[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 240005
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON SEP 23 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 ACROSS THE CAPE VERDE ISLANDS. ITS
AXIS EXTENDS FROM 17N23W TO 09N22W AND IS MOVING W NEAR 10-15
KT. TOTAL PRECIPITABLE WATER IMAGERY SHOW THE WAVE IS EMBEDDED
FOR THE MOST PART IN A MODERATE MOIST ENVIRONMENT. A CLUSTER OF
MODERATE CONVECTION AND TSTMS IS WEST OF THE AXIS FROM 12N-15N
COINCIDING WITH A SMALL SECTOR OF HIGH MOISTURE IN THE
AFOREMENTIONED IMAGERY. STRONG NORTHEASTERLY WIND SHEAR IN THE
NORTHERN REGION OF THE WAVE IS IN PART HINDERING FURTHER
CONVECTIVE ACTIVITY.

A TROPICAL WAVE AXIS EXTENDS FROM 18N36W TO 09N33W AND IS MOVING
WEST AT 10-15 KT. A 1012 MB SURFACE LOW IS ANALYZED AT THE
SOUTHERN EXTENT OF THE WAVE AXIS AND REMAINS EMBEDDED WITHIN THE
MONSOON TROUGH AXIS NEAR 08N32W. TOTAL PRECIPITABLE WATER
IMAGERY SHOW MOST OF THE WAVE IS EMBEDDED WITHIN A MODERATE
MOIST ENVIRONMENT. SCATTERED MODERATE CONVECTION IS FROM 14N-17N
BETWEEN 31W-36W.

TROPICAL WAVE AXIS EXTENDS FROM 22N47W TO 14N49W AND IS MOVING W-
NW NEAR 10 KT. WATER VAPOR AND TOTAL PRECIPITABLE WATER IMAGERY
SHOW VERY DRY AIR WITHIN THE WAVE ENVIRONMENT WHICH ALONG WITH
STRONG DEEP LAYER WIND SHEAR INHIBITS CONVECTIVE ACTIVITY AT
THIS TIME.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH AXIS EXTENDS FROM 09N18W TO A 1012 MB LOW
NEAR 08N32W TO 07N42W. SCATTERED MODERATE CONVECTION IS FROM 03N-
08N BETWEEN 20W-35W.

...DISCUSSION...

GULF OF MEXICO...
WATER VAPOR IMAGERY INDICATES AN UPPER LEVEL TROUGH AXIS EXTENDS
FROM OVER THE FLORIDA PANHANDLE NEAR 30N85W S-SW TO A BASE OVER
THE SOUTH-CENTRAL GULF WATERS NEAR 22N89W. THE TROUGHING
CONTINUES TO PROVIDE AN OVERALL DIFFLUENT ATMOSPHERE OVER THE
EASTERN GULF AND FLORIDA PENINSULA WITH SCATTERED SHOWERS AND
TSTMS OCCURRING FROM 23N-29N BETWEEN 80W-85W. THIS AREA OF
CONVECTION IS PRIMARILY LOCATED IN THE MOIST AND UNSTABLE WARM
SECTOR OF A LOW PRESSURE SYSTEM FOCUSED ON A 1004 MB SURFACE LOW
CENTERED OVER THE NW GULF WATERS NEAR 27N94W. BECOMING PARTIALLY
OCCLUDED OVER THE PAST SEVERAL HOURS...A WARM FRONT EXTENDS
NORTHEAST FROM THE LOW CENTER TO LOUISIANA NEAR 29 N92W...ACROSS
THE SOUTHERN STATES TO THE FLORIDA PANHANDLE NEAR 30N83W WHERE
IT TRANSITIONS TO A STATIONARY FRONT THAT CONTINUES EASTWARD TO
ATLC WATERS. A CLUSTER OF MODERATE CONVECTION COINCIDES WITH THE
LOCATION OF THE LOW CENTER AND EXTENDS FROM 26N-27N BETWEEN 94W-
96W. IN ADDITION...A SURFACE TROUGH EXTENDS SOUTHWARD FROM THE
FRONTAL BOUNDARY ALONG 28N93W TO 20N93W. THE LOW IS FORECAST TO
REMAIN NEARLY STATIONARY OVER THE NW GULF THROUGH LATE TUESDAY
AND BEGIN DRIFTING NORTHEASTWARD EARLY WEDNESDAY INTO THURSDAY
BECOMING ABSORBED INTO A FRONTAL TROUGH ALONG 28N/29N THEREAFTER
MOVING INTO THE SW NORTH ATLC BY FRIDAY.

