[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 121754
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI OCT 12 2012

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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURES...

TROPICAL STORM PATTY IS CENTERED NEAR 25.5N 72.0W AT 12/1500 UTC
OR ABOUT 240 NM ENE OF THE CENTRAL BAHAMAS MOVING NE AT 2 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1006 MB. MAXIMUM SUSTAINED
WIND SPEED IS 35 KT WITH GUSTS TO 45 KT. SEE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC.
THE LOW LEVEL CENTER IS BECOMING EXPOSED TO THE SW OF THE DEEP
CONVECTION. CLUSTERS OF SCATTERED/ISOLATED STRONG CONVECTION ARE
FROM 25N-28N BETWEEN 65W-72W.

A BROAD AREA OF LOW PRESSURE ASSOCIATED WITH A WEAK 1006 MB LOW
IS CENTERED W OF THE LESSER ANTILLES ABOUT 87 NM W OF DOMINICA.
AN UPPER RIDGE IS TO THE E OF THE LESSER ANTILLES PROVIDING
DIFFLUENCE ALOFT ENHANCING AN AREA OF SCATTERED/NUMEROUS STRONG
CONVECTION WITHIN A 120 NM RADIUS OF 14.5N60.5W INCLUDING THE
ISLANDS FROM SAINT LUCIA TO DOMINICA. SURFACE OBSERVATIONS
INDICATE THAT THIS SYSTEM IS PRODUCING WINDS TO TROPICAL STORM
FORCE IN RAINBANDS...HOWEVER SATELLITE IMAGERY AND SURFACE
OBSERVATIONS STILL SUGGEST THAT THE LOW LACKS A CLOSED SURFACE
CIRCULATION. UPPER LEVEL WINDS ARE EXPECTED TO BECOME MORE
CONDUCIVE FOR DEVELOPMENT AND IT IS LIKELY THAT A TROPICAL
DEPRESSION OR TROPICAL STORM WILL FORM DURING THE NEXT DAY OR
TWO. IF THIS OCCURS...A TROPICAL STORM WARNING WOULD BE REQUIRED
FOR PORTIONS OF THE LEEWARD ISLANDS. THIS SYSTEM HAS A HIGH
CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS
AS IT MOVES NW OR N-NW AT 9 TO 13 KT.

...TROPICAL WAVES...

TROPICAL WAVE EXTENDS FROM THE CAPE VERDE ISLANDS NEAR 16N24W TO
6N27W MOVING W 10-15 KT. WAVE IS EMBEDDED WITHIN A SURGE OF DEEP
MOISTURE AS DEPICTED ON THE TOTAL PRECIPITABLE WATER IMAGERY.
CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE
WITHIN 120/150 NM OF LINE FROM 5N16W TO 10N34W.

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

THE MONSOON TROUGH EXTENDS ACROSS W AFRICA INTO THE E TROPICAL
ATLC NEAR 14N16W TO E OF THE TROPICAL WAVE NEAR 12N20W. THE ITCZ
AXIS BEGINS W OF THE TROPICAL WAVE NEAR 7N31W ALONG 8N41W TO
9N52W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION
ARE WITHIN 120 NM S OF THE ITCZ BETWEEN 39W-44W.

...DISCUSSION...

GULF OF MEXICO...
A BROAD UPPER RIDGE COVERS THE GULF THIS AFTERNOON W OF 86W
ANCHORED INLAND OVER MEXICO NEAR MEXICO CITY EXTENDING A RIDGE
AXIS NNE OVER TEXAS AND THE CENTRAL PLAIN STATES. AN UPPER
TROUGH COVERS THE REMAINDER OF THE GULF E OF 86W WITH THE TROUGH
AXIS IN THE W ATLC. DRY STABLE UPPER AIR DOMINATES MOST OF THE
GULF. A WEAK SURFACE TROUGH IS IN THE SW GULF EXTENDING FROM
22N96W TO THE S COAST OF MEXICO NEAR 18N94W GENERATING SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS WITHIN 75 NM ALONG THE COAST OF
TEXAS AND MEXICO S OF CORPUS CHRISTI TEXAS AND W OF
COATZACOALCOS MEXICO. A SURFACE RIDGE IS BUILDING S OVER THE
GULF ANCHORED OVER CENTRAL GEORGIA. DRIER AIR HAS SETTLED OVER
THE AREA IN WAKE OF THE RECENT FRONTAL PASSAGE LEAVING THE
REMAINDER OF THE GULF WITH FAIR WEATHER THIS AFTERNOON. SURFACE
RIDGE WILL REMAIN OVER THE GULF SHIFTING E ON MON MAKING WAY FOR
A WEAK FRONTAL TROUGH TO SWEEP ACROSS THE FAR N GULF MON AND
TUE. A SECOND SURFACE RIDGE WILL MOVE E IN WAKE OF THE FRONTAL
TROUGH.

