[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 201745
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON JUL 20 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
1715 UTC.

...TROPICAL WAVES...
TROPICAL WAVE EXTENDS FROM 07N50W TO 16N48W MOVING W AT 20 KT.
THE WAVE COINCIDES WITH BROAD 700 MB TROUGHING ALOFT BETWEEN 45W-
53W ON THE SOUTHERN PERIPHERY OF A MID-LEVEL RIDGE CENTERED NEAR
23N46W. SCATTERED MODERATE CONVECTION IS OCCURRING WEST OF THE
WAVE IN MAXIMUM LOW-LEVEL CONVERGENCE FROM 08-12N BETWEEN 51W-
57W.

TROPICAL WAVE EXTENDS FROM 08N59W TO 18N59W MOVING W AT 20 KT.
THE WAVE REMAINS EMBEDDED WITHIN A MAXIMUM OF TOTAL PRECIPITABLE
WATER BETWEEN 57W-61W THAT STRETCHES AS FAR NORTH AS 22N THEN
NORTHEASTWARD INTO THE INFLUENCE OF AN UPPER LEVEL TROUGH AXIS
EXTENDING OVER THE CENTRAL ATLC. ISOLATED MODERATE CONVECTION IS
FROM 08N-12N BETWEEN 58W-62W.

TROPICAL WAVE EXTENDS FROM 09N67W TO 17N66W MOVING W AT 15-20
KT. THE WAVE NEARLY COINCIDES WITH 700 MB TROUGHING BETWEEN 64W-
71W AND IS LARGELY INFLUENCED ALOFT BY SOUTHWESTERLY WIND SHEAR
OVER THE CENTRAL AND EASTERN CARIBBEAN. AS A RESULT...NO
SIGNIFICANT DEEP CONVECTION IS OCCURRING WITH THE WAVE AT THIS
TIME.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH AXIS EXTENDS FROM THE AFRICAN COAST NEAR
14N17W TO 09N20W TO 07N31W. THE INTERTROPICAL CONVERGENCE ZONE
AXIS EXTENDS FROM 07N31W TO 10N45W.

...DISCUSSION...

GULF OF MEXICO...
NORTHEASTERLY FLOW ALOFT PREVAILS OVER MUCH OF THE GULF THIS
AFTERNOON BETWEEN AN UPPER LEVEL ANTICYCLONE CENTERED OVER
CENTRAL TEXAS AND AN UPPER LEVEL LOW CENTERED OVER THE NW
CARIBBEAN SEA. WHILE A MAJORITY OF THE BASIN IS UNDER THIS
RELATIVELY STABLE FLOW...AT THE SURFACE...WEAK TROUGHING AND LOW-
LEVEL MOISTURE CONVERGENCE IS PRESENT ACROSS THE NE GULF
STEMMING FROM A WEAK 1014 MB LOW CENTERED NEAR 30N84W AND A
SURFACE TROUGH THAT STRETCHES WESTWARD FROM THE LOW TO SE
LOUISIANA NEAR 30N91W. THE SURFACE TROUGH BOUNDARY IS PROVIDING
FOCUS FOR SCATTERED SHOWERS AND TSTMS OCCURRING FROM 26N-30N
BETWEEN 83W-94W. OTHERWISE...A SURFACE RIDGE AXIS EXTENDS FROM
THE SW NORTH ATLC ALONG 24N WITH LIGHT ANTICYCLONIC FLOW
FORECAST ACROSS THE BASIN THROUGH LATE TUESDAY.

CARIBBEAN SEA...
AN UPPER LEVEL LOW IS NOTED ON WATER VAPOR IMAGERY OVER THE NW
CARIBBEAN CENTERED NEAR 19N85W. WHILE CONDITIONS AT THE SURFACE
REMAIN FAIRLY TRANQUIL ACROSS THE NW CARIBBEAN...A FEW ISOLATED
SHOWERS AND TSTMS ARE OCCURRING WITHIN 90 NM OFFSHORE OF THE NE
TIP OF THE YUCATAN PENINSULA FROM 20N-22N BETWEEN 85W-87W...AND
FARTHER EAST...SOUTH OF CUBA FROM 19N-21N BETWEEN 75W-81W.
OTHERWISE...THE REMAINDER OF THE CARIBBEAN BASIN IS UNDER THE
INFLUENCE OF SOUTHWESTERLY FLOW ALOFT ON THE NORTHERN PERIPHERY
OF AN UPPER LEVEL RIDGE AXIS EXTENDING ALONG 12N. THE DIFFLUENCE
ASSOCIATED WITH THE RIDGING IS GENERATING SCATTERED SHOWERS AND
TSTMS ACROSS PORTIONS OF THE SW CARIBBEAN AND INLAND AREAS OF
PANAMA AND COSTA RICA S OF 12N BETWEEN 76W-84W. FINALLY...A PAIR
OF TROPICAL WAVES ARE MOVING ACROSS THE EASTERN CARIBBEAN.
INFLUENCE OF THE WESTERN-MOST WAVE ALONG 67W IS LARGELY CONFINED
S OF 14N WITH ISOLATED SHOWERS OCCURRING BETWEEN 65W-70W...WITH
STRONGER CONVECTION OCCURRING ACROSS PORTIONS OF NW VENEZUELA
AND NE COLOMBIA. THE EASTERN-MOST WAVE ALONG 60W IS EXPECTED TO
IMPACT THE LESSER ANTILLES THIS AFTERNOON AND EVENING WITH
INCREASED PROBABILITY OF PRECIPITATION DURING THE NEXT 24 HOURS.

...HISPANIOLA...
CURRENTLY...MOSTLY CLEAR SKIES PREVAIL...HOWEVER WITH THE
APPROACH OF MULTIPLE TROPICAL WAVES PROGRESSING WESTWARD TO THE
SOUTH OF THE ISLAND DURING THE NEXT COUPLE OF DAYS...HIGHER
PROBABILITY OF SCATTERED SHOWERS AND TSTMS IS LIKELY THROUGH
LATE THURSDAY INTO FRIDAY.

ATLANTIC OCEAN...
NORTH-NORTHEASTERLY FLOW ALOFT PREVAILS OVER MUCH OF THE SW
NORTH ATLC ON THE WESTERN PERIPHERY OF AN UPPER LEVEL TROUGH
AXIS EXTENDING FROM 32N46W TO 24N66W. WHILE OVERALL CONDITIONS
REMAIN STABLE ACROSS THE SW NORTH ATLC WITHIN A SURFACE RIDGE
WITH AXIS ALONG 25N...LOW-LEVEL MOISTURE CONVERGENCE IS
MAXIMIZED ALONG 30N BETWEEN 67W-78W GENERATING ISOLATED SHOWERS
AND TSTMS. FARTHER EAST...WITHIN THE INFLUENCE OF THE
SOUTHWESTERLY FLOW ALOFT OF THE UPPER LEVEL TROUGHING...AMPLE
MIDDLE TO UPPER LEVEL DYNAMICS AND LIFT ARE GENERATING AN AREA
OF SCATTERED SHOWERS AND TSTMS FROM 22N-28N BETWEEN 46W-53W.
THIS AREA IS OCCURRING WITHIN A NEARLY STATIONARY RIDGE ANCHORED
BY A 1024 MB HIGH CENTERED NEAR 29N46W. THE RIDGE AXIS EXTENDS
FROM THE HIGH TO THE CENTRAL BAHAMAS THEN WESTWARD INTO THE GULF
OF MEXICO ALONG 24N.

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

$$
HUFFMAN
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