[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 060003
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT FRI OCT 05 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 VALID
THROUGH 2315 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS APPROACHING THE CAPE VERDE ISLANDS ALONG
16N18W 10N23W MOVING WEST AT 10-15 KT. THE WAVE ALIGNS WITH A
LOW-AMPLITUDE SURGE OF DEEP LAYER MOISTURE PRESENT IN TOTAL
PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS FROM 6N-11N BETWEEN 22W-29W.

A TROPICAL WAVE IS MOVING THROUGH THE LESSER ANTILLES ALONG
21N58W TO 11N62W MOVING WEST AT 5-10 KT. THE WAVE LIES
UNDERNEATH THE BASE OF AN UPPER LEVEL LOW CENTERED NE OF THE
NORTHERN LEEWARD ISLANDS...WHICH IS HELPING ENHANCE CONVECTION
EAST OF THE ISLANDS. THE WAVE WILL LIKELY LOSE SOME OF ITS
ENERGY TO THE UPPER LOW. SCATTERED MODERATE CONVECTION IS FROM
14N-19N BETWEEN 54W-57W. SIMILAR ACTIVITY IS FROM 19N-22N
BETWEEN 57W-60W.

A TROPICAL WAVE IS IN THE CENTRAL CARIBBEAN ALONG 17N72W TO
8N73W MOVING W NEAR 15 KT. HIGH MOISTURE VALUES COVER THE
SOUTHERN CARIBBEAN IN THE VICINITY OF THE WAVE...BUT THE AXIS IS
BECOMING MORE DIFFICULT TO DETERMINE. CURRENTLY NUMEROUS STRONG
CONVECTION IS OVER NORTHERN COLOMBIA FROM 9N-12N BETWEEN
72W-74W.

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

THE MONSOON TROUGH EXTENDS FROM THE COAST OF GUINEA AT 10N15W
ALONG 8N23W 11N34W 9N40W. THE ITCZ BEGINS AT 9N40W ALONG 9N48W
15N53W. A LARGE CLUSTER OF MODERATE/STRONG CONVECTION IS ABOUT
TO MOVE OFF THE COAST OF GUINEA. SCATTERED MODERATE/STRONG
CONVECTION IS ALSO FROM 8N-9N BETWEEN 32W-34W. SCATTERED
MODERATE CONVECTION IS FROM 7N-9N BETWEEN 43W-46W.

...DISCUSSION...

THE GULF OF MEXICO...
MOIST CONDITIONS CONTINUE TO COVER THE GULF OF MEXICO FROM THE
SW GULF TO THE NE GULF INCLUDING MUCH OF THE YUCATAN PENINSULA
AND THE FLORIDA PENINSULA. AN UPPER LEVEL TROUGH SITS OVER THE
WESTERN GULF PROVIDING MOIST DIFFLUENT FLOW ACROSS THE CENTRAL
AND EASTERN GULF...WHILE DRY AIR AND SUBSIDENCE ARE KEEPING THE
NW GULF UNDER FAIR WEATHER AND CLEAR SKIES. AS OF 2100 UTC...THE
UPPER TROUGH SUPPORTS A SURFACE TROUGH IN THE SW GULF FROM
24N91W TO 19N90W WITH SCATTERED SHOWERS EXTENDING 150 NM IN
EITHER DIRECTION OF THE AXIS. A SECOND SURFACE TROUGH IS IN THE
NE CORNER ALONG 30N85W TO 27N87W. SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS ARE 150 NM TO EITHER SIDE OF THE AXIS WITH
WIDESPREAD SHOWERS/THUNDERSTORMS EXTENDING DOWN MUCH OF THE
WESTERN HALF OF THE FLORIDA PENINSULA. EXPECT LITTLE CHANGE OVER
THE NEXT 24 HOURS.

