[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 201758
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT WED APR 20 2016

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.

...SPECIAL FEATURES...

ATLANTIC GALE WARNING...GALE FORCE WINDS ARE OCCURRING OVER THE
CENTRAL ATLC FROM 25N TO 29N WITHIN 210 NM E OF A FRONT THAT
EXTENDS THROUGH 32N36W TO 25N46W AND BECOMES STATIONARY TO
20N55W. THESE WINDS ARE FORECAST TO CONTINUE THROUGH 1800 UTC
THIS AFTERNOON AT WHICH TIME THE FRONT WILL BEGIN TO WEAKEN AND
THE CULPRIT TIGHT PRESSURE GRADIENT BEGINS TO RELAX. PLEASE SEE
HIGH SEAS FORECAST UNDER AWIPS/WMO HEADERS MIAHSFAT2/FZNT02 KNHC
FOR MORE DETAILS.

...ITCZ/MONSOON TROUGH...

A WEAK TROUGH EXTENDS ACROSS WESTERN AFRICA TO THE COAST OF
SIERRA LEONE AT 09N13W. THE ITCZ AXIS AS DEFINED IN
SCATTEROMETER DATA...AND ON SATELLITE IMAGERY BEGINS FROM JUST
SW OF 09N13W TO 05N17W TO 04N27W TO 03N32W TO 03N40W TO 02N46W
TO S AMERICA NEAR 01N51W. SCATTERED MODERATE CONVECTION IS
WITHIN 60 NM N OF THE AXIS BETWEEN 45W-49W...AND WITHIN 60 NM S
OF THE AXIS BETWEEN 27W-29W. SIMILAR ACTIVITY IS N OF THE ITCZ
WITHIN 30 NM OF LINE 05N46W TO 05N49W.

SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 30 NM OF
LINE FROM 06N52W TO 06N55W.

...DISCUSSION...

GULF OF MEXICO...

AN UPPER TROUGH EXTENDS FROM THE LOUISIANA/TEXAS BORDER ACROSS
THE W GULF TO THE YUCATAN PENINSULA/YUCATAN CHANNEL. A SURFACE
TROUGH IS THE SW GULF EXTENDING FROM 23N96W TO THE BAY OF
CAMPECHE NEAR 19N95W. THE EARLIER SCATTERED SHOWERS AND ISOLATED
TSTM ACTIVITY HAS BECOME ISOLATED DURING THE MORNING AND EARLY
AFTERNOON. THE DIURNAL SURFACE TROUGH THAT WAS OVER THE YUCATAN
PENINSULA LAST NIGHT...HAS MOVED OVER THE EASTERN BAY OF
CAMPECHE THIS MORNING ALONG 92W S OF 21N. A RATHER VIGOROUS
MID/UPPER LEVEL SHORTWAVE TROUGH IS SEEN ON WATER VAPOR IMAGERY
MOVING ACROSS THE EASTERN GULF FROM SE LOUISIANA TO NEAR THE NW
COAST OF CUBA. A SURFACE COLD FRONT IS MOVING ACROSS CENTRAL
TEXAS...AND IS PRECEDED BY AN OUTFLOW BOUNDARY RACING SE ACROSS
EASTERN TEXAS N OF CORPUS CHRISTI. SCATTERED SHOWERS AND
TSTMS WITH THE BOUNDARY SHOULD REACH THE TEXAS COASTAL WATERS
EARLY THIS AFTERNOON WHILE WEAKENING OTHERWISE...INSTABILITY AHEAD
OF THE TROUGH IS ENOUGH TO ALLOW FOR SCATTERED SHOWERS AND
ISOLATED WEAK TSTMS TO EXIST N OF 23N E OF 88W. IN ADDITION...A
SURFACE REFLECTION OF THE TROUGH IS FROM APALACHEE BAY TO 27N86W.
ISOLATED SHOWERS AND TSTMS HAVE MOVED TO THE E OF THIS
TROUGH...AND ARE WEAKENING. A WEAKENING SURFACE RIDGE REMAINS
OVER THE EASTERN GULF AND WESTERN ATLC ANCHORED BY A 1021 MB
HIGH CENTER E OF THE NE FLORIDA. SURFACE RIDGING WILL PERSIST
THROUGH THU...THEN THE HIGH WILL MOVE EASTWARD ALLOWING FOR A
WEAK COLD FRONT TO MOVE E THROUGH THE N AND NE GULF FRI AND SAT
WITH HIGH PRESSURE FOLLOWING IN THE WAKE OF THE FRONT.

CARIBBEAN SEA...

