Tropical Weather Discussion
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800
AXNT20 KNHC 210003
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED MAY 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2345 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE TROPICAL
ATLANTIC NEAR 11N15W TO 06N17W TO 05N23W WHERE THE ITCZ BEGINS
AND CONTINUES TO 02N40W TO THE COAST OF NORTHERN BRAZIL NEAR
01N50W. SCATTERED TO ISOLATED MODERATE CONVECTION IS FROM 02N TO
09N E OF 22W. ISOLATED SHOWERS ARE WITHIN 120 NM EITHER SIDE OF
THE ITCZ BETWEEN 25W AND 35W.

...DISCUSSION...

GULF OF MEXICO...

A WEAK SURFACE RIDGE DOMINATES THE CENTRAL AND EASTERN GULF
WATERS BEING ANCHORED BY A 1017 MB HIGH NEAR 28N86W. FAIR
WEATHER PREVAILS UNDER UPPER LEVEL RIDGING AND DRY AIR
SUBSIDENCE W OF 90W AND SURFACE DRY AIR AND RIDGING E OF 90W.
LIGHT TO MODERATE ANTICYCLONIC FLOW CONTINUE TO DOMINATE THE
BASIN...EXCEPT IN THE NE GULF NEAR THE HIGH CENTER WHERE LIGHT
AND VARIABLE AIR PERSISTS. THERMAL TROUGHING DEVELOPED OVER THE
YUCATAN PENINSULA THIS EVENING...WHICH IS FORECAST TO MOVE
OFFSHORE INTO THE SW GULF INTO THU MORNING...AND YET AGAIN FRI
EVENING INTO SAT MORNING. AS A RESULT WINDS WILL INCREASE TO
FRESH NEAR THE NW YUCATAN PENINSULA WITH SEAS BUILDING TO UP TO
7 FT AS A RESULT. SURFACE RIDGING AND FAIR WEATHER WILL DOMINATE
ELSEWHERE THE NEXT TWO DAYS.

CARIBBEAN SEA...

THE CENTRAL AND EASTERN CARIBBEAN CONTINUE TO MOISTEN DUE TO
MIDDLE TO UPPER LEVEL SOUTHWESTERLY TO WESTERLY FLOW ADVECTION
OF TROPICAL MOISTURE FROM THE PACIFIC OCEAN AND NORTHERN SOUTH
AMERICA...AND ADVECTION OF ATLANTIC LOW LEVEL TROPICAL MOISTURE
BY THE TRADES. DEEP LAYER MOISTURE COMBINED WITH A DIVERGENT
ENVIRONMENT SUPPORT SCATTERED MODERATE CONVECTION AND TSTMS OVER
COSTA RICA...PANAMA...HISPANIOLA AND ADJACENT WATERS. A MIDDLE
TO UPPER LEVEL TROUGH IS ACROSS THE NW CARIBBEAN WITH DRY AND
STABLE AIR INDICATED BY WATER VAPOR AND SSMI TOTAL PRECIPITABLE
WATER IMAGERY. A LOCALIZED TIGHT PRES GRADIENT CONTINUES IN THE
S CENTRAL CARIBBEAN BETWEEN LOW PRES OVER NW COLOMBIA AND ATLC
RIDGING N-NE OF THE AREA. THIS IS SUPPORTING A MODERATE TO FRESH
BREEZE NEAR THE NW COAST OF COLOMBIA AND SEAS UP TO 8 FT. THESE
WINDS WILL CONTINUE TO PULSE NEAR THE COAST OF COLOMBIA THE NEXT
TWO DAYS BEFORE DIMINISHING AS THE PRES GRADIENT RELAXES
SLIGHTLY. OTHERWISE GENTLE TRADES AND 4-6 FT SEAS PREVAIL S OF
17N...WITH GENTLE TRADES AND 2-4 FT SEAS N OF 17N. SCATTERED TO
ISOLATED SHOWERS ARE ACROSS PUERTO RICO BEING ENHANCED BY THE
TAIL OF A SURFACE TROUGH. EXPECT SIMILAR WEATHER CONDITIONS
THROUGH THE NEXT 48 HOURS.

...HISPANIOLA...

DEEP LAYER MOISTURE OVER THE REGION ALONG WITH A MIDDLE LEVEL
DIVERGENT ENVIRONMENT IS SUPPORTING SCATTERED MODERATE
CONVECTION AND TSTMS ACROSS THE ISLAND EXTENDING TO N-NE COASTAL
WATERS. SHOWERS ARE EXPECTED TO CONTINUE THROUGH SATURDAY NIGHT.

ATLANTIC OCEAN...

A MIDDLE TO UPPER LEVEL ELONGATED LOW AND ASSOCIATED TROUGH
BETWEEN 48W AND 51W SUPPORT A 1009 MB LOW NEAR 35N52W FROM WHICH
A COLD FRONT EXTENDS TO 30N50W SW TO 25N57W WHERE IT TRANSITIONS
TO A STATIONARY FRONT TO 25N65W TO 29N68W. OVER THE SW N
ATLC...SURFACE RIDGING DOMINATES BEING ANCHORED BY A 1018 MB
HIGH NEAR 27N69W. AHEAD OF THE FRONT...A SURFACE TROUGH EXTENDS
FROM 27N49W TO 21N57W TO NE PUERTO RICO NEAR 18N66W. SCATTERED
MODERATE CONVECTION IS WITHIN 100 NM N OF CUBA AND HISPANIOLA.
ISOLATED SHOWERS ARE OFF THE NORTHERN COAST OF PUERTO RICO.
AHEAD OF THE COLD FRONT...SIMILAR CONVECTION IS N OF 24N BETWEEN
40W AND 52W. SURFACE RIDGING AND FAIR WEATHER DOMINATE ELSEWHERE
OVER THE CENTRAL AND EASTERN ATLC.

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

$$
NR



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