[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 220518
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT TUE AUG 22 2006

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND THE ATLANTIC OCEAN TO THE
AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION
IS BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...
AND METEOROLOGICAL ANALYSIS.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0415 UTC.

...SPECIAL FEATURE...
TROPICAL DEPRESSION FOUR IS CENTERED NEAR 12.2N 23.2W 0R ABOUT
170 NM SOUTH-SOUTHEAST OF THE SOUTHERN MOST CAPE VERDE ISLANDS
AT 22/0300 UTC MOVING WNW AT 13 KT. ESTIMATED MINIMUM CENTRAL
PRESSURE IS 1007 MB. MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH
GUSTS TO 40 KT. SEE LATEST NHC FORECAST/ADVISORY UNDER HEADERS
MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. LARGE WELL-ORGANIZED
SYSTEM IN SPITE OF THE LOSE OF CONVECTION SURROUNDING THE
CENTER. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN
180 NM OF THE CENTER IN THE NW QUADRANT. LARGER AREA OF SIMILAR
CONVECTION IS FROM 7N-11N BETWEEN 21W-27W. ANOTHER WAVE OF
AFRICAN DUST IS N OF THE T.D WHICH USUALLY HAMPERS CONVECTION.
SLOW DEVELOPMENT IS FORECASTED AS THE SYSTEM MOVES INTO A MORE
FAVORABLE ENVIRONMENT.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 42W/43W S OF 19N MOVING W 15-20 KT. BROAD
MID LEVEL ROTATION REMAINS ON INFRARED SATELLITE IMAGERY ALONG
THE ITCZ. CONVECTION IS CONFINED TO WITHIN THE ITCZ AREA.

TROPICAL WAVE IS ALONG 58W S OF 19N MOVING W NEAR 15-20 KT.
INVERTED-V CURVATURE PREVIOUSLY OBSERVED ON INFRARED SATELLITE
IMAGERY IS BECOMING LESS WELL-DEFINED AS THE WAVE APPROACHES THE
LESSER ANTILLES. CONVECTION IS CONFINED TO WITHIN THE ITCZ AREA.

TROPICAL WAVE IN THE CARIBBEAN IS ALONG 75W S OF 19N MOVING W 15
KT. DESPITE THE WAVE BEING BENEATH AN UPPER RIDGE LOW LEVEL
INVERTED-V CURVATURE IS OBSERVED ON INFRARED SATELLITE IMAGERY.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE FROM 17N-19N
BETWEEN 72W-77W.

TROPICAL WAVE OVER CENTRAL AMERICA IS NO LONGER EFFECTING THE
ATLC BASIN.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 15N16W 10N29W 8N48W 10N55W 9N62W
ACROSS THE N PORTION OF SOUTH AMERICA AND PANAMA INTO THE E
PACIFIC REGION. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG
CONVECTION ARE FROM 6N-14N BETWEEN 40W-60W.

...DISCUSSION...
GULF OF MEXICO...
BROAD UPPER RIDGE ANCHORED OVER THE CENTRAL MISSISSIPPI VALLEY
EXTENDS OVER THE N GULF N OF 28N. AN UPPER TROUGH EXTENDS FROM
AN UPPER LOW INLAND OVER CENTRAL MEXICO INTO THE GULF NEAR
TAMPICO TO THE COAST OF FLORIDA NEAR NAPLES PROVIDING ENOUGH
DIFFLUENCE OVER THE S GULF TO GENERATE CLUSTERS OF SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS OVER MOST OF THE GULF EXCEPT THE
N GULF COAST FROM THE FLORIDA PENINSULA THROUGH TEXAS CLEAR
MOSTLY CLEAR SKIES PREVAIL. A WEAK SURFACE TROUGH EXTENDS FROM
NEAR 24N95W INTO THE E BAY OF CAMPECHE AND S MEXICO NEAR CARMEN
ISLAND.

CARIBBEAN SEA...
BROAD UPPER RIDGE EXTENDS OVER THE W CARIBBEAN FROM AN UPPER
HIGH IN THE GULF OF HONDURAS NEAR 17N87W ENE ACROSS E CUBA TO
THE CENTRAL BAHAMAS IN THE W ATLC. THIS IS PROVIDING ENOUGH
DIFFLUENCE OVER W CARIBBEAN TO GENERATE A LARGE AREA OF
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF 17N W OF 76W AND N
OF 10N W OF 81W WITH AN AREA OF SCATTERED STRONG CONVECTION
WITHIN 90 NM OF LINE FROM NICARAGUA/HONDURAS TIP NEAR 15N83W TO
20N86W AND SCATTERED MODERATE/STRONG CONVECTION WITHIN 60 NM OF
19N FROM 78W-82W. MODERATE/STRONG TRADEWINDS ARE ACROSS THE
AREA.

ATLANTIC OCEAN...
BROAD UPPER LOW REMAINS SE OF BERMUDA NEAR 30N62W COVERING AN
AREA N OF 23N FROM 50W-79W. ASSOCIATED SURFACE TROUGH EXTENDS
FROM 24N71W-29N66W. HOWEVER...WITH DRY AIR IN PLACE THIS FEATURE
IS ONLY ABLE TO GENERATE SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS IS SMALL AREAS FROM 24N-27N BETWEEN
73W-78W....24N-27N BETWEEN 63W-70W...AND FROM 26N-28N BETWEEN
55W-58W. THE UPPER RIDGE EXTENDS FROM THE CARIBBEAN ACROSS E
CUBA TO THE CENTRAL BAHAMAS NEAR 23N75W IN THE W ATLC. THE
REMAINDER OF THE ATLC IS DOMINATED BY MOSTLY BENIGN FEATURES
WHICH INCLUDE AN UPPER TROUGH EXTENDING FROM THE E ATLC NEAR
32N19W THROUGH AN UPPER LOW NEAR 29N27W THROUGH A SECOND UPPER
LOW NEAR 20N43W TO THE TROPICAL ATLC NEAR 15N59W. DRY AIR
REMAINS IN PLACE OVER THE ATLC NO SIGNIFICANT CLOUDS OR SHOWERS
ARE ASSOCIATED WITH THESE FEATURES. BROAD SURFACE RIDGE
DOMINATES THE ATLC THUS KEEPING THE ITCZ AND ANY DEVELOPING
SYSTEMS FAR TO THE SOUTH. SIGNIFICANT AMOUNTS OF AFRICA DUST
COVER THE E TROPICAL ATLC FROM THE ITCZ TO 24N FROM 30-60W WITH
A SECOND SURGE COVERING THE FAR E ATLC BETWEEN THE CAPE VERDE
ISLANDS AND THE AFRICAN COAST.

$$
WALLACE




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