[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 180551
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SUN OCT 18 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0530 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...
TROPICAL WAVE EXTENDS FROM 16N54W TO 10N48W MOVING W AT 5-10 KT.
AN ASCAT PASS FROM 00 UTC CAPTURED CYCLONIC TURNING THE WIND
PATTERN ON THE NORTHERN END OF THE WAVE AXIS. THE WAVE COINCIDES
WITH A LOW-AMPLITUDE 700 MB TROUGH BETWEEN 47W-55W. IN
ADDITION...A NEARBY UPPER LEVEL LOW CENTERED NEAR 22N57W IS
INTERACTING WITH THE WAVE AND SHEARING THE CONVECTION TO THE
EAST OF THE WAVE AXIS. ISOLATED MODERATE CONVECTION IS FROM 09N
TO 17N BETWEEN 45W AND 53W.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH AXIS EXTENDS FROM THE AFRICAN COAST NEAR
11N15W TO LOW PRES 1013 MB NEAR 07N19W TO 08N28W...THEN RESUMES
IN THE VICINITY OF LOW PRES 1014 MB NEAR 1309N37W TO 07N45W
WHERE IT TRANSITIONS TO AN ITCZ CONTINUES TO 04N52W. ISOLATED
MODERATE CONVECTION IS NOTED FROM 04N TO 08N BETWEEN 25W AND
35W. SCATTERED MODERATE CONVECTION IS ALSO NOTED WITHIN 60 NM N
OF ITCZ AXIS BETWEEN 45W AND 50W.

...DISCUSSION...

GULF OF MEXICO...
THE MAIN ENERGY ASSOCIATED WITH A BROAD LONG WAVE TROUGH OVER
THE EASTERN UNITED STATES IS MOVING OFF THE MID ATLANTIC COAST
THIS MORNING...SUPPORTING THE MOVEMENT OF A COLD FRONT IN THE
NORTHEAST AND NORTH CENTRAL GULF OF MEXICO. UPPER FLOW IS
TURNING MORE ZONAL ACROSS THE WESTERN GULF...AND SURFACE ARE
VEERING EASTERLY ALLOWING THE FRONT TO SLOW AND STALL ALONG THE
S TEXAS COAST. FARTHER SOUTH...A STATIONARY FRONT PERSISTS OVER
THE SE AND S CENTRAL GULF BETWEEN MORE MOIST TROPICAL AIRMASS TO
THE SOUTH...AND SLIGHTLY DRIER AIRMASS FROM SOUTH FLORIDA TO THE
CENTRAL GULF. THE COLD FRONT WILL EVENTUALLY MERGE WITH THE
STATIONARY FRONT LATE TODAY...WITH NORTHERLY FLOW FUNNELING
ALONG THE MEXICAN COAST AND OVER THE FAR WESTERN GULF AS WELL.
THE STRONG HIGH PRES NORTH OF THE FRONT WILL SUPPORT CONTINUED
GALE CONDITIONS OFF THE COAST OF VERACRUZ THROUGH THE
PERIOD...WITH FRESH TO STRONG NE TO E WINDS ELSEWHERE ACROSS THE
GULF THROUGH MID WEEK.

CARIBBEAN SEA...
A BROAD UPPER LEVEL ANTICYCLONIC CIRCULATION INFLUENCES MUCH OF
THE WESTERN CARIBBEAN AND CENTRAL AMERICA TONIGHT PROVIDING AN
OVERALL DIFFLUENT ENVIRONMENT ALOFT. AN AREA OF LOW PRESSURE
ACROSS CENTRAL AMERICA FOCUSES ON A 1008 MB LOW CENTERED NEAR
18N89W. THE LOW IS ASSOCIATED WITH A LARGE AND BROAD MONSOONAL
GYRE THAT COVERS A LARGE PORTION OF CENTRAL AMERICA AND A
PORTION OF THE EASTERN PACIFIC WATERS N OF 10N BETWEEN 90W-100W.
THE OVERALL CIRCULATION SUPPORTS SCATTERED SHOWERS AND TSTMS
OVER THE NW CARIBBEAN WEST OF 85W...INCLUDING INLAND PORTIONS OF
CENTRAL AMERICA...CUBA...AND THE YUCATAN PENINSULA. AS THE AREA
OF LOW PRESSURE PERSISTS THROUGH THE REMAINDER OF THE WEEKEND...
CONTINUED PRECIPITATION IS EXPECTED ACROSS THE WESTERN CARIBBEAN
AND MORE IMPORTANTLY CENTRAL AMERICA RESULTING IN POSSIBLE FLASH
FLOODING POTENTIAL AND MUD SLIDES. ELSEWHERE ACROSS THE EASTERN
CARIBBEAN...DRIER AIR AND SUBSIDENCE ALOFT SUPPORTS GENERALLY
FAIR WEATHER CONDITIONS E OF 78W WITH ONLY A FEW ISOLATED
SHOWERS AND TSTMS OCCURRING ACROSS HISPANIOLA. MODERATE TO
OCCASIONAL FRESH TRADE WINDS PREVAIL ACROSS THE BASIN WITH
LITTLE CHANGE EXPECTED THROUGH MID WEEK.

