[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 111802
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT TUE AUG 11 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1745 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS EAST OF THE CAPE VERDE ISLANDS WITH AXIS NEAR
22W...MOVING W AT APPROXIMATELY 5 KT. CIRA LAYER PRECIPITABLE
WATER IMAGERY FROM THE SURFACE TO 850 MB SHOW MODERATE MOISTURE
ASSOCIATED WITH THIS WAVE. HOWEVER...METEOSAT ENHANCED IMAGERY
SHOW SAHARAN DRY AIR AND DUST IN THE WAVE ENVIRONMENT...WHICH
SUPPRESS CONVECTION.

A TROPICAL WAVE IS OVER THE CENTRAL ATLC WITH AXIS NEAR
44W...MOVING W AT APPROXIMATELY 10 KT. CIRA LAYER PRECIPITABLE
WATER IMAGERY FROM THE SURFACE TO 850 MB SHOW THE WAVE IS MAINLY
EMBEDDED IN A DRY ENVIRONMENT BEING CONFIRMED BY THE PRESENCE OF
SAHARAN DRY AIR AND DUST IN METEOSAT ENHANCED IMAGERY. THESE
CONDITIONS SUPPORT LACK OF CONVECTION AT THIS TIME.

A TROPICAL WAVE IS IN THE EASTERN CARIBBEAN WITH AXIS NEAR 66W
MOVING W AT APPROXIMATELY 15-20 KT. CIRA LAYER PRECIPITABLE
WATER IMAGERY FROM THE SURFACE TO 850 MB SHOW A MODERATE MOIST
ENVIRONMENT E OF THE WAVE AXIS THAT ENHANCES SCATTERED SHOWERS
AND ISOLATED TSTMS OVER THE LESSER ANTILLES...PUERTO RICO AND
ADJACENT WATERS.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM 12N16W TO 08N30W TO 07N45W. THE
ITCZ BEGINS NEAR 07N45W TO GUYANA COASTAL WATERS NEAR 06N56W.
SCATTERED MODERATE CONVECTION IS FROM 05N TO 10N BETWEEN 13W AND
20W...FROM 07N TO 09N BETWEEN 21W AND 28W AND FROM 06N TO 09N
BETWEEN 37W AND 47W.

...DISCUSSION...

...THE GULF OF MEXICO...

BROAD SURFACE HIGH PRESSURE OVER THE ATLC EXTENDS A RIDGE AXIS W-
SW ACROSS THE FLORIDA PENINSULA...THE NORTHERN AND EASTERN GULF
OF MEXICO. OVER THE W-SW BASIN...A 1014 MB LOW IS LOCATED NEAR
25N92W ENHANCING SCATTERED SHOWERS AND TSTMS FROM 23N TO 26N W
OF 92W. A SURFACE TROUGH IS SW OF THE LOW FROM 24N96W TO 19N96W
SUPPORTING SIMILAR CONVECTION FROM 20N TO 22N W OF 95W. CIRA
LAYER PRECIPITABLE WATER IMAGERY FROM THE SURFACE TO 850 MB SHOW
MODERATE MOISTURE STREAMING ACROSS THE BASIN FROM THE
CARIBBEAN...HOWEVER DRY AIR SUBSIDENCE FROM ALOFT AND STRONG
DEEP LAYER WIND SHEAR HINDER CONVECTION ELSEWHERE. WINDS ACROSS
THE BASIN ARE VARIABLE RANGING FROM 5 TO 10 KT. SHOWERS AND
TSTMS OVER THE W-SW GULF ARE EXPECTED TO CONTINUE DURING THE
NEXT TWO HOURS...ACCORDING TO THE GOES-R CONVECTIVE INITIATION
PRODUCT. A WEAK COLD FRONT IS FORECAST TO ENTER THE N-NE GULF
WED MORNING...BECOMING STATIONARY THURSDAY.

...THE CARIBBEAN SEA...

A TROPICAL WAVE IS MOVING ACROSS THE EASTERN CARIBBEAN ENHANCING
SHOWERS ACROSS PUERTO RICO AND THE LESSER ANTILLES. SEE TROPICAL
WAVES SECTION FOR DETAILS. SHALLOW MODERATE MOISTURE DOMINATES
ACROSS THE NW AND SW BASIN. AN UPPER LEVEL LOW OVER THE YUCATAN
PENINSULA SUPPORTS SCATTERED TO ISOLATED SHOWERS AND TSTMS OVER
THE NW CARIBBEAN S OF 21N W OF 82W. UPPER LEVEL DIVERGENCE ALONG
THE EASTERN CENTRAL AMERICA COASTLINE SUPPORT HEAVY SHOWERS AND
TSTMS S OF 16N W OF 78W. FAIR WEATHER IS OVER THE CENTRAL
CARIBBEAN SUPPORTED BY DRY AIR AND STRONG DEEP LAYER WIND SHEAR.
NE TO E WINDS OF 20 TO 25 KT ARE FROM 11N TO 14N BETWEEN 71W AND
78W WITH SEAS TO 10 FT. TRADES OF 15 KT DOMINATE ELSEWHERE. THE
TROPICAL WAVE IS FORECAST TO MOVE ACROSS HISPANIOLA AND CENTRAL
CARIBBEAN WEDNESDAY ENHANCING SHOWERS.

...HISPANIOLA...

DEEP LAYER DRY AIR DOMINATES ACROSS THE ISLAND AND IS EXPECTED
TO CONTINUE THROUGH TONIGHT. ON WEDNESDAY MORNING...A TROPICAL
WAVE WILL START TO MOVE ACROSS THE CENTRAL CARIBBEAN ENHANCING
SHOWERS ACROSS THE ISLAND THROUGH THURSDAY MORNING.

THE ATLANTIC OCEAN...

SHALLOW MOISTURE OVER THE SW N ATLC ASSOCIATED WITH A FORMER
FRONTAL SYSTEM AND A TROUGH OF LOW PRESSURE CONTINUE TO ENHANCE
ISOLATED SHOWERS AND TSTMS OVER THE NORTHERN AND CENTRAL BAHAMAS
AND FARTHER NE FROM 26N TO 31N BETWEEN 65W AND 71W.
OTHERWISE...SURFACE HIGH PRESSURE SUPPORT FAIR WEATHER ELSEWHERE
N OF 20N. FOR INFORMATION ABOUT TROPICAL WAVES SEE SECTION AT
THE TOP OF THE DISCUSSION. A COLD FRONT IS FORECAST TO ENTER THE
SW N ATLC LATE WEDNESDAY...STALLING OVER THIS REGION OF THE
BASIN THURSDAY AND FRIDAY. SURFACE RIDGING WILL DOMINATE
ELSEWHERE. TONIGHT...NE TO E WINDS OF 20 TO 25 KT ARE
FORECAST S OF 21N BETWEEN 70W AND 72W WITH SEAS LESS THAN 8 FT.

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

$$
NR
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