[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 131045
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SUN SEP 13 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
1015 UTC.

...TROPICAL WAVES...
TROPICAL WAVE EXTENDS FROM 10N32W TO 16N30W MOVING W AT 10-15
KT. THE WAVE COINCIDES WITH LOW AMPLITUDE 700 MB TROUGHING S OF
15N BETWEEN 28W-34W. SCATTERED MODERATE CONVECTION REMAINS
CONFINED TO THE MONSOON TROUGH REGION...DUE TO SAHARAN DUST ON
THE NORTHERN PERIPHERY OF THE WAVE AXIS...FROM 07N-14N BETWEEN
28W-36W.

TROPICAL WAVE EXTENDS FROM 11N53W TO 19N52W MOVING W AT 15-20
KT. THE WAVE COINCIDES WITH A BROAD 700 MB TROUGHING BETWEEN 49W-
57W. NO SIGNIFICANT CONVECTION IS OCCURRING WITH THE WAVE AT
THIS TIME.

TROPICAL WAVE EXTENDS FROM 11N73W TO 20N72W MOVING W AT 15 KT.
THE WAVE COINCIDES WITH A 700 MB TROUGHING BETWEEN 70W-75W AND A
850 MB RELATIVE VORTICITY MAXIMUM NEAR 20N72W. ISOLATED MODERATE
CONVECTION IS FROM 16N-22N BETWEEN 65W-72W.

TROPICAL WAVE EXTENDS FROM 09N87W TO 15N86W MOVING W AT 15-20
KT. THE WAVE COINCIDES WITH SUBTLE 700 MB TROUGHING OVER CENTRAL
AMERICA BETWEEN 84W-88W. WIDELY SCATTERED MODERATE CONVECTION IS
FROM 10N-17N BETWEEN 80W-92W.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 16N16W TO
09N29W TO 10N49W. SCATTERED MODERATE CONVECTION IS FROM 05N-08N
BETWEEN 10W-15W...FROM 09N-17N BETWEEN 15W-19W...AND FROM 07N-
13N BETWEEN 41W-47W. ISOLATED MODERATE CONVECTION IS ELSEWHERE
FROM 06N-16N BETWEEN 20W-50W.

...DISCUSSION...

GULF OF MEXICO...
LONGWAVE TROUGHING IS NOTED ON WATER VAPOR IMAGERY OVER MUCH OF
THE EASTERN CONUS THIS MORNING SUPPORTING A COLD FRONT EXTENDING
FROM THE FLORIDA BIG BEND REGION SW TO NEAR 26N94W. WHILE THIS
REMAINS THE PRIMARY BOUNDARY...A PRE-FRONTAL TROUGH EXTENDS FROM
THE FLORIDA BIG BEND REGION SW TO 27N85W WHERE THE LOW PRESSURE
VALUES ARE CURRENTLY ANALYZED. AS SURFACE RIDGING HAS BUILT IN
ACROSS EASTERN TEXAS AND EASTERN MEXICO...ANOTHER SURFACE TROUGH
IS ANALYZED OFFSHORE OF THE MEXICO COAST FROM 19N95W TO 25N97W.
MOST OF THE LOW-LEVEL MOISTURE CONVERGENCE...CLOUDINESS...AND
ONGOING SCATTERED SHOWERS AND TSTMS ARE OCCURRING WITHIN 210 NM
SOUTHEAST OF THE COLD FRONT...AND S OF 25N BETWEEN 94W-97W.
OTHERWISE...GENERALLY GENTLE TO MODERATE NE FLOW PREVAILS NORTH
OF THE COLD FRONT AND RELATIVELY VARIABLE GENTLE TO MODERATE
BREEZE CONDITIONS IN THE FRONTAL TROUGH ZONE AND ACROSS THE SE
GULF. THE MAJORITY OF THE FRONT WILL SLIDE INTO THE SW NORTH
ATLC REGION BY MONDAY WITH A DIFFUSE BOUNDARY EXTENDING ALONG
25N/26N THAT WILL GRADUALLY LIFT NORTH THROUGH TUESDAY.

