[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 301749
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SAT SEP 29 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1645 UTC.

...SPECIAL FEATURES...

HURRICANE NADINE IS LOCATED NEAR 37.1N 38.6W AT 30/1500 UTC.
THIS POSITION IS LOCATED ABOUT 555 NM W OF THE AZORES ISLANDS.
NADINE IS MOVING NW NEAR 8 KT. ESTIMATED MINIMUM CENTRAL
PRESSURE IS 979 MB. MAXIMUM SUSTAINED WIND SPEED IS 80 KT WITH
GUST TO 100 KT. PLEASE SEE LATEST NHC FORECAST/ ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS.
SCATTERED MODERATE CONVECTION IS FROM 36N-38N BETWEEN 38W-42W.

...TROPICAL WAVES...

TROPICAL WAVE IS MOVING THROUGH THE CAPE VERDE ISLANDS ALONG
18N24W TO 10N27W. THE WAVE IS FINALLY GAINING SOME WESTWARD
MOTION AT NEAR 10 KT. THE WAVE IS EMBEDDED WITHIN A BROAD AREA
OF MOISTURE COVERING THE EASTERN TROPICAL ATLC. MAXIMUM MOISTURE
VALUES ARE NOTED NEAR THE WAVE AXIS. THE LOW LEVEL CYCLONIC FLOW
AROUND THE WAVE REMAINS LOW AMPLITUDE AND BROAD AS THE WAVE
MOVES THROUGH THE MONSOON TROUGH. THIS EXPLAINS THE LARGE AREA
OF CONVECTION ASSOCIATED WITH THE WAVE. CURRENTLY...SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS FROM 14N-17N BETWEEN
21W-27W...FROM 7N-9N BETWEEN 28W-35W...AND FROM 11N-15N BETWEEN
27W-35W.

TROPICAL WAVE IS ALONG 20N38W TO 10N43W MOVING W NEAR 10 KT. IT
LIES ON THE WEST SIDE OF A SURGE OF DEEP LAYER MOISTURE PRESENT
IN TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE/ISOLATED
STRONG CONVECTION IS FROM 15N-21N BETWEEN 35W-41W. SIMILAR
ACTIVITY IS FROM 8N-15N BETWEEN 41W-44W.

TROPICAL WAVE PREVIOUSLY IN THE WESTERN CARIBBEAN HAS BEEN
ANALYZED AS A SURFACE TROUGH DUE TO ITS STATIONARY POSITION OVER
THE PAST 24 HOURS. IT WILL BE DISCUSSED IN THE CARIBBEAN
SECTION.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS WEST AFRICA TO THE COAST OF
SENEGAL AT 16N16W CONTINUING ACROSS ATLC WATERS ALONG 10N27W
8N44W. THE ITCZ BEGINS AT 8N44W CONTINUING TO 9N61W. CONVECTION
NEAR THE MONSOON TROUGH HAS BEEN ASSOCIATED WITH THE TROPICAL
WAVES. SEE ABOVE. SCATTERED MODERATE/ISOLATED STRONG CONVECTION
IS N OF THE ITCZ FROM 9N-12N BETWEEN 50W-58W.

...DISCUSSION...

GULF OF MEXICO...
AS OF 1500 UTC...A COLD FRONT IS MOVING THROUGH THE NW GULF OF
MEXICO FROM A 1003 MB SURFACE LOW OVER SE TEXAS AT 31N94W
CONTINUING ALONG 24N95W 22N98W AND INTO MEXICO TO 23N 100W WHERE
IT BECOMES STATIONARY TO 26N102W. A LINE OF
SHOWERS/THUNDERSTORMS EXTENDS 90 NM EAST OF THE FRONT TO THE
NORTH OF 27N WITH SCATTERED SHOWERS CONTINUING TO 87W AND
FARTHER E INLAND OVER THE FLORIDA PANHANDLE. STRONG WINDS ARE
BOTH AHEAD AND BEHIND THE NORTHERN PORTIONS OF THE AXIS REACHING
UP TO 30 KT. SHOWERS/THUNDERSTORMS ARE ALSO NEAR THE SOUTHERN
EXTENT OF THE FRONT NEAR THE MEXICAN COAST FROM 20N-23N BETWEEN
94W-100W. THE REMAINDER OF THE BASIN IS EXPERIENCING FAIR
WEATHER DUE TO DRY AIR ALOFT AROUND AN UPPER LEVEL RIDGE ACROSS
THE SW NORTH ATLC. AN UPPER LEVEL TROUGH MOVING THROUGH THE
CENTRAL CONUS SUPPORTS THE FRONTAL BOUNDARY AND WILL ALSO BRING
STRONG DRY AIR AND SUBSIDENCE BEHIND THE FRONT AS IT PUSHES
EASTWARD. EXPECT THE FRONT TO CONTINUE EAST WITH
SHOWERS/THUNDERSTORMS NEAR THE AXIS.