...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 COLD FRONT IS MOVING SE ACROSS THE GULF STREAM WATERS OFF NE
FLORIDA THIS MORNING AS THE SUPPORTING MAIN MID/UPPER ENERGY
PUSHES OFF THE MID ATLANTIC COAST TO THE NORTH. FARTHER
SOUTH...A STATIONARY FRONT PERSISTS FROM BERMUDA TO THE NW
BAHAMAS. A FEW MODERATE SHOWERS AND THUNDERSTORMS PERSIST SOUTH
OF THE STATIONARY FRONT...MAINLY ACROSS THE CENTRAL BAHAMAS. THE
COVERAGE AND INTENSITY OF THESE SHOWERS AND THUNDERSTORMS AS
DIMINISHED OVER THE PAST COUPLE OF DAYS AS TRADE WIND
CONVERGENCE HAS TAPERED OFF. THE COLD FRONT WILL EVENTUALLY
MERGE WITH THE STATIONARY BOUNDARY AND REACH FROM NEAR BERMUDA
TO THE NW BAHAMAS AND SOUTH FLORIDA BY LATE TODAY. STRONG HIGH
PRES BUILDING OFF THE CAROLINAS WILL ALLOW FRESH TO STRONG NE
WINDS RESULTING IN VERY ROUGH AND BUILDING SEAS W OF 65W.
FARTHER EAST...AN UPPER LOW REMAINS IN PLACE OVER 22N57W WITH AN
ADJOINING UPPER TROUGH EXTENDING ACROSS THE EASTERN CARIBBEAN TO
N CENTRAL VENEZUELA. SW FLOW ALOFT ASSOCIATED WITH THIS UPPER
TROUGH IS SHEARING CONVECTION ALONG THE TROPICAL WAVE AXIS AS
WELL AS INHIBITING THE WESTERN PROGRESSION OF THE TROPICAL WAVE.
SCATTERED MODERATE CONVECTION IS ONGOING NEAR THE CENTER OF THE
UPPER LOW AS WELL...FROM 22N TO 25N BETWEEN 52W AND 57W. A DRIER
AIRMASS PREVAILS ACROSS THE SUBTROPICAL ATLC WATERS EAST OF
45W...BEHIND AN EARLY SEASON COLD FRONT OVER THE EASTERN ATLC
THAT PENETRATED AS FAR SOUTH AS 16N BEFORE EVENTUALLY
DISSIPATING LATE YESTERDAY. A COLLECTION OF VERY WEAK LOW PRES
AREAS ARE PULSING ALONG A DISORGANIZED MONSOON TROUGH OVER THE
DEEP TROPICS OF THE EASTERN ATLC. A QUASI-STATIONARY 1014 MB LOW
PRES WAS ANALYZED NEAR 09N37W. THIS HAD BEEN CONSIDERED A
TROPICAL WAVE ON EARLY CHARTS...BUT HAS WEAKENED AND MOSTLY
STALLED IN PLACE OVER THE PAST COUPLE OF DAYS AS DRIER AIR MOVED
INTO THE TROPICAL AREA OF THE CENTRAL ATLC ASSOCIATED WITH THE
EARLIER COLD FRONT. TRADE WINDS ARE EXPECTED TO INCREASE
SLIGHTLY OVER THE CENTRAL AND EASTERN ATLC THROUGH MID WEEK AS
HIGH PRES BUILDS N OF THE AREA.

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

$$
CHRISTENSEN
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