[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 021808 AAA
TWDAT

TROPICAL WEATHER DISCUSSION...AMENDED
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT TUE AUG 02 2011

AMENDED/UPDATED SPECIAL FEATURES INFORMATION ON T.S. EMILY

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...

TROPICAL STORM EMILY IS CENTERED NEAR 15.6N 64.8W AT 02/1800 UTC
OR ABOUT 185 NM S-SE OF SAN JUAN PUERTO RICO MOVING W AT 10 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1006 MB. MAXIMUM SUSTAINED
WIND SPEED IS 40 KT WITH GUSTS TO 50 KT. A GRADUAL INCREASE IN
FORWARD SPEED IS ANTICIPATED LATER TODAY WITH THE FORECAST TRACK
W-NW TOWARDS THE SOUTHERN COAST OF HISPANIOLA. SCATTERED
MODERATE TO STRONG CONVECTION IS LOCATED WITHIN 120 NM OF THE
CENTER. ELSEWHERE SCATTERED MODERATE AND ISOLATED STRONG
CONVECTION IS FROM 12N-17N BETWEEN 59W-64W... PRIMARILY EAST OF
EMILY AND ACROSS THE LESSER ANTILLES. LOOKING AHEAD AS EMILY
IMPACTS PUERTO RICO...THE US/UK VIRGIN ISLANDS... THE DOMINICAN
REPUBLIC...AND HAITI...ASIDE FROM TROPICAL STORM FORCE
WINDS...HEAVY AMOUNTS OF PRECIPITATION ARE EXPECTED. 4 TO 6
INCHES ARE EXPECTED OVER THESE AREAS WITH MAXIMUM AMOUNTS TO 10
INCHES LOCALLY DURING THE NEXT 24-48 HOURS. LIFE-THREATENING
FLASH FLOODING AND MUDSLIDES WILL BE POSSIBLE ACROSS AREAS OF
MOUNTAINOUS TERRAIN. SEE LATEST NHC INTERMEDIATE PUBLIC ADVISORY
UNDER AWIPS/WMO HEADERS MIATCPAT5/WTNT35 KNHC AND THE FULL
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT5/WTNT25 KNHC
FOR MORE DETAILS.

...TROPICAL WAVES...

TROPICAL WAVE IS ANALYZED FROM 11N29W TO 17N30W MOVING W AT 20
KT. HOVMOLLER DIAGRAM ANALYSIS INDICATES THIS WAVE MOVED OFF THE
W AFRICA COAST DURING THE DAY ON JULY 31ST. UPPER AIR TIME-
SECTION ANALYSES FROM DAKAR SENEGAL ALSO CONFIRMS THE PASSAGE OF
THE WAVE. WELL WEST OF THE CAPE VERDE ISLANDS AT THIS POINT...A
BROAD LOW-LEVEL CYCLONIC CIRCULATION SURROUNDING THE WAVE AXIS N
OF THE MONSOON TROUGH TO 16N IS BETWEEN 25W-37W. NO SIGNIFICANT
CONVECTION IS ASSOCIATED WITH THE WAVE AT THIS TIME DUE TO THE
LARGE PRESENCE OF AFRICAN DUST ACROSS THE EASTERN TROPICAL ATLC.

