[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 271829
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON SEP 27 2010

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.

...SPECIAL FEATURES...
AN AREA OF DISORGANIZED SHOWERS/THUNDERSTORMS ARE OVER THE NW
CARIBBEAN ASSOCIATED WITH A BROAD AREA OF LOWER PRESSURE.
OBSERVATIONS FROM A NATIONAL SCIENCE FOUNDATION JET AIRCRAFT
INDICATE THAT THE LOW DOES NOT YET HAVE A WELL-DEFINED CENTER OF
CIRCULATION BUT A SURFACE TROUGH IS ANALYZED ACROSS THE NW
CARIBBEAN FROM 17N82W TO 21N86W. SCATTERED MODERATE/STRONG
CONVECTION COVERS THE AREA FROM 13N-19N BETWEEN 78W-83W AND FROM
18N-20N BETWEEN 84W-86W. ENVIRONMENTAL CONDITIONS APPEAR
FAVORABLE FOR GRADUAL DEVELOPMENT OF THIS SYSTEM DURING THE NEXT
COUPLE OF DAYS AS IT DRIFTS NORTHWARD. THERE IS A MEDIUM CHANCE
OF THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48
HOURS. INTERESTS IN CUBA...THE FLORIDA KEYS...AND THE SOUTH AND
CENTRAL FLORIDA PENINSULA SHOULD MONITOR THE PROGRESS OF THIS
SYSTEM.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 10N13W TO 7N24W THEN RESUMES NEAR
9N38W 8N43W 6N58W. A 1012 MB SURFACE LOW IS JUST N OF THE ITCZ
NEAR 12N35W GENERATING CLUSTERS OF ISOLATED MODERATE CONVECTION
FROM 11N-14N BETWEEN 34W-39W. A 1011 MB LOW IS S OF THE ITCZ
NEAR 5N25W. CLUSTERS OF SCATTERED MODERATE/STRONG CONVECTION ARE
FROM 3N-9N BETWEEN 26W-34W. CLUSTERS OF SCATTERED MODERATE/
ISOLATED STRONG CONVECTION ARE FROM 6N-10N BETWEEN 41W-46W.

...DISCUSSION...

GULF OF MEXICO...
A DEEP LAYERED TROUGH COVERING THE MISSISSIPPI VALLEY DIPS S
OVER THE N GULF N OF 25N W OF 83W TO OVER TEXAS SUPPORTING A
COLD FRONT THAT ENTERS THE GULF NEAR TALLAHASSEE FLORIDA ALONG
27N88W TO MEXICO NEAR 25N97W AND A PRE-FRONTAL TROUGH THAT
EXTENDS FROM 28N85W TO 23N93W. SCATTERED/HEAVY SHOWERS WITH
SCATTERED THUNDERSTORMS ARE WITHIN 150 NM E OF THE COLD FRONT N
OF 27N WITH DRY STABLE CONDITIONS AND CLEAR SKIES NW OF THE
FRONT. THE EXCEPTION IS AN AREA OF COLD AIR STRATOCUMULUS CLOUDS
OVER THE NW GULF W OF 92W. TROPICAL MOISTURE FROM THE REMNANTS
OF MATTHEW REMAINS OVER S MEXICO AND THE W BAY OF CAMPECHE WITH
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS S OF 22N W OF 93W. AN
UPPER RIDGE COVERS THE W CARIBBEAN EXTENDS OVER THE SE GULF S
OF 24N E OF 86W. MOSTLY CLEAR SKIES WITH POSSIBLE ISOLATED
SHOWERS COVER THE REMAINDER OF THE GULF THIS AFTERNOON.

CARIBBEAN SEA...
AN UPPER RIDGE EXTENDS FROM OVER THE YUCATAN PENINSULA INTO THE
W CARIBBEAN ALONG 19N TO 76W THEN ESE TO 13N65W PROVIDING
DIFFLUENCE ALOFT TO GENERATE THE CONVECTION ASSOCIATED WITH THE
SURFACE TROUGH IN THE SPECIAL FEATURES ABOVE AND CLUSTERS OF
SCATTERED MODERATE/ISOLATED STRONG CONVECTION ACROSS THE
REMAINDER OF THE AREA W OF 67W. THIS IS LEAVING THE REMAINDER OF
THE E CARIBBEAN TO ACROSS THE LESSER ANTILLES UNDER FAIR SKIES
THIS AFTERNOON WITH SOME ISOLATED LOW LEVEL SHOWERS MOVING
THROUGH.

ATLANTIC OCEAN...
AN UPPER TROUGH COVERS THE W ATLC ROUGHLY CENTERED NEAR 26N72W
GENERATING SCATTERED SHOWERS AT THE BASE OF THE UPPER TROUGH S
OF 23N TO OVER THE CARIBBEAN ISLANDS BETWEEN PUERTO RICO AND W
CUBA INCLUDING THE TURKS AND CAICOS. A SURFACE RIDGE EXTENDS
OVER THE W ATLC ACROSS BERMUDA SSW TO 27N69W. A 1014 MB LOW
REMAINS IN THE CENTRAL ATLC NEAR 29N58W CONTINUING TO GENERATE
SCATTERED MODERATE/ISOLATED STRONG CONVECTION FROM 29N-31N
BETWEEN 57W-60W. THE REMNANTS OF LISA IS A 1015 MB SURFACE LOW
NEAR 28N31W WITH ANY CONVECTION NOW HAS DISSIPATED. OTHERWISE
THE ATLC IS DOMINATED BY BENIGN UPPER LEVEL FEATURES WITH DRY
STABLE AIR FROM 15N-26N BETWEEN 20W-65W. HIGH PRESSURE COVERS
THE CENTRAL AND E ATLC N OF 23N WITH A WEAKNESS IN THE IMMEDIATE
VICINITY OF THE REMNANT LOW OF LISA. THERE IS A 1012 MB LOW IN
THE CENTRAL TROPICAL ATLC...SEE ITCZ ABOVE.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
WALLACE





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