CARIBBEAN SEA...
THE TROPICAL WAVE PREVIOUSLY IN THE WESTERN CARIBBEAN IS NOW
BEING ANALYZED AS A SURFACE TROUGH DUE TO THE LACK OF WESTWARD
MOTION FOR THE PAST 24-48 HOURS. THE TROUGH EXTENDS FROM WESTERN
CUBA NEAR 23N81W TO 16N84W. THE TROUGH ALSO LIES UNDER AN UPPER
LEVEL LOW SPINNING NEAR 17N85W. ACTIVITY NEAR THE SURFACE TROUGH
IS LIKELY MORE ASSOCIATED WITH THE UPPER LEVEL TROUGH. SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE MAINLY E OF THE SURFACE
TROUGH FROM 14N-22N BETWEEN 75W-83W. A FEW ISOLATED
SHOWERS/THUNDERSTORMS HAVE ALSO POPPED UP ACROSS PORTIONS OF
PANAMA ASSOCIATED WITH THE MONSOON TROUGH THAT EXTENDS THROUGH
COSTA RICA AND PANAMA TO NORTHERN COLOMBIA. A FEW ISOLATED
SHOWERS ARE ALSO ACROSS HISPANIOLA DUE TO AN EXTENSION OF THE
UPPER LOW IN THE NW CARIBBEAN THAT EXTENDS INTO THE W ATLC. THE
REMAINDER OF THE BASIN IS EXPERIENCING MOSTLY FAIR CONDITIONS
DUE TO DRY AIR ALOFT AROUND AN UPPER LEVEL RIDGE ACROSS THE
EASTERN HALF OF THE AREA. TRADEWIND FLOW OF 15-20 KT IS ACROSS
MUCH OF THE AREA WITH LIGHTER WINDS IN THE SW CORNER. EXPECT
MOIST CONDITIONS TO REMAIN OVER THE WESTERN CARIBBEAN FOR AT
LEAST THE NEXT 24 HOURS.

ATLANTIC OCEAN...
A WEAK UPPER RIDGE COVERS THE EXTREME SW NORTH ATLC CENTERED
NEAR 27N76W PROVIDING WEAK RIDGING OVER FLORIDA AND THE NW
BAHAMAS. HOWEVER...AN UPPER LEVEL TROUGH EXTENDING FROM CENTRAL
CUBA ACROSS THE CENTRAL BAHAMAS TO NEAR 31N62W IS SUPPORTING A
LARGE AREA OF SHOWERS/THUNDERSTORMS FROM 21N-25N BETWEEN
66W-77W...AND FROM 23N-29N BETWEEN 63W-68W. THIS ACTIVITY HAS
INDUCED A WEAK SURFACE TROUGH ALONG 23N71W TO 20N73W. WEAK UPPER
RIDGING IS EAST OF THE UPPER TROUGH FROM HISPANIOLA TO NEAR
32N58W. THE UPPER RIDGE SUPPORTS BROAD SURFACE RIDGING EXTENDING
FROM A 1022 MB HIGH NORTH OF THE AREA NEAR 35N49W. A LONGWAVE
UPPER TROUGH CONTINUES TO COVE THE CENTRAL ATLC EXTENDING FROM
WEST OF NADINE TO THE ITCZ REGION NEAR 10N54W. UPPER LEVEL
RIDGING COVERS THE REMAINDER OF DISCUSSION AREA CENTERED NEAR
18N33W AND IS PROVIDING FAIR CONDITIONS ACROSS THE EASTERN ATLC.

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

$$

WALTON/DELGADO




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