CARIBBEAN SEA...
A WEAK 1006 MB LOW IS W OF THE LESSER ANTILLES...SEE SPECIAL
FEATURES ABOVE. THE UPPER TROUGH OVER THE E GULF OF MEXICO DIPS
S OVER THE NW CARIBBEAN N OF 17N W OF 76W TO OVER THE YUCATAN
PENINSULA WITH SCATTERED SHOWERS/ISOLATED THUNDERSTORMS AT THE
BASE OF THE UPPER TROUGH FROM 15N-19N W OF 82W TO INLAND OVER
HONDURAS AND THE YUCATAN PENINSULA. SIMILAR ACTIVITY IS N OF
JAMAICA TO INLAND OVER CUBA BETWEEN 74W-78W. THE UPPER RIDGE
OVER THE W GULF OF MEXICO EXTENDS A RIDGE AXIS W ACROSS CENTRAL
AMERICA INTO THE CARIBBEAN NEAR THE TIP OF NICARAGUA/HONDURAS TO
16N74W. AN UPPER LOW IS S OF THE MONA PASSAGE NEAR 16N68W
COVERING THE REMAINDER OF THE CARIBBEAN AND GENERATING ISOLATED
SHOWERS/THUNDERSTORMS N OF 16N BETWEEN 64W-69W INCLUDING PUERTO
RICO AND THE VIRGIN ISLANDS. AN UPPER RIDGE OVER THE W TROPICAL
ATLC IS GENERATING A BROAD AREA OF SCATTERED/NUMEROUS SHOWERS
WITH SCATTERED THUNDERSTORMS FROM OVER THE LESSER ANTILLES
EASTWARD AND INCLUDING THE AREA ASSOCIATED WITH THE 1006 MB LOW
IN THE SPECIAL FEATURES. THE MONSOON TROUGH EXTENDS ACROSS THE
SW CARIBBEAN FROM COLOMBIA NEAR 10N75W ALONG 11N80W THEN ACROSS
COSTA RICA INTO THE E PACIFIC REGION NEAR 10N85W GENERATING
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS S OF 11N ALONG THE
COAST OF COLOMBIA AND INLAND OVER W PANAMA. THIS IS LEAVING THE
REMAINDER OF THE CARIBBEAN WITH FAIR WEATHER THIS AFTERNOON.
STRONG WINDS...ROUGH SEAS...AND NUMEROUS SQUALLS WILL ACCOMPANY
THE 1006 MB LOW OVER THE LEEWARD AND VIRGIN ISLANDS AS THIS LOW
MOVES NNW TO OVER THE VIRGIN ISLANDS SAT MORNING AND INTO THE W
ATLC E OF THE TURKS AND CAICOS BY SUN MORNING.

ATLANTIC OCEAN...
T.S. PATTY REMAINS E OF THE BAHAMA ISLANDS THIS AFTERNOON...SEE
SPECIAL FEATURES ABOVE. THE UPPER TROUGH OVER THE E GULF OF
MEXICO AND THE NW CARIBBEAN EXTENDS TO OVER THE FAR W ATLC WITH
A DISSIPATING STATIONARY FRONT ENTERING THE REGION NEAR 32N69W
TO N OF T.S. PATTY NEAR 28N71W. SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS ARE N OF 28N BETWEEN 65W AND THE FRONTAL BOUNDARY.
SIMILAR ACTIVITY IS WITHIN 120 NM OF LINE FROM OVER CUBA NEAR
21N75W TO OVER THE TURKS AND CAICOS TO NEAR 23N74W. THE SURFACE
RIDGE BUILDING S OVER THE GULF OF MEXICO COVERS THE W ATLC W OF
77W ANCHORED OVER CENTRAL GEORGIA AND LEAVING THE REMAINDER OF
THE W ATLC W OF THE T.S. PATTY WITH FAIR WEATHER THIS AFTERNOON.
AN UPPER LOW IS IN THE CENTRAL ATLC NEAR 27N58W GENERATING
ISOLATED SHOWERS/THUNDERSTORMS FROM 25N-31N BETWEEN 53W-59W. A
SECOND UPPER LOW IS IN THE E ATLC CENTERED NEAR 23N31W
GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 21N-24N
BETWEEN 31W-34W. THE REMAINDER OF THE ATLC BASIN N OF THE
TROPICS IS DOMINATED BY A SURFACE RIDGE ANCHORED BY A 1027 MB
HIGH JUST N OF THE DISCUSSION AREA NEAR 34N42W. AN UPPER RIDGE
IN THE W TROPICAL ATLC EXTENDS FROM ALONG 53W FROM 10N-23N
PROVIDING DIFFLUENCE ALOFT TO GENERATE SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS FROM 10N-17N BETWEEN 56W-62W INCLUDING A
PORTION OF THE LESSER ANTILLES. ISOLATED SHOWERS AND POSSIBLE
ISOLATED THUNDERSTORMS COVER THE REMAINDER OF THE AREA FROM
7N-21N BETWEEN 41W-55W. PATTY WILL DRIFT SLOWLY E AND WEAKEN TO
TROPICAL DEPRESSION LATE THIS AFTERNOON THEN WEAKEN TO A REMNANT
LOW CENTERED BY SUN NEAR 23.5N 75.0W. THE 1006 MB LOW WILL MOVE
OUT OF THE NE CARIBBEAN LATE SAT/EARLY SUN TO E OF THE CENTRAL
BAHAMAS BY MON MORNING.

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

$$
PAW




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