[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 121029
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SUN JUL 12 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS ALONG 42W/43W S OF 20N MOVING W 15-20 KT.
SATELLITE IMAGERY INDICATES THAT THE WAVE COINCIDES WITH A BROAD
AREA OF CYCLONIC TURNING IN THE LOW-LEVELS. DEEP CONVECTION
REMAINS ABSENT IN THE VICINITY OF THE WAVE SUPPRESSED BY SAHARAN
DUST.

A TROPICAL WAVE EXTENDS FROM 20N78W TO 9N80W MOVING W 20-25 KT.
THE WAVE POSITION IS MAINLY BASED ON A MOISTURE MAXIMUM IN TOTAL
PRECIPITABLE WATER AS LITTLE SIGNATURE IS APPARENT IN SATELLITE
IMAGERY OR OBSERVATIONS. CONVECTION IS LOCATED WELL W OF THE
WAVE FROM 11N-17N BETWEEN 80W-85W ENHANCED BY DIFFLUENCE ALOFT.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 11N15W 8N23W 8N38W 7N48W 7N59W.
SCATTERED MODERATE CONVECTION IS FROM 6N-12N BETWEEN 15W-25W.
SCATTERED MODERATE CONVECTION IS ALSO FROM 3N-6N BETWEEN 42W-49W.

...DISCUSSION...

GULF OF MEXICO...
EAST-NORTHEASTERLY UPPER FLOW COVERS MUCH OF THE GULF ON THE SE
SIDE OF AN UPPER RIDGE OVER THE SOUTHERN PLAINS OF THE
CONUS...WITH SUBSIDENCE SUPPORTING A SURFACE RIDGE ALONG 30N. AS
A RESULT...GENERALLY FAIR WEATHER CONDITIONS ARE PRESENT ACROSS
THE N HALF OF THE GULF. ACROSS THE SW GULF...AN UPPER LEVEL LOW
IS CENTERED NEAR 19N93W WITH AN ASSOCIATED SURFACE TROUGH ALONG
95W S OF 22N. ATMOSPHERIC INSTABILITY NEAR THE UPPER LOW AND LOW
LEVEL CONVERGENCE NEAR THE SURFACE TROUGH ARE SUPPORTING
SCATTERED SHOWERS AND THUNDERSTORMS ACROSS THE SW GULF S OF 22N
W OF 95W. WINDS ARE LIGHT AND VARIABLE IN THE VICINITY OF THE
SURFACE RIDGE ACROSS THE N GULF...WITH ANTICYCLONIC FLOW AROUND
THE RIDGE SUPPORTING A BROAD SWATH OF E WINDS OF 10 TO 15 KT
ACROSS THE SOUTHERN HALF OF THE GULF...HIGHEST NEAR THE STRAITS
OF FLORIDA. HOWEVER...ELY WINDS ARE IN THE 20-25 KT RANGE IN THE
VICINITY OF THE AFOREMENTIONED SURFACE TROUGH.

CARIBBEAN SEA...
FRESH TO STRONG TRADE WINDS ARE OCCURRING BETWEEN THE
SUBTROPICAL RIDGE OVER THE CENTRAL ATLC AND A BROAD TROUGH OVER
NORTHERN SOUTH AMERICA...WITH THE STRONGEST FLOW NEAR THE COAST
OF COLOMBIA. AN EARLIER QUIKSCAT PASS CONFIRMED THAT E WINDS OF
25 TO 30 KT ARE PRESENT NEAR THE COAST OF COLOMBIA. THESE WINDS
WILL REMAIN STRONG OVER THE NEXT SEVERAL DAYS AS THE SUBTROPICAL
RIDGE STRENGTHENS. ALOFT...AN UPPER LEVEL TROUGH IS OVER THE N
CENTRAL CARIBBEAN. ATMOSPHERIC INSTABILITY ASSOCIATED WITH THIS
FEATURE IS RESULTING IN ISOLATED SHOWERS AND THUNDERSTORMS N OF
19N BETWEEN 76W-80W INCLUDING PORTIONS OF E CUBA. ACROSS THE SW
CARIBBEAN...AN UPPER LEVEL HIGH IS CENTERED NEAR 12N78W...WITH
ASSOCIATED UPPER LEVEL DIVERGENCE SUPPORTING SCATTERED SHOWERS
AND THUNDERSTORMS FROM 10N-16N W OF 80W INCLUDING ADJACENT AREAS
OF CENTRAL AMERICA. ACROSS THE E CARIBBEAN...DEEP LAYER DRY AIR
AND ATMOSPHERIC STABILITY ASSOCIATED WITH AN UPPER LEVEL RIDGE
ARE SUPPORTING GENERALLY FAIR WEATHER.

ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH IS ACROSS THE SW NORTH ATLC WITH AN AXIS
EXTENDING FROM 26N75W TO 32N76W TO NE OF THE DISCUSSION AREA.
AMOSPHERIC INSTABILITY ASSOCIATED WITH THE UPPER TROUGH IS
SUPPORTING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS FROM
21N-26N W OF 63W INCLUDING THE BAHAMAS. FARTHER E...A SURFACE
TROUGH EXTENDS FROM 24N56W TO 16N58W...WITH DEEP LAYER MOISTURE
AND LOW LEVEL CONVERGENCE SUPPORTING SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS WITHIN 60 NM EITHER SIDE OF THE SURFACE
TROUGH. SUBSIDENCE AND GENERALLY FAIR WEATHER ARE PRESENT ACROSS
MUCH OF THE CENTRAL AND E ATLC AROUND A BROAD SURFACE RIDGE.
THIS RIDGE IS ASSOCIATED WITH A 1026 MB SURFACE HIGH NEAR
33N49W. HOWEVER...A SURFACE TROUGH EXTENDS FROM THE W COAST OF
AFRICA NEAR 18N16W TO 16N21W...WITH WELL-DEFINED CYCLONIC
CURVATURE IN THE LOW LEVEL FLOW REVEALED BY THE 11/2300 UTC
ASCAT PASS. LOW LEVEL CONVERGENCE IS SUPPORTING SCATTERED
SHOWERS WITHIN 60 NM EITHER SIDE OF THE SURFACE TROUGH.

$$
COHEN/CANGIALOSI


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