[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 080004
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN SEP 07 2014

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
2345 UTC.

...SPECIAL FEATURES...

A TROPICAL WAVE ASSOCIATED WITH A 1009 MB LOW IS OVER THE FAR
EASTERN ATLC. ITS AXIS EXTENDS FROM 18N17W TO THE LOW CENTER
NEAR 9N17W FORECAST TO MOVE WESTWARD AT 15 KT WITHIN THE NEXT 24
HOURS. THE WAVE IS ASSOCIATED WITH HIGH MOISTURE IN THE MIDDLE
TO LOWER LEVELS AS DEPICTED IN SSMI TPW IMAGERY SHOW WITH
PATCHES OF HIGH MOISTURE REACHING THE MIDDLE TO UPPER LEVELS
OBSERVED IN WATER VAPOR IMAGERY. CYCLONIC RAINBANDS OF SCATTERED
MODERATE CONVECTION AND ISOLATED TSTMS ARE FROM 5N-14N E OF
23W...BEING SUPPORTED BY THE AFOREMENTIONED MOISTURE AND UPPER-
LEVEL DIFFLUENCE. THERE IS A MEDIUM CHANCE OF TROPICAL CYCLONE
FORMATION ASSOCIATED WITH THIS SYSTEM WITHIN THE NEXT TWO DAYS.
SEE LATEST NHC TROPICAL WEATHER OUTLOOK UNDER AWIPS/WMO HEADERS
MIATWOAT/ABNT20 KNHC FOR MORE DETAILS.

...TROPICAL WAVES...

A TROPICAL WAVE IS ON THE CENTRAL ATLC WITH AXIS EXTENDING FROM
21N37W TO A 1012 MB LOW NEAR 15N36W TO 11N34W...MOVING WEST AT
10 KT. THIS WAVE IS BEING SUPPORTED BY AN INVERTED TROUGH IN THE
MIDDLE TO UPPER LEVELS. HOWEVER...MOISTURE IN THE MIDDLE TO
UPPER LEVELS HAS DECREASED DUE TO THE INTRUSION OF SAHARAN DRY
AIR AND DUST IN ITS ENVIRONMENT. STRONG DEEP LAYER ENVIRONMENTAL
SW WIND SHEAR IN THE VICINITY OF THE WAVE IS KEEPING THE
REMAINING CONVECTION WELL-SEPARATED FROM THE LOW CENTER.

A TROPICAL WAVE IS ON THE CENTRAL CARIBBEAN WITH AXIS EXTENDING
FROM 20N71W TO 10N73W...MOVING W AT 20-25 KT. A BROAD MIDDLE-
LEVEL INVERTED TROUGH IN THE CARIBBEAN SUPPORT THIS WAVE. DEEP
LAYER MOISTURE IN THE NORTHERN CARIBBEAN ALONG WITH UPPER-LEVEL
DIFFLUENCE ACROSS THE CENTRAL BASIN SUPPORT SCATTERED MODERATE
CONVECTION AND TSTMS FROM 14N-22N BETWEEN 64W-73W.

A TROPICAL WAVE IS MOVING ACROSS THE YUCATAN PENINSULA WITH AXIS
EXTENDING FROM 22N87W TO 13N90W WITH A WESTWARD TRANSLATION
SPEED OF 20-25 KT. A MIDDLE-LEVEL INVERTED TROUGH ON THE S-SW
GULF OF MEXICO SUPPORT THE WAVE. DEEP LAYER MOISTURE ACROSS THE
REGION ALONG WITH UPPER LEVEL DIFFLUENCE GENERATED BY AN
ELONGATED RIDGE ANCHORED OVER NORTHERN CENTRAL AMERICA ENHANCE
SCATTERED MODERATE CONVECTION AND TSTMS S OF 23N BETWEEN 84W-92W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM 9N19W AND CONTINUES ALONG 13N30W
TO 7N39W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM
7N40W TO 6N49W. NO SIGNIFICANT DEEP CONVECTION IS OCCURRING
OUTSIDE OF CONVECTION ASSOCIATED WITH THE TROPICAL WAVES
MENTIONED ABOVE.

...DISCUSSION...

GULF OF MEXICO...

