[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 171039
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT MON AUG 17 2015

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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1030 UTC.

...SPECIAL FEATURES...

A TROPICAL WAVE SEVERAL HUNDRED MILES SW OF THE CAPE VERDE
ISLANDS IS ASSOCIATED WITH A 1011 MB LOW PRESSURE CENTER
EMBEDDED IN THE MONSOON TROUGH NEAR 09N30W. THE SYSTEM IS MOVING
W AT 15 KT OVER A PERIOD OF 24 HOURS. CIRA LAYER PRECIPITABLE
WATER IMAGERY FROM THE SURFACE TO 850 MB SHOW THE WAVE IS
ASSOCIATED WITH A BROAD AREA OF MODERATE MOISTURE THAT ALONG
WITH A DIVERGENT WIND ENVIRONMENT ALOFT SUPPORT SCATTERED
MODERATE CONVECTION FROM 06N TO 11N BETWEEN 27W AND 33W. SAHARAN
DRY AIR AND DUST ENGULF THE SYSTEM...THUS HINDERING CONVECTION
ELSEWHERE. THERE IS A MEDIUM CHANCE THIS SYSTEM WILL DEVELOP
INTO A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

...TROPICAL WAVES...

A TROPICAL WAVE IS IN THE CENTRAL ATLC WITH AXIS NEAR 48W
...MOVING W AT 10 KT OVER THE PAST 24 HOURS. CIRA LAYER
PRECIPITABLE WATER IMAGERY FROM THE SURFACE TO 850 MB SHOW THE
WAVE IS WITHIN A MODERATE MOIST ENVIRONMENT. UPPER-LEVEL
DIVERGENCE SUPPORT SCATTERED MODERATE CONVECTION AND TSTMS FROM
08N TO 11N BETWEEN 45W AND 51W. SAHARAN DRY AIR AND DUST IN THE
WAVE ENVIRONMENT HINDER CONVECTION ELSEWHERE.

A TROPICAL WAVE IS IN THE CENTRAL CARIBBEAN WITH AXIS NEAR 77W
...MOVING W AT 15-20 KT OVER THE PAST 24 HOURS. THE WAVE IS
ASSOCIATED WITH A MODERATE MOIST ENVIRONMENT FROM THE SURFACE TO
850 MB ACCORDING TO CIRA LAYER PRECIPITABLE WATER IMAGERY.
EXCEPT N OF 17N AND S OF 11N...THE WAVE IS DEVOID OF CONVECTION
DUE TO DRY AIR SUBSIDENCE FROM ALOFT AND STRONG DEEP LAYER WIND
SHEAR ACROSS THE CENTRAL AND EASTERN CARIBBEAN.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE WEST AFRICAN COAST NEAR
13N17W AND CONTINUES W-SW TO THE SPECIAL FEATURES 1011 MB LOW
NEAR 09N30W THEN TO 08N38W. THE INTERTROPICAL CONVERGENCE ZONE
AXIS EXTENDS FROM 08N38W TO 06N47W TO 06N56W. ASIDE FROM
CONVECTION ASSOCIATED WITH THE SPECIAL FEATURES LOW AND TROPICAL
WAVE ALONG 48W...SCATTERED MODERATE CONVECTION IS FROM 10N TO
15N E OF 18W. A CLUSTER OF MODERATE CONVECTION IS FROM 09N TO
12N BETWEEN 20W AND 23W.

...DISCUSSION...

GULF OF MEXICO...

AN UPPER LOW OVER SOUTHERN ILLINOIS EXTENDS A TROUGH SW TO
SOUTHERN TEXAS TO A BASE OVER CENTRAL MEXICO SUPPORTING A
SURFACE TROUGH ALONG SOUTHERN MISSISSIPPI...ACROSS SOUTHERN
LOUISIANA TO 29N94W...WHICH IS ENHANCING SCATTERED TO ISOLATED
SHOWERS AND TSTMS N OF 28N BETWEEN 87W AND 94W. SIMILAR
CONVECTION IS IN THE WESTERN BASIN FROM 22N TO 27N W OF 94W. AN
ELONGATED UPPER RIDGE EXTENDS FROM THE SE CONUS...ACROSS THE
FLORIDA PENINSULA AND THE NE GULF TO A HIGH CENTER OVER BELIZE
AND GUATEMALA. DIFFLUENCE ALOFT BETWEEN THE UPPER TROUGH AND
RIDGE ALONG WITH MOISTURE INFLOW ACROSS THE BASIN FROM THE
CARIBBEAN SEA SUPPORT SCATTERED MODERATE CONVECTION AND TSTMS S
OF 22N BETWEEN 93W AND 97W AND ISOLATED SHOWERS S OF 24N BETWEEN
87W AND 92W...INCLUDING THE YUCATAN PENINSULA AND EASTERN GULF
OF CAMPECHE. OTHERWISE...BROAD SURFACE HIGH PRESSURE OVER THE
ATLC CONTINUES TO EXTEND A RIDGE AXIS SW ACROSS FLORIDA AND THE
EASTERN BASIN...THUS PROVIDING MAINLY SE WIND FLOW OF LESS THAN
15 KT ACROSS THE GULF. SURFACE RIDGING WILL BE THE DOMINANT
FEATURE ACROSS THE BASIN THE NEXT TWO DAYS.

