[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 111120
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST SUN NOV 11 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 58W S OF 13N MOVING W NEAR 20 KT. WAVE
REMAINS EMBEDDED WITHIN A SURGE OF AFRICAN DUST AND IS MOVING
OVER EASTERN PORTION OF SOUTH AMERICA. SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS ARE S OF 11N TO JUST INLAND OVER GUYANA
BETWEEN 57W-60W.

TROPICAL WAVE IS ALONG 69W S OF 14N MOVING W NEAR 10 KT. WAVE IS
MOSTLY INLAND OVER SOUTH AMERICA AND HAS NO ASSOCIATED
SHOWERS/CONVECTION.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 9N10W 6N20W 7N40W 5N50W 6N56W.
SCATTERED MODERATE/STRONG CONVECTION COVERS THE AREA FROM 3N-10N
BETWEEN 18W-32W AND ALONG THE COAST OF LIBERIA AFRICA WITHIN 60
NM OF LINE FROM 4N8W TO 6N12W. CLUSTERS OF SCATTERED MODERATE/
ISOLATED STRONG CONVECTION ARE FROM 2N-9N BETWEEN 6W-18W
INCLUDING THE COASTAL REGIONS OF SW AFRICA AND WITHIN 150 NM N
OF THE ITCZ AXIS FROM 32W-37W.

DISCUSSION...

GULF OF MEXICO...
WEAKENING BROAD UPPER RIDGE EXTENDS ALONG THE E COAST OF MEXICO
AND OVER THE W GULF ALONG 97W TO INLAND OVER THE US MOVING
TOWARD THE MISSISSIPPI VALLEY. UPPER LEVEL TROUGH IN THE W ATLC
COVERS THE FAR E GULF E OF 85W WITH DRY STABLE AIR COVERS THE
ENTIRE GULF. A SURFACE RIDGE EXTENDS OVER THE GULF INTO THE W
ATLC ANCHORED OVER WEST VIRGINIA GIVING THE W GULF RETURN FLOW
AND PRODUCING SOME WIDELY ISOLATED LOW LEVEL SHOWERS...THUS
MOSTLY FAIR SKIES DOMINATE THE GULF THIS MORNING.

CARIBBEAN SEA...
THE MAIN FOCUS OF THIS MORNING IS A 1008 MB LOW IN THE SW
CARIBBEAN NEAR 11N79W WITH A SURFACE TROUGH EXTENDING NW TO SW
OF THE CAYMAN ISLANDS NEAR 18N83W. A SURFACE TROUGH FROM THE
W/CENTRAL ATLC EXTENDS ACROSS HAITI TO S OF JAMAICA 17N77W. THIS
IS GIVING THE AREA SCATTERED SHOWERS/ISOLATED THUNDERSTORMS
WITHIN 90/120 NM OF A LINE FROM JAMAICA NEAR 18N76W ALONG 13N81W
TO ALONG THE COAST OF PANAMA TO S NICARAGUA NEAR 9N83W. UPPER
RIDGE COVERS THE W CARIBBEAN ANCHORED NEAR 14N72W WHILE AN UPPER
RIDGE COVERS THE E CARIBBEAN ANCHORED OVER THE LESSER ANTILLES
NEAR 15N60W. THIS IS PRODUCING AN UPPER LEVEL INVERTED TROUGH
OVER THE CENTRAL CARIBBEAN ALONG 69W/70W AND GENERATING CLUSTERS
OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM HISPANIOLA TO
SOUTH AMERICA BETWEEN 70W-76W AND S OF 14N BETWEEN 63W-68W. THE
SURFACE LOW IS EXPECTED TO DRIFT WESTWARD AND WEAKEN AS IT MOVES
INLAND OVER CENTRAL AMERICA AND NO SIGNIFICANT DEVELOPMENT IS
ANTICIPATED. HOWEVER...IT COULD PRODUCE LOCALLY HEAVY RAINFALL
OVER PORTIONS OF PANAMA...COSTA RICA...AND NICARAGUA TODAY AND
OVER THE NEXT FEW DAYS.

ATLANTIC OCEAN...
BROAD UPPER TROUGH COVERS THE W ATLC WITH THE UPPER LOW OVER THE
CANADIAN MARITIMES AND EXTENDING W INTO THE FAR E GULF OF
MEXICO. THE ASSOCIATED COLD FRONT EXTENDS E BERMUDA BUT N OF THE
REGION. A POST-FRONTAL SURFACE TROUGH EXTENDS ALONG 32N67W SW TO
28N77W WITH BROKEN TO OVERCAST LOW/MID CLOUDS WITH ISOLATED
SHOWERS N OF A LINE FROM 32N64W TO THE FLORIDA COAST NEAR PALM
BEACH. A JET STREAM WITH WINDS ESTIMATED TO BE 70 TO 90 KT
EXTENDS ALONG THE EASTERN EDGE OF THE UPPER TROUGH FROM NEAR
23N74W TO BEYOND 32N54W. A REMNANT STATIONARY FRONT FROM AN
UPPER SYSTEM THAT IS WELL N OF THE REGION EXTENDS INTO THE
W/CENTRAL ATLC NEAR 32N48W SW TO 25N58W CONTINUING AS A SURFACE
TROUGH ALONG 20N70W THEN ACROSS HAITI INTO THE CARIBBEAN.
SCATTERED SHOWERS AND WIDELY ISOLATED THUNDERSTORMS ARE WITHIN
150 NM OF THE FRONT AND WITHIN 120 NM OF SURFACE TROUGH TO
ACROSS HISPANIOLA. AN UPPER HIGH IS OVER THE LESSER ANTILLES
NEAR 15N60W EXTENDING AN UPPER RIDGE NE ALONG 23N52W TO BEYOND
32N37W. A WEAKENING UPPER TROUGH IS UNDERCUTTING THE UPPER RIDGE
ABOVE EXTENDING FROM 18N44W TO 9N48W. A NARROW UPPER TROUGH IS
OVER THE FAR E ATLC N OF 23N E OF 25W TO THE COAST OF W AFRICA
WITH NO ASSOCIATED SURFACE FEATURES. ZONAL WESTERLY UPPER FLOW
DOMINATES THE REMAINDER OF THE TROPICAL ATLC S OF 18N E OF 40W.
BROAD AREA OF AFRICAN DUST COVERS THE TROPICS W OF 30W N OF THE
ITCZ AND INTO THE SE CARIBBEAN S OF 15N E OF 63W. THE FIRST
VISIBLE SATELLITE IMAGES SHOW THE AREA E OF 30W IS BEGINNING TO
CLEAR OF DUST.

$$
WALLACE





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