[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 152347
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE SEP 15 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
2315 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 74W S OF 18N MOVING W NEAR 20 KT. THIS
WAVE CONTINUES MOVING BENEATH DRY NELY UPPER LEVEL FLOW WHICH IS
INHIBITING ANY SIGNIFICANT DEEP CONVECTION ACROSS THE CENTRAL
CARIBBEAN...THUS ONLY ISOLATED SHOWERS ARE LOCATED MAINLY S OF
JAMAICA FROM 14N-18N BETWEEN 75W-80W.

...ITCZ...

THE ITCZ AXIS IS ALONG 9N13W 10N27W 9N40W 8N60W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS ALONG THE W AFRICA COAST
AND WITHIN 60 NM OFFSHORE FROM 8N-14N E OF A LINE FROM 8N14W TO
14N19W. SCATTERED MODERATE CONVECTION IS FROM 5N-10N BETWEEN
19W-26W AND FROM 5N-9N BETWEEN 30W-35W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL SHORTWAVE TROUGH IS ACROSS ERN TEXAS AND SUPPORTS
A 1008 MB SURFACE LOW CENTERED OVER NE LOUISIANA NEAR 33N92W. A
COLD FRONT EXTENDS S FROM THE LOW TO THE GULF COAST NEAR CAILLOU
BAY AND INTO THE NW GULF AS A STATIONARY FRONT ALONG 29N91W
24N97W. VERY DRY SWLY FLOW ALOFT IS INHIBITING MOST CONVECTION
ALONG THIS FRONT...HOWEVER...SCATTERED SHOWERS ARE FROM 26N28N
BETWEEN 90W-92W AND ARE MOVING ENE. A SURFACE TROUGH IS ANALYZED
OVER THE WRN YUCATAN PENINSULA AND WRN GUATEMALA. THIS SURFACE
FEATURE ALONG WITH AN UPPER LEVEL DIFFLUENT PATTERN ACROSS SRN
MEXICO IS GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS SW OF
A LINE FROM 19N92W TO 22N96W OVER THE WRN BAY OF CAMPECHE. A
LARGE AREA OF UPPER DIFFLUENCE ON THE NRN PERIPHERY OF AN
ANTICYCLONIC CIRCULATION CENTERED OVER WRN CUBA IS GENERATING
SCATTERED SHOWERS AND TSTMS N OF 24N E OF 86W. THIS ACTIVITY
SPREADS ACROSS A MAJORITY OF THE WRN FLORIDA PENINSULA THIS
EVENING.

CARIBBEAN SEA...
TWO UPPER LEVEL FEATURES CONTROL THE CARIBBEAN SEA THIS EVENING.
AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED OVER WRN
CUBA NEAR 22N82W AND EXTENDS UPPER LEVEL RIDGING ACROSS CENTRAL
AMERICA TO THE WEST AND EAST TO 71W. UPPER LEVEL DIFFLUENCE
ALONG WITH DAYTIME HEATING OVER THE GREATER ANTILLES ARE
GENERATING SCATTERED SHOWERS AND TSTMS N OF 17N BETWEEN 72W-82W.
ACROSS THE ERN CARIBBEAN E OF 71W...AN UPPER LEVEL LOW IS
CENTERED S OF PUERTO RICO NEAR 17N66W AND IS PROVIDING MUCH OF
THE CENTRAL CARIBBEAN WITH N-NE FLOW ALOFT AND THE ERN CARIBBEAN
WITH MOIST SOUTHERLY FLOW E OF 66W. UPPER LEVEL DIFFLUENCE E OF
THE UPPER LOW ALONG WITH ATMOSPHERIC INSTABILITY ARE GENERATING
SCATTERED SHOWERS AND TSTMS OVER THE FAR ERN CARIBBEAN E OF 65W
AND OVER THE LESSER ANTILLES.

ATLANTIC OCEAN...
A 1009 MB SURFACE LOW IS OVER THE W ATLC NEAR 29N72W WITH A WARM
FRONT EXTENDING NE TO BEYOND 32N70W. A SURFACE TROUGH EXTENDS S
FROM THE LOW ACROSS THE CENTRAL BAHAMAS TO ERN CUBA NEAR 22N77W.
UPPER LEVEL RIDGING IS ALOFT OVER THE LOW AND IS AIDING IN
SUSTAINING CONVECTION ALONG THE SURFACE BOUNDARY. SCATTERED
SHOWERS AND TSTMS ARE STRETCHED OVER A LARGE PORTION OF THE W
ATLC FROM 22N-32N BETWEEN 64W-75W. FARTHER TO THE SE...THE UPPER
LEVEL LOW CENTERED S OF PUERTO RICO NEAR 17N66W IS PROVIDING
UPPER LEVEL DIFFLUENCE OVER THE ERN CARIBBEAN AND PORTIONS OF
THE TROPICAL N ATLC. SCATTERED SHOWERS AND TSTMS ASSOCIATED WITH
THIS UPPER LOW ARE FROM 10N-22N BETWEEN 57W-64W. A 1013 MB
SURFACE LOW...THE REMNANT OF FRED...IS CENTERED OVER THE CENTRAL
ATLC NEAR 20N47W. NEW SCATTERED STRONG CONVECTION HAS BLOSSOMED
N OF THE LOW CENTER OVER THE PAST 6 HOURS AND IS LOCATED FROM
20N-23N BETWEEN 46W-49W. ANOTHER 1013 MB LOW IS W OF THE CAPE
VERDE ISLANDS CENTERED NEAR 17N30W. DISORGANIZED SCATTERED
SHOWERS AND TSTMS ARE IN THE VICINITY OF THE LOW FROM 13N-19N
BETWEEN 28W-33W. THIS ACTIVITY IS BEING ENHANCED AND SUPPORTED
ALOFT BY AN UPPER LEVEL RIDGE THAT EXTENDS FROM W AFRICA OVER
THE TROPICAL ERN ATLC TO 40W.

$$
HUFFMAN





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