[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 122355
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2245 UTC.

...SPECIAL FEATURES...

TROPICAL STORM RAPHAEL HAS FORMED NEAR 15.0N 63.1W AT 12/2330
UTC OR ABOUT 110 NM WSW OF DOMINICA...AND 190 NM SSE OF ST.
CROIX. RAPHAEL IS MOVING NNW AT 10 KT. MINIMUM CENTRAL PRESSURE
IS 1O06 MB. MAXIMUM SUSTAINED WIND SPEED IS 35 KT WITH GUSTS TO
40 KT. SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO
HEADERS MIATCMAT2/WTNT22 KNHC. WATCHES AND WARNINGS HAVE BEEN
PLACED OVER A GOOD PORITON OF THE EASTERN CARIBBEAN. THE SYSTEM
IS CURRENTLY UNDER THE INFLUENCE OF SWLY SHEAR ALOFT...WHICH IS
CAUSING THE MAJORITY OF THE CONVECTION TO BE EAST OF THE CENTER.
WIDESPREAD MODERATE/STRONG CONVECTION IS FROM 9N-20N BETWEEN
54W-63W...AND FROM 16N-20N BETWEEN 63W-66W. MANY OF THE WINDWARD
AND LEEWARD ISLANDS ARE AT RISK FOR HEAVY RAINFALL AND GUSTY
WINDS...WHICH COULD LEAD TO FLOODING.

TROPICAL DEPRESSION PATTY IS CENTERED NEAR 25.5N 72.1W AT
12/2100 UTC OR ABOUT 230 NM ENE OF THE CENTRAL BAHAMAS. PATTY IS
STATIONARY AT THIS TIME. ESTIMATED MINIMUM CENTRAL PRESSURE IS
1007 MB. MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 40
KT. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT1/WTNT21 KNHC. THE LOW LEVEL CENTER REMAINS EXPOSED.
ONLY A FEW SMALL AREAS OF SCATTERED MODERATE CONVECTION ARE FROM
24N-26N BETWEEN 68W-70W...AND FROM 26N-28N BETWEEN 70W-71W.

...TROPICAL WAVES...

TROPICAL WAVE IS JUST WEST OF THE CAPE VERDE ISLANDS ALONG
16N26W TO 6N29W MOVING WEST AT 10-15 KT. THE WAVE COINCIDES WITH
MAXIMUM MOISTURE VALUES SEEN IN TOTAL PRECIPITABLE WATER
IMAGERY. SCATTERED MODERATE/STRONG CONVECTION IS SE OF THE WAVE
FROM 4N-9N BETWEEN 22W-27W. SCATTERED MODERATE/ISOLATED STRONG
IS WEST OF THE WAVE AXIS FROM 7N-14N BETWEEN 27W-32W.

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

THE MONSOON TROUGH EXTENDS ACROSS W AFRICA TO THE COAST OF
SENEGAL AT 14N17W CONTINUING TO NEAR 11N24W. THE ITCZ BEGINS ON
THE WEST SIDE OF A TROPICAL WAVE ALONG 10N33W TO 10N56W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 90 NM
EITHER SIDE OF THE AXIS BETWEEN 32W-43W EXCEPT FOR A LARGER AREA
OF STRONG CONVECTION FROM 7N-9N BETWEEN 39W-42W.

...DISCUSSION...

GULF OF MEXICO...
FAIR WEATHER CONTINUES ACROSS THE GULF OF MEXICO TONIGHT DUE TO
DRY AIR ALOFT AROUND AN UPPER LEVEL RIDGE COVERING THE BASIN
CENTERED OVER MEXICO NEAR 21N100W. THE UPPER RIDGE SUPPORTS A
BROAD SURFACE RIDGING WITH AXIS ALONG 89W. ONLY A FEW ISOLATED
SHOWERS/THUNDERSTORMS ARE NOTED IN THE FAR SW CORNER S OF 25N W
OF 95W. MAINLY 10-15 KT WINDS ARE PRESENT AROUND THE RIDGE WITH
SOME STRONGER WINDS NEAR THE YUCATAN PENINSULA. SURFACE RIDGING
IS EXPECTED TO REMAIN ACROSS THE BASIN FOR THE NEXT COUPLE OF
DAYS WITH WINDS INCREASING OVER THE EASTERN GULF.

CARIBBEAN SEA...
NEWLY FORMED TROPICAL STORM RAPHAEL IS IMPACTING THE EASTERN
CARIBBEAN. SEE SPECIAL FEATURES ABOVE. THE REMAINDER OF THE
BASIN IS UNDER MOSTLY FAIR CONDITIONS DUE TO DRY AIR SINKING
INTO THE BASIN AROUND THE UPPER RIDGE IN THE GULF OF MEXICO AND
WRAPPING AROUND AN UPPER LEVEL TROUGH OVER THE NW CARIBBEAN. A
THIN SWATH OF MOISTURE IS AROUND THE EAST SIDE OF THE UPPER
TROUGH SUPPORTING A FEW ISOLATED SHOWERS/THUNDERSTORMS FROM
HONDURAS TO EASTERN CUBA. MORE SCATTERED ACTIVITY IS OVER THE
LAND MASSES INCLUDING HONDURAS...NICARAGUA...EASTERN CUBA AND
HISPANIOLA. ISOLATED SHOWERS/THUNDERSTORMS ARE ALSO OVER COSTA
RICA AND PANAMA ASSOCIATED WITH THE MONSOON TROUGH THAT EXTENDS
FROM COSTA RICA TO NORTHERN PANAMA. AN UPPER LEVEL LOW IS
SPINNING NEAR THE MONA PASSAGE HELPING PROVIDE DIFFLUENT FLOW
AND SHEAR OVER THE EASTERN CARIBBEAN NEAR TROPICAL STORM
RAPHAEL.

ATLANTIC OCEAN...
TROPICAL DEPRESSION PATTY REMAINS NE OF THE BAHAMAS SUPPORTING A
FEW AREAS OF SHOWERS/THUNDERSTORMS MAINLY NE OF THE CENTER. A
FEW SCATTERED SHOWERS/THUNDERSTORMS ARE ALSO NORTH OF EASTERN
CUBA. AN UPPER LEVEL TROUGH SITS WEST OF PATTY ALONG 75W
PROVIDING DIFFLUENT FLOW NE OF PATTY WHERE SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE N OF 27N BETWEEN 63W-68W.
SHOWERS/THUNDERSTORMS ARE NORTH AND EAST OF THE FAR EASTERN
CARIBBEAN ASSOCIATED WITH TROPICAL STORM RAPHAEL. SEE SPECIAL
FEATURES ABOVE. AN UPPER LEVEL LOW IS WEST OF THE SYSTEM
CENTERED OVER THE MONA PASSAGE. A SECOND UPPER LEVEL LOW IS TO
THE NORTH OF THE SYSTEM NEAR 28N55W SUPPORTING A FEW ISOLATED
SHOWERS N OF 27N BETWEEN 52W-56W. THE REMAINDER OF THE ATLC IS
DOMINATED BY SURFACE RIDGING AROUND A 1026 MB HIGH CENTERED NEAR
34N41W. THE RIDGE IS SUPPORTED BY AN UPPER LEVEL RIDGE ALONG
44W. A BROAD UPPER LEVEL LOW IS CENTERED NEAR 24N32W SUPPORTING
A FEW SHOWERS/THUNDERSTORMS NEAR THE UPPER LOW CENTER.

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

$$
WALTON





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