[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 212353
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN JUN 21 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...

A TROPICAL WAVE IS ALONG 52W S OF 11N MOVING W NEAR 12 KT. ON
SATELLITE IMAGERY...THE WAVE EXHIBITS CYCLONIC CURVATURE IN THE
LOW-LEVEL CLOUD FIELD N OF 7N AND THIS WAS CONFIRMED BY RETURNS
ON AN EARLIER SCATTEROMETER PASS. ALSO OF NOTE...THIS WAVE
COINCIDES WITH A MAXIMUM IN DEEP LAYER MOISTURE BASED ON THE
TOTAL PRECIPITABLE WATER PRODUCT FROM CIMSS. SCATTERED MODERATE
CONVECTION IS FROM 5N-11N BETWEEN 51W-55W.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 10N14W 6N32W 7N49W 7N53W AND
INTO NRN GUYANA NEAR 6N58W. SCATTERED MODERATE CONVECTION IS
FROM 3N-5N BETWEEN 26W-34W. ALSO...CONVERGENT LOW-LEVEL WINDS N
OF THE AXIS AND E OF THE TROPICAL WAVE ALONG 52W ARE GENERATING
WIDELY SCATTERED MODERATE CONVECTION FROM 7N-14N BETWEEN
38W-50W. THIS ACTIVITY IS ALSO BEING ENHANCED BY UPPER LEVEL
DIFFLUENCE FROM AN UPPER RIDGE OVER THE AFOREMENTIONED AREA.

...DISCUSSION...

GULF OF MEXICO...
ATMOSPHERIC INSTABILITY ASSOCIATED WITH A WEAK UPPER LEVEL LOW
CENTERED OVER NERN MEXICO NEAR 24N98W IS SUPPORTING SCATTERED
SHOWERS AND ISOLATED TSTMS OVER THE BAY OF CAMPECHE S OF 21N...
INCLUDING PORTIONS OF THE INTERIOR YUCATAN PENINSULA. THIS
ACTIVITY SPREADS SWD ACROSS SRN MEXICO AND MUCH OF CENTRAL
AMERICA INTO THE E PACIFIC REGION. ACROSS THE REMAINDER OF THE
GULF N OF 21N...DEEP LAYER DRY AIR IS SUPPORTING GENERALLY FAIR
WEATHER...WHERE E-SE FLOW ALOFT IS OCCURRING BETWEEN THE UPPER
LEVEL LOW OVER NE MEXICO AND AN UPPER LEVEL HIGH CENTERED OVER
MISSISSIPPI. THIS UPPER LEVEL HIGH REFLECTS TO THE SURFACE AS A
1015 MB HIGH CENTERED OVER THE N/CENTRAL GULF NEAR 28N91W.
ANTICYCLONIC FLOW AROUND THE SURFACE HIGH IS AFFECTING MUCH OF
THE GULF...WITH SE WINDS OF 15 KT TO LOCALLY 20 KT OCCURRING
ACROSS PORTIONS OF THE SW GULF IN RESPONSE TO A BROAD SURFACE
TROUGH OVER MEXICO AND THE SRN PLAINS OF THE UNITED STATES. THE
SURFACE HIGH IS FORECAST TO DRIFT W ACROSS THE N GULF THROUGH
EARLY NEXT WEEK AS AN AREA OF BROAD LOW PRESSURE DIPS SE ACROSS
THE SE CONUS AND FLORIDA EXTENDING INTO THE W ATLC REGION.

CARIBBEAN SEA...
BROAD UPPER LEVEL TROUGHING EXISTS ACROSS A MAJORITY OF THE
CARIBBEAN BASIN WITH WEAK UPPER LEVEL RIDGING OBSERVED ACROSS
THE FAR WRN AND NW CARIBBEAN. THIS RIDGING EXTENDS ACROSS
CENTRAL AMERICA...THE YUCATAN PENINSULA AND SRN MEXICO PRODUCING
UPPER LEVEL DIFFLUENCE THAT IS GENERATING SCATTERED SHOWERS AND
ISOLATED TSTMS W OF 84W...INCLUDING THE GULF OF HONDURAS AND WRN
PORTIONS OF NICARAGUA AND HONDURAS. THE ITCZ AXIS EXTENDS FROM
THE E PACIFIC REGION S OF PANAMA ALONG 7N INTO A 1008 MB LOW
CENTERED OVER NRN COLOMBIA NEAR 8N77W. SCATTERED SHOWERS AND
TSTMS ARE OCCURRING S OF 12N BETWEEN 74W-82W OVER THE SW
CARIBBEAN AND OVER PANAMA AND COSTA RICA. ACROSS THE CENTRAL
CARIBBEAN...UPPER LEVEL MOISTURE AND HIGH LEVEL CLOUDS ARE
STREAMING EWD REMAINING S OF 15N. PEAK DAYTIME HEATING AND
ATMOSPHERIC INSTABILITY IS RESULTING IN SCATTERED SHOWERS AND
ISOLATED TSTMS OVER WRN CUBA...HISPANIOLA...JAMAICA...AND THE
NEARBY COASTAL WATERS SURROUNDING WRN PUERTO RICO. MODERATE TO
FRESH ELY TRADES ARE FORECAST TO OCCUR ACROSS THE CARIBBEAN
BASIN THROUGH THURSDAY.

ATLANTIC OCEAN...
A DEEP LAYER UPPER LEVEL LOW CENTERED N OF THE DISCUSSION AREA
NEAR 38N69W SUPPORTS A COLD FRONT THAT EXTENDS SW TO NEAR
32N78W. A PRE-FRONTAL SURFACE TROUGH ENTERS THE REGION NEAR
32N72W EXTENDING ALONG 31N76W 27N80W ACROSS SE FLORIDA TO LAKE
OKEECHOBEE. SCATTERED SHOWERS COVER A MAJORITY OF THE SW NORTH
ATLC E OF THE SURFACE TROUGH REMAINING MAINLY W OF 67W.
SCATTERED SHOWERS AND TSTMS ARE MORE CONCENTRATED ON SATELLITE
IMAGERY FROM 30N-33N BETWEEN 67W-71W. TO THE E...A SHARP AND
NARROW UPPER LEVEL RIDGE AXIS IS ALONG 32N56W 24N64W...OBSERVED
E OF THE UPPER TROUGH...AND IS PROVIDING AN UPPER LEVEL
DIFFLUENT PATTERN TO GENERATE SCATTERED SHOWERS FROM 26N TO
BEYOND 32N BETWEEN 50W-64W. ACROSS MUCH OF THE E/CENTRAL AND ERN
ATLC...GENERALLY FAIR WEATHER IS PRESENT WHERE SUBSIDENCE IS
OCCURRING NEAR A BROAD SURFACE RIDGE ANCHORED ON A 1022 MB
SURFACE HIGH NEAR 27N35W. HOWEVER...A PAIR OF SHORTWAVE TROUGHS
EXIST ACROSS THE FAR NE ATLC WATERS WITH A MIDDLE TO UPPER LEVEL
LOW CENTERED NEAR 31N34W AND MIDDLE TO UPPER LEVEL TROUGHING E
OF THE UPPER LEVEL LOW STRETCHING FROM THE MADEIRA ISLANDS
THROUGH THE CANARY ISLANDS TO 23N26W. SCATTERED SHOWERS ARE
FOUND WITH THESE TWO AREAS OF UPPER DIFFLUENCE FROM 22N-30N E OF
21W AND FROM 27N-33N BETWEEN 27W-34W.

$$
HUFFMAN




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