Tropical Weather Discussion
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000
AXNT20 KNHC 240556
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT THU APR 24 2014

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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH EXITS W AFRICA AND PASSES THROUGH COASTAL
SECTIONS OF SENEGAL NEAR 13N16.5W AND ON TO NEAR 08N20W...WHERE
IT TRANSITIONS TO ITCZ. THE ITCZ THEN EXTENDS WESTWARD THROUGH
01N29W TO 00N40W TO COASTAL BRAZIL NEAR 01.5S46W. WIDELY
SCATTERED MODERATE TO STRONG CONVECTION WAS NOTED FROM 03S TO
05N BETWEEN 13W AND 23W...WHILE SCATTERED STRONG CONVECTION WAS
NOTED N OF 04N TO WELL INLAND BETWEEN 10W AND 14W...AND N OF THE
EQUATOR BETWEEN 05E AND 04W. ISOLATED MODERATE CELLS WERE
OCCURRING IN A NARROW LINE FROM 60 TO 150 NM N OF THE ITCZ
BETWEEN 29W AND 45W.

...DISCUSSION...

...THE GULF OF MEXICO...
MILDLY DIFFLUENT UPPER LEVEL FLOW PREVAILS ACROSS THE GULF THIS
MORNING AS UPPER RIDGING IS SHIFTING SLOWLY E ACROSS THE CENTRAL
U.S. AND BROAD TROFFING EXTENDS FROM THE N CENTRAL GULF S-SW
THROUGH THE BAY OF CAMPECHE AND INTO THE TROPICAL EPAC ALONG
94W. A WEAK MIDDLE LEVEL CYCLONIC VORTEX CAN BE SEEN IN WATER
VAPOR IMAGERY ACROSS THE N CENTRAL GULF NEAR 27N87.5W AND
SHIFTING EASTWARD...AND IS BECOMING SEPARATED FROM MIDDLE TO
UPPER LEVEL TROFFING ACROSS THE NW ATLC. THIS IS YIELDING DRY
AND GENERALLY STABLE CONDITIONS ALOFT N OF 25N. THE UPPER RIDGE
WILL SHIFT E TO ALONG 80W BY 00Z THIS EVENING...FOLLOWED BY A
DEEP LAYERED TROUGH CURRENTLY CROSSING THE ROCKIES TO SHIFT E
INTO THE MS VALLEY. THIS DEEP LAYERED TROUGH WILL SUPPORT A
FRONTAL SYSTEM MOVING SE THROUGH TEXAS TODAY...THEN SLOW TONIGHT
ACROSS SE TEXAS AND NW LOUISIANA. CURRENTLY...A 1015 MB HIGH IS
CENTERED ACROSS THE NE GULF NEAR 27N86.5W...WITH MODERATE SE TO
S RETURN FLOW PREVAILING ACROSS W AND NW PORTIONS. THE HIGH WILL
SHIFT E TO THE FLORIDA PENINSULA TODAY AHEAD OF THE APPROACHING
FRONT...AND COLLAPSE. RETURN FLOW ACROSS ALL BUT SE PORTIONS
WILL PROVIDE SUFFICIENT MOISTURE FOR LATE AFTERNOON AND EVENING
CONVECTION ACROSS N AND NW COASTAL PORTIONS AS UPPER CONDITIONS
DESTABILIZE IN ADVANCE OF THE APPROACHING UPPER TROUGH. THE
FRONT IS FORECAST TO STALL LATE TONIGHT-EARLY FRI MORNING ACROSS
THE NORTHERN COASTS AND COASTAL WATERS ALONG ABOUT 30N...AND
WEAKEN.

...THE CARIBBEAN SEA...
A BROAD UPPER RIDGE DOMINATES ALL BUT FAR NW PORTIONS OF THE
CARIBBEAN THIS MORNING...YIELDING MODEST UPPER CONFLUENCE AND
MOSTLY STABLE CONDITIONS ALOFT. THE ATLANTIC RIDGE IS PRESENTLY
CENTERED ACROSS THE NE ATLC AND EXTENDS SW AND WEAKLY TO PUERTO
RICO AND THE NE CARIBBEAN...MAINTAINING GENERALLY LIGHT TO
MODERATE TRADE WINDS ACROSS THE CARIBBEAN BASIN THIS MORNING.
THE EXCEPTION IS ALONG THE COAST OF VENEZUELA...THE ABC ISLANDS
AND NE COLOMBIA...WHERE WINDS TO 20 KT ARE NOTED. ACTIVE DEEP
CONVECTION IS OCCURRING ACROSS MUCH OF N COLOMBIA ATTM AND
SPREADS N INTO THE IMMEDIATE WATERS WITHIN 45 NM OF THE COAST.
AN OLD FRONTAL ZONE PERSISTS FROM THE ATLANTIC W-SW ACROSS
HISPANIOLA THEN W TO JUST W OF THE CAYMAN ISLANDS NEAR 19N83W.
ISOLATED TO WIDELY SCATTERED SHOWERS ARE SEEN NEAR THE
BOUNDARY...MOSTLY W OF THE CAYMANS. HIGH PRES WILL BUILD N OF
THE AREA THIS WEEKEND...ALLOWING TRADE WINDS TO INCREASE OVER
THE SOUTH CENTRAL CARIBBEAN AND GULF OF HONDURAS.
ADDITIONALLY...A BROAD ZONE OF LOW LEVEL MOISTURE ACROSS THE
TROPICAL N ATLC S OF 15N WILL MOVE W-NW ACROSS THE LESSER
ANTILLES TODAY AND ACROSS THE E CARIBBEAN THROUGH TONIGHT TO
YIELD WIDELY SCATTERED TO SCATTERED BRIEF PASSING SHOWERS.

