[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 160001
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON OCT 15 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
2315 UTC.

...SPECIAL FEATURES...

TROPICAL STORM RAFAEL IS CENTERED NEAR 24.5N 65.7W AT 16/0000
UTC OR ABOUT 475 NM S OF BERMUDA. RAFAEL IS MOVING N AT 9 KT.
MINIMUM CENTRAL PRESSURE IS 974 MB. MAXIMUM SUSTAINED WIND SPEED
IS 75 KT WITH GUSTS TO 90 KT. SEE THE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC.
NUMEROUS STRONG CONVECTION IS NEAR THE STORM CENTER FROM 23N-26N
BETWEEN 63W-67W. A FEEDER BAND CONTINUES TO BRING SCATTERED
MODERATE/ISOLATED STRONG CONVECTION FROM THE NE CARIBBEAN
NORTHWARD FROM 15N-24N BETWEEN 59W-65W.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 18N32W TO 10N33W MOVING WEST AT 10-15 KT.
THE WAVE LIES WITHIN A LARGE AREA OF MAXIMUM MOISTURE VALUES
PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED
MODERATE/STRONG CONVECTION IS FROM 9N-15N BETWEEN 26W-35W.
CONVECTION NEAR THE WAVE IS ALSO BEING ENHANCED BY AN UPPER
LEVEL TROUGH.

TROPICAL WAVE IS ALONG 19N46W TO 11N43W MOVING WEST AT 10-15 KT.
THE WAVE LIES JUST WEST OF A LOW-AMPLITUDE SURGE OF DEEP LAYER
MOISTURE PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS FROM 5N-11N BETWEEN
39W-42W. ANY OTHER CONVECTION IN THE VICINITY OF THE WAVE IS
MORE RELATED TO AN UPPER LEVEL TROUGH.

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

THE MONSOON TROUGH EXTENDS FROM THE COAST OF SENEGAL AT 14N17W
TO 10N20W. THE ITCZ BEGINS AT 10N20W CONTINUING ALONG 10N31W
11N42W 10N55W. SCATTERED MODERATE/STRONG CONVECTION IS FROM
10N-11N BETWEEN 21W-24W. SCATTERED MODERATE CONVECTION IS FROM
10N-16N BETWEEN 35W-41W. SIMILAR ACTIVITY IS FROM 6N-10N BETWEEN
45W-50W...AND FROM 10N-12N BETWEEN 49W-52W.

...DISCUSSION...

GULF OF MEXICO...
A WEAK COLD FRONT IS DRAPED ACROSS THE NORTHERN GULF OF MEXICO
FROM THE FLORIDA PANHANDLE AT 31N84W TO 29N91W 29N97W. THE FRONT
IS MAINLY DEFINES A DIFFERENCE IN DEWPOINT WITH LOWER DEWPOINTS
TO THE NORTH OF THE AXIS. DUE TO A FAIRLY DRY AIRMASS
ALOFT...ONLY A FEW ISOLATED SHOWERS ARE ALONG THE FRONT OVER THE
FLORIDA PANHANDLE. THE FRONT IS SUPPORTED BY AN UPPER LEVEL
TROUGH THAT IS MOVING QUICKLY OFF TO THE EAST AND IS CURRENTLY
ALONG 79W. UPPER LEVEL RIDGING CONTINUES TO COVER THE GULF OF
MEXICO CENTERED OVER CENTRAL MEXICO PROVIDING MOSTLY FAIR
CONDITIONS ACROSS THE BASIN. A WEAK SURFACE TROUGH IS IN THE SW
GULF ALONG 24N94W TO 21N94W SUPPORTING ISOLATED SHOWERS WITHIN
75 NM EITHER SIDE OF THE AXIS. ANOTHER SURFACE TROUGH EXTENDS
THROUGH THE YUCATAN CHANNEL SUPPORTING A FEW ISOLATED SHOWERS
OVER THE EXTREME SE GULF. THE FRONT IS EXPECTED TO SINK A LITTLE
FARTHER SOUTH BEFORE DISSIPATING. A SECOND FRONT IS EXPECTED TO
MOVE INTO THE BASIN LATER IN THE WEEK.

CARIBBEAN SEA...
A WEAK SURFACE TROUGH EXTENDS THROUGH THE YUCATAN CHANNEL
SUPPORTING A FEW ISOLATED SHOWERS ACROSS THE FAR NW CARIBBEAN.
THE REMAINDER OF THE NW CARIBBEAN IS EXPERIENCING MOSTLY FAIR
CONDITIONS DUE TO DRY AIR ALOFT WRAPPING AROUND AN UPPER LEVEL
RIDGE IN THE GULF OF MEXICO AND AROUND A NARROW UPPER LEVEL
TROUGH EXTENDING FROM CENTRAL CUBA TO HONDURAS. SOME MODERATE
MOISTURE IS AROUND THE EAST SIDE OF THE UPPER TROUGH SUPPORTING
A FEW ISOLATED SHOWERS NEAR THE MONSOON TROUGH THAT EXTENDS FROM
SOUTHERN NICARAGUA TO NORTHERN COLOMBIA. THE CENTRAL CARIBBEAN
IS MOSTLY CLEAR TONIGHT DUE TO MORE DRY AIR ALOFT AROUND A
SECOND UPPER LEVEL RIDGE COVERING THE REMAINDER OF THE BASIN.
SHOWERS/THUNDERSTORMS CONTINUE TO IMPACT THE NE CARIBBEAN
ASSOCIATED WITH A FEEDER RAIN BAND OF WHAT IS NOW HURRICANE
RAFAEL. THE CONTINUED RAINFALL OVER THESE AREAS POSES THE RISK
FOR SEVERE FLOODING. UNFORTUNATELY...RAINFALL IS EXPECTED TO
CONTINUE OF THE EASTERN CARIBBEAN FOR THE NEXT COUPLE OF DAYS.

ATLANTIC OCEAN...
UPPER LEVEL TROUGHING COVERS THE FAR WESTERN ATLC ALONG 79W. THE
UPPER TROUGH SUPPORTS A WEAK SURFACE TROUGH ALONG 29N75W TO
26N76W. ISOLATED SHOWERS ARE NEAR THE TROUGH AXIS. HURRICANE
RAFAEL SPINS TO THE EAST PROVIDING A LARGE AREA OF
SHOWERS/THUNDERSTORMS ACROSS THE CENTRAL ATLC. SEE SPECIAL
FEATURES ABOVE FOR MORE DETAILS. AN UPPER LEVEL RIDGE...OUTFLOW
FROM RAFAEL IS TO THE EAST ALONG 57W SUPPORTING A SURFACE RIDGE
ANCHORED BY A 1027 MB HIGH NEAR 38N51W. AN UPPER LEVEL TROUGH
EXTENDS FROM THE AZORES ISLANDS INTO THE TROPICAL ATLC ALONG
26N34W TO 8N47W. THE UPPER TROUGH IS HELPING ENHANCE CONVECTION
NEAR BOTH THE ITCZ AND TWO TROPICAL WAVES. UPPER LEVEL RIDGING
COVERS THE REMAINDER OF THE E ATLC WITH AXIS ALONG 20W. IT
SUPPORTS A WEAK SURFACE RIDGE AROUND A 1019 MB HIGH BETWEEN THE
AZORES AND THE MADEIRA ISLANDS.

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

$$
WALTON





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