[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 200604
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT FRI SEP 20 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...SPECIAL FEATURES...
A 1006 MB LOW CENTER IS IN THE BAY OF CAMPECHE NEAR 21N95W. THIS
AREA OF LOW PRESSURE IS WITHIN A ZONE OF VERY MOIST AIR AS
DEPICTED IN TOTAL PRECIPITABLE WATER IMAGERY. HOWEVER...STRONG
NORTHWESTERLY WIND SHEAR IN THE VICINITY OF THE LOW IS HINDERING
IN PART CONVECTIVE ACTIVITY. MIDDLE-LEVEL DIFFLUENCE WEST OF THE
LOW CENTER IS SUPPORTING SCATTERED MODERATE/ISOLATED STRONG
CONVECTION AND TSTMS INLAND SOUTHERN AND EASTERN MEXICO.
ENVIRONMENTAL CONDITIONS ARE ONLY MARGINALLY CONDUCIVE AND
SIGNIFICANT DEVELOPMENT OF THIS SYSTEM IS BECOMING LESS LIKELY
THUS GIVING IT A MEDIUM CHANCE OF BECOMING A TROPICAL CYCLONE
DURING THE NEXT 48 HOURS. THIS DISTURBANCE WILL CONTINUE TO
PRODUCE LOCALLY HEAVY RAINS OVER PORTIONS OF EASTERN AND
SOUTHERN MEXICO DURING THE NEXT FEW DAYS.

...TROPICAL WAVES...
THE AXIS OF A TROPICAL WAVE EXTENDS ALONG 23N31W TO 13N32W AND
IS MOVING W NEAR 10 KNOTS. TOTAL PRECIPITABLE WATER IMAGERY SHOW
MOST OF THE WAVE ENVIRONMENT HAS BEEN UNDERCUT BY VERY DRY AIR
WHICH IS LIMITING CONVECTION. SCATTERED MODERATE CONVECTION IS
NW OF THE WAVE AXIS FROM 20N-23N BETWEEN 31W-34W AND SE OF THE
AXIS FROM 12N-15N BETWEEN 28W-32W. THESE AREAS OF CONVECTION
COINCIDE WITH SMALL SECTORS OF VERY MOIST AIR IN TOTAL
PRECIPITABLE WATER IMAGERY.

...THE ITCZ/THE MONSOON TROUGH...
THE MONSOON TROUGH PASSES THROUGH COASTAL WEST AFRICA NEAR
11N15W TO 11N30W 08N37W. THE ITCZ CONTINUES FROM 08N38W TO
09N46W. A SQUALL LINE OF MODERATE TO ISOLATED STRONG CONVECTION
IS FROM 08N-13N BETWEEN 16W-19W. BESIDES THE CONVECTION
ASSOCIATED WITH THE TROPICAL WAVE...SCATTERED MODERATE CONVECTION
IS FROM 07N-12N BETWEEN 27W-36W AND FROM 06N-09N BETWEEN 38W-42W.

...DISCUSSION...

GULF OF MEXICO...
A VERY MOIST ENVIRONMENT AT THE LOWER LEVELS DOMINATE THE
WESTERN GULF WATERS AS DEPICTED IN IMAGERY OF TOTAL PRECIPITABLE
WATER. HOWEVER...STRONG NORTHWESTERLY WIND SHEAR ACROSS GREAT
PORTIONS OF THE BASIN INHIBITS IN PART CONVECTIVE ACTIVITY THIS
MORNING. A 1006 MB LOW CENTER IS IN THE BAY OF CAMPECHE NEAR
21N95W.  MIDDLE-LEVEL DIFFLUENCE WEST OF THE LOW CENTER IS
SUPPORTING SCATTERED MODERATE/ISOLATED STRONG CONVECTION AND
TSTMS INLAND SOUTHERN AND EASTERN MEXICO. THE CONVECTION OVER
SOUTHERN MEXICO EXTENDS OFFSHORE TO THE BAY OF CAMPECHE S OF 20N
BETWEEN 92W-96W. SEE THE SPECIAL FEATURES SECTION FOR MORE
INFORMATION ABOUT THIS DISTURBANCE. SCATTERED SHOWERS ARE NW OF
THE BASIN N OF 25N BETWEEN 92W-96W. AN UPPER-LEVEL TROUGH
EXTENDS ACROSS THE FLORIDA PENINSULA AND THE STRAITS SUPPORTING
ISOLATED SHOWERS OVER THE EASTERN GULF S OF 29N E OF 85W.