TROPICAL WAVE IS ANALYZED FROM 07N52W TO 17N50W MOVING W AT 15
KT. THE WAVE REMAINS EMBEDDED WITHIN ELEVATED VALUES OF TOTAL
PRECIPITABLE WATER VALUES W OF 46W TO TROPICAL STORM EMILY IN
THE EASTERN CARIBBEAN SEA. WATER VAPOR IMAGERY INDICATES STRONG
DRY AIR AND SUBSIDENCE ALOFT...THEREFORE NO SIGNIFICANT
CONVECTION IS ASSOCIATED WITH THE WAVE AT THIS TIME.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 14N17W
ALONG 10N33W 11N42W TO 09N50W. ISOLATED MODERATE CONVECTION IS
FROM 09N-12N BETWEEN 22W-28W...AND FROM 08N-12N BETWEEN 30W-35W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED OVER THE
LOWER MISSISSIPPI RIVER VALLEY AND IS PROVIDING MUCH OF THE GULF
WITH NORTHEASTERLY UPPER LEVEL FLOW. AT THE SURFACE...OVERALL
RIDGING IS PROVIDING FAIR CONDITIONS W OF 90W. HOWEVER...A
WEAKNESS EXISTS IN THIS RIDGE ACROSS THE NE GULF AND NORTHERN
FLORIDA PENINSULA N OF 27N. A 1012 MB LOW IS ANALYZED NEAR
29N85W WITH A TRAILING SURFACE TROUGH EXTENDING SW TO 27N89W.
MOSAIC DOPPLER RADAR IMAGERY AND LIGHTNING DATA INDICATES THAT
SCATTERED SHOWERS AND TSTMS ARE OCCURRING FROM 27N-30N BETWEEN
84W-90W. THE SURFACE RIDGE IS FORECAST TO REMAIN ACROSS THE GULF
ALONG 26N THROUGH THE WEEKEND.

CARIBBEAN SEA...
TROPICAL STORM EMILY CONTINUES TO BE THE PRIMARY FOCUS ACROSS
THE EASTERN AND CENTRAL CARIBBEAN OVER THE NEXT FEW DAYS. AS
NOTED ABOVE...LARGE AMOUNTS OF RAINFALL ARE ANTICIPATED ACROSS
PUERTO RICO...THE US/UK VIRGIN ISLANDS...DOMINICAN REPUBLIC...
AND HAITI WITH EMILY AS IT TRACKS W-NW TOWARDS THE SOUTHERN
COAST OF HISPANIOLA. ONE FACTOR CONTRIBUTING IN A POSITIVE WAY
TO EMILY IS A LARGE ANTICYCLONE CENTERED NEAR 16N71W AND
ASSOCIATED RIDGE AXIS EXTENDING EASTWARD TO 14N44W. THE ONLY
OTHER AREA OF ACTIVE WEATHER ACROSS THE CARIBBEAN ARE SOME
SCATTERED SHOWERS AND ISOLATED TSTMS ACROSS BELIZE AND THE
YUCATAN PENINSULA...INCLUDING THE ADJACENT COASTAL WATERS W OF
86W. THIS ACTIVITY IS LIKELY ENHANCED BY AN UPPER LEVEL LOW
CENTERED IN THE SW GULF OF MEXICO NEAR 20N93W. THE REMAINDER OF
THE CARIBBEAN BETWEEN 70W-85W IS UNDER MOSTLY CLEAR SKIES AND
FAIR CONDITIONS WITH LIGHT EASTERLY WINDS OF 10-15 KT.

ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH IS EVIDENT ON WATER VAPOR IMAGERY ALONG
THE EASTERN CONUS SEABOARD AND DIPS SOUTHWARD INTO THE
DISCUSSION AREA TO A BASE NEAR 29N75W. THIS TROUGH SUPPORTS A
1011 MB LOW CENTERED NW OF BERMUDA NEAR 33N66W AND A STATIONARY
FRONT ANALYZED FROM THE LOW SW ALONG 31N70W TO 29N78W. LOW-LEVEL
MOISTURE CONTINUES TO CONVERGE ALONG THE FRONT AND GENERATE
SCATTERED SHOWERS AND ISOLATED TSTMS WITHIN 150 NM EITHER SIDE
OF THE BOUNDARY. THIS FRONTAL TROUGHING IS EXPECTED TO MOVE NE
AND NORTH OF THE AREA OF THE NEXT 24 HOURS AS A SURFACE RIDGE
AXIS CURRENTLY ALONG 25N SHIFTS NORTHWARD. THE REMAINDER OF THE
EASTERN AND CENTRAL ATLC IS UNDER THE INFLUENCE OF A SURFACE
RIDGE ANCHORED BY A 1025 MB HIGH CENTERED SW OF THE AZORES NEAR
34N33W. THE RIDGE AXIS EXTENDS FROM THE HIGH SW TO 25N64W THEN
WESTWARD ACROSS THE CENTRAL BAHAMAS AND FLORIDA STRAITS.

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

$$
HUFFMAN





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