[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 031751
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT WED OCT 03 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURES...

AS OF 1500 UTC...A 1005 MB SFC LOW IS ANALYZED IN THE GULF OF
MEXICO NEAR 25N87W. SHOWER ACTIVITY ASSOCIATED WITH THIS
NON-TROPICAL AREA OF LOW PRESSURE HAS BECOME LESS ORGANIZED
TODAY...AND THE RECONNAISSANCE AIRCRAFT MISSION SCHEDULED FOR
THIS AFTERNOON HAS BEEN CANCELLED. HOWEVER...THIS SYSTEM STILL
HAS SOME POTENTIAL TO EVOLVE INTO A TROPICAL OR SUBTROPICAL
DEPRESSION DURING THE NEXT DAY OR TWO AS IT MOVES TO THE
WEST-NORTHWEST OR NORTHWEST AT ABOUT 10 MPH. A SWIRL OF LOW
CLOUDS DEFINES THE PRESENCE OF THE LOW WITH SCATTERED SHOWERS
AND TSTMS WITHIN 150 NM NW OF CENTER.

SATELLITE IMAGERY AND SURFACE OBSERVATIONS INDICATE THAT A BROAD
AREA OF LOW PRESSURE IS FORMING A COUPLE HUNDRED MILES EAST OF
THE NORTHWESTERN BAHAMAS. UPPER-LEVEL WINDS HAVE BECOME
FAVORABLE FOR FURTHER DEVELOPMENT OF THIS SYSTEM...AND A
TROPICAL DEPRESSION COULD FORM IN THIS AREA DURING THE NEXT DAY
OR TWO. THIS SYSTEM IS EXPECTED TO MOVE LITTLE TODAY...BUT BEGIN
A SLOW WESTWARD MOTION ON THURSDAY OR FRIDAY. A CLUSTER OF
MODERATE TO ISOLATED STRONG CONVECTION IS WITHIN 60 NM OF
22N69.5W.

AN AREA OF LOW PRESSURE ANALYZED 1012 MB...ASSOCIATED WITH A
TROPICAL WAVE IS LOCATED ABOUT 1130 NM EAST OF THE SOUTHERN
WINDWARD ISLANDS. ALTHOUGH THIS SYSTEM IS SHOWING SIGNS OF
ORGANIZATION...UPPER-LEVEL WINDS ARE EXPECTED TO GRADUALLY
BECOME LESS FAVORABLE FOR DEVELOPMENT OVER THE NEXT COUPLE OF
DAYS. THE WAVE AXIS IS ALONG 40W/41W. SCATTERED MODERATE
CONVECTION IS FROM 7N-11N BETWEEN 37W-43W.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 40W/41W S OF 15N MOVING W 15 KT. SEE
SPECIAL FEATURES ABOVE.

TROPICAL WAVE IS ALONG 48W S OF 14N MOVING W 10-15 KT. WEAK LOW
LEVEL INVERTED-V CURVATURE IS NOTED ON SATELLITE IMAGERY WITH NO
ASSOCIATED DEEP CONVECTION.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 9N13W 8N25W 9N38W 8N47W 8N62W. MOST
OF THE CONVECTION ALONG THE ITCZ IS FOUND NEAR THE INTERSECTION
OF THE TROPICAL WAVE ALONG 40W/41W WITH A LOW NEAR 9N40W.
SCATTERED MODERATE CONVECTION IS 130 NM S OF THE AXIS BETWEEN
17W-21W. CLUSTERS OF MODERATE TO ISOLATED STRONG CONVECTION ARE
INLAND OVER WEST AFRICA FROM 9N-14N BETWEEN 7W-14W.

DISCUSSION...

GULF OF MEXICO...
THE MAIN SHOWER ACTIVITY IN THE GULF OF MEXICO IS ASSOCIATED
WITH THE NON-TROPICAL AREA OF LOW PRES LOCATED NEAR 25N87W. SEE
SPECIAL FEATURES FOR MORE DETAILS. A WEAK SFC RIDGE DOMINATES
THE FAR WEST GULF AND EASTERN MEXICO. THE SFC PRES GRADIENT IS
WEAKER IN THE WRN GULF WITH WINDS MOSTLY 15 KT OR LESS. ALOFT...
AN UPPER-LEVEL LOW DOMINATES ALMOST THE ENTIRE GULF WITH AN
UPPER HIGH LOCATED OVER NE MEXICO. STRONG SW WINDS ON THE EAST
SIDE OF THE UPPER LOW IS KEEPING THE CONVECTION SHEARED FROM THE
LOW LOCATED OVER THE SE GULF. VERY DRY MID TO UPPER AIR IS
ROTATING AROUND THE PERIPHERY OF THE UPPER-LEVEL LOW ANCHORED
OVER THE BAY OF CAMPECHE/SOUTH MEXICO. WV IMAGERY SHOWS ANOTHER
UPPER-LOW SPINNING OVER THE NE CORNER OF THE GULF.

