[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 171048
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0900 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 14N38W TO 07N37W 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.

TROPICAL WAVE EXTENDS FROM 16N51W TO 08N48W MOVING W AT 10 TO 15
KT. AN EARLIER SCATTEROMETER PASS INDICATED SURFACE TROUGH
RELATED TO THIS WAVE NEAR. 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. SCATTERED MODERATE
CONVECTION IS NOTED E OF THE WAVE AXIS...FROM 10N TO 13N BETWEEN
45W AND 50W.

TROPICAL WAVE EXTENDS FROM 21N89W IN THE N CENTRAL YUCATAN
PENINSULA TO 1008 MB LOW PRES NEAR 17N89W OVER SOUTHERN BELIZE.
THE WAVE IS MOVING W AT 10-15 KT AND COINCIDES WITH A FAIRLY
BROAD AND ELONGATED 700 MB TROUGH ANCHORED OVER THE EAST PACIFIC
WATERS SOUTH OF GUATEMALA AND SOUTHERN MEXICO FOCUSED ON THE LOW
PRES OVER SOUTHERN BELIZE. SCATTERED MODERATE TO STRONG
CONVECTION IS OCCURRING OVER NORTHERN BELIZE AND SOUTHERN
QUINTANA ROO...AS WELL AS FROM 17N TO 20N W OF 85W. SCATTERED
MODERATE CONVECTION IS ALSO NOTED FROM 19N TO 17N BETWEEN 78W
AND 83W.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH AXIS EXTENDS FROM A 1010 MB LOW NEAR 13N27W
TO 06N42W. SCATTERED MODERATE CONVECTION IS NOTED WITHIN 60 NM
OF THE MONSOON TROUGH AXIS BETWEEN 36N AND 38N. SCATTERED
MODERATE CONVECTION IS ALSO NOTED WITHIN 120 NM NE QUADRANT OF
THE LOW PRES CENTERED NEAR 13N27W.

...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
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 1008 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 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
This weather bulletin was brought to you by:
www.nashvilleweather.net