[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 151805
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SUN JUL 15 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
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...METEOROLOGICAL ANALYSIS...
WEATHER OBSERVATIONS...AND RADAR.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1715 UTC.

...TROPICAL WAVES...

CENTRAL ATLANTIC TROPICAL WAVE IS TILTED ALONG AXIS 19N32W
3N36W...MOVING WEST 15-20 KT. THIS IS A VERY LARGE AMPLITUDE
WAVE WITH VISIBLE SATELLITE IMAGERY INDICATING BROAD TURNING IN
THE STRATOCUMULUS FIELD BETWEEN 30W AND 48W. IN ADDITION CIMSS
ANALYSES SHOW A LARGE OF AREA OF SAHARAN DUST AHEAD OF AND IN
THE WAKE OF THE WAVE AXIS. THIS DUST WAS INHIBITING DEEP
CONVECTION WITH THE EXCEPTION OF A SMALL CLUSTER OF SCATTERED
MODERATE CONVECTION NEAR THE INTERSECTION OF THE WAVE AXIS AND
ITCZ FROM 5N TO 8N BETWEEN 30W AND 35W.

STRONGLY TILTED TROPICAL WAVE ALONG 20N55W TO NEAR TRINIDAD WAS
MOVING WEST ABOUT 15 KT. SURFACE OBSERVATIONS IN THE WINDWARD
ISLANDS CLEARLY SHOW A WINDSHIFT WITH THE PASSAGE OF THE WAVE.
THE 1200 UTC SOUNDING FROM TRINIDAD INDICATED AN INCREASE IN LOW
LEVEL WINDS AND PW VALUES EXCEEDING 2 INCHES. THE WAVE IS COMING
UNDER THE INFLUENCE OF AN UPPER LEVEL TROUGH OVER THE MID
ATLANTIC OCEAN WITH DIFLUENT FLOW E OF THE TROUGH AXIS AIDING IN
THE DEVELOPMENT OF SCATTERED MODERATE ISOLATED STRONG CONVECTION
WITHIN 120-180 NM E OF THE WAVE AXIS. THIS ACTIVITY IS EXPECTED
TO PUSH NORTHWESTWARD TOWARD PUERTO RICO BY 24 HOURS.

TROPICAL WAVE S OF 19N ALONG 90W WAS ADJUSTED WESTWARD AND HAS
NOW MOVED INLAND OVER PORTIONS OF BELIZE...GUATEMALA AND THE
YUCATAN PENINSULA. VERY LITTLE IN THE WAY OF THUNDERSTORM
ACTIVITY WAS NOTED WITH THE WAVE OVER CENTRAL AMERICA. THE
PORTION OF THE WAVE WHICH EXTENDED INTO THE EAST PACIFIC WAS
MORE ACTIVITY WITH WELL DEFINED TURNING IN THE LOW CLOUDS NOTED
ALONG THE WAVE AXIS NEAR 12N.

...THE ITCZ...
AXIS OF THE ITCZ IS ALONG 11N16W 10N21W 12N34W 4N44W 4N52W.
OTHER THAN THE CONVECTION DESCRIBED IN ASSOCIATION WITH THE
TILTED WAVE ALONG 19N32W 3N36W...ONLY ISOLATED MODERATE
THUNDERSTORMS NOTED ELSEWHERE WITHIN 90-120 NM OF THE WAVE
AXIS BETWEEN AFRICA AND 52W.

...DISCUSSION...
THE GULF OF MEXICO...
EXTENSION OF AN ATLANTIC SURFACE RIDGE IS FROM SOUTH FLORIDA
THROUGH 26N90W TO THE NORTHERN COAST OF MEXICO NEAR MONTERREY.
HIGHLY AMPLIFIED FLOW EXISTS OVER THE CONUS WITH THE AXIS OF A
SHARP UPPER LEVEL TROUGH EXTENDING FROM THE RED RIVER VALLEY
SOUTHWARD ALONG THE TEXAS COAST TO NEAR BROWNSVILLE. THE
ASSOCIATED SOUTHWESTERLY UPPER LEVEL FLOW AND UPPER DIFFLUENCE
WAS INCREASING IN AREA OVER THE GULF OF MEXICO. AS A RESULT
SCATTRED MODERATE TO STRONG THUNDERSTORMS WERE ERUPTING ALONG
A SURFACE TROUGH WHICH EXTENDED FROM THE S-CENTRAL COAST OF
LOUISIANA TO THE CENTRAL TEXAS COAST. THE SMALL CYCLONIC
CIRCULATION NEAR 25N86W YESTERDAY WAS BECOMING ABSORBED INTO THE
LARGER AREA OF SOUTHWESTERLY FLOW ALOFT AND BECOMING LESS
DISTINCT NEAR 27N84W. NARROW RIDGE AXIS BETWEEN ANTICYCLONES
OVER BELIZE AND THE W ATLANTIC WAS OVER SOUTH FLORIDA AND THE
FLORIDA STRAITS.

THE CARIBBEAN SEA...
A MID TO UPPER LEVEL ANTICYCLONE OVER BELIZE WAS INFLUENCING
LESS AND LESS OF THE CARIBBEAN AS THE FEATURE MOVED WWD OVER
CENTRAL AMERICA. THIS ANTICYCLONE WAS CONNECTED TO THE
ANTICYCLONE OVER THE WESTERN ATLANTIC OCEAN. THE BASE OF A MID
TO UPPER LEVEL TROUGH WAS SPREADING WESTWARD OVER THE CARIBBEAN
AND ENTERED THE BASIN OVER HAITI AND EXTENDED SOUTHWARD TO
12N79W WITH A DEVELOPING CYCLONIC CIRCULATION NOTED NEAR
15N77W. A BROAD SWATH OF AMPLIFYING SOUTHWESTERLY FLOW AT THE
MID AND UPPER LEVELS COVERS THE AREA SOUTHEAST OF THE UPPER
TROUGH AND 73W. THIS DIFLUENT FLOW REGIME WAS ENHANCING
SCATTERED MODERATE ISOLATED STRONG CONVECTION ALONG THE TILTED
TROPICAL WAVE ENTERING THE FAR EASTERN CARIBBEAN. ELSEWHERE ONLY
LOW TOPPED SHOWERS AND ISOLATED THUNDERSTORMS WERE NOTED OVER
THE CARIBBEAN.

THE ATLANTIC OCEAN...
A PERSISTENT POSITIVELY TILTED MID TO UPPER LEVEL TROUGH EXTENDS
FROM A MIDDLE TO UPPER LEVEL CYCLONIC CIRCULATION CENTER NEAR
30N56W THROUGH 25N64W TO A SECOND CYCLONIC CENTER JUST NORTH OF
HISPANIOLA NEAR 21N69W THEN CONTINUES SOUTHWESTWARD TO
HAITI. WIDELY SCATTERED MODERATE CONVECTION IS NOTED IN
ASSOCIATION WITH THE SECOND CYCLONIC CIRCULATION. AN EXPANDING
ANTICYCLONE WAS NOTED OVER THE TROPICAL ATLANTIC NEAR 17N49W
WITH A SMALLER ANTICYCLONE NEAR 22N35W. BOTH FEATURES DOMINATED
THE AREA BETWEEN 25W AND 55W. A SHEARED EASTERN ATLANTIC MIDDLE
TO UPPER LEVEL TROUGH EXTENDS FROM 32N10W TO 27N27W 27N35W.
SURFACE ANTICYCLONIC FLOW IS NORTH OF 20N BETWEEN AFRICA AND 80W.

$$
COBB




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