[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 201143
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SAT OCT 20 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...

A CARIBBEAN SEA TROPICAL WAVE IS ALONG 70W...FROM THE EASTERN
HALF OF THE DOMINICAN REPUBLIC...TO THE NORTHWESTERN CORNER OF
VENEZUELA. CONVECTIVE PRECIPITATION...SCATTERED MODERATE TO
STRONG WITHIN 90 NM ON EITHER SIDE OF 12N66W...SCATTERED
MODERATE TO ISOLATED STRONG BETWEEN 70W AND 75W AND FROM 15N TO
17N BETWEEN 76W AND 77W. THE 24-HOUR RAINFALL TOTAL IN INCHES
FOR GUADELOUPE FOR THE PERIOD ENDING AT 20/0000 UTC IS 0.69.
ENVIRONMENTAL CONDITIONS ARE FORECAST TO BECOME MORE FAVORABLE
FOR DEVELOPMENT DURING THE NEXT DAY OR TWO AS THE DISTURBANCE
MOVES WESTWARD AND THIS SYSTEM HAS A MEDIUM CHANCE OF BECOMING A
TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

...TROPICAL WAVES...

AN ATLANTIC OCEAN TROPICAL WAVE POSITION HAS BEEN RE-LOCATED
TO BE ALONG 44W FROM 10N TO 20N...BASED ON SATELLITE IMAGERY.
RAINSHOWERS ARE POSSIBLE FROM 10N TO 20N BETWEEN 40W AND 47W.

AN ATLANTIC OCEAN TROPICAL WAVE POSITION HAS BEEN RE-LOCATED
TO BE 57W FROM 13N TO 25N...BASED ON SATELLITE IMAGERY.
RAINSHOWERS ARE POSSIBLE FROM 17N TO 26N BETWEEN 56W AND 60W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH PASSES THROUGH COASTAL GUINEA-BISSAU NEAR
12N16W TO 10N20W...CURVING TO 9N30W. THE ITCZ CONTINUES FROM
9N30W TO 5N40W AND 5N50W. CONVECTIVE PRECIPITATION...SCATTERED
MODERATE TO STRONG FROM 5N TO 12N BETWEEN AFRICA AND 23W FROM
11N TO 12N BETWEEN 26W AND 30W FROM 7N TO 12N BETWEEN 31W AND
34W...WIDELY SCATTERED TO SCATTERED MODERATE AND ISOLATED
STRONG ELSEWHERE FROM 6N TO 13N BETWEEN 37W AND 45W.

...DISCUSSION...

FROM THE WESTERN ATLANTIC OCEAN INTO THE GULF OF MEXICO...
AND THE REST OF THE GULF OF MEXICO...

A DEEP LAYER TROUGH PASSES THROUGH THE GREAT LAKES REGION OF THE
U.S.A....THROUGH THE SOUTHEASTERN U.S.A....INTO THE EAST CENTRAL
AND SOUTHEASTERN GULF OF MEXICO. THE TROUGH SUPPORTS A SLOWLY-
MOVING COLD FRONT THAT PASSES THROUGH 32N76W IN THE ATLANTIC
OCEAN...TO 27N81W IN FLORIDA...TO 25N90W IN THE CENTRAL GULF OF
MEXICO...TO 23N98W ALONG THE MEXICO COAST. COMPARATIVELY DRIER
AIR IN SUBSIDENCE IN WATER VAPOR IMAGERY IS TO THE NORTH AND
NORTHWEST OF THE LINE THAT PASSES THROUGH 32N77W...INTO THE
SOUTH CENTRAL GULF OF MEXICO NEAR 23N90W...TO THE LOWER TEXAS
GULF COAST.

BROKEN TO OVERCAST MULTILAYERED CLOUDS AND POSSIBLE RAINSHOWERS
ARE WITHIN 60 TO 90 NM ON EITHER SIDE OF THE LINE THAT PASSES
THROUGH 28N80W TO 24N90W...AND IN THE WATERS THAT ARE FROM 22N
TO 28N TO THE WEST OF 90W. OTHER BROKEN TO OVERCAST MULTILAYERED
CLOUDS AND POSSIBLE PRECIPITATION ARE IN THE WATERS THAT ARE
TO THE SOUTH OF 22N TO THE WEST OF 90W.

CONVECTIVE PRECIPITATION THAT IS TO THE EAST OF THE COLD FRONT
AND THE DEEP LAYER TROUGH...SCATTERED MODERATE TO STRONG TO THE
NORTH OF 29N BETWEEN 70W AND 76W...ISOLATED MODERATE TO LOCALLY
STRONG ELSEWHERE THE NORTH OF 20N TO THE WEST OF 65W.

THE CARIBBEAN SEA...