THE DISTURBANCE IN THE SW GULF HAS A MEDIUM CHANCE OF BECOMING A
TROPICAL CYCLONE DURING THE NEXT 48 HOURS. THIS SYSTEM WILL
CONTINUE TO PRODUCE LOCALLY HEAVY RAINS OVER PORTIONS OF EASTERN
AND SOUTHERN MEXICO DURING THE NEXT FEW DAYS. A COLD FRONT IS
EXPECTED TO ENTER THE NORTHERN GULF WATERS BY SATURDAY
AFTERNOON.

CARIBBEAN SEA...
TOTAL PRECIPITABLE WATER IMAGERY SHOW A REDUCTION IN MOISTURE
ACROSS GREAT PORTIONS OF THE BASIN THIS MORNING. MIDDLE LEVEL
DIFFLUENT FLOW IN THE NW CARIBBEAN BASIN ENHANCES SCATTERED
SHOWERS N OF 15N W OF 78W. HOWEVER...UPPER-LEVEL DIFFLUENCE FROM
THE TROUGH OVER THE N WESTERN ATLC AND A RIDGE COVERING WESTERN-
CENTRAL CARIBBEAN SEA SUPPORTS SCATTERED MODERATE CONVECTION
OVER THE WINDWARD PASSAGE AND HISPANIOLA. ISOLATED SHOWERS ARE
ELSEWHERE IN THE BASIN...EXCEPT BETWEEN 66W-71W WHERE FAIR
WEATHER DOMINATES. A SURFACE TROUGH IS EXPECTED TO ENTER THE
EASTERN CARIBBEAN SEA EARLY SUNDAY AFTERNOON GENERATING SHOWERS
POSSIBLY AFFECTING THE LESSER ANTILLES.

HISPANIOLA...
UPPER-LEVEL DIFFLUENCE FROM A TROUGH OVER THE N WESTERN ATLC AND
A RIDGE COVERING WESTERN-CENTRAL CARIBBEAN SEA SUPPORTS
SCATTERED MODERATE CONVECTION OVER THE WINDWARD PASSAGE...HAITI
AND WESTERN DOMINICAN REPUBLIC. BESIDES THE TYPICAL
AFTERNOON/EARLY EVENING SHOWERS ACTIVITY DUE TO SURFACE
HEATING...CONVECTIVE ACTIVITY DUE TO THE UPPER-LEVEL FEATURES
MENTIONED ABOVE IS EXPECTED TO CONTINUE UNTIL SATURDAY NIGHT.

ATLANTIC OCEAN...
AN UPPER-LEVEL TROUGH IN THE N WESTERN ATLC SUPPORTS A FRONTAL
SYSTEM THAT ENTERS THE DISCUSSION AREA AS A COLD FRONT FROM
30N52W TO 29N55W WHERE IT TRANSITIONS TO A STATIONARY FRONT TO
29N61W TO 29N68W. IN ADDITION...THE UPPER-LEVEL TROUGH SUPPORTS
A SURFACE TROUGH ASSOCIATED WITH A 1011 MB LOW PRESSURE CENTER
NEAR 25N70W. DISORGANIZED CLOUDINESS AS WELL AS SCATTERED
SHOWERS AND TSTMS ASSOCIATED WITH THE FRONT AND THE LOW ARE FROM
22N-31N BETWEEN 59W-73W. DIFFLUENT FLOW ALOFT FROM THE UPPER-
LEVEL TROUGH AND A RIDGE COVERING THE WESTERN-CENTRAL CARIBBEAN
SUPPORTS SCATTERED SHOWERS IN THE BAHAMAS. A SURFACE TROUGH
EMBEDDED WITHIN A VERY MOIST ENVIRONMENT EXTENDS ALONG 17N53W TO
10N54W. TRAILING SCATTERED MODERATE CONVECTION AND ISOLATED
TSTMS IS FROM 12N-18N BETWEEN 46W-53W.

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

$$
RAMOS


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