CARIBBEAN SEA...
GENERALLY NORTHERLY FLOW ALOFT PREVAILS OVER MUCH OF THE WESTERN
CARIBBEAN THIS MORNING BETWEEN AN UPPER LEVEL RIDGE ANCHORED
OVER WEST-CENTRAL MEXICO AND AN UPPER LEVEL LOW CENTERED NEAR
17N69W. MOSTLY CLEAR SKIES AND FAIR CONDITIONS ARE NOTED ACROSS
THE NW CARIBBEAN...HOWEVER THE PRESENCE OF A TROPICAL WAVE ALONG
87W IMPACTING CENTRAL AMERICA IS GENERATING SCATTERED SHOWERS
AND TSTMS S OF 17N BETWEEN 80W-90W. THE WAVE IS EXPECTED TO
CONTINUE WESTWARD ON SUNDAY WITH PRECIPITATION AND CONVECTION
PERSISTING ACROSS NICARAGUA...HONDURAS...EL SALVADOR...AND
GUATEMALA UNTIL THE WAVE FULLY ENTERS THE EAST PACIFIC REGION.
FARTHER EAST...A TROPICAL WAVE ALONG 73W IS INTERACTING WITH THE
UPPER LEVEL LOW PREVIOUSLY MENTIONED AND CONTINUES TO GENERATE
ISOLATED SHOWERS AND TSTMS FROM 16N-22N BETWEEN 65W-74W. LOW-
LEVEL MOISTURE AND POSSIBLE ISOLATED SHOWER ACTIVITY STRETCHES
SE ACROSS THE LESSER ANTILLES AND INTO THE TROPICAL CENTRAL
ATLC. OTHERWISE...MODERATE TO FRESH TRADES PREVAIL AND ARE
EXPECTED TO INCREASE SLIGHTLY ACROSS THE CENTRAL CARIBBEAN WITH
THE APPROPRIATE  TROPICAL WAVE ON SUNDAY INTO MONDAY.

...HISPANIOLA...
CURRENTLY ISOLATED SHOWERS AND TSTMS ARE APPROACHING THE ISLAND
FROM THE EAST IN ASSOCIATION WITH A TROPICAL WAVE ALONG 72W. THE
OVERALL INCREASE IN MOISTURE AND CLOUDINESS WILL CONTINUE TO
PROVIDE A HIGHER PROBABILITY OF PRECIPITATION ON SUNDAY AS THE
WAVE CONTINUES TO MOVE WEST OF THE ISLAND BY LATE SUNDAY.

ATLANTIC OCEAN...
MIDDLE TO UPPER LEVEL ENERGY ASSOCIATED WITH LONGWAVE TROUGHING
OVER THE EASTERN CONUS IS SUPPORTING A FRONTAL BOUNDARY ANALYZED
ALONG THE EASTERN COAST AND FLORIDA PANHANDLE. PRE-FRONTAL
SURFACE TROUGHING ALSO EXTENDS FROM 28N80W SW TO 24N85W
PROVIDING FOCUS FOR SCATTERED SHOWERS AND TSTMS GENERALLY ACROSS
THE FLORIDA STRAITS E OF 80W. OTHERWISE...THE REMAINDER OF THE
SW NORTH ATLC IS UNDER THE INFLUENCE OF SURFACE RIDGING WITH
AXIS EXTENDING FROM A 1020 MB HIGH CENTERED NEAR 29N58W SW TO
THE CENTRAL CUBA COAST NEAR 23N79W. OTHERWISE...THE REMAINDER OF
THE CENTRAL AND EASTERN ATLC IS DOMINATED BY BROAD SURFACE
RIDGING ANCHORED BY A 1026 MB HIGH CENTERED WEST OF THE AZORES
NEAR 38N37W. A WEAK 1018 MB LOW IS EMBEDDED WITHIN THE SOUTHERN
PERIPHERY OF THE RIDGE CENTERED NEAR 30N42W THAT CONTINUES TO
GENERATE AN AREA OF SCATTERED SHOWERS AND ISOLATED TSTMS FROM
25N-33N BETWEEN 42W-49W.

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

$$
HUFFMAN
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