CARIBBEAN SEA...
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION PERSISTS SOUTH
OF CUBA THIS AFTERNOON...MOST CONCENTRATED BETWEEN JAMAICA AND
EASTERN CUBA. A DIFFLUENT PATTERN ALOFT ASSOCIATED WITH A STRONG
UPPER HIGH SITUATED OVER THE CENTRAL BAHAMAS IS ENHANCING THIS
CONVECTIVE ACTIVITY. THIS UPPER FEATURE COVERS MOST OF THE
BASIN. THE FAR NW PORTION OF THE AREA AND THE YUCATAN CHANNEL
HAS VERY LITTLE CLOUD COVER/SHOWER ACTIVITY DUE TO A SWATH OF
DRY AIR ROTATING THROUGH THE AREA AROUND THE UPPER LOW FROM THE
GULF. UPPER LEVEL MOISTURE AND A FEW SHOWERS ARE OVER THE FAR SE
CARIBBEAN ASSOCIATED WITH AN UPPER LOW LOCATED JUST E OF
BARBADOS. SCATTERED MODERATE CONVECTION IS FOUND OVER THE SW
CARIBBEAN...PANAMA AND COSTA RICA RELATED TO THE ITCZ AND UPPER
DIFFLUENCE. SLY LOW LEVEL FLOW IS OBSERVED OVER THE WESTERN
CARIBBEAN AND CUBA DUE TO THE LOW OVER THE GULF OF MEXICO. THESE
WINDS ARE EXPECTED TO BECOME LIGHT AND VARIABLE DUE TO A WEAK
PRES GRADIENT PATTERN OVER THE REGION. LIGHT TO MODERATE E TO SE
WINDS DOMINATES THE REMAINDER OF THE AREA.

ATLANTIC OCEAN...
MESSY WEATHER PERSISTS OVER THE WRN ATLC ASSOCIATED WITH A VERY
DIFFLUENT PATTERN ALOFT...BETWEEN THE UPPER LOW OVER THE ERN
GULF AND AN UPPER HIGH OVER THE CENTRAL BAHAMAS. CURRENTLY...
SATELLITE IMAGERY AND SURFACE OBSERVATIONS INDICATE THAT A BROAD
AREA OF LOW PRESSURE IS FORMING IN THIS REGION. SEE SPECIAL
FEATURES ABOVE FOR MORE DETAILS. THIS ACTIVITY IS AFFECTING
PARTS OF THE BAHAMAS PARTICULARLY THE SE ISLANDS. FARTHER
EAST...SATELLITE IMAGERY SHOWS AN INCREASE IN CONVECTIVE
ACTIVITY ASSOCIATED WITH THE REMNANTS OF TROPICAL STORM
MELISSA..ANALYZED AS A WEAK 1015 MB LOW NEAR 21N47W. UPPER-LEVEL
WINDS ARE UNFAVORABLE FOR SIGNIFICANT REDEVELOPMENT OF THIS
SYSTEM OVER THE NEXT COUPLE OF DAYS. A COLD FRONT ENTERS THE
FORECAST AREA NEAR 31N37W THEN CONTINUES MAINLY WEST ALONG 29N
TO 58W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE WITHIN 125 NM
MAINLY S OF THE FRONT BETWEEN 50W-58W. AN UPPER-LEVEL LOW IS
PRODUCING A FEW SHOWERS AND TSTMS NEAR BARBADOS. THE REMAINDER
OF THE E ATLC SFC PATTERN IS DOMINATED BY A 1020MB HIGH NEAR
26N29W AND MOSTLY STABLE CONDITIONS. BROAD UPPER RIDGE EXTENDS
FROM OFF AFRICA TO NEAR 50W WITH THE AXIS ALONG 14W/15N.

$$
GR





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