[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 071052
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT WED AUG 07 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
1022 UTC.

...TROPICAL WAVES...
A TROPICAL WAVE HAS COME OFF THE AFRICAN COAST WITH AXIS
EXTENDING FROM 20N17W TO 06N17W. THE WAVE IS EMBEDDED WITHIN A
HIGH MOIST ENVIRONMENT AS DEPICTED IN TOTAL PRECIPITABLE WATER
IMAGERY AND SCATTERED MODERATE CONVECTION IS FROM 07N-15N E OF
20W. THE METEOSAT-9 SAL TRACKING IMAGERY SHOW DRY AIR ENGULFING
THE WAVE N OF 15N WITHIN 200 NM OF THE AXIS.

A TROPICAL WAVE IS OVER THE E CARIBBEAN WITH AXIS EXTENDING FROM
21N65W TO 10N65W MOVING W NEAR 10 KT. TOTAL PRECIPITABLE WATER
IMAGERY DEPICT A DRY ENVIRONMENT AHEAD OF IT S OF 18N WHILE
MODERATE MOISTURE LIES BEHIND ITS AXIS. DRY AIR SUBSIDENCE AS
WELL AS STRONG DEEP LAYER WIND SHEAR ARE HINDERING CONVECTION IN
THE GULF WATERS...HOWEVER RAINSHOWERS ARE OCCURRING ACROSS
NORTHERN PUERTO RICO AND ADJACENT WATERS OFF THE NORTHERN COAST.

...THE ITCZ/THE MONSOON TROUGH...
THE MONSOON TROUGH AXIS EXTENDS FROM THE WEST AFRICAN COAST NEAR
15N16W TO 09N25W 06N36W. THE INTERTROPICAL CONVERGENCE ZONE AXIS
STARTS NEAR 06N36W AND CONTINUES ALONG 07N42W TO 09N47W. BESIDES
THE CONVECTION ASSOCIATED WITH THE WAVE COMING OFF THE W AFRICAN
COAST ALREADY DISCUSSED...A CLUSTER OF MODERATE CONVECTION IS
FROM 07N-11N BETWEEN 25W-29W. OTHERWISE...ISOLATED SHOWERS ARE
WITHIN 100 NM EITHER SIDE OF THE AXES BETWEEN 30W-45W.

...DISCUSSION...

THE GULF OF MEXICO...
AS OF 0900 UTC...ANTICYCLONIC FLOW IN THE RANGE OF 5-15 KT
SPREADS ACROSS THE BASIN W OF 86W ANCHORED BY A 1015 MB HIGH
NEAR 26N91W WHICH IS BEING SUPPORTED BY A BROAD MIDDLE TO UPPER
LEVEL RIDGE CENTERED OVER TEXAS. A COLD FRONT EXTENDS FROM A
1012 MB LOW IN THE FLORIDA PANHANDLE TO 30N86W 29N87W 30N88W. A
SURFACE TROUGH EXTENDS FROM THE SAME LOW TO ANOTHER 1012 MB LOW
JUST WEST OF TAMPA TO 25N82W 23N82W...ACROSS WESTERN CUBA TO
21N83W IN THE W CARIBBEAN. ISOLATED SHOWERS ARE OVER THE EASTERN
GULF E OF 86W ASSOCIATED WITH THIS FRONTAL SYSTEM.
OTHERWISE...DRY AIR SUBSIDENCE IS SUPPORTING FAIR WEATHER OVER
THE WESTERN GULF.

THE CENTER OF HIGH PRESSURE IS EXPECTED TO DRIFT NW AND THEN
DISSIPATE EARLY ON THURSDAY. THE SURFACE TROUGH THAT EXTENDS
OVER THE SE GULF IS EXPECTED TO DRIFT WESTWARD AND MOVE TO THE
PENINSULA OF YUCATAN THURSDAY NIGHT. RAINSHOWERS ARE LIKELY TO
CONTINUE OVER THE EASTERN GULF.

