[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 221022
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EST TUE APR 22 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1115 UTC.

...THE ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH PASSES THROUGH COASTAL SECTIONS OF SENEGAL
NEAR 12N16W TO 04N24W. THE ITCZ CONTINUES FROM THERE CROSSING
THE EQUATOR ALONG 38W TO 02S45W NEAR THE COAST OF BRAZIL. A
SURFACE TROUGH...A CONVERGENCE LINE...EXISTS FROM THE COAST OF
LIBERIA NEAR 06N10W TO 04N24W. NUMEROUS MODERATE SCATTERED
STRONG CONVECTION WAS NOTED SOUTH OF THE SURFACE TROUGH
EAST OF 25W.

...DISCUSSION...

...THE GULF OF MEXICO...

A BROAD 1017 MB SURFACE HIGH IS CENTERED SOUTH OF COASTAL
MISSISSIPPI AT 28N89W.  A SECOND BROAD HIGH OF 1018 MB IS
LOCATED NEAR SOUTHERNMOST TEXAS AT 26N97W.  DUE TO A FLAT
PRESSURE GRADIENT...SURFACE WINDS ACROSS THE GULF ARE GENTLE
BREEZE OR WEAKER.  ISOLATED DEEP CONVECTION FIRED UP OVER THE
HIGH TERRAIN OF MEXICO DURING THE LATE AFTERNOON DIURNAL MAXIMUM
YESTERDAY.  FORCING FOR THIS DEEP CONVECTION NORTH OF 25N MAY BE
DUE IN PART TO A MID TO UPPER LEVEL TROUGH MOVING ACROSS TEXAS.
A COUPLE OF ISOLATED THUNDERSTORMS ARE STILL OCCURRING ALONG THE
EASTERN FLANK OF THE SIERRA MADRE MOUNTAINS...THOUGH THESE
SHOULD DIMINISH SHORTLY.  ELSEWHERE ACROSS THE GULF...NO
SIGNIFICANT DEEP CONVECTION OR SHOWERS ARE OCCURRING.  OVER THE
NEXT TWO DAYS...THE WEAK HIGH SHOULD REMAIN RELATIVELY
STATIONARY OVER THE GULF.  A WEAK COOL FRONT WILL APPROACH THE
U.S. GULF COAST LATE TODAY AND MAY BARELY REACH THE NORTHERN
GULF.  DEEP CONVECTION MAY OCCUR IN ASSOCIATION WITH THIS WEAK
FRONT...BUT WITH LITTLE TO NO MOIST SOUTHERLY RETURN FLOW IN
ADVANCE...EXPECT THE EXTENT OF THUNDERSTORMS TO BE RATHER
LIMITED.

...THE CARIBBEAN SEA...

A SURFACE TROUGH EXTENDS FROM HAITI TO THE NORTHWESTERN
CARIBBEAN SEA.  THIS...ALONG WITH SOME SUBSTANTIAL LOW-LEVEL
MOISTURE DEPICTED IN THE TOTAL PRECIPITABLE WATER IMAGERY...
PROMOTED DEVELOPMENT OF ISOLATED DEEP CONVECTION IN ASSOCIATION
WITH AFTERNOON HEATING OVER EASTERN CUBA...JAMAICA...THE EASTERN
BAHAMAS...AND HISPANIOLA LATE ON MONDAY. WITH THE NORTH-SOUTH
PRESSURE GRADIENT RATHER FLAT...EASTERLY TRADES ACROSS THE
CARIBBEAN ARE MODERATE TO GENTLE BREEZES...WITH THE EXCEPTION OF
FRESH BREEZE NORTHEASTERLIES JUST NORTH OF COLOMBIA.  IF
ANYTHING...THE PRESSURE GRADIENT AND ASSOCIATED TRADEWINDS MAY
WEAKEN EVEN MORE DURING THE NEXT TWO DAYS. AS THE TROUGH IS
EXPECTED TO DISSIPATE IN THE NEXT DAY OR SO...THIS MAY REDUCE
CHANCES OF DEEP CONVECTION OVER THE NEXT TWO DAYS OVER THE
CARIBBEAN...WHICH IS OVERLAID BY SUBSIDENT UPPER LEVEL
WESTERLIES TYPICAL FOR THIS TIME OF YEAR.