...HISPANIOLA...
AN OLD FRONTAL ZONE MENTIONED ABOVE...IN THE FORM OF A
TROUGH...EXTENDS W-SW ACROSS THE N HALF OF HISPANIOLA. TPW
ANIMATIONS SUGGEST THE BEST MOISTURE IS CONVERGING N OF THIS
TROUGH AND ACROSS N COASTAL SECTIONS AND THE IMMEDIATE COASTAL
WATERS TO 21N. THIS BOUNDARY WILL CONTINUE TO WEAKEN TODAY...BUT
SUFFICIENT LLVL MOISTURE WILL COMBINE WITH PREVAILING LIGHT TO
MODERATE E-SE LLVL FLOW TO FOCUS AFTERNOON AND EVENING
CONVECTION ACROSS N CENTRAL AND NW PORTIONS OF THE ISLAND. DUE
TO A NARROW MID LEVEL RIDGE ACROSS THE AREA...CONDITIONS ARE NOT
EXPECTED TO BE VERY UNSTABLE...AND ONLY ISOLATED MODERATE TSTMS
ARE EXPECTED. LOOKING AHEAD...THE TRAILING END OF A WEAK COLD
FRONT PASSING EASTWARD TO THE NORTH OF HISPANIOLA WILL DRIFT TO
THE NORTHERN COAST OF HISPANIOLA BY SUNDAY. THIS WILL COINCIDE
WITH THE ARRIVAL OF WEAK TROUGH IN THE MID TO UPPER
LEVELS...ALLOWING FOR INCREASED SHOWERS AND INLAND THUNDERSTORMS
BY SUNDAY.

...THE ATLANTIC OCEAN...
A BROAD MID TO UPPER LEVEL TROUGH CONTINUES TO MOVE EASTWARD
OVER THE NW ATLANTIC...REACHING FROM OFFSHORE OF NEW ENGLAND SE
TO A BASE NEAR 28N64W. MIDDLE TO UPPER LEVEL DYNAMICS AHEAD OF
THIS TROUGH AREA INTERACTING WITH A STALLED AND WEAKENING
FRONTAL ZONE...EXTENDING FROM 31N54W TO NW HAITI...TO PRODUCE AN
AREA OF SCATTERED MODERATE CONVECTION WITHIN 180 NM SE OF THE
FRONTAL TROUGH N OF 26N. THE BROAD DEEP LAYERED TROUGH ALSO
SUPPORTS A FRONTAL BOUNDARY APPROACHING BERMUDA AND N PORTIONS
OF THE AREA...FROM THE NW. A WEAK 1015 MB HIGH WAS NOTED BETWEEN
THESE TWO BOUNDARIES...CENTERED OVER THE SE BAHAMAS. THE NEW
FRONT WILL DRIFT SE ACROSS THE WATERS NORTH OF 25N THROUGH
SATURDAY FOLLOWED BY MODERATE RIDGING. THIS WILL INCREASE TRADE
WIND FLOW S OF 22N W OF 60W THIS WEEKEND.

FARTHER EAST...THE ATLC RIDGE EXTENDS FROM 1029 MB HIGH NEAR
34N30W TO PUERTO RICO AND THE WATERS JUST N OF THE MONA PASSAGE.
RECENT ASCAT DATA INDICATED MODERATE TRADEWINDS 15-20 KT
OCCURRING S OF THE RIDGE W OF 30W...AND GENERALLY S OF 18-20N...
WITH SEAS 8 TO 9 FT AS NOTED BY ALTIMETER SATELLITE PASSES
BETWEEN 40W AND 45W. MODERATE TO FRESH N TO NE FLOW IS NOTED
OVER THE FAR EASTERN TROPICAL ATLC WATERS EAST OF 35W TO THE
COAST OF AFRICA. MINIMAL TRADE WIND CONVERGENCE IS INHIBITING
SIGNIFICANT CONVECTION ALONG THE ITCZ...ALTHOUGH UPPER RIDGING
ACROSS EQUATORIAL E ATLC AND CENTRAL AFRICA ARE ENHANCING
SHOWERS AND THUNDERSTORMS IN THE DEEP TROPICS SOUTH OF 10N EAST
OF 20W.

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

$$
STRIPLING


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