[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 062357
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST TUE NOV 06 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 LOW AMPLITUDE TROPICAL WAVE IS LOCATED ALONG 47W SOUTH OF
13N...MOVING W NEAR 10 KT. THE WAVE IS BEGINNING TO INTERACT
WITH AN UPPER-LEVEL LOW THAT REMAINS NEAR 18N55W. THIS FEATURE
PAIRED WITH UPPER DIFFLUENCE BETWEEN THE ABOVE MENTIONED LOW AND
AN UPPER HIGH THAT ALSO REMAINS NEAR THE GUYANAS IS GENERATING
BROKEN TO OVERCAST MULTILAYERED CLOUDS WITH EMBEDDED SHOWERS
FROM 5N-10N BETWEEN 40W-48W.

...THE ITCZ...

ITCZ AXIS IS CENTERED ALONG 9N13W 7N30W 7N45W 7N60W. BESIDES FOR
THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVE...SCATTERED
MODERATE CONVECTION IS WITHIN 150 NM N OF AXIS BETWEEN 28W-32W.
SIMILAR CONVECTION IS WITHIN 200 NM SOUTH OF AXIS BETWEEN
23W-29W.

DISCUSSION...

GULF OF MEXICO...
A NEW COLD FRONT IS MOVING ACROSS THE NORTHERN GULF WATERS. IT
ENTERED THE REGION DURING THE AFTERNOON HOURS. AS OF 2100 UTC...
THE FRONT EXTENDS FROM THE FLORIDA PANHANDLE TO THE DEEP SOUTH
THEN ACROSS THE STATES OF COAHUILA AND CHIHUAHUA IN MEXICO. A
NARROW BAND OF LOW/MID CLOUDS WITH SCATTERED SHOWERS IS RELATED
TO THE FRONT. STRONG HIGH PRES WILL BUILD IN BEHIND THE FRONT
BRINGING AN INCREASE IN WINDS AND SEAS TONIGHT THROUGH WED
NIGHT. FAIRLY UNIFORM UPPER NW FLOW IS OVER THE GULF THIS
EVENING BETWEEN A LONGWAVE TROUGH OVER THE ERN UNITED STATES AND
RIDGING OVER MEXICO. DRY MID/UPPER AIR DOMINATES MOST OF THE
REGION. THE FRONT IS FORECAST TO MOVE RAPIDLY S AND EXTEND FROM
THE STRAITS OF FLORIDA TO NE MEXICO BY LATE WED.

CARIBBEAN SEA...
A STATIONARY FRONT PERSISTS OVER THE WRN CARIBBEAN AND EXTENDS
FROM NEAR THE COAST NE HONDURAS TO THE ERN TIP OF CUBA...THEN
CONTINUES ACROSS THE TURKS AND CAICOS ISLANDS INTO THE W ATLC.
THE TAIL END OF THE FRONT IS GENERATING SCATTERED SHOWERS AND
TSTMS...PARTICULARLY OVER NE HONDURAS AND ADJACENT WATERS S OF
19N BETWEEN 79W-85W. THIS FRONT WILL GRADUALLY BECOME DIFFUSE BY
WED NIGHT. AN EARLIER QUIKSCAT PASS SHOWED NELY WINDS OF 20 KT
BEHIND THE FRONT OVER THE NW CARIBBEAN. TYPICAL ISOLATED TSTMS
ARE ALSO NOTED OVER PANAMA AND COSTA RICA...ASSOCIATED WITH LOW
LEVEL CONVERGENCE. SCATTERED MODERATE CONVECTION IS NEAR THE
CARIBBEAN PLAINS OF NICARAGUA. A DIFFLUENT PATTERN ALOFT...
ASSOCIATED WITH A BROAD UPPER RIDGE THAT COVERS MOST OF THE
BASIN...IS ENHANCING THIS CONVECTIVE ACTIVITY. AN UPPER LOW
REMAINS JUST E OF THE LESSER ANTILLES IN THE TROPICAL ATLC. NLY
FLOW AND DRY AIR BETWEEN THESE TWO UPPER FEATURES IS KEEPING THE
E CARIBBEAN MOSTLY TRANQUIL. A WEAK SFC TROUGH IS MOVING ACROSS
PUERTO RICO HELPING TO INDUCE SOME CONVECTIVE ACTIVITY MAINLY
OVER THE W AND NW PORTION OF THE ISLAND WHERE DOPPLER RADAR
DEPICTS SCATTERED SHOWERS AND A FEW TSTMS. THE LAST FEW VIS SAT
IMAGERY SHOWED A SWIRL OF LOW CLOUDS ASSOCIATED WITH THE TROUGH
NEAR 21N66W. THIS TROUGH IS EXPECTED TO MOVE AWAY FROM PUERTO
RICO TOMORROW.

