[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 091030
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT FRI AUG 09 2013

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
0952 UTC.

...TROPICAL WAVES...
A TROPICAL WAVE IS WEST OF THE CAPE VERDE ISLANDS WITH AXIS
EXTENDING FROM 21N33W TO 09N29W MOVING W NEAR 5 KT. METEOSAT
SATELLITE IMAGERY SHOW SAHARAN DRY AIR SPREADING OVER THE WAVE
ENVIRONMENT WHICH IS HINDERING CONVECTION.

A TROPICAL WAVE IS OVER THE WESTERN CARIBBEAN WITH AXIS
EXTENDING FROM 24N79W TO 11N79W MOVING W NEAR 5 KT. THE WAVE IS
EMBEDDED IN A LIGHT TO MODERATE MOIST ENVIRONMENT AS DEPICTED ON
TOTAL PRECIPITABLE WATER IMAGERY. AN UPPER LEVEL LOW CENTERED
NEAR 23N80W WHICH EXTENDS A TROUGH ACROSS THE WESTERN CARIBBEAN
SUPPORTS SCATTERED MODERATE CONVECTION AND TSTMS OVER CUBA AND
ADJACENT WATERS.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH AXIS EXTENDS FROM THE WEST AFRICAN COAST NEAR
13N16W TO 09N29W 07N40W. THE INTERTROPICAL CONVERGENCE ZONE AXIS
STARTS NEAR 07N40W AND CONTINUES ALONG 07N50W TO 07N58W.
SCATTERED MODERATE CONVECTION IS FROM 04N-10N BETWEEN 14W-20W AS
WELL AS FROM 05N-10N BETWEEN 21W-33W.

...DISCUSSION...

GULF OF MEXICO...
AS OF 0900 UTC...SURFACE TROUGHINESS AND ABUNDANT MOISTURE
CONTINUE TO DOMINATE ACROSS THE BASIN ASSOCIATED WITH A SURFACE
TROUGH WITH AXIS EXTENDING FROM 27N89W TO 18N91W. STRONG
NORTHEASTERLY WIND FLOW AROUND AN UPPER LEVEL RIDGE EXTENDING
ALONG THE EASTERN CONUS INTO THE GULF IS LIMITING CONVECTIVE
ACTIVITY ASSOCIATED WITH THE TROUGH TO ISOLATED RAINSHOWERS
WITHIN 100 NM EITHER SIDE OF ITS AXIS N OF 20N. OTHERWISE...FAIR
WEATHER IS W OF 95W AND E OF 87W FAVORED BY DRY AIR SUBSIDENCE
AND HIGH VALUES OF DEEP LAYER ENVIRONMENTAL WIND
SHEAR...RESPECTIVELY.

SURFACE RIDGING WILL START TO BUILD AGAIN ACROSS THE BASIN
STEERING THE SURFACE TROUGH TOWARDS THE SW GULF. THE TROUGH IS
EXPECTED TO ENTER SE MEXICO VERY EARLY ON SUNDAY. THE UPPER
LEVEL LOW CURRENTLY ENHANCING SHOWERS OVER THE BAHAMAS AND
WESTERN CARIBBEAN WILL ENTER THE SE GULF LATER TODAY AND IS
EXPECTED TO PERSIST OVER THE GULF WITHIN 48 HOURS...THUS
RAINSHOWERS ARE LIKELY DURING THIS PERIOD.

CARIBBEAN SEA...
A TROPICAL WAVE IS OVER THE WESTERN CARIBBEAN WITH AXIS
EXTENDING FROM 24N79W TO 11N79W. AN UPPER LEVEL LOW CENTERED
NEAR 23N80W WHICH EXTENDS A TROUGH ACROSS THE WESTERN CARIBBEAN
SUPPORTS SCATTERED MODERATE CONVECTION AND TSTMS OVER CUBA AND
ADJACENT WATERS N OF 18N W OF 78W. A SURFACE TROUGH EXTENDS FROM
THE DOMINICAN REPUBLIC NEAR 18N69W TO 11N70W. SCATTERED MODERATE
CONVECTION ASSOCIATED WITH THIS TROUGH IS FROM 16N-18N BETWEEN
66W-71W. CLUSTERS OF MODERATE CONVECTION WITH EMBEDDED TSTMS ARE
IN THE SOUTHERN BASIN S OF 13N E OF 81W ASSOCIATED WITH THE
MONSOON TROUGH AXIS WHICH MOVES ACROSS PANAMA TO A LOW CENTER
OVER NORTHERN COLOMBIA.

THE WAVE WILL CONTINUE TO MOVE WESTWARD AND IS EXPECTED TO BE
ALONG HONDURAS AND NICARAGUA BY SATURDAY MORNING. THE TRAILING
SURFACE TROUGH IS EXPECTED TO DISSIPATE FRIDAY
AFTERNOON...HOWEVER ANOTHER SURFACE TROUGH IS EXPECTED TO MOVE
ACROSS THE LESSER ANTILLES FRIDAY MORNING INCREASING THE CHANCES
OF PRECIPITATION FOR THIS PART OF THE BASIN.

HISPANIOLA...
A SURFACE TROUGH EXTENDS FROM THE DOMINICAN REPUBLIC NEAR 18N69W
TO 11N70W ENHANCING SCATTERED MODERATE CONVECTION OVER ITS
ADJACENT WATERS FROM 16N-18N BETWEEN 66W-71W. CONVECTION WILL
BUILD ACROSS THE ISLAND IN THE AFTERNOON/EARLY EVENING HOURS
ASSOCIATED WITH DAYTIME HEATING. WEATHER CONDITIONS ARE EXPECTED
TO IMPROVE EARLY ON SATURDAY DUE TO THE WESTWARD TRANSIT OF A
DRY AIRMASS.

ATLANTIC OCEAN...
AN UPPER LEVEL LOW CENTERED NEAR 23N80W WHICH EXTENDS A TROUGH
ACROSS THE WESTERN CARIBBEAN SUPPORTS LOW VALUES OF DEEP LAYER
ENVIRONMENTAL WIND SHEAR...THUS ENHANCING SCATTERED MODERATE
CONVECTION AND TSTMS OVER THE ADJACENT WATERS OF NORTHERN CUBA
AND THE BAHAMAS S OF 25N W OF 74W. A SURFACE TROUGH EXTENDS FROM
16N58W TO 09N56W WITH ISOLATED RAINSHOWERS WITHIN 100 NM EITHER
SIDE OF ITS AXIS FROM 13N-15N. OTHERWISE...BESIDES THE TROPICAL
WAVE ALREADY DISCUSSED...SURFACE RIDGING AND FAIR WEATHER
SUPPORTED BY LOWER-MIDDLE LEVELS DRY AIR DOMINATE THE REMAINDER
BASIN.

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

$$
NR


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