[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 052342
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST MON NOV 05 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 TROPICAL WAVE IS LOCATED ALONG 45W SOUTH OF 19N...MOVING W 10
TO 15 KT. A 1008 MB LOW IS LOCATED ALONG THE WAVE AXIS AT 13N.
SCATTERED MODERATE CONVECTION IS ASSOCIATED WITH THE LOW CENTER
FROM 12N-15N BETWEEN 42W-47W. A GOOD SURGE OF MOISTURE IS SEEN
ASSOCIATED WITH THIS FEATURE IN THE UW-CIMSS TPW PRODUCT.

ANOTHER TROPICAL WAVE IS JUST ENTERING THE E CARIBBEAN. IT AXIS
IS ALONG 61W/62W...MOVING W 10 TO 15 KT. THE WAVE IS INTERACTING
WITH AN UPPER LOW CENTERED NEAR 17N59W. A LARGE AREA OF LAYERED
CLOUDS WITH EMBEDDED SHOWERS IS DISPLACED WELL E OF THE WAVE
AXIS...AND IS MAINLY RELATED TO THE UPPER-LEVEL FEATURE. SWLY
WINDS AHEAD OF THE UPPER LOW ARE TRANSPORTING TROPICAL MOISTURE
FROM N SOUTH AMERICA INTO THE TROPICAL ATLC. A SMALL CLUSTER OF
MODERATE CONVECTION IS NEAR 12N51W.

...THE ITCZ...

ITCZ AXIS IS CENTERED ALONG 11N14W 7N30W 8N46W 8N61W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS WITHIN AROUND 100 NM N OF
AXIS BETWEEN 25W-30W. SCATTERED MODERATE CONVECTION IS FROM
3N-6N BETWEEN 38W-42W.

DISCUSSION...

GULF OF MEXICO...
A BROAD MIDDLE/UPPER LEVEL TROUGH DOMINATES THE FLOW ACROSS THE
REGION WITH THE BASE OF THIS TROUGH REACHING WESTERN CUBA. A JET
STREAM BRANCH IS ON THE SOUTHERN PERIPHERY OF THIS TROUGH WITH
CORE WINDS OF 75-85 KT. THIS JET STREAM CROSSES SOUTH FLORIDA
AND THE NW BAHAMAS...THEN CONTINUES NEWD ACROSS THE CENTRAL
ATLC. WATER VAPOR IMAGERY INDICATES VERY DRY AIR RESULTING IN
STRONG SUBSIDENCE OVER THE GULF. AN UPPER-LEVEL HIGH IS LOCATED
OVER CENTRAL MEXICO WHERE A DRY MID/UPPER LEVEL ATMOSPHERE
PREVAILS. AT THE SURFACE...A WEAK 1019 MB HIGH IS LOCATED NEAR
30N87W EXTENDING A RIDGE SW TO THE BAY OF CAMPECHE. THIS FEATURE
IS FORECAST TO MOVE EAST AND WEAKEN AS A NEW COLD FRONT ENTERS
THE NORTHERN GULF WATERS TUE AFTERNOON. STRONG CONTINENTAL HIGH
PRES WILL BUILD IN BEHIND THE FRONT BRINGING AN INCREASE IN
WINDS AND SEAS TUE NIGHT THROUGH WED NIGHT. CURRENTLY...LIGHT E
TO SE WINDS DOMINATES THE AREA.

