[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 092344
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST FRI NOV 09 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...
TROPICAL WAVE IS ALONG 49W S OF 13N MOVING W 20 KT. THIS WAVE
APPEARS TO BE MOVING FASTER THAN AN AVERAGE TROPICAL WAVE AND IS
ALONG THE LEADING EDGE OF A DENSE AREA OF AFRICA DUST. THE
HOVMOLLER DIAGRAM SHOWS THE WWD PROPAGATION OF THE WAVE.
CLUSTERS OF SCATTERED MODERATE CONVECTION ARE BEHIND THE WAVE
AXIS FROM 5N-9N WEST OF 43W. COMPUTER MODELS HAVE MOISTURE FROM
THIS TROPICAL WAVE AFFECTING THE LESSER ANTILLES TOMORROW AND
THE UK/US VIRGIN ISLANDS AND PUERTO RICO SUNDAY INTO MONDAY.

TROPICAL WAVE IS ALONG 63W S OF 12N MOVING W NEAR 15 KT WITH NO
ASSOCIATED DEEP CONVECTION. A WEAK SIGNATURE IS APPARENT ON THE
TOTAL PRECIPITABLE WATER IMAGERY.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 6N10W 5N30W 7N47W 5N55W. BESIDES FOR
THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVE...SCATTERED
MODERATE CONVECTION IS WITHIN 50 NM S OF THE AXIS BETWEEN
25W-33W. SIMILAR CONVECTION IS WITHIN 60 NM N OF AXIS BETWEEN
37W-42W.

DISCUSSION...

GULF OF MEXICO...
THE ENTIRE GULF IS UNDER THE INFLUENCE OF A 1020 MB HIGH PRES
CENTERED OVER SE LOUISIANA. FLOW AROUND THIS FEATURE CONTINUES
TO PRODUCE FAIR CONDITIONS AND COLD AIR STRATOCUMULUS ACROSS THE
MAJORITY OF THE REGION. RETURN FLOW ON THE WESTERN SIDE OF THIS
HIGH IS GENERATING THIN LINES OF SHOWERS OVER THE NW GULF INTO E
TEXAS AND SW LOUISIANA. THIN LINES OF DEPICTED AS A SURFACE
TROUGH EXTENDING FROM 24N97W TO 20N96W WITH POSSIBLE ISOLATED
SHOWERS WITHIN 30 NM OF THE TROUGH. LIGHT TO MODERATE WINDS
AROUND THE HIGH WILL PERSIST THROUGHOUT THE WEEKEND. ALOFT...
FAIRLY UNIFORM NW FLOW BETWEEN RIDGE OVER MEXICO AND LONG WAVE
UPPER TROUGH OVER THE EASTERN U.S./W ATLC IS OVER THE GULF. DRY
MID/UPPER AIR DOMINATES THE REGION...AIDING IN THE PLEASANT
CONDITIONS.

CARIBBEAN SEA...
DISORGANIZED SHOWERS AND THUNDERSTORMS ASSOCIATED WITH A SFC
TROUGH EXTENDING BETWEEN JAMAICA AND THE W PANAMA/COSTA RICA
BORDER REMAIN OVER THE SOUTHWESTERN CARIBBEAN SEA. UPPER-LEVEL
WINDS ARE NOT FAVORABLE FOR DEVELOPMENT AT THIS TIME. CLUSTERS
OF MODERATE TO STRONG CONVECTION ARE OVER THE SW CARIBBEAN FROM
10N-14N BETWEEN 76W-81W. SIMILAR CONVECTION IS ON THE PACIFIC
SIDE ALONG THE COAST OF PANAMA...AND ALSO OVER N COLOMBIA AND
WESTERN VENEZUELA. THE COLOMBIAN LOW IS AIDING IN THE FORMATION
OF THIS CONVECTIVE ACTIVITY. MODERATE TO STRONG N TO NE WINDS OF
20-25 KT ARE BLOWING ON THE WEST SIDE OF THE SFC TROUGH. AN
EARLIER QUIKSCAT PASS ALONG WITH A FEW SHIP OBSERVATIONS
CONFIRMED THESE FORCE WINDS. MOST OF THE COMPUTER MODELS SUGGEST
THE DEVELOPMENT OF A SFC LOW IN THIS AREA. A BROAD UPPER RIDGE
COVERS THE CARIBBEAN ANCHORED BY AN UPPER HIGH INLAND OVER SOUTH
AMERICA AND IS ADVECTING TROPICAL MOISTURE OVER THE W CARIBBEAN
ENHANCING THE ABOVE MENTIONED ACTIVITY. ANOTHER SFC TROUGH...
REMNANTS OF A FRONTAL BOUNDARY IS ENHANCING SOME SHOWER/TSTM
ACTIVITY OVER HISPANIOLA AND PUERTO RICO.

ATLANTIC OCEAN...
A SURFACE TROUGH ENTERS THE REGION NEAR 31N75W AND EXTENDS TO
27N79W. A LINE OF MAINLY LOW CLOUDS WITH ISOLATED SHOWERS IS
ASSOCIATED WITH THIS TROUGH. ANOTHER SFC TROUGH...PREVIOUSLY THE
TAIL END OF A COLD FRONT...RUNS FROM A 1010 MB LOW LOCATED N OF
AREA NEAR 36N55W TO NEAR HISPANIOLA. THIS FEATURE IS PRODUCING A
BROAD AREA OF CLOUDINESS WITH EMBEDDED SHOWERS AND TSTMS MAINLY
N OF 25N BETWEEN 51W-56W. THIS CONVECTIVE ACTIVITY IS BEING
ENHANCED BY UPPER LEVEL DIFFLUENCE ALONG AN UPPER RIDGE AXIS
THAT EXTENDS FROM THE CARIBBEAN ACROSS THE LEEWARD ISLANDS TO
BEYOND 32N49W. THE THIRD SURFACE TROUGH EXTENDS FROM A 1007 MB
LOW SOUTH OF THE AZORES TO 31N22W THEN SW TO 25N35W. MOST OF THE
SHOWER/TSTM ACTIVITY RELATED TO THIS TROUGH IS N OF THE FORECAST
AREA. THE LAST FEW VIS SATELLITE PICTURES INDICATE A LARGE AREA
OF AFRICAN DUST COVERING THE E ATLC S OF 26N E OF 41W. THE
SAHARAN AIR LAYER FROM CIMSS DEPICTS THE WWD PROPAGATION OF THIS
SURGE OF DRY/STABLE AIR ON THE HEELS OF A TROPICAL WAVE LOCATED
NEAR 49W. AN UPPER LOW IS JUST SOUTH OF THE AZORES NEAR 35N28W
WHILE AN UPPER RIDGE COVERS THE REMAINDER OF THE ATLC FORECAST
AREA AND THE WEST COAST OF AFRICA.

$$
GR




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