ATLANTIC OCEAN...
A WEAKENING RIDGE DOMINATES THE W ATLC AND THE NW/CENTRAL
BAHAMAS. AHEAD OF THIS RIDGE...THERE IS A STATIONARY FRONT THAT
ENTERS THE FORECAST AREA NEAR 31N58W...THEN CONTINUES TO THE
TURKS AND CAICOS ISLANDS INTO THE CARIBBEAN SEA. THE FRONTAL
BOUNDARY HAS FRACTIONED...PARTICULARLY OVER THE SE BAHAMAS WITH
THE SHOWER ACTIVITY NOW MORE CONCENTRATED N OF 25N BETWEEN 60W
AND 70W. EARLIER SCATTEROMETER DATA SHOWED NE WINDS OF NEAR 20
KT WITHIN 120NM BEHIND THE FRONT. THE NEXT COLD FRONT IS
EXPECTED TO MOVE OFF THE NE FL COAST TONIGHT. AN INCREASE IN
WINDS AND SEAS WILL FOLLOW THE FRONT.

THE NEXT WEATHER FEATURE OF INTEREST IS THE OCCLUDED 1000 MB SFC
LOW THAT IS JUST ENTERING THE FORECAST AREA. SHOWERS AND TSTMS
REMAIN POORLY ORGANIZED IN ASSOCIATION WITH THIS NON-TROPICAL
LOW PRESSURE AREA CENTERED ABOUT 630 NM SOUTHWEST OF THE AZORES.
TROPICAL OR SUBTROPICAL DEVELOPMENT OF THIS SYSTEM IS NOT
EXPECTED AS THE LOW MOVES TOWARD THE SOUTHEAST AT 5 TO 10 MPH.
THE ASSOCIATED COLD FRONT ENTERS THE AREA NEAR 31N26W AND
CONTINUES SW TO 23N35W...THEN W AND NW TO 27N48W. SCATTERED
MODERATE CONVECTION IS WITHIN 50 NM EITHER SIDE OF FRONT EAST OF
30W. A PRE-FRONTAL TROUGH EXTENDS ALONG 28N24W 21N30W 16N41W.
THE TAIL END OF THE TROUGH IS GENERATING CLUSTERS OF MODERATE TO
ISOLATED STRONG CONVECTION NEAR 17N38W AND 15N42W. WEAK SFC
RIDGING DOMINATES THE REMAINDER OF THE E ATLC...EXTENDING S
THROUGH THE CANARY ISLANDS. SCATTERED SHOWERS/TSTMS ALSO NOTED
OVER THE TROPICAL ATLC FROM 14N-18N BETWEEN 27W-34W...ASSOCIATED
WITH DIFFLUENT FLOW ALOFT. ANOTHER SFC TROUGH...WHICH APPEARS TO
BE PART OF AN OLD FRONT RUNS ALONG 30N54W 25N55W 22N50W. THIS
TROUGH IS ALSO ENHANCING THE DEVELOPMENT OF SCATTERED SHOWERS
MAINLY N OF 24N. ALOFT...A TROUGH/RIDGE/TROUGH/RIDGE PATTERN
DOMINATES THE DISCUSSION AREA.

$$
GR





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