000
AXNT20 KNHC 121151
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1015 UTC.

...SPECIAL FEATURES...

TROPICAL STORM PATTY AT 11/0900 UTC IS CENTERED NEAR 25.1N 72.5W 
OR ABOUT ABOUT 230 MI...375 KM ENE OF THE CENTRAL BAHAMAS. 
PRESENT MOVEMENT IS SSW AT 3 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. NIGHTTIME VISIBLE IMAGES SHOW THE 
WELL-DEFINED LOW-LEVEL CENTER EXPOSED ABOUT 60 N MI SOUTHWEST OF 
THE NEAREST DEEP CONVECTION...AS A CONSEQUENCE OF STRONG 
SOUTHWESTERLY SHEAR. AN INCREASINGLY DRIER AND MORE STABLE AIR 
MASS IS ALSO WRAPPING AROUND THE CIRCULATION OF THE STORM DUE 
ITS PROXIMITY TO A FRONT. SCATTERED MODERATE TO ISOLATED STRONG 
CONVECTION IS FROM 25N-31N BETWEEN 66W-72W.

AS OF 0600 UTC...A BROAD AREA OF LOW PRESSURE ASSOCIATED WITH A 
TROPICAL WAVE IS LOCATED NEAR 13.6N 60.4W OR ABOUT 32 NM SE OF 
ST LUCIA. ALTHOUGH THIS SYSTEM IS LIKELY PRODUCING WINDS TO 
TROPICAL STORM FORCE IN RAIN BANDS...SATELLITE AND SURFACE DATA 
SUGGEST THAT THE LOW STILL LACKS A CLOSED CIRCULATION.  UPPER 
LEVEL WINDS ARE EXPECTED TO BECOME MORE CONDUCIVE FOR 
DEVELOPMENT AND A TROPICAL DEPRESSION OR TROPICAL STORM IS 
LIKELY TO FORM DURING THE NEXT DAY OR SO AND A TROPICAL STORM 
WARNING COULD 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. 
STRONG GUSTY WINDS AND LOCALLY HEAVY RAINFALL ARE POSSIBLE 
ACROSS PORTIONS OF THE LESSER ANTILLES DURING THE NEXT COUPLE OF 
DAYS. SCATTERED MODERATE TO STRONG CONVECTION IS E OF THE CENTER 
FROM 7N-17N BETWEEN 57W-60W. CLUSTERS OF SCATTERED MODERATE TO 
ISOLATED STRONG CONVECTION ARE ELSEWHERE FROM 9N-19N BETWEEN 
44W-57W.  
 
...TROPICAL WAVES...

A TROPICAL WAVE IS S OF THE CAPE VERDE ISLANDS FROM 16N22W TO 
5N24W BASED ON SATELLITE IMAGERY MOVING W AT 15 KT. ISOLATED 
MODERATE CONVECTION IS FROM 3N-10N BETWEEN 20W-30W.  

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

THE MONSOON TROUGH EXTENDS ACROSS WEST AFRICA ENDING ALONG THE 
COAST OF GUINEA BISSAU AT 12N16W. THE ITCZ IS W OF THE TROPICAL 
WAVE FROM 5N27W TO 5N34W TO 7N40W TO 10N54W. SCATTERED MODERATE 
TO ISOLATED STRONG CONVECTION IS ALONG THE COAST OF W AFRICA 
FROM 5N-11N BETWEEN 14W-18W. ISOLATED MODERATE CONVECTION IS N 
OF THE ITCZ FROM 7N-12N BETWEEN 35W-39W.

...DISCUSSION...

GULF OF MEXICO...
A 1025 MB HIGH IS CENTERED OVER N ALABAMA AT 34N87W. 10-20 KT 
EASTERLY SURFACE WINDS ARE OVER THE GULF OF MEXICO WITH 
STRONGEST WINDS N OF THE YUCATAN PENINSULA. SCATTERED MODERATE 
TO STRONG CONVECTION IS OVER THE BAY OF CAMPECHE AND S MEXICO 
FROM 17N-20N BETWEEN 93W-97W MOVING W. IN THE UPPER LEVELS...THE 
BASE OF AN UPPER LEVEL TROUGH IS OVER THE E GULF AND FLORIDA E 
OF 87W. AN UPPER LEVEL HIGH IS CENTERED OVER MEXICO NEAR 20N99W. 
STRONG SUBSIDENCE COVERS THE GULF EXCEPT OVER THE BAY OF 
CAMPECHE. EXPECT OVER THE NEXT 24 HOURS FOR CONVECTION TO 
PERSIST OVER THE BAY OF CAMPECHE...AND ALONG THE COAST OF MEXICO 
NEAR TAMPICO.  

THE CARIBBEAN SEA...
A WEAK 1006 MB LOW IS IN THE VICINITY OF ST LUCIA. A 
CONSIDERABLE AMOUNT OF CONVECTION IS E OF THE ISLAND. SEE ABOVE. 
EXPECT THE LOW CENTER TO BE OVER THE LEEWARD ISLANDS IN 24 HOURS 
WITH WINDS NEAR TROPICAL STORM FORCE N AND E OF CENTER. 
ELSEWHERE...THE SURFACE PRESSURE GRADIENT IS TIGHTENING OVER THE 
NW CARIBBEAN WHERE 20 KT NE WINDS ARE EXPECTED IN 12-24 HOURS. 
PRESENTLY ISOLATED MODERATE CONVECTION IS OVER THE NW CARIBBEAN. 
SCATTERED MODERATE CONVECTION IS OVER N COLOMBIA...PANAMA. 
WIDELY SCATTERED MODERATE CONVECTION IS OVER JAMAICA...E 
CUBA...AND HAITI FROM 17N-21N BETWEEN 72W-78W. SCATTERED SHOWERS 
ARE OVER THE E CARIBBEAN E OF 70W. IN THE UPPER LEVELS...AN 
UPPER LEVEL RIDGING IS OVER THE W CARIBBEAN W OF 83W...WHILE NE 
UPPER LEVEL FLOW IS OVER THE REMAINDER OF THE CARIBBEAN. EXPECT 
INCLEMENT WEATHER OVER THE E CARIBBEAN OVER THE NEXT 24 
HOURS...AND ALSO INCREASED CONVECTION OVER THE SW CARIBBEAN. 
  

THE ATLANTIC OCEAN...
T.S. PATTY IS E OF THE BAHAMAS. SEE ABOVE. A LARGE 1027 MB HIGH 
IS OVER THE CENTRAL ATLANTIC NEAR 33N42W. A LARGE AREA OF 
AFRICAN DUST AND DRY AIR IS OVER THE E ATLANTIC N OF 20N E OF 
50W. IN THE UPPER LEVELS...AN UPPER LEVEL LOW IS CENTERED OVER 
THE CENTRAL ATLANTIC NEAR 25N32W. ISOLATED MODERATE CONVECTION 
IS E OF THE CENTER FROM 23N-27N BETWEEN 29W-32W. ANOTHER UPPER 
LEVEL LOW IS CENTERED N OF THE LEEWARD ISLANDS NEAR 27N57W. 
ISOLATED MODERATE CONVECTION IS FROM 25N-29N BETWEEN 50W-54W.    

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

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FORMOSA