[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 162337
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN OCT 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
2315 UTC.

...SPECIAL FEATURES...

A BROAD AREA OF LOW PRESSURE COVERS THE NW CARIBBEAN...SE GULF
OF MEXICO...AND YUCATAN PENINSULA FOCUSED ON A 1004 MB SURFACE
LOW CENTERED NEAR 20N87W. THIS AREA OF LOW PRESSURE LIES BENEATH
AN UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED OVER WESTERN
CUBA WHICH IS PROVIDING A LARGE AREA OF DIFFLUENCE ALOFT TO
SUPPORT AND SUSTAIN NUMEROUS SHOWERS AND SCATTERED TSTMS FROM
19N-25N BETWEEN 78W-90W. FURTHER ORGANIZATION AND DEVELOPMENT OF
THIS SYSTEM IS POSSIBLE OVER THE NEXT COUPLE OF DAYS AS THE LOW
DRIFTS NW. REGARDLESS OF DEVELOPMENT...LOCALLY HEAVY RAINFALL IS
EXPECTED TO CONTINUE THROUGH THE OVERNIGHT HOURS ACROSS THE
YUCATAN PENINSULA...NW CARIBBEAN SEA...SE GULF OF MEXICO...
INCLUDING THE FLORIDA STRAITS...AND INLAND PORTIONS OF WESTERN
AND CENTRAL CUBA AND THE SOUTHERN FLORIDA PENINSULA. IN
ADDITION...NORTHEAST TO EAST GALE FORCE WINDS ARE EXPECTED TO
CONTINUE OVER THE SE GULF OF MEXICO WATERS FROM 21N-26N BETWEEN
81W-89W THROUGH MONDAY MORNING.

...TROPICAL WAVES...

TROPICAL WAVE IS ANALYZED FROM 10N19W TO 18N16W MOVING W AT
10-15 KT. CYCLONIC FLOW IS NOTED IN THE LOW-LEVEL CLOUD FIELD IN
THE VICINITY OF THE WAVE AXIS AND ALSO IN SURFACE OBSERVATIONS
LOCATED ALONG THE COAST OF W AFRICA. THE ONLY SIGNIFICANT
CONVECTION AT THIS TIME IS SCATTERED MODERATE AND ISOLATED
STRONG CONVECTION ALONG THE COAST OF W AFRICA FROM 07N-13N
BETWEEN 12W-15W.

TROPICAL WAVE IS ANALYZED FROM 07N39W TO 15N38W MOVING W AT
15-20 KT. SATELLITE IMAGERY INDICATES LOW-LEVEL CYCLONIC FLOW IN
THE VICINITY OF THE WAVE AXIS WHICH WAS ALSO CONFIRMED BY AN
EARLIER ASCAT PASS AROUND 16/1144 UTC. EMBEDDED WITHIN THE
ITCZ...SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS FROM
08N-13N BETWEEN 35W-39W.

TROPICAL WAVE IS ANALYZED FROM 10N59W TO 16N59W MOVING W AT
10-15 KT. WEAK CYCLONIC FLOW IS NOTED IN THE LOW-LEVEL CLOUD
FIELD IN THE VICINITY OF THE WAVE AXIS BETWEEN 57W-61W. THE WAVE
IS ALSO EMBEDDED WITHIN AN AREA OF DEEP LAYER MOISTURE INDICATED
BY TOTAL PRECIPITABLE WATER IMAGERY OVER THE SE CARIBBEAN SEA
AND PORTIONS OF THE TROPICAL NORTH ATLC. SCATTERED MODERATE
CONVECTION IS FROM 11N-14N BETWEEN 57W-61W.

...ITCZ/MONSOON TROUGH...

THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 09N26W TO
10N38W THEN FROM 08N41W TO 04N47W. ISOLATED MODERATE CONVECTION
IS FROM 03N-09N BETWEEN 14W-25W...AND FROM 09N-13N BETWEEN
21W-28W. SCATTERED MODERATE CONVECTION IS FROM 03N-09N BETWEEN
40W-47W.

...DISCUSSION...

