[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 171748
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SUN MAY 17 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1715 UTC.

...TROPICAL WAVES...
A TROPICAL WAVE IS ALONG 42W/43W S OF 12N MOVING W NEAR 15 KT. A
SUBTLE CYCLONIC CURVATURE TO THE LOW-LEVEL CLOUDS IS OBSERVED ON
VISIBLE IMAGERY NEAR THE WAVE AXIS AS SURFACE TO 700 MB MODEL
DATA ALSO POINTS TO A CYCLONIC PERTURBATION IN THE WIND FIELD.
WAVE REMAINS VOID OF ANY DEEP CONVECTION...WITH SCATTERED TO
BROKEN MULTILAYERED CLOUDS FROM 3N-9N BETWEEN 38W-45W.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 8N12W 2N20W CROSSING THE EQUATOR
NEAR 24W TO NE BRAZIL NEAR 4S39W. SCATTERED MODERATE CONVECTION
IS S OF 4N BETWEEN 14W-29W.

...DISCUSSION...

GULF OF MEXICO...
A BROAD UPPER-LEVEL TROUGH IS ACROSS THE CENTRAL CONUS AND
SUPPORTS A COLD FRONT THAT AS OF 1500 UTC ENTERS THE GULF ALONG
THE CENTRAL LOUISIANA COAST NEAR 29N91W AND CONTINUES ALONG
27N95W 23N96W TO TAMPICO MEXICO AND INLAND ACROSS E/CENTRAL
MEXICO AS A STATIONARY FRONT. SCATTERED SHOWERS AND TSTMS ARE
WITHIN 60 NM EITHER SIDE OF THE COLD FRONT. ANOTHER CONCENTRATED
AREA OF SCATTERED SHOWERS AND TSTMS IS OVER THE WRN BAY OF
CAMPECHE FROM 20N-23N W OF 95W. A PRE-FRONTAL SURFACE TROUGH
EXTENDS INTO THE GULF FROM MOBILE BAY SWD ACROSS THE CENTRAL
GULF TO THE YUCATAN PENINSULA NEAR 21N89W. SCATTERED SHOWERS AND
ISOLATED TSTMS ARE MAINLY E OF THE SURFACE TROUGH N OF 24N
BETWEEN 85W-88W. CONTINUED MOIST SE SURFACE FLOW N OF A SURFACE
TROUGH ACROSS CENTRAL CUBA EXTENDING INTO THE WRN CARIBBEAN IS
GENERATING SCATTERED SHOWERS ACROSS THE STRAITS OF FLORIDA...SRN
FLORIDA PENINSULA AND SE GULF. EXPECT THE FRONT TO CONTINUE
MOVING SEWD AND WEAKEN BY MONDAY INTO TUESDAY. EARLY NEXT WEEK
AS THE FRONT LIFTS NEWD...MANY OF THE GLOBAL MODELS ARE SHOWING
LOW PRESSURE DEVELOPING OVER CUBA OR THE FLORIDA STRAITS...
EITHER EXTRATROPICAL OR SUBTROPICAL...AND MOVING GENERALLY N.
DEVELOPMENT AND TRACK IS UNCERTAIN BUT MODELS ARE IN ENOUGH
AGREEMENT TO WARRANT GALE HEADLINES OVER A PORTION OF THE E AND
MIDDLE WATERS FOR EARLY NEXT WEEK.

CARIBBEAN SEA...
A MIDDLE TO UPPER TROUGH OVER THE WRN CARIBBEAN ALONG WITH A
SURFACE TROUGH EXTENDING FROM CENTRAL CUBA ALONG 79W TO NEAR 16N
IS PRODUCING SCATTERED SHOWERS AND TSTMS N OF 16N BETWEEN
74W-79W. LIGHTNING DATA SHOWS THE GREATEST CONCENTRATION OF
STRIKES OVER THE ADJACENT WATERS BETWEEN ERN JAMAICA AND  SW
HISPANIOLA. LATEST VISIBLE SATELLITE IMAGES AND GLOBAL MODEL
DATA INDICATE CYCLONIC ROTATION IN THE MID-LEVEL FIELDS ALONG
79W JUST S OF CUBA. THIS FEATURE MAY BUILD CLOSER TO THE SURFACE
OVER THE NEXT COUPLE OF DAYS AND DRIFT GENERALLY NWD...
CONTINUING THE THREAT FOR SCATTERED SHOWERS AND TSTMS OVER THE
N/CENTRAL CARIBBEAN. STRONG SWLY UPPER FLOW ON THE E SIDE OF THE
AFOREMENTIONED UPPER TROUGH IS ADVECTING MOISTURE ACROSS THE SE
CARIBBEAN AND LESSER ANTILLES. THIS FLOW COMBINED WITH A LOW-
LEVEL TROUGH A COUPLE HUNDRED NM E OF THE AREA OVER THE TROPICAL
N ATLC IS GENERATING SCATTERED SHOWERS ACROSS THE NE CARIBBEAN N
OF 14N AND E OF 65W. MEANWHILE...HIGH PRESSURE CENTERED W OF
BERMUDA IS MAINTAINING 15-20 KT TRADES ACROSS THE MUCH OF THE
AREA E OF 78W AS CAPTURED ON AN EARLIER QSCAT PASS. THESE WINDS
ARE EXPECTED TO REMAIN SIMILAR OVER THE ERN ONE-THIRD OF THE
CARIBBEAN THROUGH WED AS THE HIGH WEAKENS IN PLACE OVER THE NEXT
DAY OR TWO.

ATLANTIC OCEAN...
AN OCCLUDED 1005 MB LOW IS QUASI-STATIONARY ALONG THE NRN BORDER
OF THE DISCUSSION AREA NEAR 32N52W. A COLD FRONT EXTENDS FROM
32N47W TO 27N47W CONTINUING SW TO 22N51W AND CONTINUING AS A
STATIONARY FRONT TO 19N55W. FROM 19N55W THE BOUNDARY WEAKENS TO
A SURFACE TROUGH AND EXTENDS SW TO 15N59W. ASSOCIATED SCATTERED
SHOWERS AND ISOLATED TSTMS ARE CONFINED TO THE ERN SEMICIRCLE OF
THE LOW N OF 27N BETWEEN 42W AND 49W. S OF 27N...SCATTERED
SHOWERS ARE OBSERVED WITHIN 90/120 NM EITHER SIDE OF THE FRONTAL
BOUNDARY. A SECONDARY WAVE OF ENERGY...ANALYZED AS A DEVELOPING
COLD FRONT EXTENDS FROM 30N48W TO 27N51W TO 27N56W WITH ENHANCED
CLOUDINESS AND POSSIBLE ISOLATED SHOWERS WITHIN 30 NM EITHER
SIDE OF THE FRONT. DEEP LAYER RIDGING W OF THE LOW IS PROVIDING
MAINLY FAIR WEATHER ACROSS MUCH OF THE W ATLC. HOWEVER...WITH
THE PROXIMITY OF THE AFOREMENTIONED SURFACE TROUGH ACROSS
CENTRAL CUBA...SCATTERED SHOWERS AND TSTMS SPREAD N OF 18N
BETWEEN 72W-81W OVER THE GREATER ANTILLES...BAHAMAS AND NEARBY
WATERS. SEE CARIBBEAN SECTION FOR MORE DETAILS. SURFACE HIGH
PRESSURE RIDGING AND MAINLY ZONAL FLOW ALOFT DOMINATE MUCH OF
THE E ATLC...SUPPORTING MAINLY FAIR WEATHER.

$$
HUFFMAN



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