[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 091805
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SUN SEP 08 2013

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...
AS OF 1500 UTC TROPICAL STORM HUMBERTO IS LOCATED NEAR 13.6N
24.1W OR ABOUT 73 NM SSE OF FOGO CAPE VERDE ISLANDS. ITS
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1005 MB. MAXIMUM SUSTAINED
WIND SPEED IS 40 KT WITH GUSTS TO 50 KT. NUMEROUS STRONG
CONVECTION IS FROM 12N-14N BETWEEN 24W-26W. NUMEROUS MODERATE
CONVECTION IS FROM 09N-16N BETWEEN 23W-30W. SCATTERED MODERATE
CONVECTION IS ELSEWHERE FROM 08N-16N BETWEEN 20W-34W. SEE LATEST
NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS
MIATCPAT4/WTNT34 KNHC AND THE FULL FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS.

...TROPICAL WAVES...
A TROPICAL WAVE IS IN THE CENTRAL ATLC BEING ANALYZED FROM
24N42W THROUGH A 1013 MB LOW NEAR 18N40W TO 16N39W...MOVING W-NW
NEAR 10 KT. NORTH OF THE LOW PRESSURE CENTER THE WAVE IS
EMBEDDED WITHIN A HIGH MOIST ENVIRONMENT WHEREAS A VERY DRY
ENVIRONMENT IS W AND SW OF THE LOW. A SMALL CLUSTER OF MODERATE
CONVECTION WITH ISOLATED TSTMS IS NW OF THE LOW FROM 18N-20N
BETWEEN 42W-44W.

TROPICAL WAVE IS IN THE BAY OF CAMPECHE WITH AXIS EXTENDING FROM
21N90W TO 15N91W AND HAS BEEN MOVING NEAR 5 KT. AN ELONGATED LOW-
LEVEL CYCLONIC CIRCULATION OVER THE YUCATAN PENINSULA HAS BEEN
ADVECTING MOISTURE FROM THE E PACIFIC DURING THE LAST COUPLE OF
HOURS THUS ENHANCING SCATTERED MODERATE CONVECTION WITHIN 150 NM
EITHER SIDE OF THE AXIS FROM 18N-23N.

...THE ITCZ/THE MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS ACROSS AFRICA TO OVER BURKINA FASO.
THE MONSOON TROUGH AND ITCZ HAVE BEEN DISRUPTED BY THE
DEVELOPMENT OF TROPICAL STORM HUMBERTO. BESIDES THE CONVECTION
ASSOCIATED WITH HUMBERTO AND THE TRPCL WAVE...A CLUSTER OF
MODERATE CONVECTION WITH EMBEDDED TSTMS IS FROM 16N-20N E OF
21W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LOW IS OVER W TEXAS EXTENDING A SHORTWAVE UPPER TROUGH
ALONG THE WESTERN GULF WHICH IS SUPPORTING A SURFACE TROUGH
ALONG 27N97W TO 23N97W 19N95W. MIDDLE-LEVEL DIFFLUENCE OVER THE
WESTERN GULF W OF 90W IS SUPPORTING SCATTERED MODERATE
CONVECTION AND ISOLATED TSTMS S OF 29N W OF 89W. A WEAK SURFACE
RIDGING IS OVER THE NE GULF WHERE TOTAL PRECIPITABLE WATER AND
WATER VAPOR IMAGERY SHOW A VERY DRY ENVIRONMENT. SUBSIDENCE OF
DRY AIR IN THIS PART OF THE GULF SUPPORTS FAIR WEATHER N OF 22N
E OF 89W. THE TROPICAL WAVE WILL CONTINUE A WESTWARD TRACK OVER
THE BAY OF CAMPECHE AND WILL MOVE INLAND LATE ON TUESDAY. THE
SURFACE TROUGH IS EXPECTED TO DISSIPATE LATER TODAY. HOWEVER...A
NEW SURFACE TROUGH OR AREA OF LOW PRESSURE IS EXPECTED TO
DEVELOP OVER THE SW GULF WATERS BY WED. RAINSHOWERS ARE EXPECTED
TO CONTINUE OVER THE WESTERN GULF THROUGH WED WHILE FAIR
WEATHER IS EXPECTED TO CONTINUE IN THE N-NE GULF.

