[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 152340
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED AUG 15 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURES...

TROPICAL DEPRESSION EIGHT IS CENTERED NEAR 29.9N 55.1W AT
15/2100 UTC OR ABOUT 520 NM ESE OF BERMUDA MOVING N AT 16 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1013 MB. MAXIMUM SUSTAINED
WIND SPEED IS 30 KT WITH GUSTS TO 40 KT. WIDELY SCATTERED
MODERATE CONVECTION IS FROM 28N-34N BETWEEN 52W-58W. SEE LATEST
NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23
KNHC FOR MORE DETAILS.

...TROPICAL WAVES...

TROPICAL WAVE EXTENDS FROM 12N24W TO 20N25W MOVING W AT 15-20
KT. THE WAVE REMAINS EMBEDDED WITHIN A LARGE AREA OF ENHANCED
DEEP LAYER MOISTURE AS NOTED ON THE TOTAL PRECIPITABLE WATER
IMAGERY FROM 08N-19N BETWEEN 16W-30W. AN EARLIER ASCAT PASS
AROUND 15/1154 UTC INDICATED WEAK LOW-LEVEL CYCLONIC FLOW IN THE
VICINITY OF THE WAVE AXIS N OF 15N...AND GLOBAL MODEL DATA SHOWS
THAT THE WAVE COINCIDES WITH A 700 MB TROUGH AXIS ALONG 25W. DUE
TO A LARGE DRY AIRMASS ASSOCIATED WITH A SAHARAN AIR LAYER...NO
DEEP CONVECTION IS CURRENTLY ASSOCIATED WITH THE WAVE.

TROPICAL WAVE EXTENDS FROM 10N41W TO 18N46W MOVING W AT 20-25
KT. ENERGY FROM THE WAVE CONTINUES TO STRETCH IN A NW-SE
ORIENTATION DUE TO BROAD LOW-LEVEL CYCLONIC FLOW ACROSS THE
CENTRAL TROPICAL ATLC. A MAXIMUM IN 700 MB GLOBAL MODEL WINDS
ARE NOTED ACROSS THE NORTHERN EXTENT OF THE WAVE AND CONTINUE TO
FUEL A SURGE OF SAHARAN DUST WHICH IS LOCATED E OF 54W TO THE
AFRICAN COAST. SAHARAN DUST IS WRAPPED AROUND THE WAVE RESULTING
IN A LACK OF ANY DEEP CONVECTION AT THIS TIME.

TROPICAL WAVE EXTENDS FROM 11N65W TO 18N64W MOVING W AT 15-20
KT. THE WAVE REMAINS RATHER WEAK DUE TO THE FACT THAT MOST OF
THE ENERGY FRACTURED OFF A FEW DAYS AGO AND IS TIED IN WITH
TROPICAL DEPRESSION EIGHT ACROSS THE CENTRAL ATLC. OTHERWISE...
TOTAL PRECIPITABLE WATER IMAGERY SHOWS THAT INCREASED LOW-LEVEL
MOISTURE IS LOCATED ACROSS THE LEEWARD ISLANDS AND NE CARIBBEAN
SEA WHICH SEEMS TO INDICATE THE LOCATION OF THE WAVE THIS
EVENING. ISOLATED SHOWERS ARE OCCURRING FROM 13N-17N BETWEEN
60W-63W...AND FROM 17N-19N BETWEEN 54W-68W...INCLUDING PUERTO
RICO.

TROPICAL WAVE EXTENDS FROM 14N86W TO 21N88W MOVING W AT 15 KT.
THE WAVE HAS SLOWED OVER THE PAST 24 HOURS AS IT ENCOUNTERS THE
CENTRAL AMERICAN LANDMASS AND IS EXPECTED TO TRACK ACROSS THE SW
GULF OF MEXICO IN THE NEXT FEW DAYS. THE WAVE ALSO LIES NEAR AN
AREA OF DIFFLUENCE ALOFT...WHICH IS ENHANCING SCATTERED MODERATE
CONVECTION OCCURRING FROM 12N-22N BETWEEN 80W-92W. LOCALLY HEAVY
RAINFALL...FLOODING...AND POTENTIAL MUDSLIDES OVER THE HIGHER
TERRAIN ARE POSSIBLE ACROSS SOUTHERN MEXICO AND CENTRAL AMERICA.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 18N16W TO
12N24W TO 10N38W. THE INTERTROPICAL CONVERGENCE ZONE AXIS
EXTENDS FROM 10N42W TO 05N52W. DUE TO THE LARGE AREA OF SAHARAN
DUST ACROSS THE EASTERN AND CENTRAL ATLC...ONLY ISOLATED
MODERATE CONVECTION IS FROM 05N-09N BETWEEN 34W-41W.

