[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 151805
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT WED JUL 15 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 ENTERING THE CENTRAL ATLC. ITS AXIS IS
APPROXIMATELY ALONG 31W AND MOVES W AT NEARLY 5-10 KT PER DAY.
SSMI TPW IMAGERY INDICATE THE WAVE IS EMBEDDED IN A DEEP MOIST
ENVIRONMENT E OF ITS AXIS AND A MODERATE MOIST ENVIRONMENT AHEAD
OF IT. ENHANCEMENTS OF METEOSAT IMAGERY SHOW SAHARAN DRY AIR AND
DUST ENGULFING THE WAVE. SCATTERED MODERATE CONVECTION IS FROM
07N TO 12N BETWEEN 24W AND 34W BEING SUPPORTED BY MIDDLE TO
UPPER LEVEL DIVERGENCE.

A TROPICAL WAVE IS E OF THE LESSER ANTILLES WITH AXIS
APPROXIMATELY ALONG 57W...MOVING W AT 20 KT PER DAY. SSMI TPW
AND ENHANCEMENTS OF METEOSAT IMAGERY INDICATE DRY AIR
ENTRAINMENT TO THE WAVE ENVIRONMENT WHICH IS HINDERING
CONVECTION. DUST IS ALSO PRESENT IN THE WAVE ENVIRONMENT AS
OBSERVED IN SATELLITE IMAGERY AND IS BEING REPORTED THROUGH THE
LESSER ANTILLES.

A TROPICAL WAVE IS OVER THE CENTRAL CARIBBEAN WITH AXIS
APPROXIMATELY ALONG 75W...MOVING W AT 15 KT. SSMI TPW IMAGERY
INDICATE THE WAVE IS EMBEDDED IN A MODERATE MOIST ENVIRONMENT.
DIVERGENT FLOW AHEAD OF THE WAVE IN THE MIDDLE LEVELS SUPPORT
SCATTERED MODERATE CONVECTION AND TSTMS FROM 15N TO 16N BETWEEN
76W AND 79W. STRONG DEEP LAYER WIND SHEAR HINDER CONVECTION
ELSEWHERE.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH ENTERS THE ATLANTIC OCEAN THROUGH GUINEA
BISSAU NEAR 12N17W CONTINUING TO 11N20W. THE ITCZ EXTENDS FROM
THAT POINT TO 10N29W THEN RESUMES W OF A TROPICAL WAVE NEAR
09N33W TO 06N47W TO 07N59W. ASIDE FROM THE CONVECTION ASSOCIATED
WITH THE TRPCL WAVES...SCATTERED MODERATE CONVECTION AND
ISOLATED TSTMS ARE OBSERVED FROM 05N TO 12N E OF 24W AND FROM
04N TO 11N BETWEEN 38W AND 55W.

...DISCUSSION...

GULF OF MEXICO...

A BROAD RIDGE COVERING GREAT PORTIONS OF THE ATLC BASIN EXTENDS
AN AXIS SW ACROSS THE CENTRAL AND SOUTHERN FLORIDA PENINSULA AND
THE SE GULF OF MEXICO. ALOFT...AN UPPER LOW IS OBSERVED CENTERED
OVER SOUTHERN MEXICO SUPPORTING A SURFACE TROUGH OVER THE BAY OF
CAMPECHE FROM 22N92W TO 17N92W...LACKING CONVECTION. MIDDLE TO
UPPER LEVEL RIDGING DOMINATES ACROSS THE BASIN EXCEPT OVER THE
NE GULF WHERE THE BASE OF A MIDDLE LEVEL TROUGH ALONG THE
EASTERN CONUS AND SEABOARD GENERATES DIFFLUENT FLOW. TROUGHING
ALOFT SUPPORT A SURFACE TROUGH EXTENDING ACROSS NORTHERN FLORIDA
TO 29N83W TO 29N87W AND SCATTERED HEAVY SHOWERS AND TSTMS FROM
28N TO 30N E OF 87W BEING FUELED BY MOISTURE INFLOW FROM THE
CARIBBEAN. WINDS ARE MAINLY FROM THE S IN THE RANGE OF 5 TO 10
KT...EXCEPT IN THE NE GULF N OF 27N WHERE WIND FLOW IS FROM THE
WEST. SURFACE RIDGING WILL BE THE DOMINANT FEATURE DURING THE
NEXT THREE DAYS.