CARIBBEAN SEA...

AN UPPER LEVEL ANTICYCLONE CENTERED OVER BELIZE AND GUATEMALA
EXTENDS A RIDGE AXIS E-SE ACROSS THE CARIBBEAN...EXCEPT THE N-NE
BASIN WHERE A DIFFLUENT ENVIRONMENT PREVAILS BEING GENERATED BY
A SMALL UPPER LOW BETWEEN HISPANIOLA AND SOUTHERN BAHAMAS.
DIFFLUENCE ALOFT ALONG WITH SHALLOW MOISTURE SUPPORT SCATTERED
TO ISOLATED SHOWERS OVER WESTERN PUERTO RICO...THE MONA
PASSAGE...DOMINICAN REPUBLIC AND ADJACENT WATERS. SHOWERS AND
TSTMS ARE BETWEEN JAMAICA AND EASTERN CUBA. A TROPICAL WAVE IS
MOVING ACROSS THE CENTRAL BASIN...HOWEVER DRY AIR SUBSIDENCE
FROM ALOFT AND STRONG DEEP LAYER WIND SHEAR ACROSS THE CENTRAL
AND EASTERN CARIBBEAN HINDER CONVECTION. SEE TROPICAL WAVES SECTION
FOR MORE DETAILS. EAST WINDS OF 20 TO 25 KT ARE FROM 11N TO 15N
BETWEEN 70W AND 77W WITH SEAS TO 9 FT. THESE CONDITIONS ARE
EXPECTED TO PREVAIL IN THIS REGION FOR THE NEXT TWO DAYS. THE
WAVE WILL MOVE ACROSS THE WESTERN BASIN LATER TODAY AND OVER THE
EPAC WATERS TUESDAY EVENING.

...HISPANIOLA...

A DIFFLUENT ENVIRONMENT ALOFT PREVAILS OVER THE N-NE CARIBBEAN
BEING GENERATED BY AN UPPER LEVEL ANTICYCLONE CENTERED OVER
BELIZE AND GUATEMALA EXTENDING A RIDGE AXIS E-SE TO THE WINDWARD
ISLANDS AND A SMALL UPPER LOW BETWEEN HISPANIOLA AND SOUTHERN
BAHAMAS. DIFFLUENCE ALOFT ALONG WITH SHALLOW MOISTURE SUPPORT
SCATTERED TO ISOLATED SHOWERS OVER THE MONA PASSAGE...DOMINICAN
REPUBLIC AND ADJACENT N AND S WATERS. SHOWERS ARE EXPECTED TO
CONTINUE THROUGH TONIGHT.

ATLANTIC OCEAN...

LINGERING SCATTERED TO ISOLATED SHOWERS ARE S OF 23N BETWEEN 61W
AND 70W ASSOCIATED WITH A FORMER SURFACE TROUGH. FARTHER
EAST...A MIDDLE TO UPPER LEVEL LOW SUPPORTS A SURFACE TROUGH
FROM 28N53W TO 23N57W WITH NO CONVECTION ASSOCIATED WITH IT.
OTHERWISE...THE REMAINDER OF THE EASTERN ATLC IS UNDER THE
INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1027 MB HIGH CENTERED
NW OF THE AZORES NEAR 39N29W. FOR TROPICAL WAVES SEE SECTION
ABOVE. THERE IS A MEDIUM CHANCE OF TROPICAL CYCLONE DEVELOPMENT
ASSOCIATED WITH THE EASTERNMOST TROPICAL WAVE. SEE SPECIAL
FEATURES FOR DETAILS.

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

$$
NR
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