[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 082353
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN JUL 08 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
2315 UTC.

...TROPICAL WAVES...
A NEW TROPICAL WAVE IS INTRODUCED ALONG 37W BASED ON SATELLITE
IMAGERY AND SSMI DERIVED PRECIPITABLE WATER. THIS IS A HIGH
AMPLITUDE TROPICAL WAVE WITH SOME TURNING NEAR 11N. THE SAL
VERTICAL SOUNDING SHOWED THE PASSAGE OF THE WAVE ON THE 4TH OF
JULY. THIS TROPICAL WAVE WILL BE ADDED ON THE 00Z SURFACE MAP.

THE TROPICAL WAVE THAT WAS PREVIOUSLY ALONG 40W/41W IS RELOCATED
FURTHER W ALONG 51W BASED ON THE HOVMOLLER DIAGRAM THAT CLEARLY
SHOWS THE WESTWARD PROPAGATION OF THE WAVE...AND LATEST
SATELLITE IMAGERY THAT REVEALS AN INCREASE IN CONVECTIVE
ACTIVITY ON EITHER SIDE OF THE WAVE AXIS. THE CAYENNE VERTICAL
SOUNDING ALSO INDICATES THAT THE WAVE IS JUST OVER THE AREA.
CONVECTION HAS FLARED UP OVER FRENCH GUIANA AND SURINAME.

A TROPICAL WAVE IS ALONG 66W SOUTH OF 16N MOVING W 10-15 KT.
THIS WAVE HAS LOST MUCH OF ITS IDENTITY OVER THE LAST COUPLE OF
DAYS...AND NOW IS MAINLY JUST A SURGE OF MOISTURE AS DEPICTED
WELL BY SSMI DERIVED PRECIPITABLE WATER. DEEP CONVECTION REMAINS
MINIMAL ON BOTH SIDES OF THE AXIS.

A TROPICAL WAVE IN THE CARIBBEAN IS ALONG 82W/83W MOVING W NEAR
15 KT. THE WAVE...COUPLE WITH THE EPAC ITCZ IS GENERATING
SCATTERED MODERATE CONVECTION OVER THE SW CARIBBEAN AND CENTRAL
AMERICA S OF 13N. A DIFFLUENT PATTERN ALOFT IS ALSO ENHANCING
THIS CONVECTIVE ACTIVITY.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 8N12W 5N25W 6N38W 9N50W 7N60W.
CLUSTERS OF MODERATE CONVECTION ARE FROM 7N-12N BETWEEN 49W-56W
MAINLY ASSOCIATED WITH THE TROPICAL WAVE ALONG 51W. WIDELY
SCATTERED MODERATE CONVECTION IS WITHIN 80NM N OF THE AXIS
BETWEEN 22W-32W...AND WITHIN 100 NM SOUTH OF THE AXIS BETWEEN
40W-45W.

...DISCUSSION...
GULF OF MEXICO...
A SFC TROUGH REMAINS OVER THE SE PORTION OF THE GULF EXTENDING
FROM THE WEST COAST OF FLORIDA NEAR 27N82W TO 24N86W. THE TROUGH
IS STILL GENERATING SCATTERED SHOWERS OVER THE AREA...INCLUDING
THE FLORIDA PENINSULA. THIS ACTIVITY ALSO AIDED BY UPPER
DIFFLUENCE ASSOCIATED WITH AN UPPER HIGH LOCATED OVER CENTRAL
FLORIDA. A WEAK 1016 MB HIGH ALSO REMAINS OVER THE NORTH-CENTRAL
GULF WATERS NEAR 28N88W. THIS FEATURE IS EXPECTED TO DISSIPATE
AS THE ATLC RIDGE BUILDS WWD BEGINNING TONIGHT. AN UPPER LOW IS
SPINNING OVER CENTRAL MEXICO NEAR 20N100W SUPPORTING SCATTERED
SHOWERS AND ISOLATED TSTMS OVER THE SW PORTION OF THE GULF. FAIR
WEATHER AND LIGHT TO MODERATE WINDS AROUND RIDGING DOMINATE THE
REMAINDER OF THE REGION.

CARIBBEAN SEA...
ONCE AGAIN...THE MOST ACTIVE WEATHER ACROSS THE BASIN IS FOUND
OVER THE SW CARIBBEAN AND SOUTHERN CENTRAL AMERICA DUE TO THE
PRESENCE OF A TROPICAL WAVE AND THE EPAC ITCZ. SEE ABOVE. A
SEMI-PERMANENT LOW PRES OVER COLOMBIA IS PRODUCING CLUSTERS OF
MODERATE TO ISOLATED STRONG CONVECTION OVER WESTERN VENEZUELA
AND NORTHERN COLOMBIA. WV IMAGERY SHOWS A BAND OF HIGH CLOUDS
ASSOCIATED WITH UPPER WLY WINDS OVER THE SOUTHERN CARIBBEAN
SOUTH OF 14N AND E OF NICARAGUA. DIFFLUENCE BETWEEN THE UPPER
HIGH OVER FLORIDA AND AN UPPER LOW THAT PERSISTS JUST SOUTH OF
JAMAICA IS ENHANCING SCATTERED SHOWERS AND TSTMS OVER CUBA AND
JAMAICA. MODERATE TO FRESH TRADES ARE IN PLACE S OF THE ATLC SFC
RIDGE...AND EXPECTED TO PERSIST THROUGH MIDWEEK. THE TRADES ARE
ALLOWING TYPICAL PATCHES OF LOW LEVEL MOISTURE WITH EMBEDDED
ISOLATED SHOWERS TO PUSH W ACROSS THE AREA. ACCORDING TO THE
SAHARAN AIR LAYER FROM CIMSS...A PATCH OF AFRICAN DUST IS
REACHING THE NE CARIBBEAN...INCLUDING PUERTO RICO AND THE VIRGIN
ISLANDS BRINGING A MORE DRY AND STABLE ATMOSPHERE.

ATLANTIC OCEAN...
AN AREA OF SCATTERED SHOWERS/TSTMS REMAINS OFF THE FLORIDA
COAST...WITHIN 120NM EITHER SIDE OF A LINE FROM PALM BEACH TO
31N70W. THE ACTIVITY IS BEING SUPPORTED BY UPPER DIFFLUENCE
AROUND AN UPPER RIDGE AXIS. THE REMAINDER OF THE DISCUSSION AREA
IS DOMINATED BY THE BERMUDA-AZORES HIGH ANCHORED ON A 1032 MB
HIGH NEAR 42N20W. THIS IS PRODUCING ABUNDANT FAIR WEATHER AND
LIGHT TO MODERATE TRADES E OF 70W. THE WEAK TROUGHING/LOW LEVEL
CONFLUENCE OVER THE WRN ATLC WILL GRADUALLY DISSIPATE/LIFT NE
OVER THE NEXT DAY OR SO AS THE ATLC RIDGE BUILDS W ACROSS
FLORIDA AND INTO THE GULF. ELSEWHERE ALOFT ON THE LARGE
SCALE...RIDGING CONTINUES TO DOMINATE THE FAR W AND E PORTIONS
OF THE DISCUSSION AREA WITH BROAD TROUGHING OVER THE CENTRAL
ATLC. OTHER SMALLER SCALE UPPER FEATURES ARE EMBEDDED IN THIS
PATTERN BUT ARE NOT GENERATING SIGNIFICANT WEATHER.

$$
GR



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