[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 221745
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SAT OCT 22 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURES...

AN AREA OF LOW PRESSURE COVERS THE SW CARIBBEAN FOCUSED NEAR A
1007 MB LOW ANALYZED NEAR 13N82W. A STATIONARY FRONTAL BOUNDARY
LINGERS TO THE NORTH FROM 21N78W TO 17N84W KEEPING THIS LOW
WITHIN A TROPICAL AIRMASS WITH PLENTIFUL MOISTURE AND STABILITY.
HOWEVER...ALOFT AN UPPER LEVEL ANTICYCLONE IS POSITIONED TO THE
NORTH CENTERED OVER THE NW CARIBBEAN NEAR 18N84W WHICH IS
PROVIDING MODEST NORTHERLY WIND SHEAR TO THE ONGOING CONVECTION.
ISOLATED STRONG CONVECTION IS WITHIN 90 NM OF THE CENTER OF THE
LOW WITH SCATTERED MODERATE CONVECTION COVERING A LARGER AREA
FROM 09N-19N BETWEEN 79W-86W. WHILE CONVECTIVE DEVELOPMENT
REMAINS UNORGANIZED AT THIS TIME...THE DEVELOPMENT OF A TROPICAL
DEPRESSION IS STILL POSSIBLE OVER THE NEXT DAY OR TWO.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 15N17W TO
07N33W. SCATTERED MODERATE CONVECTION IS FROM 04N-09N BETWEEN
22W-28W...AND FROM 02N-06N BETWEEN 31W-37W.

...DISCUSSION...

GULF OF MEXICO...
NEARLY ZONAL WESTERLY FLOW ALOFT IS IN CONTROL ACROSS THE GULF
THIS AFTERNOON WITH WATER VAPOR IMAGERY INDICATING A VERY DRY
AND STABLE AIRMASS IN PLACE. THIS IS SUPPORTIVE OF A SURFACE
RIDGE ANCHORED BY A 1024 MB HIGH CENTERED OVER NW ALABAMA WHICH
EXTENDS S-SW TO 29N91W TO 20N97W. STRATOCUMULUS CLOUDS ARE NOTED
ON VISIBLE SATELLITE IMAGERY WITH ONLY A FEW ISOLATED SHOWERS
OCCURRING OVER THE SW GULF S OF 20N. THE RIDGE AXIS IS FORECAST
TO REMAIN NEARLY STATIONARY DRIFTING A NW SLIGHTLY BY MONDAY
PROVIDING THE BASIN WITH MOSTLY FAIR CONDITIONS AND LIGHT NE
WINDS THROUGH TUESDAY.

CARIBBEAN SEA...
WATER VAPOR IMAGERY INDICATES THAT AN UPPER LEVEL ANTICYCLONE IS
CENTERED OVER THE NW CARIBBEAN NEAR 18N84W THAT IS SUPPORTIVE OF
SCATTERED SHOWERS AND TSTMS ASSOCIATED WITH A STATIONARY FRONTAL
BOUNDARY ANALYZED FROM EASTERN CUBA NEAR 21N78W TO OFFSHORE OF
NORTHEASTERN HONDURAS NEAR 17N84W. SOUTH OF THIS BOUNDARY AND
NORTH OF THE SPECIAL FEATURES LOW PRESSURE AREA OFFSHORE OF
CENTRAL NICARAGUA NEAR 13N82W IS GENERATING SCATTERED SHOWERS
AND TSTMS FROM 09N-19N BETWEEN 79W-86W. AS THE LOW DRIFTS SLOWLY
NORTHWARD OVER THE NEXT 24-36 HOURS...CONTINUED RAINFALL...
LOCALLY HEAVY AT TIMES...WILL PRESENT THE POSSIBILITY OF
FLOODING AND MUDSLIDES OVER INTERIOR PORTIONS OF NICARAGUA AND
HONDURAS. FARTHER EAST...SW MONSOONAL WINDS ACROSS PANAMA AND
INTO THE SOUTH-CENTRAL CARIBBEAN ARE PROVIDING FOR AN AREA OF
LOW-LEVEL MOISTURE CONVERGENCE FOCUSED ALONG A SURFACE TROUGH
ANALYZED FROM 11N62W TO 15N72W. SCATTERED SHOWERS AND WIDELY
SCATTERED TSTMS ARE OCCURRING FROM 12N-15N WEST OF THE SURFACE
TROUGH TO 78W. OTHER LINGERING ISOLATED SHOWERS ARE NOTED ON
SATELLITE IMAGERY OCCURRING FROM 15N-18N BETWEEN 68W-72W.

