[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 060004
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT FRI JUL 05 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...TROPICAL WAVES...
A TROPICAL WAVE IS MOVING WEST NEAR 15 KT ACROSS THE EASTERN
ATLC. ITS AXIS EXTENDS FROM 20N32W TO 09N31W AND BOTH THE TOTAL
PRECIPITABLE WATER IMAGERY AS WELL AS THE METEOSAT-9 SAL
TRACKING PRODUCT INDICATE THE WAVE IS EMBEDDED IN A VERY DRY
ENVIRONMENT FROM THE LOWER TO THE MIDDLE LEVELS. THIS DRY AIR IS
INHIBITING CONVECTION OR RAINSHOWERS IN THE VICINITY OF THE WAVE
AXIS.

A TROPICAL WAVE IS MOVING W-NW NEAR 5 KT...TOWARDS THE EASTERN
CARIBBEAN. CURRENTLY ITS AXIS EXTENDS ALONG 18N46W TO 12N52W AND
IS EMBEDDED MAINLY WITHIN A MODERATE MOIST ENVIRONMENT. THERE IS
MINIMUM SAL DRY AIR INTERACTION WITH THIS WAVE AND SCATTERED
RAINSHOWERS ARE FROM 15N-17N BETWEEN 49W-51W.

A TROPICAL WAVE IS OVER THE FAR WESTERN CARIBBEAN MOVING W NEAR
10 KT. AS OF 2100 UTC THE AXIS OF THE WAVE IS ALONG 18N84W TO
09N81W AND EMBEDDED MAINLY IN A DRY ENVIRONMENT AT BOTH MIDDLE
AND LOWER LEVELS. THERE IS NO CONVECTION ASSOCIATED WITH THIS
WAVE AT THIS TIME.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE WEST AFRICAN COAST NEAR
17N16W TO 13N22W TO A 1011 MB LOW NEAR 07N27W TO 06N35W. THE
INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 06N35W TO
06N43W 04N50W. WIDELY SCATTERED MODERATE CONVECTION IS FROM 06N-
11N E OF 18W. A CLUSTER OF SCATTERED MODERATE CONVECTION IS
ASSOCIATED WITH THE AFOREMENTIONED LOW FROM 04N-08N BETWEEN 26W-
33W. ISOLATED MODERATE CONVECTION IS WITHIN 70 NM EITHER SIDE OF
THE ITCZ AXIS W OF 40W.

...DISCUSSION...

GULF OF MEXICO...
SURFACE TROUGHING DOMINATES THE WESTERN GULF W OF 90W WHILE
RETURN FLOW COVERS THE BASIN E OF THAT LONGITUDE. THE SURFACE
TROUGH EXTENDS FROM 29N90W SW TO A 1011 MB LOW NEAR 22N96W.
THESE SURFACE FEATURES ARE BEING SUPPORTED BY A NARROW UPPER
LEVEL TROUGH THAT EXTENDS FROM THE GREAT LAKES TO THE GULF N OF
23N W OF 90W. ABUNDANT MOISTURE ACROSS THE BASIN AS WELL AS
UPPER LEVEL DIFFLUENCE JUST EAST OF THE SURFACE TROUGH ARE
ENHANCING NUMEROUS MODERATE/ISOLATED STRONG CONVECTION WITH
EMBEDDED THUNDERSTORMS WITHIN 220 NM EAST OF THE AXIS. NUMEROUS
MODERATE CONVECTION WITH ISOLATED THUNDERSTORMS EXTEND TO THE NE
GULF N OF 25N.

BY EARLY SUNDAY...THE SURFACE TROUGHING IS EXPECTED TO DISSIPATE
AND RETURN FLOW WILL DOMINATE ACROSS THE BASIN. IN THE UPPER
LEVELS...THE RIDGE THAT HAS BEEN CAUSING DIFFLUENCE WILL
CONTINUE TO DRIFT W-NW WHICH COMBINED WITH ABUNDANT LOW LEVEL
MOISTURE WILL SUSTAIN PRECIPITATION ACTIVITY ACROSS MOST OF THE
BASIN.

CARIBBEAN SEA...
ABUNDANT LOWER LEVELS MOISTURE AND MIDDLE LEVEL DIFFLUENCE
CONTINUE TO ENHANCE RAINSHOWERS AND ISOLATED THUNDERSTORMS OVER
THE WESTERN CARIBBEAN N OF 17N W OF 75W...INCLUDING CUBA.
PATCHES OF LOW LEVEL MOISTURE HAS BEEN ENHANCING RAINSHOWERS
ACROSS THE LESSER ANTILLES WITHIN THE LAST COUPLE OF HOURS.
THESE SHOWERS CAN EXTEND S OF 16N E OF 67W. A WEAK TROPICAL WAVE
IS MOVING OFF THE WESTERN CARIBBEAN INTO CENTRAL AMERICA...AND
CURRENTLY THERE IS NO CONVECTIVE ACTIVITY ASSOCIATED WITH IT.
FOR THE MOST PART THE REST OF THE CARIBBEAN BASIN ENJOYS FAIR
WEATHER SUPPORTED BY VERY DRY AIR AT THE LOWER AND MIDDLE
LEVELS. OTHERWISE...TRADEWINDS IN THE RANGE OF 15-20 KT SPREAD
ACROSS THE BASIN WITH THE STRONGEST WINDS BEING ON THE CENTRAL
CARIBBEAN.

WEATHER CONDITIONS FOR THE WESTERN CARIBBEAN COULD IMPROVE EARLY
ON SUNDAY WHILE NO MAJOR CHANGES ARE EXPECTED FOR THE REST OF
THE BASIN. EARLY ON MONDAY A TROPICAL WAVE IS EXPECTED TO MOVE
ACROSS THE EASTERN CARIBBEAN.

HISPANIOLA...
CURRENTLY MODERATE LOW LEVEL MOISTURE IS ACROSS THE ISLAND WHICH
COMBINED WITH UPPER LEVEL DIFFLUENCE IS GENERATING A CLUSTER OF
MODERATE/ISOLATED STRONG CONVECTION WITH EMBEDDED THUNDERSTORMS
OVER HAITI. OVER THE REST OF THE ISLAND...ISOLATED SHOWERS AND
TSTMS ARE POSSIBLE. EXCEPT FOR AFTERNOON SHOWERS DUE TO DAYTIME
HEATING AND INSTABILITY...FAIR WEATHER MUST SET DURING SATURDAY
AND SUNDAY.

ATLANTIC OCEAN...
BESIDES THE TROPICAL WAVES ALREADY MENTIONED ABOVE...BROAD
SURFACE RIDGING COVERS THE ATLC WATERS ANCHORED BY A 1028 MB
HIGH NEAR 34N70W AND ANOTHER HIGH NE OF THE AREA.
OTHERWISE...TOTAL PRECIPITABLE WATER IMAGERY SHOW VERY DRY AIR
ACROSS THE REMAINDER REGION AT THE LOWER LEVELS WHICH IS
ASSISTING IN SUPPRESSING CONVECTIVE ACTIVITY.

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

$$
NR

This weather bulletin was brought to you by:
www.nashvilleweather.net