CARIBBEAN SEA...
TOTAL PRECIPITABLE WATER IMAGERY SHOW A MODERATE TO HIGH MOIST
ENVIRONMENT IN THE BASIN W OF 70W. MIDDLE-LEVEL DIFFLUENCE OVER
THE WESTERN CARIBBEAN IS ENHANCING SCATTERED MODERATE CONVECTION
AND ISOLATED TSTMS N OF 15N W OF 78W. IN THE UPPER-LEVEL...A
WEAK RIDGE COVERS THE BASIN W OF 75W WHILE AN ELONGATED LOW IS
OVER THE REMAINDER BASIN. THIS IS GENERATING UPPER LEVEL
DIFFLUENCE THUS SUPPORTING SCATTERED MODERATE CONVECTION IN THE
CENTRAL BASIN FROM THE NORTHERN COAST OF COLOMBIA TO THE TRENCH
BETWEEN CUBA AND JAMAICA BETWEEN 72W-77W. THIS DIFFLUENCE IS
ALSO ENHANCING ISOLATED SHOWERS AND TSTMS OVER HISPANIOLA.
TRAILING MOISTURE FROM THE REMNANTS OF GABRIELLE OVER THE SW N
ATLC IS ENHANCING ISOLATED SHOWERS ACROSS PUERTO RICO. IN THE
SOUTHERN BASIN...THE MONSOON TROUGH IS GENERATING SHOWERS AND
TSTMS S OF 11N E OF 80W. DRY AIR IN THE LOWER AND MIDDLE
SUPPORTS FAIR WEATHER IN THE REMAINDER EASTERN BASIN. TRADE
WINDS ARE BECOMING ESTABLISHED ACROSS THE CENTRAL AND E
CARIBBEAN THROUGH EARLY WED THEN DIMINISH INTO FRI.

HISPANIOLA...
UPPER-LEVEL DIFFLUENCE FROM A WEAK RIDGE THAT COVERS THE
CARIBBEAN BASIN W OF 75W AND AN ELONGATED LOW OVER THE REMAINDER
BASIN IS SUPPORTING ISOLATED SHOWERS AND TSTMS OVER HISPANIOLA.
THESE SHOWERS ARE BEING REINFORCED BY TRAILING MOISTURE FROM THE
REMNANTS OF GABRIELLE OVER THE SW N ATLC. TUE THROUGH FRI EXPECT
THE DAILY SCATTERED AFTERNOON SHOWERS/THUNDERSTORMS TO DEVELOP.

ATLANTIC OCEAN...
A MIDDLE TO UPPER LEVEL TROUGH ALONG THE W ATLC IS SUPPORTING
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 22N-32N BETWEEN
71W-79W. A SURFACE TROUGH EXTENDS FROM 31N64W TO A 1008 MB
LOW...REMNANTS OF GABRIELLE...NEAR 25N67W TO 21N69W. AN UPPER
RIDGE E OF THE TROUGH IS GENERATING DIFFLUENCE ALOFT THUS
ENHANCING A WIDE LINE OF MODERATE CONVECTION N OF 21N BETWEEN
62W-66W. SIMILAR CONVECTION IS N OF 27N BETWEEN 57W-62W. THE
REMAINDER OF THE ATLC IS DOMINATED BY A SURFACE RIDGE ANCHORED
BY A 1035 MB HIGH NEAR THE AZORES. THE REMNANT LOW OF GABRIELLE
AND SURFACE TROUGH ARE FORECAST TO LIFT NE OF THE AREA TUE. A
WEAK PRESSURE PATTERN WILL PREVAIL ELSEWHERE ACROSS THE AREA.

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

$$
NR

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