ATLANTIC OCEAN...
A BROAD LONGWAVE UPPER LEVEL TROUGH IS LOCATED ACROSS THE
EASTERN CONUS IN SUPPORT OF A STATIONARY FRONT EXTENDING INTO
THE DISCUSSION AREA NEAR 32N70W TO THE CENTRAL BAHAMAS NEAR
24N76W TO EASTERN CUBA NEAR 21N77W. SCATTERED SHOWERS AND WIDELY
SCATTERED TSTMS ARE OCCURRING WITHIN 120 NM EITHER SIDE OF THE
FRONT. AN UPPER LEVEL RIDGE AXIS EXTENDS FROM THE NW CARIBBEAN
TO 30N70W PROVIDING UPPER LEVEL DIFFLUENCE TO THE CONVECTION
ALONG AND EAST OF THE FRONTAL BOUNDARY. FARTHER EAST...WATER
VAPOR IMAGERY INDICATES AN ELONGATED UPPER LEVEL LOW IS CENTERED
NEAR 24N66W THAT IS REFLECTED AS A TROUGH AT THE SURFACE
ANALYZED FROM EAST OF PUERTO RICO NEAR 18N66W TO 27N67W.
LOW-LEVEL CONVERGENCE AND MIDDLE TO UPPER LEVEL LIFTING DYNAMICS
ARE GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS FROM 20N-27N
BETWEEN 63W-67W...AND FROM 25N-32N BETWEEN 56W-64W. ELSEWHERE...
ASIDE FROM A 1027 MB SUBTROPICAL RIDGE CENTERED NORTH OF THE
AREA NEAR 35N45W...DEEPER INTO THE TROPICS WEAK TROUGHING
EXTENDS FROM A 1007 MB LOW CENTERED NEAR 10N56W E-NE TO A 1011
MB LOW CENTERED NEAR 15N42W. THESE FEATURES ARE LOCATED
PRIMARILY ON THE SOUTHERN PERIPHERY OF AN UPPER LEVEL
ANTICYCLONIC CIRCULATION CENTERED NEAR 18N48W THAT IS GENERATING
SCATTERED SHOWERS AND ISOLATED TSTMS NEAR THE WESTERN-MOST LOW
WITHIN 180 NM OF THE CENTER. THIS LOW IS FORECAST TO GRADUALLY
DRIFT NW OVER THE NEXT 24-36 HOURS AND BRING INCREASED CHANCE OF
PRECIPITATION TO THE WINDWARD ISLANDS THROUGH THE EARLY PORTION
OF NEXT WEEK. FINALLY...A 1013 MB LOW IS CENTERED SW OF THE
CANARY ISLANDS NEAR 25N24W. THIS LOW IS SUPPORTED BY AN UPPER
LEVEL TROUGH AXIS WHICH EXTENDS FROM THE IBERIAN PENINSULA SW TO
20N33W. THE LOW IS EXPECTED TO DISSIPATE OVER THE NEXT 24
HOURS...HOWEVER MIDDLE TO UPPER LEVEL MOISTURE AND DIFFLUENCE
CONTINUE TO PROVIDE ISOLATED SHOWERS AND TSTMS WITHIN 240 NM
EITHER SIDE OF A LINE FROM SOUTHERN MOROCCO NEAR 28N11W TO
15N35W.

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

$$
HUFFMAN



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