[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 170549
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SAT OCT 17 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
0515 UTC.

...SPECIAL FEATURES...

THE COMBINATIONS OF HIGH PRES BUILDING OVER THE MISSISSIPPI
VALLEY AND LOWER PRES OVER THE EASTERN PACIFIC SOUTH OF MEXICO
IS RESULTING IN A TIGHTENING PRES GRADIENT ACROSS THE SW GULF OF
MEXICO THIS MORNING. OBSERVATIONS FROM ISLA DE SACRIFICIO OFF
THE COAST OF VERACRUZ MEXICO SHOW PEAK WINDS ALREADY REACHING
MINIMAL GALE FORCE. SUSTAINED WINDS ALONG THE COAST OF VERACRUZ
ARE EXPECTED TO REACH MINIMAL GALE FORCE LATER THIS
MORNING...MAINLY S OF 21N W OF 95W...AND PERSIST THROUGH EARLY
NEXT WEEK.

...TROPICAL WAVES...
TROPICAL WAVE EXTENDS FROM 08N37W TO 14N38W MOVING W AT 10 TO 15
KT. DRY AIR IS ENTRAINING IN THE NORTHERN PORTIONS OF THE
TROPICAL WAVE...AND CONVECTION NEAR THE TROPICAL WAVE IS LIMITED
TO WHERE THE WAVE AXIS INTERSECTS THE MONSOON TROUGH FARTHER
SOUTH. THE WAVE REMAINS LOW AMPLITUDE AND COINCIDES WITH WEAK
700 MB TROUGHING BETWEEN 34W-40W.

TROPICAL WAVE EXTENDS FROM 10N48W TO 18N52W MOVING W AT 10 TO 15
KT. BUOY OBSERVATIONS AND AN ASCAT PASS FROM 01 UTC INDICATED
SHARP SURFACE TROUGHING ASSOCIATED WITH THIS WAVE. SCATTERED
MODERATE CONVECTION IS ONGOING NW OF THE TROPICAL WAVE...FROM
18N TO 23N BETWEEN 50W AND 55W. WESTERLY FLOW ASSOCIATED WITH AN
UPPER TROUGH REACHING FROM AN UPPER LOW CENTERED NEAR 25N55W TO
NE VENEZUELA. THE TROPICAL WAVE WILL BECOME LESS AMPLIFIED AS IT
DRIFTS WEST OVER THE NEXT COUPLE OF DAYS TOWARD THE WINDWARD
ISLANDS AND CLOSER TO THE UPPER TROUGH AXIS.

TROPICAL WAVE EXTENDS FROM 21N88W IN THE N CENTRAL YUCATAN
PENINSULA TO 1007 MB LOW PRES NEAR 17N88W IN THE GULF OF
HONDURAS. THE WAVE IS MOVING W AT 10-15 KT. THE WAVE COINCIDES
WITH A FAIRLY BROAD AND ELONGATED 700 MB TROUGH ANCHORED OVER
THE EAST PACIFIC WATERS SOUTH OF GUATEMALA AND SOUTHERN MEXICO.
THE NORTHERN PORTION OF OVERALL LOW-LEVEL WAVE ENERGY IS FOCUSED
ON A 1007 MB LOW.  SCATTERED MODERATE TO STRONG CONVECTION IS
OCCURRING WITHIN 90 NM OF THE LOW. SCATTERED MODERATE CONVECTION
IS NOTED ELSEWHERE N OF 18N BETWEEN 80W AND 85W.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH AXIS EXTENDS FROM THE AFRICAN COAST NEAR
15N23W INTO A 1010 MB LOW NEAR 13N25W TO 10M35W TO 07N40W.
SCATTERED MODERATE CONVECTION IS NOTED WITHIN 60 NM OF THE
MONSOON TROUGH AXIS BETWEEN 25N AND 28N AND BETWEEN 36W AND 38W.

...DISCUSSION...

GULF OF MEXICO...
A MID/UPPER LEVEL SHORT WAVE TROUGH IS MOVING
EASTWARD ACROSS THE NE GULF THIS MORNING...AHEAD OF A STRONG
IMPULSE MOVING THROUGH THE OHIO VALLEY AND ACROSS THE NE UNITED
STATES. THE COMBINED EFFECT WILL BE TO SUPPORT A WEAK COLD FRONT
MOVING SOUTH FROM THE NORTHERN GULF COAST INTO THE CENTRAL GULF
BY LATE TODAY. STRONG HIGH PRES BEHIND THE FRONT WILL ENERGIZE
NE TO E WINDS ACROSS THE GULF TODAY THROUGH EARLY NEXT WEEK. A
SCATTEROMETER PASS FROM AROUND 03 UTC INDICATED FRESH TO STRONG
NE TO E WINDS ALREADY IN PLACE OVER THE S CENTRAL GULF BETWEEN
THE APPROACHING HIGH PRES TO THE NORTH...AND THE NORTHERN
PORTION OF A TROPICAL WAVE MOVING INTO THE YUCATAN PENINSULA.
FUNNELING NORTHERLY FLOW IS ALREADY REACHING NEAR GALE FORCE
OVER THE FAR SW GULF...AND GALE WARNINGS HAVE BEEN POSTED FOR
LATER THIS MORNING OFF VERACRUZ. DEEP LAYER MOISTURE REMAINS
FAIRLY HIGH ACROSS THE SOUTHERN PORTIONS OF THE GULF THIS
MORNING...AND A FEW SHOWERS AND THUNDERSTORMS ARE NOTED ACROSS
PORTIONS OF THE SE GULF AND STRAITS OF FLORIDA. THIS MOISTURE
WILL SHIFT SLIGHTLY SOUTHWARD AHEAD OF THE ADVANCING DRIER
AIRMASS MOVING INTO THE AREA FROM THE NORTH THROUGH TONIGHT. THE
FRONT WILL STALL OVER THE FAR S CENTRAL AND SE GULF THROUGH LATE
MON AND REMAIN THE FOCUS OF SCATTERED CONVECTION THROUGH THAT
TIME.