CARIBBEAN SEA...
A STATIONARY FRONT REMAINS OVER THE WESTERN CARIBBEAN AND
EXTENDS FROM NEAR CABO GRACIAS A DIOS IN NICARAGUA TO THE
EASTERN TIP OF CUBA...THEN CONTINUES ACROSS THE SE BAHAMAS AND
THE ATLC. THE TAIL END OF THE FRONT IS GENERATING SCATTERED
SHOWERS AND TSTMS...PARTICULARLY OVER NE HONDURAS AND THE N
PORTION OF NICARAGUA...INCLUDING THE COASTAL WATERS. THIS FRONT
WILL GRADUALLY BECOME DIFFUSE THROUGH MIDWEEK. AN EARLIER
QUIKSCAT PASS SHOWED NELY WINDS OF 20 TO 25 KT BEHIND THE FRONT
OVER THE NW CARIBBEAN. A 1007 MB SFC LOW IS NEAR 11N76W. A SWIRL
OF LOW CLOUDS IS ASSOCIATED WITH THE CIRCULATION OF THE LOW.
THIS SYSTEM IS PRODUCING ISOLATED POCKETS OF SHOWERS AND TSTMS
OVER THE SW CARIBBEAN. A SFC TROUGH RUNS FROM THE LOW TO 16N80W.
FURTHER EAST...THERE IS A TROPICAL WAVE INTERACTING WITH AND
UPPER-LEVEL LOW. SEE TROPICAL WAVE SECTION FOR DETAILS.
ALOFT...A RIDGE ANCHORED ON A HIGH LOCATED BETWEEN HAITI AND
JAMAICA DOMINATES MOST OF THE BASIN. THIS FEATURE IS HELPING TO
INDUCE SOME SHOWER ACTIVITY ALONG THE FRONTAL BOUNDARY. NLY
WINDS BETWEEN THIS HIGH AND AN UPPER LOW JUST E OF THE LEEWARD
ISLANDS NEAR 17N59W ARE ADVECTING DRY AIR OVER THE EASTER
CARIBBEAN.

ATLANTIC OCEAN...
HIGH PRES CENTERED OVER THE NE GULF ALSO EXTENDS A RIDGE OVER
FLORIDA...THE W ATLC AND THE NW/CENTRAL BAHAMAS. LIGHT WINDS...
COOL TEMPERATURES AND QUIET WEATHER PREVAILS UNDER THE INFLUENCE
OF THIS SYSTEM. AHEAD OF THIS RIDGE...THERE IS A STATIONARY
FRONT THAT ENTERS THE FORECAST AREA NEAR 32N60W...THEN CONTINUES
TO THE SE BAHAMAS INTO THE CARIBBEAN SEA. A 100 NM WIDE BAND OF
MAINLY LOW CLOUDS WITH SCATTERED SHOWERS IS ASSOCIATED WITH THE
FRONT. SCATTERED TO BROKEN COLD AIR STRATOCUMULUS CLOUDS ARE
FOUND BEHIND THE FRONT. AN OCCLUDED SURFACE LOW IS LOCATED JUST
NORTH OF THE AREA NEAR 33N35W WITH THE ATTACHED COLD FRONT
AFFECTING THE CENTRAL ATLC ALONG 31N28W 25N38W 31N49W. A NARROW
BAND OF SHOWERS IS RELATED TO THE COLD FRONT. A SFC TROUGH...
REMNANTS OF AN OLD FRONTAL BOUNDARY...IS WITHIN 240 NM OF THE
ABOVE MENTIONED COLD FRONT. A WEAK SFC RIDGE DOMINATES THE
CANARY/MADEIRA ISLANDS. IN THE UPPER LEVELS...A SUBTROPICAL JET
STREAM WITH CORE WINDS OF 75-85 KT IS OVER THE W ATLC. AN UPPER
RIDGE EXTENDS FROM THE CARIBBEAN THROUGH THE WEST-CENTRAL ATLC
TO BEYOND 32W53W. A CUT-OFF LOW IS NEAR 33N36W WITH A TROUGH
EXTENDING SW TO NEAR 18N40W. THIS LOW/TROUGH IS SUPPORTING THE
OCCLUDED LOW/COLD FRONT PREVIOUSLY MENTIONED. A DIFFLUENT
PATTERN ALOFT BETWEEN THE CUT-OFF LOW AND AN UPPER-LEVEL HIGH
CENTERED NEAR THE GUYANAS IS ENHANCING AN AREA OF MODERATE TO
ISOLATED STRONG CONVECTION IN THE EAST-CENTRAL ATLC FROM 12N-16N
BETWEEN 34W-40W.

$$
GR





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