[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 181037
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT TUE AUG 18 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 IS OVER THE CENTRAL ATLC ASSOCIATED WITH A 1010
MB LOW PRESSURE CENTER EMBEDDED IN THE MONSOON TROUGH NEAR
10N34W. THE SYSTEM IS MOVING W AT 10-15 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 07N TO 12N BETWEEN
31W AND 39W. SAHARAN DRY AIR AND DUST ENGULF THE SYSTEM...THUS
HINDERING CONVECTION ELSEWHERE. THERE IS A HIGH CHANCE THIS
SYSTEM WILL DEVELOP INTO A TROPICAL CYCLONE DURING THE NEXT 48
HOURS. SEE LATEST NHC TROPICAL WEATHER OUTLOOK UNDER AWIPS/WMO
HEADERS MIATWOAT/ABNT20 KNHC FOR MORE DETAILS.

...TROPICAL WAVES...

A TROPICAL WAVE IS WITHIN 500 NM SE OF THE LESSER ANTILLES WITH
AXIS NEAR 52W...MOVING W AT 10-15 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. MIDDLE TO
UPPER LEVEL DIVERGENCE SUPPORT SCATTERED MODERATE CONVECTION AND
TSTMS FROM 06N TO 12N BETWEEN 47W AND 55W. DRY AIR INTRUSION IN
THE WAVE ENVIRONMENT FROM A SAHARAN AIRMASS HINDER CONVECTION
ELSEWHERE.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 17N16W SW
TO THE SPECIAL FEATURES 1010 MB LOW NEAR 10N34W TO 08N39W. THE
INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 08N39W TO
05N52W. ASIDE FROM CONVECTION ASSOCIATED WITH THE SPECIAL
FEATURES LOW AND TROPICAL WAVE ALONG 52W...ISOLATED MODERATE
CONVECTION IS FROM 10N-17N E OF 27W.

...DISCUSSION...

GULF OF MEXICO...

A MIDDLE TO UPPER LEVEL LOW EXTENDS FROM SOUTHERN TEXAS TO NE
MEXICO AND PART OF THE NW GULF WHILE A BROAD RIDGE COVERS THE
REMAINDER BASIN. DIVERGENT WIND FLOW BETWEEN THESE TWO FEATURES
ALOFT ALONG WITH MOISTURE INFLOW ACROSS THE BASIN FROM THE
CARIBBEAN SEA SUPPORT SCATTERED MODERATE CONVECTION AND TSTMS S
OF 24N W OF 90W. UPPER LEVEL DIVERGENCE IS ALSO OVER THE
NORTHERN-CENTRAL GULF...THUS SUPPORTING ISOLATED SHOWERS N OF
27N BETWEEN 86W AND 94W. OTHERWISE...A WEAK SURFACE RIDGE AXIS
EXTENDS ACROSS THE CENTRAL FLORIDA PENINSULA TO THE CENTRAL GULF
WITH MOSTLY GENTLE TO MODERATE E-SE FLOW THAT IS EXPECTED
THROUGH TUESDAY NIGHT LATE. THEREAFTER...THE S-SE WINDS WILL
INCREASE SLIGHTLY ACROSS THE WESTERN GULF AS AN AREA OF LOW
PRESSURE DEVELOPS ACROSS THE SOUTHERN PLAINS TUESDAY NIGHT INTO
WEDNESDAY.

CARIBBEAN SEA...

SHALLOW MOISTURE OVER THE NW BASIN IS ENHANCING SHOWERS OVER
SOUTHERN-EASTERN CUBA ADJACENT WATERS AND THE WINDWARD PASSAGE.
THE OTHER AREA OF CONVECTION IS WITHIN 60 NM OFF THE COASTS OF
COLOMBIA AND PANAMA BETWEEN 74W AND 79W WHERE SHOWERS AND TSTMS
ARE BEING ENHANCED BY AN AREA OF LOW PRESSURE OVER NORTHERN
COLOMBIA. DRY AIR SUBSIDENCE FROM ALOFT AND STRONG DEEP LAYER
WIND SHEAR HINDER CONVECTION ELSEWHERE IN THE CENTRAL AND
SOUTHERN CARIBBEAN. NE TO E WINDS OF 20 TO 25 KT ARE FROM 11N TO
13.5N BETWEEN 72W AND 77W WITH SEAS TO 9 FT. THESE CONDITIONS
ARE EXPECTED TO PREVAIL IN THIS REGION FOR THE NEXT TWO DAYS.
THE NEXT TROPICAL WAVE WILL ENTER THE E CARIBBEAN WED NIGHT.

...HISPANIOLA...

SHALLOW MOISTURE ALONG WITH THE PRESENCE OF AN UPPER LOW
CENTERED BETWEEN EASTERN CUBA AND JAMAICA SUPPORT CLOUDINESS
ACROSS THE ISLAND WITH POSSIBLE ISOLATED SHOWERS. ISOLATED
SHOWERS AND TSTMS ARE IN THE WINDWARD PASSAGE. SIMILAR
CONDITIONS ARE EXPECTED TO CONTINUE THROUGH THIS EVENING AS THE
UPPER LOW MOVES SW OF JAMAICA AND DRY AIR MOVES ACROSS THE
ISLAND.

ATLANTIC OCEAN...

ISOLATED SHOWERS CONTINUE BETWEEN THE SOUTHERN FLORIDA PENINSULA
AND THE NORTHERN BAHAMAS ASSOCIATED TO A FORMER SURFACE TROUGH.
OTHERWISE...THE REMAINDER OF THE CENTRAL AND EASTERN ATLC IS
UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1025 MB
HIGH CENTERED JUST N OF THE AZORES ISLANDS. FOR TROPICAL WAVES
SEE SECTION ABOVE. THERE IS A HIGH 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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