[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 281745
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI SEP 28 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 29.6N 34.7W AT 28/1500 UTC.
THIS POSITION IS LOCATED ABOUT 635 NM SW OF THE AZORES ISLANDS.
NADINE IS MOVING NW NEAR 7 KT. ESTIMATED MINIMUM CENTRAL
PRESSURE IS 988 MB. MAXIMUM SUSTAINED WIND SPEED IS 65 KT WITH
GUST TO 80 KT. PLEASE SEE LATEST NHC FORECAST/ ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS.
NUMEROUS MODERATE/SCATTERED STRONG CONVECTION IS FROM 29N-32N
BETWEEN 34W-37W. SCATTERED MODERATE CONVECTION IS FROM 29N-32N
BETWEEN 32W-34W.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 17N32W TO 8N36W MOVING W NEAR 10 KT. IT
LIES ON THE WEST SIDE OF A SURGE OF DEEP LAYER MOISTURE PRESENT
IN TOTAL PRECIPITABLE WATER IMAGERY. ONLY A SMALL CLUSTER OF
MODERATE CONVECTION IS FROM 14N-16N BETWEEN 33W-34W.

TROPICAL WAVE IS IN THE WESTERN CARIBBEAN ALONG 19N81W TO 12N81W
MOVING W AT 15-20 KT. THE WAVE LIES WITHIN A BROAD AREA OF DEEP
LAYER MOISTURE PRESENT ACROSS THE CENTRAL AND WESTERN CARIBBEAN.
THE WAVE ALSO CONTINUES TO LIE UNDERNEATH THE DIFFLUENT SIDE OF
AN UPPER LEVEL TROUGH...WHICH IS HELPING ENHANCE CONVECTION NEAR
IT. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM
19N-21N BETWEEN 79W-82W. ACTIVITY IS PRESENT FARTHER E...BUT IS
LIKELY MORE INFLUENCE BY THE UPPER LEVEL DYNAMICS.


...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS WEST AFRICA TO THE COAST OF
SENEGAL AT 13N16W CONTINUING SE ALONG 9N25W 7N36W. THE ITCZ
CONTINUES FROM 7N36W ALONG 7N49W 7N58W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS FROM 5N-10N BETWEEN
15W-26W. SIMILAR ACTIVITY IS FROM 13N-16N BETWEEN 27W-29W. A
SURFACE TROUGH IS ANALYZED NORTH OF THE ITCZ ALONG 17N46W TO
10N48W. THE TROUGH IS BEING ENHANCED BY AN UPPER LEVEL TROUGH TO
THE WEST. THIS COMBINATION IS HELPING PRODUCE SCATTERED
MODERATE/ISOLATED STRONG CONVECTION FROM 7N-18N BETWEEN 43W-51W.

...DISCUSSION...

GULF OF MEXICO...
WEAK SURFACE RIDGING IS ACROSS THE GULF OF MEXICO EXTENDING FROM
A HIGH CENTER OVER SOUTH CAROLINA. THE RIDGE ALONG WITH A SMALL
AREA OF DRY AIR ALOFT IS HELPING PRODUCE FAIR WEATHER OVER A
GOOD PORTION OF THE CENTRAL..EASTERN...AND SOUTHERN GULF
INCLUDING FLORIDA AND THE YUCATAN PENINSULA. A SURFACE TROUGH IS
PARALLEL TO THE TEXAS COAST SUPPORTING SCATTERED SHOWERS UP TO
150 NM OFFSHORE AND WELL AS OVER SOUTHERN LOUISIANA.
ALOFT...MAINLY NORTHERLY FLOW COVERS THE BASIN BETWEEN AN UPPER
LEVEL RIDGE EXTENDING UP MEXICO INTO TEXAS...AND AN UPPER LEVEL
TROUGH EXTENDING DOWN THE EAST COAST OF FLORIDA. EXPECT SURFACE
RIDGING TO REMAIN ACROSS THE BASIN WITH CONTINUED SHOWER
ACTIVITY ALONG THE TEXAS COAST THROUGH THE MAJORITY OF THE
WEEKEND. A SURFACE LOW AND ASSOCIATED FRONT WILL ENTER THE NW
GULF ON SUNDAY.

CARIBBEAN SEA...
A TROPICAL WAVE IS MOVING THROUGH THE WESTERN CARIBBEAN ALONG
81W/82W. IT IS PRODUCING SHOWERS/THUNDERSTORMS NEAR THE NORTHERN
EXTENT OF THE AXIS JUST SOUTH OF WESTERN CUBA.
SHOWERS/THUNDERSTORMS CONTINUE TO THE E FROM COLOMBIA TO EASTERN
CUBA BETWEEN 74W-79W...AS WELL AS ACROSS PORTIONS OF CENTRAL
CUBA ASSOCIATED WITH DIFFLUENCE ALOFT AROUND AN UPPER LEVEL
TROUGH EXTENDING WESTERN CUBA TO NICARAGUA. THE UPPER TROUGH IS
LIKELY THE MAIN CAUSE OF ALL THE CONVECTION WITH A SMALLER
INFLUENCE BY THE WAVE. SOME OF ACTIVITY SOUTH OF THE WAVE NEAR
COLOMBIA AND ACROSS PANAMA IS ALSO INFLUENCED BY THE MONSOON
TROUGH EXTENDING FROM THE E PACIFIC ACROSS NORTHERN COSTA RICA
TO NORTHERN COLOMBIA. THE EASTERN CARIBBEAN IS EXPERIENCING
MOSTLY FAIR WEATHER AT THIS TIME ASSOCIATED WITH DRY AIR ALOFT
AROUND AN UPPER LEVEL RIDGE OVER THAT HALF OF THE BASIN. EXPECT
THE TROPICAL WAVE TO CONTINUE TO MOVE WESTWARD AS THE UPPER
LEVEL TROUGH REMAINS SOMEWHAT STATIONARY. THIS PATTERN WILL
CONTINUE TO PRODUCE SHOWERS/THUNDERSTORMS ACROSS MUCH OF THE
WESTERN CARIBBEAN.

ATLANTIC OCEAN...
ISOLATED SHOWERS/THUNDERSTORMS COVER THE EXTREME SW NORTH ATLC
ASSOCIATED WITH AN UPPER LEVEL TROUGH EXTENDING DOWN THE EAST
COAST OF FLORIDA INTO THE WESTERN CARIBBEAN. THE UPPER TROUGH
SUPPORTS A WEAK SURFACE TROUGH ALONG 30N79W TO 25N79W. THE
REMAINDER OF THE W ATLC IS EXPERIENCING FAIR CONDITIONS WITH AN
UPPER LEVEL RIDGE COVERING THE AREA ALONG 66W. AN UPPER LEVEL
TROUGH COVERS THE CENTRAL ATLC ALONG 27N49W ENHANCING CONVECTION
NEAR A SURFACE TROUGH NORTH OF THE ITCZ REGION. A SECOND AND
WEAKER SURFACE TROUGH IS ALONG 23N59W TO 20N61W. SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE E OF THE AXIS FROM 19N-24N
BETWEEN 54W-57W. BROAD UPPER LEVEL RIDGING IS ACROSS THE
REMAINDER OF THE BASIN PROVIDING MOSTLY FAIR CONDITIONS EXCEPT
NEAR HURRICANE NADINE NEAR THE NORTHERN BOUNDARY OF THE
DISCUSSION AREA. SEE SPECIAL FEATURES ABOVE FOR MORE DETAILS.

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

$$

WALTON




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