CARIBBEAN SEA...

A TROPICAL WAVE IS OVER THE CENTRAL CARIBBEAN ASSOCIATED WITH A
BROAD MODERATE AIRMASS THAT EXTENDS ACROSS THE WESTERN BASIN
INTO THE GULF OF MEXICO. HOWEVER STRONG DEEP LAYER WIND SHEAR
INHIBITS CONVECTION FOR THE MOST PART. OVER THE SW
CARIBBEAN...LOW PRESSURE ASSOCIATED WITH A LOW CENTER OVER N
COLOMBIA AND THE EPAC MONSOON TROUGH SUPPORT SCATTERED MODERATE
CONVECTION S OF 12N BETWEEN 74W AND 84W. SAHARAN DRY AIR AND
DUST ENGULFING THE NEXT TRPCL WAVE TO ENTER THE BASIN COVERS THE
E CARIBBEAN E OF 70W...THUS INHIBITING CONVECTION. REFER TO THE
TROPICAL WAVES SECTION FOR MORE DETAILS. A GENERALLY TIGHT
PRESSURE GRADIENT BETWEEN A RIDGE OVER THE ATLC EXTENDING ACROSS
THE NORTHERN BASIN AND LOWER PRESSURE OVER COLOMBIA SUPPORT
WINDS OF 20 KT TO 25 KT ACROSS THE CENTRAL CARIBBEAN MAINLY S OF
17N BETWEEN 66W-80W. TRADES OF 15 KT DOMINATE ELSEWHERE. THE
NEXT TRPCL WAVE WILL ENTER THE E CARIBBEAN LATE TONIGHT POSSIBLY
ENHANCING ISOLATED SHOWERS.

...HISPANIOLA...

MOISTURE ASSOCIATED WITH THE PASSAGE OF A TRPCL WAVE WITH AXIS
CURRENTLY NEAR 77W COVERS THE ISLAND AND ADJACENT WATERS. AT THE
UPPER LEVELS...A DIVERGENT ENVIRONMENT SITS OVER THE ISLAND
BEING GENERATED BY A LOW OVER THE BAHAMAS AND RIDGING COVERING
THE CENTRAL AND SOUTHERN CARIBBEAN. BOTH THE MOIST AIR AND UPPER
DIVERGENCE SUPPORT CLOUDINESS ISLAND-WIDE WITH POSSIBLE ISOLATED
SHOWERS.

ATLANTIC OCEAN...

TWO TROPICAL WAVES ARE OVER THE TROPICAL ATLANTIC. PLEASE SEE
THE TROPICAL WAVES SECTION ABOVE FOR MORE DETAILS. AS IT IS
NORMAL FOR THIS TIME OF THE YEAR...THE AZORES HIGH EXTENDS A
RIDGE ACROSS GREAT PORTIONS OF THE TROPICAL ATLANTIC SUPPORTING
MAINLY FAIR WEATHER. OVER THE SW N ATLC...THE BASE OF A MIDDLE
LEVEL TROUGH ALONG THE EASTERN CONUS AND SEABOARD GENERATES
DIFFLUENT FLOW. THIS WIND FLOW ALOFT ALONG WITH MOISTURE BEING
ADVECTED FROM THE CARIBBEAN AND SE CONUS SUPPORT SCATTERED HEAVY
SHOWERS AND TSTMS N OF 29N W OF 77W. FARTHER SOUTH...AN UPPER
LOW ANCHORED NEAR ANDROS SUPPORT SIMILAR CONVECTION FROM 21N TO
28N W OF 71W. OTHERWISE...A WEAK COLD FRONT EXTENDS OVER THE N-
CENTRAL ATLC FROM 31N45W TO 29N57W WITH NO CONVECTION.

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

$$
NR
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