[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 140400
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE OCT 13 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2200 UTC.

...TROPICAL WAVES...

TROPICAL WAVE EXTENDS FROM 15N56W TO 8N57W MOVING W NEAR 15 KT.
THE WAVE COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM OBSERVED
IN TOTAL PRECIPITABLE WATER IMAGERY. AN UPPER LEVEL LOW NEAR
16N55W CONTINUES TO PROVIDE A SHEARED ENVIRONMENT. DUE TO THE
SHEAR...ISOLATED MODERATE CONVECTION IS MAINLY E OF THE WAVE
AXIS FROM 10N-14N BETWEEN 51W-59W.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 10N12W 9N24W 7N36W 10N44W
10N56W. A SURFACE TROUGH IS EMBEDDED WITHIN THE ITCZ ALONG
10N26W TO 6N26W. A SECOND EMBEDDED SURFACE TROUGH IS EXTENDS
FROM 13N44W 7N46W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION
IS FROM 4N-7N BETWEEN 20W-23W...FROM 5N-10N BETWEEN 23W-28W NEAR
THE TROUGH ALONG 26W...AND FROM 4N-8N BETWEEN 29W-34W. SIMILAR
CONVECTION IS NEAR THE SECOND SURFACE TROUGH FROM 5N-12N BETWEEN
44W-49W...AND FROM 7N-11N BETWEEN 49W-55W.

...DISCUSSION...

GULF OF MEXICO...
A DYING STATIONARY FRONT LINES THE NE GULF OF MEXICO COASTLINE
FROM NEAR THE FLORIDA BIG BEND AT 29N83W TO SE LOUISIANA NEAR
NEW ORLEANS AT 30N89W CONTINUING AS A WARM FRONT INLAND OVER
LOUISIANA. ISOLATED SHOWERS/THUNDERSTORMS ARE NW OF LINE FROM
26N97W TO 30N88W. THESE SHOWERS/THUNDERSTORMS ARE SUPPORTED BY
DIFFLUENT FLOW ALOFT AROUND THE NW PERIPHERY OF AN UPPER LEVEL
RIDGE CENTERED OVER THE CENTRAL GULF NEAR 26N90W WITH AN AXIS
EXTENDING ALONG 24N ACROSS S FLORIDA AND IN THE WRN ATLC. A
SMALL CLUSTER OF SHOWERS/THUNDERSTORMS IS NOTED IN THE CENTRAL
GULF NEAR 26N87W. THE REMAINDER OF THE GULF IS EXPERIENCING
GENERALLY FAIR WEATHER THIS EVENING AS A WEAK SURFACE RIDGE
EXTENDS S OF THE FRONT FROM NE TO SW TO THE BAY OF CAMPECHE.
EXPECT THE SURFACE RIDGE TO PERSIST THROUGH THU...FOLLOWED BY A
COLD FRONT PUSHING OFF THE NW COAST LATE THU.

CARIBBEAN SEA...
THE CARIBBEAN REMAINS FAIRLY CALM UNDER THE INFLUENCE OF A LARGE
MASS OF DRY STABLE AIR ALOFT EVIDENT ON WATER VAPOR IMAGERY. AN
UPPER LEVEL RIDGE COVERING THE GULF OF MEXICO AND THE WRN ATLC
IS PROVIDING E TO NE UPPER LEVEL FLOW OVER THE BASIN. MODERATE
TRADE WINDS ARE ACROSS THE CENTRAL AND WRN CARIBBEAN WITH
STRONGER WINDS IN THE E CARIBBEAN AND NEAR THE COAST OF
COLOMBIA. LOW-LEVEL SPEED CONVERGENCE IS SUPPORTING A FEW
ISOLATED SHOWERS SHOWERS/THUNDERSTORMS ACROSS PORTIONS OF THE
NRN AND NW PORTIONS OF THE CARIBBEAN NW OF A LINE FROM PUERTO
RICO NEAR 18N67W TO NICARAGUA NEAR 15N83W. A FEW ISOLATED
SHOWERS/THUNDERSTORMS ARE ALSO IN THE SW CARIBBEAN S OF 11N W OF
78W DUE TO SURFACE CONVERGENCE NEAR THE E PACIFIC ITCZ. EXPECT A
TROPICAL WAVE CURRENTLY NEAR 57W TO ENTER THE E CARIBBEAN
TOMORROW.

ATLANTIC OCEAN...
A COLD FRONT ENTERS THE DISCUSSION AREA NEAR 32N72W CONTINUING
TO THE N FLORIDA COAST NEAR 29N81W CONTINUING AS A DYING
STATIONARY FRONT ACROSS THE NRN GULF COAST. THE FRONT IS
SUPPORTED BY A SHORTWAVE UPPER LEVEL TROUGH N OF THE AREA. MOST
OF THE ASSOCIATED SHOWER ACTIVITY HAS SPED AHEAD OF THE FRONTAL
SYSTEM AND DIED OUT. HOWEVER...DIFFLUENT FLOW ALOFT TO THE E OF
THE UPPER LEVEL SHORTWAVE TROUGH IS SUPPORTING ISOLATED SHOWERS
OVER THE AREA N OF 27N BETWEEN 43W-68W. FARTHER E...A 1011 MB
LOW IS ANALYZED NEAR 31N35W. A SURFACE TROUGH EXTENDS FROM THE
LOW CENTER ALONG 30N33W 28N34W 25N46W. SCATTERED SHOWERS ARE N
OF 27N BETWEEN 30W-32W. ISOLATED SHOWERS ARE FROM 28N-30N
BETWEEN 35W-37W...AND ARE POSSIBLE ALONG THE TROUGH AXIS. A
SECOND SURFACE TROUGH EXTENDS FROM 32N23W ALONG 29N25W TO
27N28W. SCATTERED SHOWERS ARE WITHIN 120 NM E OF THE TROUGH
AXIS. AN UPPER LEVEL TROUGH BETWEEN 15W-40W IS SUPPORTING  THE
SURFACE LOW AND SURFACE TROUGHS. A WEAK 1015 MB HIGH IS CENTERED
NEAR 25N25W. ACROSS THE TROPICAL ATLC...AN UPPER LEVEL RIDGE
CENTERED OVER WRN AFRICA IS SUPPORTING SHOWER ACTIVITY ALONG THE
ERN ITCZ. A SECOND UPPER LEVEL RIDGE WITH AXIS ALONG 26W IS
SUPPORTING SHOWER ACTIVITY ALONG THE WRN ITCZ.

$$
WALTON







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