GULF OF MEXICO...
WATER VAPOR IMAGERY INDICATES MOSTLY WESTERLY ZONAL FLOW IS
LOCATED ACROSS THE EASTERN CONUS WITH AN UPPER LEVEL SHORTWAVE
TROUGH PROGRESSING ACROSS THE CANADIAN MARITIMES. FARTHER SOUTH
INTO THE GULF REGION...AN UPPER LEVEL ANTICYCLONIC CIRCULATION
IS CENTERED NEAR 21N80W. WHILE THE UPPER LEVEL SHORTWAVE IS WELL
NORTH OF THE AREA...A STATIONARY FRONT EXTENDS ACROSS THE SW
NORTH ATLC...SOUTHERN FLORIDA PENINSULA...AND INTO THE SE GULF
ALONG 26N81W TO 25N86W. AT THE WESTERN EXTENT OF THE FRONT...THE
SPECIAL FEATURES LOW PRESSURE AREA CARRIES INFLUENCE OVER MUCH
OF THE SOUTHEASTERN GULF...FLORIDA STRAITS AND SOUTHERN FLORIDA
PENINSULA THIS EVENING. WITH THE FRONT...LOW...AND UPPER LEVEL
DIFFLUENCE IN PLACE...NUMEROUS SHOWERS AND SCATTERED TSTMS ARE
OCCURRING FROM 19N-25N BETWEEN 78W-90W. ELSEWHERE...SURFACE HIGH
PRESSURE IS LOCATED ACROSS THE NORTHERN GULF AND WESTERN GULF W
OF 93W...ANCHORED BY A 1020 MB HIGH CENTERED OVER SOUTHERN
ALABAMA NEAR 32N87W. WATER VAPOR IMAGERY INDICATES DRY AIR AND
RELATIVELY STRONG SUBSIDENCE NW OF A LINE FROM 22N98W TO 29N83W
AND THE LAST FEW VISIBLE SATELLITE IMAGES OF THE DAY INDICATE
CLEAR SKIES AND MOSTLY FAIR WEATHER. THE SPECIAL FEATURES LOW IS
FORECAST TO DRIFT NORTHWESTWARD OVER THE NEXT COUPLE OF DAYS
BEFORE LIFTING NORTHWARD DUE TO A COLD FRONT EXPECTED TO ENTER
THE NW GULF WATERS TUESDAY.

CARIBBEAN SEA...
SIGNIFICANT LOW-LEVEL MOISTURE IS EVIDENT ON TOTAL PRECIPITABLE
WATER IMAGERY W OF 80W ACROSS MUCH OF THE NW CARIBBEAN...WESTERN
CUBA...THE YUCATAN PENINSULA...AND PORTIONS OF NORTHERN CENTRAL
AMERICA FOCUSED ON A 1004 MB LOW CENTERED NEAR 20N87W. NUMEROUS
SHOWERS AND SCATTERED TSTMS ARE OCCURRING FROM 19N-25N BETWEEN
78W-90W...INCLUDING THE YUCATAN CHANNEL AND WESTERN CUBA THIS
EVENING. LOW-LEVEL MOISTURE EXTENDS SE OF THE LOW TO NORTHERN
COLOMBIA AND PANAMA WITH SCATTERED SHOWERS AND ISOLATED TSTMS
OCCURRING OVER THE SW CARIBBEAN FROM 07N-16N BETWEEN 79W-86W.
THE REMAINDER OF THE CARIBBEAN REMAINS UNDER THE INFLUENCE OF
DRY NORTHEASTERLY UPPER LEVEL WINDS AS INDICATED BY WATER VAPOR
IMAGERY...HOWEVER...ISOLATED LOW-TOPPED SHOWERS ARE NOTED E OF
79W. LASTLY...A TROPICAL WAVE ALONG 59W E OF THE LESSER ANTILLES
IS FORECAST TO MOVE WESTWARD AND INCREASE MOISTURE AND
INSTABILITY OVER THE ISLANDS THROUGH THE OVERNIGHT PERIOD INTO
MONDAY. WHILE SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING
BETWEEN BARBADOS AND TRINIDAD AT THIS TIME...THIS AREA OF
PRECIPITATION IS EXPECTED TO IMPACT THE WINDWARD ISLANDS AS THE
WAVE PASSES TO THE WEST.

ATLANTIC OCEAN...
AN UPPER LEVEL SHORTWAVE TROUGH LOCATED WELL NORTH OF THE
DISCUSSION AREA OVER THE CANADIAN MARITIMES SUPPORTS A
STATIONARY FRONT THAT EXTENDS FROM 35N61W TO 30N66W TO 25N75W TO
THE SOUTHERN FLORIDA PENINSULA NEAR 26N81W. SCATTERED TO
NUMEROUS SHOWERS AND ISOLATED TSTMS ARE OCCURRING WITHIN 210 NM
EITHER SIDE OF A LINE FROM 32N65W TO 24N81W. MOST OF THIS
CONVECTION IS SUPPORTED ALOFT BY AN UPPER LEVEL ANTICYCLONIC
CIRCULATION CENTERED NEAR 22N80W WHICH EXTENDS AN UPPER LEVEL
RIDGE AXIS NE TO BEYOND 32N56W. FARTHER EAST...AN UPPER LEVEL
LOW CENTERED NEAR 32N33W SUPPORTS A 1017 MB LOW EMBEDDED WITHIN
THE SUBTROPICAL SURFACE RIDGE NEAR 33N32W. A SURFACE TROUGH
EXTENDS S-SW FROM THE LOW TO 26N38W. SCATTERED SHOWERS ARE
OCCURRING MAINLY NORTH OF THE LOW CENTER FROM 32N-37N BETWEEN
27W-34W.

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

$$
HUFFMAN




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