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.