CARIBBEAN SEA...

A BROAD UPPER LEVEL ANTICYCLONIC CIRCULATION INFLUENCES MUCH OF
THE WESTERN CARIBBEAN AND CENTRAL AMERICA THIS EVENING ANCHORED
OVER THE NW CARIBBEAN NEAR 17N86W. WHILE PROVIDING AN OVERALL
DIFFLUENT ENVIRONMENT ALOFT...THE MAIN SURFACE FEATURE IS A
TROPICAL WAVE MOVING INTO THE YUCATAN PENINSULA...BELIZE AND
GUATEMALA WITH A 1007 MB LOW CENTERED OVER SOUTHERN BELIZE ALONG
THE WAVE AXIS. WITH THE UPPER LEVEL DIFFLUENT ENVIRONMENT IN
PLACE...THE WAVE AND LOW PRES ARE GENERATING NUMEROUS SHOWERS
AND SCATTERED TSTMS OVER BELIZE AND THE GULF OF HONDURAS. A
SCATTEROMETER PASS FROM AROUND 03 UTC INDICATED FRESH TO STRONG
E FLOW ACROSS THE GULF OF HONDURAS AS WELL. OTHERWISE...THE
REMAINDER OF THE BASIN IS UNDER THE INFLUENCE OF RELATIVELY DRY
NORTHERLY FLOW ALOFT E OF 70W WITH ONLY A FEW ISOLATED SHOWERS
NOTED ACROSS THE LEEWARD ISLANDS ON THE EAST SIDE OF TUTT
ANCHORED ACROSS THE FAR EASTERN CARIBBEAN. OUTSIDE THE INFLUENCE
OF THE TROPICAL WAVE ALONG 87W...MODERATE TO FRESH BREEZE TRADES
ARE EXPECTED TO PERSIST THROUGH WEEKEND.

...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 STATIONARY FRONT IN PLACE FROM BERMUDA TO THE NW BAHAMAS FORMS
THE BOUNDARY BETWEEN DEEP LAYER MOISTURE TO THE SOUTH AND A A
DRIER AIRMASS OVER THE WATERS BETWEEN NE FLORIDA AND BERMUDA.
SCATTERED SHOWERS AND THUNDERSTORMS ARE NOTED ALONG AND TO THE
SOUTH OF THE STATIONARY FRONT...MAINLY OVER PORTIONS OF THE
SOUTHERN BAHAMAS AND TURKS/CAICOS AREA. THE FRONT WILL LOSE
DEFINITION THROUGH TODAY JUST AHEAD OF A REINFORCING COLD FRONT
THAT IS MOVING OFF THE CAROLINA COAST CURRENTLY. THE COLD FRONT
WILL SHIFT SOUTH AND MERGE WITH THE DYING STATIONARY FRONT
THROUGH EARLY NEXT WEEK. STRONG HIGH PRES BEHIND THE SECOND
FRONT WILL ALLOW NE TO E WINDS TO INCREASE OVER MUCH OF THE
REGION N OF 22N W OF 65W THROUGH SUNDAY. AN UPPER LOW IS
CENTERED NEAR 25N55W WITH A TROUGH REACHING ACROSS THE FAR
EASTERN CARIBBEAN TO NE VENEZUELA. SCATTERED SHOWERS AND
THUNDERSTORMS ARE NOTED NEAR THE CENTER OF THE UPPER LOW...FROM
20N TO 25N FROM 55W TO 60W...AND IN THE DIVERGENT AREA ALOFT SE
OF THE UPPER LOW FROM 18N TO 23N BETWEEN 50W AND 55W. A DRIER
MID LATITUDE AIR MASS COVERS THE SUBTROPICAL ATLC W OF 50W NORTH
OF DISSIPATING COLD FRONT EXTENDING FROM THE CANARY ISLANDS TO
20N22W THEN DISSIPATING TO 17.5N40W. SCATTERED MODERATE
CONVECTION IS NOTED ALONG THE MONSOON TROUGH SOUTH OF THIS
BOUNDARY...PARTICULARLY NEAR WEAK 1013 MB LOW PRES AT 13N27W.

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

$$
CHRISTENSEN
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