[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 172350
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 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 09N37W TO 14N36W MOVING W AT 5-10 KT.
THE WAVE COINCIDES WITH 700 MB TROUGHING BETWEEN 35W-43W. A WEAK
1012 MB CENTERED AT THE INTERSECTION OF THE SOUTHERN EXTENT OF
THE WAVE AXIS AND THE MONSOON TROUGH INDICATES THE MAXIMUM LOW-
LEVEL CYCLONIC ENERGY GENERATING SCATTERED MODERATE CONVECTION
WITHIN 120 NM OF THE LOW CENTER.

TROPICAL WAVE EXTENDS FROM 09N50W TO 17N53W MOVING W AT 5-10 KT.
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 SHEARING MOST ONGOING
CONVECTION TO THE EAST. ISOLATED MODERATE CONVECTION IS FROM 09N-
17N BETWEEN 45W-53W.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH AXIS EXTENDS FROM THE AFRICAN COAST NEAR
11N16W TO 08N20W TO 08N25W...THEN RESUMES IN THE VICINITY OF A
1012 MB LOW NEAR 13N27W TO A 1012 MB LOW NEAR 09N37W TO 08N41W.
ISOLATED MODERATE CONVECTION IS FROM 03N-10N BETWEEN 15W-
29W...AND FROM 13N-20N BETWEEN 17W-25W.

...DISCUSSION...

GULF OF MEXICO...
BROAD LONGWAVE TROUGHING IS NOTED ON WATER VAPOR IMAGERY OVER
THE EASTERN CONUS AND THE FAR WESTERN NORTH ATLC WATERS. THE
TROUGHING SUPPORTS A PAIR OF FRONTAL BOUNDARIES ANALYZED ACROSS
THE GULF THIS EVENING. FIRST...A STATIONARY FRONT EXTENDS FROM
THE FLORIDA STRAITS NEAR 25N80W WESTWARD TO 24N92W AND PROVIDES
LOW-LEVEL MOISTURE CONVERGENCE ACROSS THE SOUTHERN GULF FOR
SCATTERED SHOWERS AND ISOLATED TSTMS OCCURRING MOSTLY S OF THE
BOUNDARY ALONG 25N. ACROSS THE SW GULF...THE ADDITION OF A
SURFACE TROUGH IN THE VICINITY OF 21N96W IS ALSO GENERATING
SCATTERED SHOWERS AND ISOLATED TSTMS ALONG WITH NEAR GALE TO
GALE FORCE NW WINDS WEST OF THE BOUNDARY OFF THE COAST OF
VERACRUZ. THE SECOND FRONT IS ANALYZED AS A COLD FRONT FROM
29N83W WESTWARD TO THE TEXAS COAST NEAR 28N97W. WHILE THE FRONT
REMAINS NEARLY PRECIPITATION-FREE AT THIS TIME...SHIP...BUOY...
AND OFFSHORE OIL PLATFORM OBSERVATIONS INDICATE A COOLER AND
DRIER AIRMASS IN WAKE OF THE FRONT WHICH IS EXPECTED TO BECOME
STATIONARY OVERNIGHT AND BEGIN GRADUALLY SLIDING SOUTHEASTWARD
AGAIN ON SUNDAY. AS STRONG HIGH PRESSURE CONTINUES TO BUILD IN
NORTH OF THE COLD FRONT AND THE PRESSURE GRADIENT ACROSS THE
BASIN STRENGTHENS...STRONG NE WINDS ARE EXPECTED TO PERSIST
THROUGH MONDAY.

CARIBBEAN SEA...
A BROAD UPPER LEVEL ANTICYCLONIC CIRCULATION INFLUENCES MUCH OF
THE WESTERN CARIBBEAN AND CENTRAL AMERICA THIS EVENING 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
FROM 10N-23N WEST OF 78W...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 EARLY NEXT WEEK.

...HISPANIOLA...
CURRENTLY A FEW ISOLATED SHOWERS AND TSTMS LINGER ACROSS THE
ISLAND DUE TO A RELATIVELY DIFFLUENT ENVIRONMENT ALOFT AND PEAK
DAYTIME HEATING. THIS ACTIVITY SHOULD DIMINISH GRADUALLY THROUGH
THE OVERNIGHT HOURS LEAVING ONLY ISOLATED...SHALLOW...AND
WESTWARD MOVING LOW-LEVEL SHOWERS INTO EARLY SUNDAY.

ATLANTIC OCEAN...
A STATIONARY FRONT REMAINS IN PLACE FROM 31N69W SW TO THE
FLORIDA STRAITS NEAR 25N80W AND DELINEATES A DIFFERENCE IN
AIRMASSES...DEEP LAYER MOISTURE TO THE SOUTH AND DRIER COOLER
AIR ACROSS THE SW NORTH ATLC WATERS AND FLORIDA PENINSULA TO THE
NORTH AND WEST. SCATTERED SHOWERS AND ISOLATED TSTMS ARE
OCCURRING GENERALLY WITHIN 300 NM SOUTHEAST OF THE FRONT. TO THE
NW...A REINFORCING COLD FRONT EXTENDS FROM 32N77W TO THE FLORIDA
PENINSULA NEAR DAYTONA BEACH. THESE TWO BOUNDARIES ARE EXPECTED
TO MERGE LATE SUNDAY NIGHT INTO EARLY MONDAY. FARTHER EAST...A
SURFACE TROUGH EXTENDS NORTH OF A TROPICAL WAVE FROM 19N54W TO
23N53W AND IS INTERACTING WITH AN UPPER LOW CENTERED NEAR
21N57W. SCATTERED SHOWERS AND TSTMS ARE OCCURRING FROM 19N-26N
BETWEEN 51W-59W. OTHERWISE...THE SUBTROPICAL HIGH REMAINS
ANCHORED IN THE CENTRAL ATLC AT 1025 MB NEAR 33N43W. FINALLY...A
VIGOROUS UPPER LEVEL LOW CENTERED NEAR 39N15W SUPPORTS A
DISSIPATING COLD FRONT EXTENDING ACROSS NW AFRICA FROM 32N06W TO
23N16W TO 16N30W WHERE IT BECOMES A SHEAR LINE TO 16N38W TO
19N49W. ISOLATED SHOWERS ARE OCCURRING WITHIN 60 NM EITHER SIDE
OF THE BOUNDARY.

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

$$
HUFFMAN
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