[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 112340
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE OCT 11 2011

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...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL
ANALYSIS.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 2315 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE APPEARS TO BE MOVING OFF THE W AFRICAN COAST AND
WILL LIKELY BE ADDED TO THE 12/0000 UTC ANALYSIS.

TROPICAL WAVE IN THE ERN CARIBBEAN EXTENDS FROM 18N64W TO 10N65W
MOVING W NEAR 10 KT. THE WAVE APPEARS TO BE WEAKENING AS THE
MOISTURE SIGNAL PREVIOUSLY EVIDENT IN TOTAL PRECIPITABLE WATER
HAS NOW BECOME LESS DISTINCT. HOWEVER...MODEL GUIDANCE DOES
MAINTAIN A COHERENT FEATURE MOVING SLOWLY FROM THE ERN CARIBBEAN
INTO THE CENTRAL CARIBBEAN. CLUSTERS OF STRONG CONVECTION ARE S
OF THE WAVE AXIS OVER VENEZUELA. IT IS HARD TO SAY WHETHER THIS
IS ASSOCIATED WITH THE WAVE OR NOT. NO DEEP CONVECTION IS
PRESENT ELSEWHERE AT THIS TIME DUE TO DRY AIR ALOFT EVIDENT IN
WATER VAPOR IMAGERY...BUT ISOLATED SHOWERS DO REMAIN FROM
15N-20N BETWEEN 60W-67W.

...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 12N16W
EXTENDING SW TO NEAR 7N18W AND WWD TO 7N22W. THE ITCZ CONTINUES
FROM 7N22W ALONG 9N29W 7N39W 8N49W. A CLUSTER OF STRONG
CONVECTION IS JUST APPROACHING THE AFRICAN COAST FROM 8N-12N.
SCATTERED MODERATE/STRONG CONVECTION IS FROM 4N-8N BETWEEN
17W-21W. ISOLATED MODERATE/STRONG CONVECTION IS FROM 4N-12N
BETWEEN 25W-32W...AND FROM 7N-10N BETWEEN 34W-41W. SIMILAR
ACTIVITY IS ALSO FROM 7N-13N BETWEEN 46W-56W.

...DISCUSSION...

THE GULF OF MEXICO...

UPPER LEVEL RIDGING COVERS THE MAJORITY OF THE GULF OF MEXICO
EXTENDING FROM SRN MEXICO NEAR 18N92W TO THE N CENTRAL GULF NEAR
MISSISSIPPI. A NARROW UPPER LEVEL TROUGH EXTENDS DOWN THE
FLORIDA PENINSULA TO ERN CUBA. MOSTLY DRY AIR ALOFT ACCOMPANIES
THE UPPER RIDGE WHICH IS HELPING MAINTAIN MOSTLY FAIR
CONDITIONS. HOWEVER...A PAIR OF SURFACE LOWS ARE CAUSING A FEW
AREAS OF ISOLATED SHOWERS. A 1009 MB LOW IS CENTERED NW OF THE
YUCATAN PENINSULA NEAR 23N92W SUPPORTING ISOLATED SHOWERS WITHIN
150 NM NW OF THE CENTER. A SMALL AREA OF SHOWERS IS ALSO FARTHER
NW FROM 25N-27N BETWEEN 93W-96W. SOME UPPER LEVEL MOISTURE IS
ALSO BEING DRAWN OVER THE NW GULF FROM HURRICANE JOVA IN THE E
PACIFIC. A SURFACE TROUGH CONNECTS THE AFOREMENTIONED SURFACE
LOW WITH A SECOND 1007 MB LOW OVER THE FLORIDA PANHANDLE NEAR
30N85W. THE TROUGH AXIS EXTENDS ALONG 24N89W 27N83W 30N85W.
ISOLATED SHOWERS ARE ALONG THE TROUGH AXIS AS WELL AS WITHIN 150
NM AROUND THE NW SEMICIRCLE FROM THE LOW CENTER. EXPECT THE LOW
IN THE CENTRAL GULF TO DISSIPATE WHILE THE LOW OVER THE FLORIDA
PANHANDLE MOVES NE. A WEAK COLD FRONT IS EXPECTED TO ENTER THE
NW GULF IN A COUPLE OF DAYS.

THE CARIBBEAN SEA...

