[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 230005
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN SEP 22 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 WEST OF THE CAPE VERDE ISLANDS WITH AXIS
EXTENDING FROM 19N26W TO 10N28W...MOVING W NEAR 5 KT. SSMI TOTAL
PRECIPITABLE WATER IMAGERY SHOW THE WAVE IS EMBEDDED WITHIN A
MODERATE MOIST ENVIRONMENT. A REGION OF MIDDLE-LEVEL DIFFLUENCE
IN THE VICINITY OF THE WAVE IS ENHANCING ISOLATED SHOWERS WITHIN
200 NM EITHER SIDE OF THE AXIS.

A TROPICAL WAVE AXIS EXTENDS ALONG 20N42W TO 09N44W AND MOVES W
NEAR 5 KT. THIS WAVE CONTINUES EMBEDDED WITHIN A VERY DRY
ENVIRONMENT DEPICTED IN TOTAL PRECIPITABLE WATER IMAGERY AND
THERE IS NO CONVECTION ASSOCIATED WITH IT.

...THE ITCZ/THE MONSOON TROUGH...
THE MONSOON TROUGH AXIS EXTENDS FROM THE WEST AFRICAN COAST NEAR
12N16W TO 07N26W TO 07N33W. THE INTERTROPICAL CONVERGENCE ZONE
AXIS EXTENDS FROM 07N33W TO 09N42W...THEN RESUMES W OF A
TROPICAL WAVE FROM 08N47W TO 06N57W. A SQUAL LINE OF MODERATE TO
ISOLATED STRONG CONVECTION IS FROM 10N-15N E OF 18W. SCATTERED
MODERATE CONVECTION IF FROM 06N-09N E OF 14W AS WELL AS FROM 02N-
09N BETWEEN 18W-28W.

...DISCUSSION...

THE GULF OF MEXICO...
A BROAD UPPER-LEVEL TROUGH CENTERED NE OF THE LOWER GREAT LAKES
EXTENDS A NARROW AXIS SW INTO THE WESTERN GULF TO SUPPORT A
STATIONARY FRONT ACROSS THE FLORIDA PANHANDLE TO A 1003 MB LOW
NEAR 25N93W. A COLD FRONT EXTENDS FROM THE SAME LOW PRESSURE
CENTER TO THE SW GULF ALONG 23N93W TO 19N95W. THE FRONTAL SYSTEM
IS IN A REGION OF VERY MOIST AIR AT THE LOWER AND MIDDLE-LEVELS
WHICH ALONG WITH DIFFLUENT FLOW ALOFT SUPPORTS SCATTERED
MODERATE CONVECTION AND ISOLATED TSTMS N OF 25N E OF 93W.
SIMILAR CONVECTION IS WITHIN 100 NM WEST OF THE COLD FRONT
BOUNDARY. SMALL CLUSTERS OF MODERATE TO ISOLATED STRONG
CONVECTION ARE OVER THE YUCATAN PENINSULA ASSOCIATED WITH A
SURFACE TROUGH. THIS CONVECTIVE ACTIVITY EXTENDS OFFSHORE TO THE
WESTERN YUCATAN CHANNEL. SUBSIDENCE OF VERY DRY AIR FROM THE
MIDDLE LEVELS IS KEEPING THE REMAINDER GULF FREE OF CONVECTION.
THE LOW PRESSURE ASSOCIATED WITH THE FRONT WILL SHIFT TO THE NE
GULF IN 48 HOURS WHERE IT IS EXPECTED TO TRANSITION INTO A
SURFACE PRE-FRONTAL TROUGH. THE STATIONARY PORTION OF THE
FRONTAL BOUNDARY WILL STALL OVER THE NORTHERN GULF TILL WED
AFTERNOON.

THE CARIBBEAN SEA...
EXCEPT FOR THE NW AND SOUTHERN CARIBBEAN SEA...DRY AIR AT LOWER
AND MIDDLE LEVELS IS KEEPING GREATER PORTIONS OF THE BASIN FREE
OF CONVECTIVE ACTIVITY. A SURFACE TROUGH OVER THE YUCATAN
PENINSULA IS GENERATING CLUSTERS OF MODERATE/ISOLATED STRONG
CONVECTION THAT EXTENDS TO THE NW BASIN FROM 20N-22N W OF 85W.
OVER THE SOUTHERN BASIN...SCATTERED MODERATE CONVECTION AND
TSTMS ASSOCIATED WITH THE MONSOON TROUGH ARE S OF 12N W OF 77W.
DIFFLUENT FLOW FROM AN UPPER-LEVEL RIDGE CENTERED IN THE FLORIDA
STRAITS AND A TROUGH COVERING THE CENTRAL-EASTERN BASIN IS
ENHANCING SCATTERED SHOWERS OVER HISPANIOLA AND ADJACENT WATERS
N OF 15N BETWEEN 72W-78W. A SURFACE TROUGH IS MOVING ACROSS THE
LESSER ANTILLES ALONG 18N59W TO 12N61W ENHANCING ISOLATED
SHOWERS. THE SURFACE TROUGH IS EXPECTED TO DRIFT W-NW WITHIN 24
HOURS TO BRING SHOWERS ACTIVITY TO THE VIRGIN ISLANDS AND
EASTERN PUERTO RICO. A TROPICAL WAVE IS EXPECTED TO ENTER THE
EASTERN CARIBBEAN LATE WED AFTERNOON.

HISPANIOLA...
DIFFLUENT FLOW FROM AN UPPER-LEVEL RIDGE CENTERED IN THE FLORIDA
STRAITS AND A TROUGH COVERING THE CENTRAL-EASTERN CARIBBEAN SEA
IS ENHANCING SCATTERED SHOWERS OVER HISPANIOLA AND ADJACENT
WATERS N OF 15N BETWEEN 72W-78W. EXCEPT FOR AFTERNOON SHOWERS
DUE TO SURFACE HEATING...NO SIGNIFICANT CONVECTIVE ACTIVITY IS
EXPECTED OVER THE NEXT 48 HOURS.

THE ATLANTIC OCEAN...
ISOLATED SHOWERS AND TSTMS ASSOCIATED WITH A COLD FRONT N OF THE
AREA OF DISCUSSION ARE N OF 28N WEST OF 73W. A SURFACE
TROUGH...PART OF A FRONTAL SYSTEM...EXTENDS ALONG 30N59W TO
24N63W. FURTHER EAST A WARM FRONT ENTERS THE DISCUSSION AREA
NEAR 30N50W TO 28N50W WHERE IT TRANSITIONS TO A COLD FRONT TO
27N40W 30N31W. ISOLATED SHOWERS ARE IN THE REGION WITHIN THE
TROUGH AND THE FRONTAL BOUNDARY N OF 22N BETWEEN 51W-62W AS WELL
AS FROM 24N-29N BETWEEN 32W-41W. OVER THE EASTERN BASIN...A 1021
MB HIGH IS NEAR 27N23W WHICH IS EXPECTED TO DRIFT SW WITHIN THE
NEXT 24 HOURS. OTHERWISE...A SURFACE TROUGH WITH NO CONVECTION
ASSOCIATED WITH IT IS BETWEEN TWO TROPICAL WAVES FROM 16N39W TO
13N35W.

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

$$
NR


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