[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 191049
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT MON OCT 19 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0930 UTC.

...SPECIAL FEATURES...
THE COMBINATION OF STRONG HIGH PRESSURE ACROSS EASTERN MEXICO...
LOWER PRESSURE ACROSS CENTRAL AMERICA AND SOUTHERN MEXICO...AND
A SURFACE TROUGH ANALYZED ACROSS THE SW GULF OF MEXICO WATERS IS
SUPPORTING NEAR GALE TO GALE FORCE NW WINDS ALONG THE COAST OF
VERACRUZ...MAINLY S OF 21N W OF 95W. SEE LATEST NWS HIGH SEAS
FORECAST UNDER AWIPS/WMO HEADERS MIAHSFAT2/FZNT02 FOR MORE
DETAILS.

...TROPICAL WAVES...
NONE.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH AXIS EXTENDS FROM THE AFRICAN COAST NEAR
12N17W TO A 1014 MB LOW NEAR 09N23W TO 08N28W...THEN RESUMES IN
THE VICINITY OF A 1014 MB LOW NEAR 13N30W TO A 1014 MB LOW NEAR
10N38W TO 09N42W. SCATTERED MODERATE TO ISOLATED STRONG
CONVECTION IS NOTED 10N TO 15N BETWEEN 20W AND 25W. SCATTERED
MODERATE CONVECTION IS NOTE FROM 06N TO 11N BETWEEN 33W AND 37W.

...DISCUSSION...

GULF OF MEXICO...
A MID TO UPPER LEVEL RIDGE IS BUILDING ACROSS THE CENTRAL
PLAINS...FOLLOWING A BROAD UPPER TROUGH NOW MOVING THROUGH THE
CANADIAN MARITIMES AND NW ATLC. THE MID TO UPPER RIDGE IS COMING
INTO PHASE WITH A BROAD UPPER ANTICYCLONE PARKED OVER SOUTHERN
MEXICO AND NORTHERN CENTRAL AMERICA. THIS IS RESULTING IN ZONAL
FLOW ALOFT ACROSS THE GULF OF MEXICO...WHICH IN TURN IS ALLOWING
A COLD FRONT MOVING ACROSS THE CENTRAL GULF TO WEAKEN AND SLOW.
RECENT SURFACE OBSERVATIONS INDICATE THE TEMPERATURE AND
MOISTURE GRADIENT ARE MORE SPREAD OUT ACROSS SOUTHERN AND
CENTRAL FLORIDA...AND NO DISCERNIBLE GRADIENT IS EVIDENT OVER
THE WESTERN GULF...SOUTH TEXAS OR NE MEXICO AT THIS TIME.
SIMILARLY A LONG LIVED STATIONARY FRONT THAT HAD BEEN PLACE
ACROSS THE BAHAMAS AND STRAITS OF FLORIDA HAS FINALLY BECOME
DIFFUSE AS THE AIRMASSES MODIFY AND MIX OUT AHEAD OF THE NEARBY
COLD FRONT. RICH DEEP LAYER MOISTURE SOUTH OF COLD FRONT ALONG
WITH CONVERGENCE OF FRESH TO STRONG NE TO E FLOW IS SUPPORTING
SCATTERED SHOWERS OVER SOUTH FLORIDA AND THE STRAITS OF FLORIDA.
CONVERGENCE OF STRONG TO NEAR GALE FORCE NE WINDS IS ALSO
SUPPORTING SCATTERED SHOWERS AND A FEW THUNDERSTORMS OVER THE
FAR SW GULF OF MEXICO ALONG THE COAST BETWEEN CIUDAD DEL CARMEN
TO COATZACOALCOS. MULTILEVEL CLOUDINESS PREVAILS ALONG AND SOUTH
OF THE FRONT ELSEWHERE OVER THE SOUTHERN GULF...WITH CLEAR TO
SCATTERED HIGH CLOUD OVER THE NORTHERN GULF. ASIDE FROM THE
GALES OFF VERACRUZ...FRESH TO STRONG NE TO E WINDS PERSIST
ACROSS THE GULF WITH 8 TO 12 FT OVER MUCH OF THE SW GULF AND 6
TO 9 FT ELSEWHERE.