AN UPPER RIDGE OVER S AMERICA AND THE WESTERN TROPICAL ATLC IS
SUPPLYING THE UPPER ATMOSPHERE OVER THE BASIN WITH SW TO W FLOW
THIS AFTERNOON. THE TAIL-END OF THE CENTRAL ATLC COLD FRONT
EXTENDS AS A DISSIPATING STATIONARY FRONT SW TO NEAR GUADELOUPE
IN THE LEEWARD ISLANDS. LINGERING LOW AND MID LEVEL MOISTURE IN
COMBINATION WITH UPPER JET DYNAMICS CONTINUE TO RESULT IN
SCATTERED SHOWERS AND ISOLATED TSTMS ARE OBSERVED BETWEEN 72W
AND 65W...AND ALSO N OF 15N E OF 65W TO THE AREA OF THE LEEWARD
ISLANDS. CURRENTLY...THE NWS SAN JUAN DOPPLER RADAR IS SHOWING
SCATTERED SHOWERS STAYING TO THE S AND SW OF THE ISLAND...
HOWEVER SCATTERED TO BROKEN LOW CLOUDS ARE FORMING OVER THE
INTERIOR PORTION OF THE ISLANDS WITH DAYTIME HEATING UNDERWAY.
SOME OF THESE CLOUDS COULD SOON LEAD TO THE DEVELOPMENT OF SCATTERED
SHOWERS AND TSTMS. THE SAME APPLIES FOR HISPANIOLA WHERE PRECIPITABLE
TYPE CLOUDS ARE NOTED ON SATELLITE IMAGERY. THE SURFACE RIDGE OVER
THE EASTERN GULF OF MEXICO AND THE WESTERN ATLC EXTENDS S TO
OVER CUBA AND THE FAR NW CARIBBEAN. MODERATE TO FRESH TRADE
WINDS WILL PERSIST ACROSS THE CARIBBEAN THROUGH THU NIGHT. NE
WINDS ARE EXPECTED TO PULSE FRESH TO STRONG EACH NIGHT S OF
HISPANIOLA AND INTO THE WINDWARD PASSAGE THROUGH THU NIGHT. W
ATLC SURFACE HIGH PRES WILL SHIFT EASTWARD OVER BERMUDA FRI...
THEN BECOME CENTERED NE OF THE AREA ON SAT DIMINISHING TRADE
WINDS ACROSS MUCH OF THE CARIBBEAN.

HISPANIOLA...

WITH DAYTIME HEATING UNDERWAY SCATTERED TO BROKEN CUMULUS CLOUDS ARE
DEVELOPING OVER THE INTERIOR OF THE ISLAND. THE EFFECTS OF OROGRAPHIC
LIFTING SHOULD LEAD TO SOME OF THESE DEVELOPING INTO SCATTERED SHOWERS
AND TSTMS IN THE AFTERNOON. THIS PATTERN IS EXPECTED TO REPEAT ITSELF
ON THU. ON FRI...IT IS POSSIBLE THAT AN INCREASE OF LOW-LEVEL
MOISTURE FROM THE S MAY AID IN THE DEVELOPMENT OF SCATTERED
SHOWER/TSTM ACTIVITY.

ATLANTIC OCEAN...

A WEAKENING SURFACE RIDGE COVERS THE W ATLC W OF 65W TO OVER
CUBA AND THE EASTERN GULF OF MEXICO ANCHORED BY A 1021 MB HIGH CENTER
OFF THE NE FLORIDA COAST NEAR 30N78W. BROAD UPPER TROUGH COVERS THE W
AND CENTRAL ATLC WITH AN AXIS EXTENDING THROUGH 32N38W SW TO
23N52W TO 21N64W. THE TROUGH SUPPORTS A COLD FRONT THAT EXTENDS FROM
A LOW PRES CENTER N OF THE AREA SW THROUGH 32N36W TO 26N46W
WHERE IT BECOMES STATIONARY TO 20N54W...AND DISSIPATING FROM
THERE SW TO THE LEEWARD ISLANDS. A RE-ENFORCING SURGE IN THE
FORM OF A SURFACE TROUGH TRAILS THE FRONT ALONG A POSITION FROM
NEAR 32N46W SW TO 28N47W AND TO 23N54W. A BROAD UPPER RIDGE
COVERS THE REMAINDER OF THE ATLC E OF THE UPPER TROUGH. A STRONG
JET STREAM BRANCH EXTENDS IN BETWEEN BOTH OF THESE FEATURES FROM
NEAR 20N62W NEWD TO 23N49W TO NE OF THE AREA AT 32N34W. RIPPLES
OF SHORTWAVE ENERGY RIDING ALONG THE JET IN COMBINATION WITH
DEEP MOISTURE WITHIN 200-500 NM SE OF THE FRONT ARE LEADING TO
WAVES OF SCATTERED SHOWERS AND ISOLATED TSTMS UNDERNEATH THESE
CLOUDS TO THE SE OF THE FRONT N OF 19N. SE OF THE FRONT S OF
19N...THE ACTIVITY HAS BECOME ISOLATED IN COVERAGE. A SURFACE
RIDGE COVERS THE REMAINDER OF THE ATLC ANCHORED BY A 1021 MB
HIGH NEAR 28N20W. THE AFOREMENTIONED COLD FRONT WILL MOVE SLOWLY
EASTWARD THROUGH THIS EVENING WHILE WEAKENING TO A STATIONARY
FRONT. THE STATIONARY FRONT IS FORECAST TO GRADUALLY DISSIPATE
THROUGH THU. ANOTHER COLD FRONT WILL QUICKLY SWEEP SE ACROSS THE
NE WATERS ON WED. HIGH PRESSURE WILL BUILD SE ACROSS THE WESTERN
ATLC IN THE WAKE OF THE FRONTS THEN WEAKEN AS IT SHIFTS E ACROSS
BERMUDA FRI AND SAT. A WEAK COLD FRONT IS FORECAST TO MOVE OFF
THE SE U.S. COAST EARLY ON SAT.

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

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AGUIRRE
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