[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 182359
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED JUL 18 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2345 UTC.

...TROPICAL WAVES...
LARGE AMPLITUDE E ATLC TROPICAL WAVE IS ALONG 18N32W 6N34W. A
1012 MB LOW IS ALONG THE WAVE AXIS NEAR 14N MOVING W NEAR 18 KT.
THE LOW ITSELF CONSISTS OF ELONGATED CYCLONIC TURNING IN BROKEN
STRATOCUMULUS. ISOLATED MODERATE CONVECTION IS LIMITED TO THE
INTERSECTION OF THE WAVE AXIS AND THE ITCZ GENERALLY FROM 7N-11N
BETWEEN 31W-38W.

TROPICAL WAVE IS ALONG 59W/60W S OF 17N MOVING W 15-20 KT. THIS
WAVE CONTINUES TO EXHIBIT A BROAD INVERTED V SHAPE. MODERATE
UPPER LEVEL E/SE FLOW S OF AN UPPER HIGH IS DISPLACING MOST OF
THE ASSOCIATED CONVECTION WELL TO THE W OF THE AXIS. THIS
SCATTERED MODERATE CONVECTION IS AFFECTING THE NRN WINDWARD
ISLANDS AND ADJACENT WATERS FROM 15N-17N BETWEEN 58W-62W. SOME
CYCLONIC TURNING WAS NOTED IN THE MID LEVEL CONVECTIVE DEBRIS
OVER THE E-CENTRAL CARIBBEAN NEAR 13N64W. ADDITIONAL SCATTERED
MODERATE CONVECTION IS NOTED WITHIN 90 N OF THE ITCZ W OF
54W.

TROPICAL WAVE IS ALONG 86/87W S OF 19N MOVING W NEAR 15 KT.
SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED OVER
HONDURAS...GUATEMALA...EL SALVADOR AND THE WESTERN YUCATAN
PENINSULA. THIS WAVE ALSO EXTENDS INTO THE FAR NE PACIFIC AS
DESCRIBED IN THE PACIFIC DISCUSSION UNDER AWIPS HEADER
MIATWDEP.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 14N16W 14N25W 11N30W 9N35W 8N50W
12N58W...13N60W 10N65W. EXCEPT AS NOTED WITH THE TROPICAL
WAVES...SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 90-120
NM OF THE AXIS BETWEEN 49W-52W. ISOLATED MODERATE ELSEWHERE
WITHIN 90 NM OF THE AXIS BETWEEN 38W-45W. SCATTERED STRONG
CONVECTION IS EMERGING OFF THE WEST COAST OF AFRICA FROM 10N-13N
IN ADVANCE OF A FAIRLY LARGE TROPICAL WAVE STILL OVER THE
AFRICAN CONTINENT.

...DISCUSSION...
GULF OF MEXICO...
THE MOST ACTIVE WEATHER CONTINUES TO BE IN THE WRN PORTION.
NUMEROUS MODERATE/SCATTERED STRONG CONVECTION IS OFF AND ALONG
THE NE MEXICO COAST FROM 22N-27N W OF 95W. ADDITIONALLY
SCATTERED MODERATE CONVECTION IS NOTED OFF THE MIDDLE AND UPPER
TEXAS COAST AND SW LOUISIANA. LATEST SFC OBSERVATIONS INDICATE A
1012 MB LOW WAS LOCATED NEAR MONTERREY MEXICO WITH A SURFACE
TROUGH EXTENDING NE TO 28N94W. WSR-88D IMAGERY FROM BROWNSVILLE
TEXAS SHOWS WELL DEFINED TURNING IN THE PRECIPITATION FIELD OVER
NORTHERN MEXICO. THIS ACTIVITY IS EXPECTED TO SPREAD NWD ALONG
THE TEXAS COAST WITH LOCALLY HEAVY RAINS POSSIBLE. ADDITIONALLY
SOME SUPPORT FOR THIS ACTIVITY LIES ALOFT WITH DIFFLUENT FLOW
BETWEEN THE UPPER LOW OVER NRN MEXICO NEAR 27N104W AND AN UPPER
HIGH OVER THE CENTRAL GULF NEAR 25N92W. A WEAK 1021 MB HIGH IS
JUST S OF MOBILE NEAR 29N88W. THIS LOOKS TO REMAIN QUASI
STATIONARY OVER THE NEXT COUPLE OF DAYS...KEEPING LIGHT/VARIABLE
WINDS IN THE NE PORTION AND LIGHT TO MODERATE E/SE FLOW IN THE
SW PORTION.

CARIBBEAN SEA...
THE ACTIVE WEATHER THAT WAS NOTED OVER THE FAR W AND E PORTIONS
OF THE CARIBBEAN HAS DIMINISHED MARKEDLY OVER THE PAST SEVERAL
HOURS AS THE TROPICAL WAVE ALONG 87W PUSHES FURTHER WWD. THE
AREA BETWEEN 68W-80W IS UNDER MOSTLY CLEAR SKIES WITH ONLY A FEW
PATCHES OF LOW LEVEL MOISTURE BEING CARRIED WWD BY THE MODERATE
TO FRESH TRADES IN PLACE. THE LATEST UW-CIMSS SAHARAN AIR LAYER
PRODUCT SUGGESTS THE AREA OF DUST IN THE CENTRAL CARIB IS
DECREASING WITH TIME. ISOLATED TSTMS ARE AFFECTING
HISPANIOLA...JAMAICA AND CUBA AND ADJACENT WATERS FROM 18N-22N
MAINLY IN ASSOCIATION WITH AN UPPER LOW NEAR 19N81W AND
FAVORABLE DIFFLUENT PATTERN ALOFT BETWEEN THE UPPER LOW
AND AN UPPER HIGH JUST E OF THE WINDWARD ISLANDS. SHOWERS/TSTMS
ASSOCIATED WITH THE TROPICAL WAVE JUST E OF THE WINDWARD ISLANDS
WILL PUSH THROUGH THE ERN CARIB OVER THE NEXT COUPLE OF DAYS.
OVERALL MODERATE TO FRESH TRADES TO PERSIST.

ATLANTIC OCEAN...
OVERALL PATTERN IS CHARACTERIZED BY A SFC RIDGE WHICH DOMINATES
MUCH OF THE DISCUSSION AREA S OF A 1030 MB HIGH PRES CENTER NEAR
37N51W. INVERTED SFC TROUGHING EMBEDDED IN THIS RIDGE IS ALONG
30N65W 25N64W 21N66W. THIS...ALONG WITH LIFT AHEAD OF THE MID TO
UPPER LOW NEAR 27N66W...IS SUPPORTING MULTILAYERED CLOUDS WITH
EMBEDDED SHOWERS/ISOLATED TSTMS N OF 20N BETWEEN 58W-64W. THE
AREA N OF 17N AND E OF 55W IS DOMINATED BY FAIR WEATHER...
SCATTERED LOW TO MID CLOUDS AND MODERATE TRADES. AN UPPER LEVEL
ANTICYCLONE CENTERED NEAR 17N58W DOMINATES THE TROPICAL ATLANTIC
WEST OF 40W WITH ANOTHER UPPER RIDGE OVER THE FAR ERN ATLC. IN
BETWEEN IS AN UPPER TROUGH AND EXPANDING CYCLONIC CIRCULATION
GENERALLY N OF 17N BETWEEN 35W-52W. UW-CIMSS SAHARAN AIR LAYER
PRODUCT DEPICTS A DENSE AREA OF AFRICAN DUST NOTED OVER MUCH OF
THE AREA E OF 50W.

$$
COBB


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