[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 222345
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE SEP 22 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...

TROPICAL WAVE IS ALONG 39W/40W S OF 18N MOVING NW 15 KT. WAVE IS
WELL DEFINED IN THE LOW LEVEL CLOUD FIELD WITH SMALL CLUSTERS OF
SCATTERED MODERATE/ISOLATED STRONG CONVECTION WITHIN 75 NM OF
LINE FROM 8N44W TO 13N40W. A LARGE AREA OF SAHARAN DUST IS JUST
E OF THE WAVE AXIS.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 10N13W 8N21W 8N31W 10N42W 9N48W
11N58W 10N63W. SMALL ISOLATED CLUSTERS OF SCATTERED MODERATE
CONVECTION DOT THE AREA WITHIN 120 NM OF THE ITCZ E OF 27W. A
BROAD AREA OF MID LEVEL CYCLONIC ROTATION IS JUST INLAND OVER
THE COAST OF W AFRICA AND WILL MOVE INTO THE ATLC WATERS LATE
TONIGHT INTO WED.

...DISCUSSION...

GULF OF MEXICO...
A STRONG COLD FRONT IS INLAND OVER TEXAS AND N MEXICO WITH A
PRE-FRONTAL SURFACE TROUGH OVER THE NW GULF EXTENDING FROM LAKE
CHARLES LOUISIANA ALONG 29N94W TO ACROSS S TEXAS NEAR CORPUS
CHRISTI TO LAREDO GENERATING SCATTERED/NUMEROUS SHOWERS WITH
SCATTERED THUNDERSTORMS COVERING THE AREA W OF A LINE FROM
PENSACOLA FLORIDA TO BROWNSVILLE TEXAS. THE UPPER RIDGE REMAINS
ACROSS THE GULF EXTEND FROM AN UPPER HIGH OVER S/CENTRAL MEXICO
INTO THE GULF NEAR TAMPICO NE TO FLORIDA N OF TAMPA. AFTERNOON
SEABREEZE THUNDERSHOWERS GENERATED INLAND OVER THE FLORIDA
PENINSULA ARE MOVING INTO THE GULF WATERS WITHIN 60 NM OF THE
COAST FROM EVERGLADES CITY TO JUST N OF TAMPA. POSSIBLE ISOLATED
SHOWERS/THUNDERSTORMS ARE MOVING THROUGH THE STRAITS OF FLORIDA
S OF THE FLORIDA KEYS TO INLAND OVER CUBA W OF 84W. THE COLD
FRONT WILL MOVE INTO THE GULF WATERS LATER TONIGHT AND STALL
OVER THE NW GULF LATE WED THROUGH FRI.

CARIBBEAN SEA...
THE CARIBBEAN IS DOMINATED BY W TO NW UPPER FLOW AND WITH AN
ABUNDANCE OF DEEP LAYER MOISTURE IS GENERATING SCATTERED/
NUMEROUS SHOWERS AND SCATTERED THUNDERSTORMS OVER CUBA WITH
SCATTERED SHOWERS/THUNDERSTORMS ACROSS THE REMAINDER OF THE N
CARIBBEAN N OF 17N FROM 64W-74W AND N OF 15N BETWEEN 74W-83W
INCLUDING THE GREATER ANTILLES AND THE VIRGIN ISLANDS. SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE ACROSS THE S CARIBBEAN S OF
12N W OF 70W TO INLAND OVER COLOMBIA TO NICARAGUA. ISOLATED
SHOWERS DOT THE REMAINDER OF THE CARIBBEAN W OF 75W WHILE THE
REMAINDER OF THE E CARIBBEAN REMAINS REMARKABLY CLEAR THIS
EVENING.

ATLANTIC OCEAN...
A WEAK SURFACE TROUGH IS IN THE FAR W ATLC EXTENDING FROM THE
NORTH CAROLINA COAST NEAR WILMINGTON THROUGH A 1018 MB LOW NEAR
31N79W TO OFF THE FLORIDA COAST NEAR FORT LAUDERDALE. SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 75 NM OF LINE FROM
28N79W TO BEYOND 32N78W. AN UPPER RIDGE IS ANCHORED NEAR THE
SURFACE LOW COVERING THE W ATLC N OF 27N FROM 74W TO 81W AND
ENHANCING THE ACTIVITY ASSOCIATED WITH THE TROUGH/LOW. AN UPPER
TROUGH DIPS S INTO THE W ATLC N OF 25N BETWEEN 57W-70W
SUPPORTING A STATIONARY BOUNDARY THAT EXTENDS TO 32N60W AND A
SURFACE TROUGH THAT CONTINUES TO 27N65W GENERATING SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS OVER THE AREA FROM 25N-32N
BETWEEN 57W-65W AND FROM 30N-32N BETWEEN 52W-57W. A BROAD E/W
UPPER RIDGE DOMINATES THE TROPICAL ATLC ANCHORED NEAR OVER W
AFRICA EXTENDING W ALONG 16W/17W TO NEAR 60W. BENEATH THIS UPPER
RIDGE EMBEDDED WITHIN SOME DRIER AIR IS A SURFACE TROUGH THAT
EXTENDS FROM 24N46W THROUGH A 1010 MB LOW NEAR 15N49W TO 11N50W.
THIS UPPER RIDGE IS PROVIDING ENOUGH DIFFLUENCE ALOFT IN SPITE
OF THE DRIER AIR TO GENERATE SCATTERED MODERATE/ISOLATED STRONG
CONVECTION FROM 20N-22N BETWEEN 45W-48W AND A SECOND AREA FROM
17N-19N BETWEEN 57W-59W. THE LAST VISIBLE SATELLITE IMAGES SHOW
AN AREA OF SAHARAN DUST THAT COVERS THE E TROPICAL ATLC N OF 20N
AND SE OF A LINE FROM 30N18W TO 16N35W.

$$
WALLACE



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