THE CARIBBEAN SEA...
UPPER LEVEL MOISTURE IS BEING DRAWN AROUND AN UPPER LEVEL RIDGE
COVERING THE NW CARIBBEAN HELPING SUPPORT A FEW WIDELY ISOLATED
SHOWERS/THUNDERSTORMS OVER THE NW CARIBBEAN AND PORTIONS OF
CUBA...JAMAICA...AND CENTRAL AMERICA. A TROPICAL WAVE IN THE
CENTRAL CARIBBEAN IS HELPING SUPPORT STRONG
SHOWERS/THUNDERSTORMS OVER NORTHERN COLOMBIA. SCATTERED SHOWERS
ALSO COVERS THE SW CARIBBEAN S OF 12N INFLUENCED BY THE MONSOON
TROUGH THAT EXTENDS THROUGH COSTA RICA AND PANAMA TO NORTHERN
COLOMBIA. THIS ACTIVITY IS ALSO ENHANCED BY DIFFLUENCE ALOFT
AROUND THE BASE OF AN UPPER LEVEL TROUGH EXTENDING FROM EASTERN
CUBA TO NICARAGUA. WEAK UPPER RIDGING ALONG WITH DRY AIR ALOFT
COVER THE EASTERN CARIBBEAN PROVIDING MOSTLY FAIR CONDITIONS.
HOWEVER...A TROPICAL WAVE IS JUST MOVING INTO THE BASIN AND
COULD SUPPORT A FEW SHOWERS/THUNDERSTORMS OVER THE LESSER
ANTILLES. RIGHT NOW...MOST OF THE ACTIVITY ASSOCIATED WITH THE
WAVE IS WELL TO THE EAST. STRONG SHOWERS/THUNDERSTORMS ARE
INLAND OVER VENEZUELA THOUGH. EXPECT BOTH WAVES TO CONTINUE
WESTWARD WITH CONTINUED SHOWER ACTIVITY ACROSS THE SOUTHERN
CARIBBEAN AND INCREASING IN THE EASTERN CARIBBEAN.

THE ATLANTIC OCEAN...
A FEW SHOWERS/THUNDERSTORMS EXTEND OFF THE EAST COAST OF FLORIDA
ASSOCIATED WITH DIFFLUENCE ALOFT AROUND AN UPPER LEVEL TROUGH
OVER THE WESTERN GULF OF MEXICO. THE REMAINDER OF THE W ATLC IS
UNDER WEAK SURFACE RIDGING EXTENDING FROM GEORGIA AND SUPPORTED
BY AN UPPER LEVEL RIDGE COVERING THE WESTERN ATLC. A SURFACE
TROUGH ALONG 27N58W TO 25N65W IS SUPPORTING SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS FROM 23N-26N BETWEEN
65W-69W...AND WITHIN 30 NM EITHER SIDE OF THE TROUGH AXIS. AN
UPPER LEVEL LOW TO THE SE NEAR 20N60W IS ENHANCING CONVECTION
NEAR A TROPICAL WAVE MOVING THROUGH THE LESSER ANTILLES. SEE
SPECIAL FEATURES ABOVE. AN UPPER LEVEL TROUGH ALONG 35W SUPPORTS
A COLD FRONT THAT EXTENDS INTO THE AREA NEAR 32N34W ALONG 26N44W
27N55W 30N62W. SCATTERED SHOWERS EXTEND 80 NM S OF THE AXIS. A
LARGE AREA OF STRONG CONVECTION IS EAST OF THE FRONT N OF 27N
BETWEEN 28W-32W. THIS IS LIKELY DUE TO WIND SPEED CONVERGENCE
FROM GALE FORCE WINDS EAST OF THE FRONT NEAR 30N ALONG WITH
DIFFLUENCE ALOFT AROUND THE UPPER TROUGH. A SURFACE TROUGH IS
ALSO AHEAD OF THE FRONT ALONG 26N37W TO 21N38W. THIS TROUGH IS
THE REMNANTS OF OSCAR WHICH DISSIPATED EARLIER TODAY. AN AREA OF
SCATTERED SHOWERS IS EAST OF THE TROUGH FROM 24N-26N BETWEEN
32W-33W ALSO LIKELY DUE TO WIND SPEED CONVERGENCE FROM GALE
FORCE WINDS EAST OF THE TROUGH AXIS NEAR 24N34W. AN UPPER LEVEL
RIDGE COVERS THE FAR EASTERN ATLC SUPPORTING A WEAK SURFACE
RIDGE...WHICH IS PROVIDING FAIR CONDITIONS ACROSS THE FAR
EASTERN ATLC.

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

$$
WALTON






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