...DISCUSSION...

GULF OF MEXICO...
A MIDDLE TO UPPER LEVEL TROUGH IS NOTED ON WATER VAPOR IMAGERY
ACROSS THE EASTERN CONUS THAT EXTENDS INTO A TROUGH AXIS FROM
OVER THE FLORIDA PANHANDLE NEAR 30N85W SW TO AN UPPER LEVEL LOW
CENTERED OVER THE SW GULF NEAR 22N94W. NORTH AND WEST OF THIS
TROUGH AXIS RELATIVELY DRY AIR ALOFT IS IN PLACE PROVIDING MUCH
OF THE WESTERN GULF WITH CLEAR SKIES THIS EVENING. THE ONLY
EXCEPTION ARE APPROACHING SCATTERED SHOWERS AND TSTMS OCCURRING
ALONG THE WESTERN YUCATAN PENINSULA THIS EVENING IN ASSOCIATION
WITH THE TROPICAL WAVE ALONG 88W. EAST OF THE UPPER LEVEL LOW...
PLENTY OF MOISTURE CONTINUES TO ADVECT NORTHWARD ON THE WESTERN
PERIPHERY OF AN ANTICYCLONIC CIRCULATION CENTERED OVER THE
FLORIDA STRAITS NEAR 23N80W. UPPER LEVEL DIFFLUENCE IS MAXIMIZED
E OF 90W AND ALONG WITH MAXIMUM DAYTIME HEATING AND INSTABILITY
IS GENERATING WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS S OF
27N E OF 90W AND N OF 29N. OTHERWISE...A SURFACE RIDGE ALONG 27N
IS EXPECTED TO REMAIN OVER THE GULF THROUGH LATE THURSDAY.

CARIBBEAN SEA...
A TROPICAL WAVE IN COMBINATION WITH DIFFLUENCE ALOFT ON THE
SOUTHERN PERIPHERY OF AN UPPER LEVEL ANTICYCLONIC CIRCULATION
CENTERED NEAR 23N80W IS GENERATING SCATTERED SHOWERS AND TSTMS
ACROSS MUCH OF THE WESTERN CARIBBEAN N OF 11N W OF 80W THIS
EVENING. THE WAVE IS FORECAST TO CONTINUE TRACKING WESTWARD
ACROSS CENTRAL AMERICA AND SOUTHERN MEXICO THE NEXT FEW DAYS
WITH EXPECTED PRECIPITATION CREATING A HIGH PROBABILITY OF
LOCALLY HEAVY RAINFALL...FLOODING...AND THE POTENTIAL FOR
MUDSLIDES OVER THE HIGHER TERRAIN. THE REMAINDER OF THE
CARIBBEAN IS EXPERIENCING MOSTLY FAIR WEATHER DUE TO AN AREA OF
DRY AIR ALOFT E OF 70W. WITHIN THIS DRY AIR ALOFT HOWEVER A FEW
ISOLATED SHOWERS AND TSTMS ARE OCCURRING ACROSS EASTERN CUBA...
HISPANIOLA...AND PUERTO RICO THIS EVENING. A WEAK TROPICAL WAVE
ALONG 65W HAS CONTRIBUTED TO SOME OF THIS CONVECTIVE ACTIVITY AS
WELL AS ISOLATED SHOWERS ACROSS THE LESSER ANTILLES AND THE
ADJACENT COASTAL WATERS.

ATLANTIC OCEAN...
UPPER LEVEL DIFFLUENCE IS MAXIMIZED ACROSS THE SW NORTH ATLC
THIS EVENING BETWEEN A MIDDLE TO UPPER LEVEL TROUGH ACROSS THE
EASTERN CONUS AND AN ANTICYCLONIC CIRCULATION CENTERED OVER THE
FLORIDA STRAITS NEAR 23N80W. LOW-LEVEL CONVERGENCE FOCUSED ALONG
A SURFACE TROUGH ANALYZED FROM 32N70W TO 29N75W CONTINUES TO
GENERATE SCATTERED SHOWERS AND TSTMS WITHIN 300 NM SE OF THE
SURFACE TROUGH AND AREAS STRETCHING WESTWARD ACROSS THE
BAHAMAS...FLORIDA PENINSULA...AND THE ADJACENT COASTAL WATERS W
OF 79W. FARTHER EAST...TROPICAL DEPRESSION EIGHT REMAINS
EMBEDDED WITHIN A BROAD SURFACE RIDGE ACROSS THE CENTRAL AND
EASTERN ATLC ANCHORED BY A 1024 MB HIGH NEAR 32N46W AND A 1020
MB HIGH NEAR 34N21W.

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

$$
HUFFMAN




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