[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 222357
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT THU OCT 22 2009

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...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND
RADAR.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
WWWW UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS TILTED FROM 19N32W TO 11N38W MOVING NW NEAR 10
KT. WAVE IS AT THE LEADING EDGE OF A MAXIMUM IN TOTAL
PRECIPITABLE WATER. DENSE OVERCAST MULTILAYERED CLOUDS COVER A
BROAD AREA MASKING THE LOW LEVEL SIGNATURE. SCATTERED MODERATE
WITH CLUSTERS OF SCATTERED STRONG CONVECTION COVERS THE AREA
FROM 12N-20N BETWEEN 27W-30W BEING ENHANCED BY AN UPPER LEVEL
RIDGE OVER THE TROPICAL EASTERN ATLC.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 10N12W 8N23W 10N35W 12N45W 8N52W
9N62W. CLUSTERS OF SCATTERED MODERATE/STRONG CONVECTION ARE FROM
4N-8N BETWEEN 27W-30W.

...DISCUSSION...

GULF OF MEXICO...
A COLD FRONT THAT HAS MOVED INTO THE W GULF IS MOVING RAPIDLY
EASTWARD AND AT 2100 UTC ENTERS THE GULF OVER LAKE CHARLES
LOUISIANA ALONG 26N94W THEN W INTO MEXICO NEAR 24N97W TO ALONG
THE E SLOPES OF THE SIERRA MADRE MOUNTAINS. SCATTERED/HEAVY
SHOWERS WITH SCATTERED/NUMEROUS THUNDERSTORMS ARE WITHIN 60/75
NM OF LINE FROM 25N93W TO INLAND OVER E LOUISIANA/MISSISSIPPI
NEAR 30N90W. THIS FRONT IS BEING SUPPORTED BY A BROAD UPPER
TROUGH WITH THE UPPER LOW OVER THE MIDWEST STATES AND DRY STABLE
AIRMASS BEHIND THE FRONT. AN UPPER RIDGE ANCHORED OVER THE BAY
OF CAMPECHE NEAR 19N95W EXTENDING AN AXIS NE ACROSS THE FLORIDA
PANHANDLE AND ALONG THE COAST OF GEORGIA TO NORTH CAROLINA THUS
ENHANCING THE ACTIVITY ASSOCIATED WITH THE FRONT. FRONT IS
EXPECTED TO MOVE ACROSS THE GULF BEFORE WEAKENING OVER THE E
GULF DURING THE WEEKEND.

CARIBBEAN SEA...
A 1008 MB LOW REMAINS IN THE SW CARIBBEAN OFF THE COAST OF
NICARAGUA/COSTA RICA NEAR 11N82W. HIGHLY AMPLIFIED UPPER TROUGH
EXTENDS FROM THE W ATLC ACROSS E/CENTRAL CUBA TO OVER
NICARAGUA/HONDURAS BETWEEN THE BROAD UPPER RIDGE OVER THE GULF
OF MEXICO AND A SECOND UPPER RIDGE ANCHORED OVER VENEZUELA
ACROSS THE E CARIBBEAN AND PUERTO RICO INTO THE W/CENTRAL ATLC.
THIS SCENARIO IS GIVING THE NW AND FAR E CARIBBEAN STRONG
SUBSIDENCE AND A DRIER AIRMASS. A SWATH OF MOISTURE IS ACROSS
THE CENTRAL CARIBBEAN WITH SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS FROM 11N-15N BETWEEN 74W-83W. THE ITCZ AXIS
EXTENDS FROM COLOMBIA ACROSS THE SW CARIBBEAN INTO THE E PACIFIC
REGION OVER PANAMA/COSTA RICA GENERATING SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS S OF 10N W OF 81W WITH ISOLATED SHOWERS
WITHIN 150 NM OF LINE FROM 15N77W ACROSS HAITI AND E CUBA NEAR
THE WINDWARD PASSAGE LEAVING THE REMAINDER OF THE CARIBBEAN
UNDER MOSTLY CLEAR SKIES THIS EVENING.

ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH COVERS THE W AND CENTRAL ATLC N OF 30N
WITH A NARROW AMPLIFIED TROUGH AXIS EXTENDING S THROUGH THE W
ATLC ALONG 30N67W 26N75W ACROSS CENTRAL CUBA AND INTO THE W
CARIBBEAN. THIS AMPLIFIED UPPER LEVEL TROUGH IS PROVIDING STRONG
SUBSIDENCE AND DRY STABLE AIR MAINLY W OF 75W AND SUPPORTING A
SURFACE TROUGH JUST TO THE E ALONG 26N72W TO 21N74W. LOW-LEVEL
CONVERGENCE NEAR THE SURFACE TROUGH COUPLED WITH UPPER LEVEL
DIFFLUENCE IS GENERATING SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS FROM 21N-28N BETWEEN 60W-74W AND S OF 21N OVER
HAITI AND E CUBA BETWEEN 71W-76W. THE BROAD UPPER LEVEL TROUGH
OVER THE CENTRAL ATLC N OF 30N IS SUPPORTING A COLD FRONT N OF
THE REGION AND A SURFACE TROUGH ANALYZED FROM 29N41W ALONG
23N54W TO 21N68W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE
WITHIN 90/120 NM OF LINE FROM 25N43W TO BEYOND 32N35W. WEST OF
THE SURFACE TROUGH...A SURFACE RIDGE ANCHORED BY A 1021 MB HIGH
WNW OF BERMUDA WITH A SURFACE RIDGE E OF THE SURFACE TROUGH
ANCHORED BY A 1020 MB HIGH OVER THE MADEIRA ISLANDS. IN THE
TROPICAL ATLC...A 1009 MB LOW IS N OF THE ITCZ AND W OF THE
TROPICAL WAVE NEAR 14N43W WITH ISOLATED SHOWERS WITHIN 150 NM
RADIUS OF THE LOW.

$$
WALLACE





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