MIDDLE LEVEL TO UPPER LEVEL WIND FLOW MOVES FROM THE
SOUTHWESTERN CORNER OF THE GULF OF MEXICO...ACROSS THE YUCATAN
PENINSULA...INTO THE NORTHWESTERN CORNER OF THE AREA. THE
DIRECTIONAL COMPONENT OF THE WIND EVENTUALLY CHANGES SLIGHTLY
TO WESTERLY AND SOUTHWESTERLY AS THE WIND MOVES FROM THE YUCATAN
PENINSULA THROUGH THE WINDWARD PASSAGE. THE SOUTHWESTERLY WIND
FLOW THAT MOVES THROUGH THE WINDWARD PASSAGE EVENTUALLY MERGES
INTO THE LONGER WAVE LARGER-SCALE TROUGH THAT SUPPORTS THE GULF
OF MEXICO COLD FRONT. THE WIND FLOW THAT DOES NOT MERGE INTO THE
TROUGH AREA BECOMES PART OF AN AREA OF MIDDLE LEVEL TO UPPER
LEVEL ANTICYCLONIC WIND FLOW WITH A MEAN CENTER NEAR 16N70W.
PART OF THE WIND THAT IS TO THE EAST OF 67W EVENTUALLY MERGES
INTO CYCLONIC FLOW THAT IS MOVING AROUND AN ATLANTIC OCEAN
18N52W CYCLONIC CIRCULATION CENTER AND A RELATED TROUGH.
THE MIDDLE LEVEL TO UPPER LEVEL WIND FLOW THAT IS IN THE
SOUTHWESTERN CORNER OF THE AREA IS LARGELY
EASTERLY-TO-NORTHEASTERLY.

A TROPICAL WAVE IS ALONG 70W...FROM THE EASTERN HALF OF THE
DOMINICAN REPUBLIC...TO THE NORTHWESTERN CORNER OF VENEZUELA.
CONVECTIVE PRECIPITATION...SCATTERED MODERATE TO STRONG WITHIN
90 NM ON EITHER SIDE OF 12N66W...SCATTERED MODERATE TO ISOLATED
STRONG BETWEEN 70W AND 75W AND FROM 15N TO 17N BETWEEN 76W AND
77W. THE 24-HOUR RAINFALL TOTAL IN INCHES FOR GUADELOUPE
FOR THE PERIOD ENDING AT 20/0000 UTC IS 0.69.

A SURFACE TROUGH IS ALONG 82W/83W FROM 11N TO 20N. SCATTERED
MODERATE TO ISOLATED STRONG CONVECTIVE PRECIPITATION IS FROM
14N TO 16N BETWEEN 79W AND 83W...AND IN THE NORTHWESTERN CORNER
OF THE AREA FROM 16N AT THE HONDURAS COAST TO 21N NEAR CUBA
BETWEEN 79W AND 86W. THE 24-HOUR RAINFALL TOTAL IN INCHES FOR
TEGUCIGALPA HONDURAS FOR THE PERIOD ENDING AT 20/0000 UTC IS
0.31.

THE REST OF THE ATLANTIC OCEAN...

AN UPPER LEVEL SHEAR AXIS PASSES THROUGH 32N43W TO 25N50W...
CURVING TO AN 18N52W ATLANTIC OCEAN MIDDLE TO UPPER LEVEL
CYCLONIC CIRCULATION CENTER. THE TROUGH CONTINUES FROM 18N52W
TO 13N52W AND 8N59W ALONG THE COAST OF GUYANA. MIDDLE LEVEL TO
UPPER LEVEL NORTHERLY WIND FLOW THAT IS IN THE ATLANTIC OCEAN
BETWEEN THE SHEAR AXIS AND 61W EVENTUALLY FEEDS INTO THE
LARGER-SCALE CYCLONIC WIND FLOW AROUND THE WHOLE SYSTEM.
CONVECTIVE PRECIPITATION...NUMEROUS STRONG FROM 20N TO 22N
BETWEEN 43W AND 46W...WARMING CLOUD TOP TEMPERATURES AND
WEAKENING/DISSIPATING BUT POSSIBLY STILL LINGERING CONVECTIVE
PRECIPITATION IS FROM 22N TO 24N BETWEEN 49W AND 51W.

A 1016 MB LOW PRESSURE CENTER IS NEAR 31N56W. A SURFACE TROUGH
EXTENDS FROM THE LOW CENTER TO 27N58W. ISOLATED TO WIDELY
SCATTERED MODERATE CONVECTIVE PRECIPITATION IS FROM 27N TO 32N
BETWEEN 53W AND 57W.

RAINSHOWERS ARE POSSIBLE FROM 25N TO 28N BETWEEN 61W AND 63W.
THIS AREA IS ON THE EASTERN SIDE OF AN UPPER LEVEL RIDGE...
TO THE SOUTHWEST OF THE 31N56W 27N58W SURFACE TROUGH.

AN UPPER LEVEL TROUGH EXTENDS FROM A WESTERN SAHARA CYCLONIC
CIRCULATION CENTER THAT IS NEAR 24N13W TO 21N19W AND 13N20W.
NO SIGNIFICANT DEEP CONVECTIVE PRECIPITATION IS ASSOCIATED
WITH THE TROUGH.

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

$$
MT




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