[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 162343
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT FRI SEP 16 2011

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
2330 UTC.

...SPECIAL FEATURES...

THE CENTER OF MARIA MADE LANDFALL JUST NORTHWEST OF CAPE PINE ON
THE AVALON PENINSULA OF NEWFOUNDLAND ABOUT 1830Z THIS AFTERNOON
AND HAS RACED ACROSS THE PENINSULA INTO THE ATLANTIC OCEAN.
MARIA HAS LOST ENOUGH TROPICAL CHARACTERISTICS TO BE CONSIDERED
POST-TROPICAL...AND IN ADDITION IT APPEARS TO BE LOSING ITS
CLOSED CIRCULATION. THE CYCLONE SHOULD BECOME ABSORBED WITHIN A
FRONTAL ZONE WITHIN 12 HOURS WITH A DECREASE IN WINDS.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST OF GUINEA
BISSAU NEAR 12N16W TO A 1010 MB LOW NEAR 11N18W TO ANOTHER 1012
MB LOW NEAR 10N32W TO NEAR 7N42W. THE INTERTROPICAL CONVERGENCE
ZONE AXIS EXTENDS FROM 7N42W TO THE EASTERN COAST OF VENEZUELA
NEAR 9N61W. THE LARGE AND STRETCHED OUT MONSOON GYRE IS
PRODUCING WIDELY SCATTERED MODERATE TO ISOLATED STRONG
CONVECTION WITHIN 200 NM ON EITHER SIDE OF THE MONSOON TROUGH
AXIS. SCATTERED WEAK CONVECTION IS WITHIN 100 NM EITHER SIDE OF
THE ITCZ AXIS W OF 55W...MOST LIKELY ASSOCIATED TO THE SW
MID-UPPER LEVEL FLOW FROM THE UPPER LEVEL CYCLONIC CIRCULATION
CENTERED E OF PUERTO RICO.

...DISCUSSION...

GULF OF MEXICO...
A WEAK STATIONARY FRONT IS ANALYZED ACROSS THE NORTHERN GULF
WATERS FROM THE TEXAS COAST TO THE NORTHERN COAST OF FLORIDA
ALONG 29N96W 27N88W 29N83W. NO SIGNIFICANT CONVECTION IS
OCCURRING ALONG THIS BOUNDARY. THIS FRONT HAS INTRODUCED A
MILDER AIRMASS TO THE NORTH-CENTRAL AND PORTIONS OF THE NE GULF
WATERS. THIS FRONT IS EXPECTED TO CONTINUE TO WEAKEN AND BECOME
MORE DIFFUSE THROUGH SATURDAY. OTHERWISE...SATELLITE VISIBLE
IMAGERY SHOWS MOSTLY CLEAR SKIES WITH A FEW ISOLATED WEAK
SHOWERS...MOVING WITH THE LIGHT ANTICYCLONIC FLOW PRESENT ACROSS
THE BASIN. WATER VAPOR IMAGERY SHOWS A LARGE RIDGE OF HIGH
PRESSURE CENTERED OVER THE CENTRAL MEXICO REGION PROVIDING MUCH
OF THE GULF WITH MIDDLE TO UPPER LEVEL DRY AIR AND SUBSIDENCE.
THE RIDGE IS FORECAST TO DISSIPATE OVER THE NEXT 24 HOURS.

CARIBBEAN SEA...
BROAD SURFACE CYCLONIC FLOW IS WEST OF 75W. WHILE SCATTERED
HEAVY SHOWERS ROAM THIS AREA...STRONGER ACTIVITY FOCUSES ALONG A
SLOW MOVING SURFACE TROUGH ANALYZED FROM 17N81W TO 10N81W...
GENERATING GUSTY SCATTERED SHOWERS AND THUNDERSTORMS S OF 17N W
OF 78W. MOST OF THE ACTIVITY IS ALSO ENHANCED BY THE MONSOON
TROUGH ANALYZED OVER THE FAR SW BASIN EXTENDING ACROSS COSTA
RICA INTO NORTHERN COLOMBIA. THIS AREA OF CONVECTION IS ALREADY
MOVING INLAND OVER CENTRAL AMERICA...WITH THE ACTIVITY EXPECTED
TO LAST THROUGH THE WEEKEND. WATER VAPOR IMAGERY SHOWS A BROAD
UPPER LEVEL CYCLONIC CIRCULATION JUST EAST OF PUERTO RICO NEAR
18N64W. THIS CIRCULATION IS ADVECTING MOISTURE NORTHWARD FROM
THE INTERTROPICAL CONVERGENCE ZONE AND ENHANCING AN AREA OF
SCATTERED MODERATE TO STRONG CONVECTION AFFECTING THE FAR SE
CARIBBEAN S OF DOMINICA E OF 64W. THE ACTIVITY LIES AHEAD OF A
SURFACE TROUGH ANALYZED JUST E OF THE LESSER ANTILLES AND IT IS
EXPECTED TO MOVE INTO THE EAST CARIBBEAN OVER THE NEXT 24 HOURS.
THE REMAINDER OF  THE BASIN REMAINS UNDER FAIR WEATHER
CONDITIONS.

ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH MOVES OFF THE EASTERN CONUS SEABOARD THIS
EVENING...WATER VAPOR IMAGERY SHOWS SSW FLOW ALOFT AHEAD OF THE
UPPER TROUGH...MOVING MID-UPPER LEVEL MOISTURE FROM THE WESTERN
CARIBBEAN INTO THE SW NORTH ATLC. LOW-LEVEL CONVERGENCE LIES
UNDERNEATH THIS AREA OF MOISTURE FOCUSED ON A SURFACE TROUGH
ANALYZED FROM 30N70W TO 22N75W. SCATTERED SHOWERS ARE WITHIN 70
NM ON EITHER SIDE OF THE SURFACE TROUGH AXIS. A BROAD UPPER
LEVEL CYCLONIC CIRCULATION IS CENTERED JUST EAST OF PUERTO RICO
NEAR 18N64W. THIS FEATURE IS PROVIDING MOISTURE NORTHWARD FROM
THE INTERTROPICAL CONVERGENCE ZONE AND ENHANCING AN AREA OF
SCATTERED MODERATE TO STRONG CONVECTION FROM 10N-18N BETWEEN
54W-64W. A SURFACE TROUGH IS ANALYZED WITHIN THIS AREA FROM
16N57W TO 11N60W. THE REMAINDER OF THE CENTRAL AND EASTERN ATLC
IS UNDER THE INFLUENCE OF A WEAK BROAD SURFACE RIDGE N OF THE
AREA. HOWEVER...AN UPPER LEVEL LOW CENTERED SOUTH OF THE AZORES
NEAR SUPPORTS A WEAK LOW PRESSURE SYSTEM AND AND ASSOCIATED COLD
FRONT WITH A NARROW LINE OF ISOLATED SHOWERS EXTENDING ALONG THE
BOUNDARY.

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

$$

GARCIA




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