THE CARIBBEAN SEA...
AS DEPICTED IN TOTAL PRECIPITABLE WATER AND WATER VAPOR
IMAGERY...DRY AIR SPREADS ACROSS THE BASIN MAINLY S OF 18N
PROVIDING A STABLE...CONVECTION FREE ENVIRONMENT. N OF 18 N...A
MODERATE MOIST ENVIRONMENT AND UPPER LEVEL DIFFLUENCE FROM A
BROAD RIDGE EXTENDING TO THE W CARIBBEAN AND A LOW CENTERED N OF
THE HISPANIOLA ARE ENHANCING SCATTERED MODERATE CONVECTION AND
TSTMS OVER THE WINDWARD PASSAGE AS WELL AS BETWEEN SE CUBA AND
JAMAICA. ISOLATED SHOWERS ARE OCCURRING WITHIN 180 NM OFF THE
SOUTHERN COAST OF CUBA W OF 79W ASSOCIATED WITH THE SURFACE
TROUGH THAT EXTENDS FROM THE EASTERN GULF TO THE W CARIBBEAN. A
TROPICAL WAVE IS MOVING ACROSS THE EASTERN CARIBBEAN WITH AXIS
CURRENTLY MOVING ACROSS EASTERN PUERTO RICO GENERATING SCATTERED
RAINSHOWERS ACROSS THE ISLAND AND NORTHERN ADJACENT WATERS. A
SURFACE TROUGH ASSOCIATED WITH A 1011 MB LOW NEAR 13N60W IS
GENERATING A CLUSTER OF MODERATE CONVECTION AND TSTMS OVER THE
LESSER ANTILLES FROM 12N-15N BETWEEN 60W-63W. THE VIRGIN ISLANDS
REPORTED RAINSHOWERS WITHIN THE LAST HOUR ASSOCIATED WITH THE
PASSAGE OF THIS WAVE. TRADEWINDS UP TO 20 KT ARE OVER THE
CENTRAL-SOUTHERN CARIBBEAN NEAR THE COAST OF COLOMBIA WHILE
WINDS OF 5-15 KT DOMINATE ELSEWHERE IN THE BASIN. ISOLATED
MODERATE CONVECTION IS S OF 10N ASSOCIATED WITH THE MONSOON
TROUGH AXIS.

WINDS OVER THE CENTRAL-SOUTHERN CARIBBEAN ARE EXPECTED TO
SUBSIDE TO 15 KT WEDNESDAY AFTERNOON. RAINSHOWERS ACTIVITY IS
EXPECTED FOR THE GREATER ANTILLES AND ADJACENT WATERS DURING THE
NEXT 48 HOURS...ASSOCIATED WITH THE WESTWARD PASSAGE OF THE
TROPICAL WAVE AS WELL AS A FAVORABLE UPPER LEVEL SYNOPTIC
PATTERN.

HISPANIOLA...
THE UPPER LEVEL LOW FORMERLY ASSISTING IN GENERATING CONVECTIVE
ACTIVITY ACROSS THE ISLAND HAS DRIFTED WESTWARD JUST N OF THE
WINDWARD PASSAGE WHERE UPPER LEVEL DIFFLUENCE IS SUPPORTING
SCATTERED MODERATE CONVECTION AND TSTMS. RAINSHOWERS ARE
EXPECTED FOR THE ISLAND AND ADJACENT WATERS DURING THE NEXT 48
HOURS...ASSOCIATED WITH THE WESTWARD PASSAGE OF A TROPICAL WAVE
AS WELL AS A FAVORABLE UPPER LEVEL SYNOPTIC PATTERN.

THE ATLANTIC OCEAN...
AS OF 0900 UTC...A SURFACE TROUGH FORMERLY PART OF THE TROPICAL
WAVE AXIS IN THE E CARIBBEAN IS MOVING W-NW AROUND THE PERIPHERY
OF A RIDGE WITH AXIS EXTENDING FROM 30N60W TO 22N70W. SCATTERED
MODERATE CONVECTION ASSOCIATED WITH THIS TROUGHINESS IS FROM 23N-
32N BETWEEN 58W-67W. A SURFACE TROUGH ASSOCIATED WITH A 1011 MB
LOW NEAR 13N60W IS GENERATING A CLUSTER OF MODERATE CONVECTION
AND TSTMS OVER THE LESSER ANTILLES FROM 12N-15N BETWEEN 60W-63W.
ANOTHER SURFACE TROUGH EXTENDS FROM 14N49W TO 09N51W WITH
ISOLATED MODERATE CONVECTION WITHIN 150 NM EITHER SIDE OF THE
AXIS N OF 11N. OTHERWISE...SURFACE RIDGING AND FAIR WEATHER
SUPPORTED BY LOWER-MIDDLE LEVEL DRY AIR DOMINATE THE REMAINDER
BASIN.

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

$$
RAMOS

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