Atlantic Tropical Weather Discussion

000
AXNT20 KNHC 130548
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT THU SEP 13 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0515 UTC.

...SPECIAL FEATURES...
TROPICAL STORM NADINE IS CENTERED NEAR 20.7N 50.1W 13/0300 UTC 
OR ABOUT 715 NM ENE OF THE LESSER ANTILLES MOVING NW AT 14 KT. 
ESTIMATED MINIMUM CENTRAL PRESSURE IS 990 MB. MAXIMUM SUSTAINED 
WIND SPEED IS 60 KT WITH GUSTS TO 75 KT. SEE LATEST NHC 
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC 
FOR MORE DETAILS. SCATTERED MODERATE TO STRONG CONVECTION IS 
FROM 19N-23N BETWEEN 46W-52W. SCATTERED MODERATE/ISOLATED STRONG 
CONVECTION IS WITHIN 60 NM OF LINE FROM 17N52W TO 19N48W. 

...TROPICAL WAVES...

TROPICAL WAVE IS SW OF THE CAPE VERDE ISLANDS EXTENDING FROM 
14N36W TO A WEAK 1013 MB LOW NEAR 9N33W MOVING W 15-20 KT. WAVE 
IS EMBEDDED WITHIN AN AREA OF DEEP MOISTURE AS DEPICTED ON THE 
TOTAL PRECIPITABLE WATER IMAGERY. CLUSTERS OF SCATTERED SHOWERS/ 
ISOLATED THUNDERSTORMS ARE FROM 5N-14N BETWEEN 33W-40W. 

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS AFRICA BUT DOES NOT ENTER THE 
E TROPICAL ATLC. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG 
CONVECTION ARE FROM 5N-10N E OF 22W TO INLAND OVER W AFRICA. 

...DISCUSSION...

GULF OF MEXICO...
THE CUTOFF UPPER LOW REMAINS OVER THE LOWER MISSISSIPPI VALLEY 
WITH THE UPPER TROUGH EXTENDING S OVER THE N GULF OF MEXICO. AN 
UPPER TROUGH OVER THE NW ATLC IS SUPPORTING A DISSIPATING 
FRONTAL BOUNDARY THAT ENTERS THE GULF OF MEXICO OVER W CUBA NEAR 
22N84W ALONG 25N90W TO OFF THE COAST OF LOUISIANA NEAR 29N92W. 
CLUSTERS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE N OF 
27N BETWEEN 83W-95W. AN UPPER RIDGE EXTENDS ACROSS SW MEXICO TO 
OVER THE SW GULF ENHANCING CLUSTERS OF SCATTERED SHOWERS/ 
ISOLATED THUNDERSTORMS FROM 20N-26N W OF 94W TO INLAND OVER 
MEXICO. SURFACE RIDGE IS BUILDING S OVER THE N GULF ANCHORED BY 
A 1026 MB HIGH OVER NORTH CAROLINA. THE REMAINDER OF THE GULF IS 
UNDER FAIR WEATHER TONIGHT. HIGH PRESSURE WILL PREVAIL THROUGH 
THE WEEKEND. 

CARIBBEAN SEA...
A BROAD UPPER RIDGE OVER THE W ATLC DOMINATES THE N CARIBBEAN 
WHILE A SECOND UPPER RIDGE DOMINATES THE SW WATERS. THE 
DISSIPATING FRONTAL BOUNDARY THAT EXTENDS ACROSS THE W ATLC AND 
GULF OF MEXICO DIPS S OFF THE S COAST OF CUBA BETWEEN 80W-84W. 
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE OVER THE NW 
CARIBBEAN N OF 20N BETWEEN 77W-85W AND IN THE GULF OF HONDURAS S 
OF 18N W OF 82W TO INLAND OVER HONDURAS. THE MONSOON TROUGH 
EXTENDS FROM COLOMBIA ALONG 10N ACROSS COSTA RICA INTO THE E 
PACIFIC REGION GENERATING SCATTERED SHOWERS/ISOLATED 
THUNDERSTORMS S OF 11N BETWEEN 75W-82W. A CUTOFF UPPER LOW IS 
CENTERED JUST N OF THE VIRGIN ISLANDS EXTENDING AN UPPER TROUGH 
OVER THE E CARIBBEAN E OF 71W. CLUSTERS OF SCATTERED SHOWERS AND 
POSSIBLE ISOLATED THUNDERSTORMS ARE ACROSS THE E CARIBBEAN E OF 
710W. MODERATE TO FRESH TRADE WINDS ARE ACROSS THE S CENTRAL 
CARIBBEAN WATERS WITH LIGHT TO MODERATE TRADE WINDS ELSEWHERE. 
OTHERWISE THE REMAINDER OF THE CARIBBEAN IS UNDER FAIR WEATHER 
TONIGHT. HIGH PRESSURE OVER THE W ATLC WILL MAINTAIN TRADE 
THROUGH THU.

ATLANTIC OCEAN...
THE PRIMARY CONCERN THIS MORNING IS TROPICAL STORM NADINE IN THE 
CENTRAL TROPICAL ATLC. SEE SPECIAL FEATURES ABOVE. AN UPPER 
RIDGE DOMINATES THE W ATLC ANCHORED OVER THE CENTRAL BAHAMA 
ISLANDS. A SURFACE RIDGE CONTINUES TO BUILD S OVER THE W ATLC W 
OF THE FRONTAL BOUNDARY DESCRIBED BELOW AND ANCHORED BY A 1026 
MB HIGH OVER NORTH CAROLINA. AN UPPER TROUGH COVERS THE NW ATLC 
SUPPORTING A STATIONARY FRONT THAT EXTENDS INTO THE CENTRAL ATLC 
NEAR 32N57W EXTENDING TO 26N64W WHERE IT DISSIPATES ALONG 23N69W 
TO OVER CUBA NEAR 22N78W. SCATTERED SHOWERS/ISOLATED 
THUNDERSTORMS ARE N OF THE FRONT TO 26N BETWEEN 75W-80W WITH 
ISOLATED SHOWERS WITHIN 150 NM W OF THE FRONT E OF 68W. 
SATELLITE IMAGERY OVER THE PORTION OF THE FRONT NEAR THE BAHAMA 
ISLANDS AND THE FLORIDA STRAITS SUGGEST THAT A N/S SURFACE 
TROUGH IS DEVELOPING AND WILL BE ADDED TO THE 13/0600 UTC 
ANALYSIS. A CUTOFF UPPER LOW IS CENTERED N OF THE VIRGIN 
ISLANDS NEAR 20N64W EXTENDING AN UPPER TROUGH OVER THE E 
CARIBBEAN AND NNE TO NEAR 28N58W PRECEDING TROPICAL STORM 
NADINE. BROAD UPPER LOW IS CENTERED OVER THE NE ATLC COVERING 
THE AREA N OF 23N BETWEEN 15W-40W GENERATING CLUSTERS OF 
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF 26N BETWEEN 
22W-38W. HIGH PRESSURE PREVAILS ACROSS THE W ATLC IN THE WAKE OF 
A DISSIPATED FRONTAL BOUNDARY. TROPICAL STORM NADINE OVER THE 
CENTRAL TROPICAL ATLC IS FORECAST TO REACH HURRICANE INTENSITY 
OVERNIGHT WHILE MAINTAINING A NW TRACK. 

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

$$
PAW