CARIBBEAN SEA...
UPPER LEVEL RIDGING EXTENDS OVER CENTRAL AMERICA AND MUCH OF THE
WESTERN CARIBBEAN WITH AXIS EXTENDING FROM OVER HONDURAS NE TO
BEYOND THE WINDWARD PASSAGE. THE COMBINATION OF DIVERGENT FLOW
ALOFT ASSOCIATED WITH THE UPPER ANTICYCLONE...CONVERGENCE OF
MODERATE FRESH EAST FLOW...AND RICH DEEP LAYER MOISTURE ARE
SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS OVER MAINLY THE
NW CARIBBEAN. NO SIGNIFICANT CONVECTION IS NOTED ELSEWHERE
ACROSS THE BASIN AT THIS TIME WHERE SUBSIDENT AND DRY NORTHERLY
FLOW ALOFT CONTINUES BETWEEN THE UPPER ANTICYCLONE TO THE WEST
AND A SHARP AND PERSISTENT UPPER TROUGH OVER THE FAR EASTERN
CARIBBEAN. GENTLE TO MODERATE TRADES CONTINUE WITH ONLY
OCCASIONAL FRESH BREEZE CONDITIONS EXPECTED WITHIN CLOSE
PROXIMITY TO THE NW VENEZUELA AND COLOMBIA COASTS THROUGH THE
MORNING.

...HISPANIOLA...
NW TO N WINDS ALOFT PERSIST ACROSS HISPANIOLA BETWEEN AN UPPER
ANTICYCLONE TO THE WEST AND A AN UPPER TROUGH TO THE EAST. WITH
RELATIVELY HIGH DEEP LAYER MOISTURE IN PLACE...THIS PATTERN
FAVORS LOW TOPPED AND FAST MOVING SHOWERS AND THUNDERSTORMS
FAVORING THE HIGHLAND PORTIONS OF WESTERN DOMINICAN REPUBLIC AND
EASTERN HAITI DURING THE AFTERNOON AND EVENING HOURS OVER THE
NEXT COUPLE OF DAYS.

ATLANTIC OCEAN...
A BROAD MID/UPPER LEVEL TROUGH MOVING ACROSS THE NW ATLC IS
PROVIDING SUPPORT TO A COLD FRONT EXTENDING FROM BERMUDA SW TO
THE FLORIDA PENINSULA NEAR WEST PALM BEACH. IN ADDITION...A PRE-
FRONTAL SURFACE TROUGH EXTENDS FROM 32N60W SW TO 25N68W.
SCATTERED MODERATE SHOWERS AND THUNDERSTORMS ARE ONGOING WITHIN
150 NM E OF THE SURFACE TROUGH...WITH A FEW SHOWERS NOTED
BETWEEN THE TWO BOUNDARIES. STRONG HIGH PRES IS BUILDING BEHIND
THE FRONT OVER THE EASTERN UNITED STATES AND WESTERN ATLC...AND
THE FRONT OVER THE WATERS NORTH OF THE BAHAMAS AND EAST OF NE
FLORIDA. FARTHER EAST...AN UPPER LOW REMAINS ANCHORED NEAR
23N53W WITH A TROUGH EXTENDS SW ACROSS THE EASTERN CARIBBEAN. SW
FLOW ALOFT ON THE EAST SIDE OF THIS TROUGH HAS BEEN SHEARING
CONVECTION ACROSS A QUASI-STATIONARY SURFACE TROUGH REACHING
FROM 16N55W TO WEAK 1014 MB LOW PRES CENTERED NEAR 11N53W.
SCATTERED CONVECTION IS NOTED FROM 10N TO 15N BETWEEN 48W AND
51W. A DRY AIRMASS REMAINS IN PLACE ACROSS THE SUBTROPICAL ATLC
WHERE A RIDGE ANCHORED BY A 1027 MB HIGH NEAR 33N40W DOMINATES N
OF 18N BETWEEN 30W AND 40W. FARTHER EAST...A SHARP UPPER TROUGH
REACHES FROM AN UPPER LOW OFF SOUTHERN PORTUGAL TO 16N40W. AN
ASSOCIATED COLD FRONT IS PUSHING SOUTH ACROSS THE ATLC WATERS
EAST OF 35W N OF 24N...ANCHORED BY A DEEP 999 MB LOW PRES AREA
CENTERED UNDER THE UPPER LOW. STRONG NE WINDS OVER ARE NOTED
BEHIND THE FRONT OVER THE ATLANTIC WATERS WEST OF MOROCCO...WITH
STRONG TO NEAR GALE CONDITIONS BETWEEN THE CANARY ISLANDS AND
MADEIRA. IN THE TROPICAL EASTERN ATLC...DIFFLUENT FLOW ALOFT TO
THE SOUTHEAST OF THE UPPER TROUGH IS SUPPORTING A SERIES OF WEAK
1014 MB LOW PRES CENTERS ALONG THE MONSOON TROUGH NEAR
10N38W...12N30W...AND 09N23N. THESE FEATURES WILL REMAIN QUASI-
STATIONARY THROUGH TODAY.

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

$$
CHRISTENSEN
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