A MIDDLE-LEVEL INVERTED TROUGH IS OVER THE S-SW GULF SUPPORTING
A TROPICAL WAVE MOVING ACROSS THE YUCATAN PENINSULA TONIGHT. SEE
THE TROPICAL WAVES SECTION FOR MORE DETAILS. IN THE UPPER-
LEVELS...TROUGHING FROM AN ELONGATED LOW OVER SW MEXICO COVERS
THE WESTERN BASIN. TROUGHINESS ALOFT ALSO SUPPORT A SURFACE
TROUGH ALONG 23N97W TO 17N95W...WHICH ENHANCES SCATTERED SHOWERS
AND TSTMS S OF 23N W OF 92W. A TROUGH OF LOW PRESSURE IS ALONG
THE FLORIDA PENINSULA FROM 30N81W TO 25N81W. LOW-LEVEL MOISTURE
CONVERGENCE ALONG MIDDLE-LEVEL DIVERGENCE IN THE REGION SUPPORT
SCATTERED SHOWERS AND ISOLATED TSTMS ACROSS MOST OF THE
PENINSULA AND THE FLORIDA KEYS. OTHERWISE SHOWERS AND TSTMS ARE
WITHIN 20 NM OFF THE NW GULF COASTLINE ASSOCIATED WITH A
STATIONARY FRONT EXTENDING FROM THE SE CONUS SW TO SOUTHERN
TEXAS. THE TROPICAL WAVE WILL BE MOVING ACROSS THE SW GULF MONDAY
AND IS FORECAST TO MOVE TO E PAC WATERS BY EARLY TUE. LOW
PRESSURE WILL DOMINATE ACROSS THE GULF THROUGH TUE.

CARIBBEAN SEA...

A MIDDLE-LEVEL INVERTED TROUGH DOMINATES THE BASIN TONIGHT WHICH
ALONG WITH ABUNDANT MOISTURE PROVIDE A VERY UNSTABLE ENVIRONMENT
ACROSS MUCH OF THE CARIBBEAN. THIS TROUGHINESS ALOFT IS
SUPPORTING A TROPICAL WAVE MOVING ACROSS THE CENTRAL BASIN. SEE THE
TROPICAL WAVES SECTION FOR MORE DETAILS. ON THE NW BASIN...THE
PASSAGE OF A TROPICAL WAVE CURRENTLY MOVING ACROSS THE YUCATAN
PENINSULA CONTINUE TO ENHANCE SCATTERED SHOWERS AND TSTMS N OF
16N WEST OF 74W. ON THE UPPER-LEVELS...A CYCLONIC CIRCULATION
ANCHORED ON THE CENTRAL BAHAMAS EXTENDS A TROUGH SE ACROSS THE
CENTRAL AND EASTERN CARIBBEAN GENERATING A DIFFLUENT ENVIRONMENT
THAT SUPPORT THE CONVECTION OF THE AFOREMENTIONED TROPICAL
WAVE...WHICH EXTENDS FROM HISPANIOLA TO PUERTO RICO AND NORTHERN
ADJACENT WATERS. ON THE SW CARIBBEAN...THE MONSOON TROUGH
CROSSES FROM COSTA RICA TO NORTHERN COLOMBIA AND ENHANCES
SCATTERED SHOWERS AND TSTMS S OF 12N. TRADES OF 20-25 KT ARE ON
THE CENTRAL BASIN ASSOCIATED WITH THE PASSAGE OF THE TROPICAL WAVE.
TRADES OF 15 KT DOMINATE ELSEWHERE. THE TROPICAL WAVE IS EXPECTED
TO MOVE WESTWARD AND OUT OF THE BASIN BY TUE NIGHT.

...HISPANIOLA...

CURRENTLY HISPANIOLA IS INFLUENCED BY UPPER LEVEL WEST-
NORTHWESTERLY WINDS ALOFT THAT TRANSITION TO MORE DIFFLUENT FLOW
E OF 71W. WITH AN UPPER LEVEL LOW CENTERED OVER THE SW NORTH
ATLC TO THE NORTH OF THE ISLAND NEAR 23N74W... MOISTURE AND
CLOUDINESS CONTINUES TO ADVECT ACROSS THE ISLAND. IN
ADDITION...A TROPICAL WAVE SUPPORTED BY A MIDDLE-LEVEL INVERTED
TROUGH ENHANCES SCATTERED MODERATE CONVECTION AND TSTMS ACROSS
WESTERN DOMINICAN REPUBLIC AND HAITI AND ADJACENT NORTHERN
WATERS. RAINSHOWERS ARE EXPECTED ACROSS MUCH OF THE ISLAND
THROUGH TUE MORNING.

ATLANTIC OCEAN...

AN UPPER-LEVEL LOW IS ANCHORED OVER THE CENTRAL BAHAMAS
SUPPORTING SCATTERED MODERATE CONVECTION AND TSTMS S OF 26N
BETWEEN 64W-78W. FARTHER EAST...A BROAD MIDDLE TO UPPER LOW
SUPPORT A PAIR OF 1017 MB SURFACE LOW PRESSURE CENTERS...ONE
NEAR 29N55W AND OTHER NEAR 28N49W...THE LATER DISSIPATING BY
TOMORROW AFTERNOON. ON THE EASTERN ATLC...SURFACE RIDGING
DOMINATE BEING ANCHORED BY A 1020 MB HIGH NEAR 27N34W.
OTHERWISE...SEE THE TROPICAL WAVES SECTION ABOVE.

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

$$
NR


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