACROSS THE ERN CARIBBEAN.
ELY TRADE WINDS UP TO 25 KT ARE OBSERVED ACROSS THE BASIN AND ARE
FORECAST TO PERSIST THROUGH THE WEEKEND.

ATLANTIC OCEAN...
A DEEP LAYER CENTRAL ATLC TROUGH IS SUPPORTING A COLD FRONT THAT
ENTERS THE DISCUSSION AREA NEAR 32N52W AND EXTENDS W-SW TO 29N61W
CONTINUING AS A STATIONARY FRONT TO 31N70W AND AS A WARM FRONT FROM
THAT POINT INTO A 1013 MB LOW CENTERED NEAR 32N74W. A SURFACE TROUGH
EXTENDS S-SW FROM THE SURFACE LOW ALONG 30N75W 27N78W 26N80W AND
ACROSS EXTREME SRN FLORIDA INTO THE SE GULF OF MEXICO. ISOLATED
SHOWERS ACCOMPANY THE SURFACE TROUGH N OF 27N W OF 70W. ELSEWHERE...
SCATTERED SHOWERS ARE WITHIN 200 NM N OF THE STATIONARY FRONT
BETWEEN 55W-70W AND WITHIN 150 NM EITHER SIDE OF THE COLD FRONT
BETWEEN 45W-55W. ACROSS THE MAJORITY OF THE CENTRAL AND E ATLC A
BROAD SURFACE RIDGE DOMINATES ANCHORED BY A 1028 MB SURFACE HIGH N
OF THE DISCUSSION AREA NEAR 41N26W. HOWEVER...A DEEP LAYER LOW OVER
THE NE ATLC IS ASSOCIATED WITH A 1015 MB SURFACE LOW NW OF THE
CANARY ISLANDS NEAR 30N19W. LOW LEVEL CONVERGENCE NEAR THIS SURFACE
LOW IS SUPPORTING ISOLATED SHOWERS N OF 30N BETWEEN 17W-24W.

$$
HUFFMAN




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