CARIBBEAN SEA...
AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED OVER WESTERN
CUBA NEAR 23N84W THAT IS PROVIDING THE NW CARIBBEAN WITH
EASTERLY FLOW ALOFT...AND THE SW CARIBBEAN WITH NE TO NORTHERLY
FLOW ALOFT. WATER VAPOR IMAGERY INDICATES THAT BOTH OF THESE
AREAS ARE RELATIVELY DRY AND OVERALL STABLE KEEPING MOSTLY FAIR
CONDITIONS W OF 76W. DIFFLUENCE FROM THE FLOW ALOFT OCCURS OVER
HONDURAS AND NICARAGUA TO SUPPORT SCATTERED MODERATE CONVECTION
INLAND AND WITHIN 50 NM OF ITS COASTLINES. LOW-LEVEL MOISTURE
CONVERGENCE FROM THE MONSOON TROUGH WHICH AXIS MOVES ACROSS
NICARAGUA TO NORTHERN COLOMBIA SUPPORTS SCATTERED SHOWERS S OF
15N W OF 80W AND S OF 12N E OF 78W. FARTHER EAST...AN ELONGATED
UPPER LEVEL LOW DEVELOPED OVER THE EASTERN CARIBBEAN WITH CENTER
NEAR 14N68W. WATER VAPOR AND TOTAL PRECIPITABLE WATER IMAGERY
SHOW DRY AIR IN THE MIDDLE AND LOWER LEVELS WHICH IS SUPPORTING
FAIR WEATHER IN THIS REGION OF THE BASIN W OF 64W. OVER THE NE
CARIBBEAN...A WEAK SURFACE TROUGH IS ANALYZED FROM 20N61W TO
16N63W. MOISTURE BEING CARRIED BY THIS FEATURE HAS BEEN
ENHANCING SHOWERS ACROSS THE LESSER ANTILLES. ISOLATED SHOWERS
ARE POSSIBLE ACROSS THE VIRGIN ISLANDS AND EASTERN PUERTO RICO
TONIGHT ASSOCIATED WITH THE PASSAGE OF THE SURFACE TROUGH.
OTHERWISE...EAST-SOUTHEASTERLY TRADES ARE EXPECTED TO PERSIST
THROUGH THE WEEK AHEAD WITH THE STRONGEST TRADES REMAINING
GENERALLY S OF 16N BETWEEN 68W-78W.

HISPANIOLA...
CLEAR SKIES AND FAIR WEATHER CONDITIONS CONTINUES DUE TO DRY
STABLE AIR AND STRONG NORTHERLY WIND SHEAR MOVING ACROSS THE
ISLAND. COMBINATION OF DRY AIR AND UNFAVORABLE MIDDLE TO UPPER
LEVEL SYNOPTIC PATTERN WILL SUPPORT FAIR WEATHER THROUGH WED
AFTERNOON. THUS...AFTERNOON AND EVENING CONVECTION IS EXPECTED
TO BE RELATIVELY MINIMUM.

ATLANTIC OCEAN...
WESTERLY UPPER LEVEL FLOW BECOMES MOSTLY DIFFLUENT OVER THE SW
NORTH ATLC BETWEEN AN ANTICYCLONIC CIRCULATION CENTERED OVER
WESTERN CUBA NEAR 23N84W AND A BROAD MIDDLE TO UPPER LEVEL
TROUGH OVER THE NW NORTH ATLC. FURTHERMORE...THE UPPER LEVEL
TROUGH SUPPORTS A COLD FRONT EXTENDING FROM 30N75W TO 30N79W
WHERE IT BECOMES STATIONARY TO JACKSONVILLE. WIDELY SCATTERED
SHOWERS AND TSTMS ARE OCCURRING N OF 24N W OF 69W. FARTHER
EAST...A SURFACE TROUGH EXTENDS FROM 32N54W TO 27N57W WITH NO
CONVECTION ASSOCIATED WITH IT. FINALLY...AN UPPER LEVEL TROUGH
AXIS SUPPORTS A COLD FRONT ANALYZED FROM 29N26W TO 29N31W WHERE
IT BECOMES STATIONARY TO 25N48W. A 1020 MB HIGH IS CENTERED NEAR
25N30W AND IS EXPECTED TO MOVE WESTWARD WITHIN THE NEXT 24 HOURS.

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

$$
NR

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