...HISPANIOLA...

A SURFACE TROUGH EXTENDS FROM HAITI TO THE NORTHWESTERN
CARIBBEAN SEA.  THIS...ALONG WITH SOME SUBSTANTIAL LOW-LEVEL
MOISTURE DEPICTED IN THE TOTAL PRECIPITABLE WATER IMAGERY...
PROMOTED DEVELOPMENT OF ISOLATED DEEP CONVECTION IN ASSOCIATION
WITH AFTERNOON HEATING OVER HISPANIOLA LATE ON MONDAY. AS THE
SURFACE TROUGH IS EXPECTED TO DISSIPATE IN THE NEXT DAY OR
SO...THIS MAY REDUCE CHANCES OF DEEP CONVECTION OVER THE NEXT
TWO DAYS OVER HISPANIOLA...WHICH IS OVERLAID BY SUBSIDENT UPPER
LEVEL WESTERLIES TYPICAL FOR THIS TIME OF YEAR.

...THE ATLANTIC OCEAN...

A 1002 MB SURFACE LOW WAS LOCATED A FEW HUNDRED MILES EAST OF
NORTH CAROLINA NEAR 34N67W.  A COLD FRONT FROM THE LOW EXTENDS
SOUTHWESTWARD IN OUR AREA FROM 32N64W TO HISPANIOLA.  ISOLATED
DEEP CONVECTION EXISTS WITHIN 60 NM OF THE FRONT NORTH OF 28N.
SURFACE SOUTHWESTERLY WINDS AHEAD OF FRONT ARE FRESH TO STRONG
BREEZE CONDITIONS...BUT ARE WEAKER BEHIND THE FRONT.  A SURFACE
TROUGH ALSO IS PRESENT FROM THE LOW SOUTHWESTWARD TO THE EASTERN
BAHAMAS...THOUGH THIS FEATURE HAS NO SIGNIFICANT CONVECTION OR
WINDS WITH IT.  THE LOW IS VERTICALLY STACKED WITH AN UPPER LOW
OBSERVED IN THE WATER VAPOR IMAGERY AT THE SAME LOCATION.  THE
UPPER LOW IS STARTING TO OPEN UP INTO A TROUGH AND BE ADVECTED
QUICKLY TOWARD THE EAST.  THE COLD FRONT ASSOCIATED WITH THE LOW
HAS LIMITED BAROCLINICITY...BUT IT WILL CONTINUE TO INITIATE
ISOLATED TO SCATTERED DEEP CONVECTION ALONG AND JUST EAST OF THE
FRONT.  IN A COUPLE OF DAYS...THE LOW AND THE FRONT WILL BE
ABSORBED WITHIN A NEWLY DEVELOPING EXTRATROPICAL LOW AND MORE
VIGOROUS COLD FRONT...THE LATTER WILL REACH OUR NORTHERN BORDER
LATE WEDNESDAY.

FARTHER EAST...A FRONTAL BOUNDARY STRADDLES THE NORTHERN BORDER
FROM 32N48W TO 30N37W TO 32N29W WITH THE WESTERNMOST PORTION
BEING A WARM FRONT AND THE REMAINDER A COLD FRONT. THIS FRONTAL
BOUNDARY IS WELL-DEFINED...THOUGH SURFACE WINDS IN ASSOCIATION
WITH IT ONLY REACH FRESH BREEZE CONDITIONS.  THE FRONT WILL
PROGRESS EASTWARD...BUT NOT MUCH FARTHER EQUATORWARD...AND HAVE
LIMITED TO NO ASSOCIATED DEEP CONVECTION.

ELSEWHERE...A 1022 MB SURFACE HIGH IS LOCATED AT 29N45W WITH
ASSOCIATED RIDGING EXTENDING ZONALLY ACROSS MOST OF THE ATLANTIC
AROUND 28N.  THE MODEST PRESSURE GRADIENT EQUATORWARD OF THE
RIDGE IS PRODUCING TRADEWINDS OF AT MOST FRESH BREEZE
CONDITIONS.  LITTLE CHANGE IS EXPECTED FOR THE NEXT COUPLE OF
DAYS.

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

$$
LANDSEA


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