DRY AIR ALOFT IS BEING WRAPPED AROUND THE ERN SIDE OF AN UPPER
LEVEL RIDGE OVER THE GULF OF MEXICO WHICH IS HELPING MAINTAIN
FAIR CONDITIONS ACROSS THE FAR NW CARIBBEAN. HOWEVER...AN UPPER
LEVEL TROUGH OVER THE FLORIDA PENINSULA REACHES CENTRAL AND ERN
CUBA WHICH IS PLACING DIFFLUENT FLOW OVER FAR ERN CUBA AND
HISPANIOLA. THIS UPPER TROUGH SUPPORTS A 1009 MB SURFACE LOW
JUST N OF ERN CUBA NEAR 22N76W WITH A TROUGH AXIS EXTENDING S TO
JAMAICA. SCATTERED SHOWERS/THUNDERSTORMS ARE N OF 17N BETWEEN
72W-77W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE FROM
15N-18N BETWEEN 70W-73W. CENTRAL AMERICA AND THE SW CARIBBEAN
ARE CURRENTLY BEING IMPACTED BY THE MONSOON TROUGH WHICH HAS
BEEN GRADUALLY LIFTING N. THE AXIS NOW EXTENDS ACROSS EL
SALVADOR...HONDURAS...AND INTO THE CARIBBEAN ALONG 14N90W 15N84W
12N75W. STRONG SHOWERS/THUNDERSTORMS ASSOCIATED WITH THIS
FEATURE ARE OVER SRN GUATEMALA...EL SALVADOR...HONDURAS...AND
NRN NICARAGUA. SCATTERED SHOWERS/THUNDERSTORMS ARE ALSO S OF THE
AXIS OVER WATER INCLUDING COSTA RICA AND PANAMA. THE MONSOON
TROUGH IS EXPECTED TO CONTINUE TO LIFT N WHICH WILL DRAW
MOISTURE ACROSS NRN CENTRAL AMERICA AND SRN MEXICO. A TROPICAL
WAVE IS IN THE ERN CARIBBEAN BETWEEN 63W-65W...BUT DUE TO DRY
AIR ALOFT WRAPPED AROUND AN UPPER LEVEL RIDGE ALONG 70W...NO
STRONG SHOWERS/THUNDERSTORMS ARE ASSOCIATED. A FEW ISOLATED
SHOWERS DO EXIST N OF 15N BETWEEN 60W-67W.

THE ATLANTIC OCEAN...

A NARROW UPPER LEVEL TROUGH EXTENDING DOWN THE FLORIDA PENINSULA
IS PLACING DIFFLUENT FLOW ALOFT OVER THE BAHAMAS AND WRN ATLC.
THE UPPER TROUGH SUPPORTS A 1009 MB LOW N OF ERN CUBA NEAR
22N76W. SCATTERED SHOWERS/THUNDERSTORMS ARE MAINLY E OF THE LOW
CENTER FROM 20N-23N BETWEEN 71W-75W. SCATTERED SHOWERS/POSSIBLE
THUNDERSTORMS ARE ALSO TO N OF 23N BETWEEN 68W-76W. AN UPPER
LEVEL RIDGE IS TO THE E ALONG 69W SUPPORTING A WEAK 1019 MB HIGH
NEAR 32N64W. DRY AIR ALOFT IS BEING WRAPPED AROUND THE ERN SIDE
OF THE UPPER RIDGE WHICH IS MAINTAINING FAIR WEATHER BETWEEN
52W-68W. ANOTHER UPPER LEVEL TROUGH IS BETWEEN 40W-55W
SUPPORTING A DISSIPATING STATIONARY FRONT ALONG 32N36W 26N42W
23N52W. ISOLATED SHOWERS ARE WITHIN 300 NM S OF THE AXIS BETWEEN
40W-52W...AND WITHIN 100 NM EITHER SIDE OF THE AXIS ELSEWHERE.
UPPER LEVEL RIDGING IS ALONG 30W AND ALSO COVERS MOST THE
TROPICAL ATLC. OVER THE FAR ERN ATLC...AN UPPER LEVEL RIDGE IS
CENTERED NEAR 44N10W SUPPORTING A SURFACE RIDGE AROUND A 1026 MB
HIGH NEAR 44N14W WITH AXIS EXTENDING SW. AN UPPER LEVEL LOW IS
TO THE S OVER THE CANARY ISLANDS NEAR 27N16W SUPPORTING A WEAK
SURFACE TROUGH ALONG 26N27W TO 21N24W. NO ACTIVE WEATHER IS
ASSOCIATED WITH THE SURFACE TROUGH.

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

$$
WALTON





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