[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 282346
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE OCT 28 2008

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS
OF SOUTH AMERICA...AND 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 ALONG 50W S OF 16N MOVING W 10-15 KT. THE
CIMSS VORTICITY PRODUCT SUPPORTS THE WAVE POSITION INDICATED.
CONVECTION IS MAINLY WITHIN THE ITCZ. A CLUSTER OF MODERATE TO
ISOLATED STRONG CONVECTION COVERS THE AREA FROM 9N-12N BETWEEN
45W-47W. THIS WAVE IS INTERACTING WITH AN UPPER-LEVEL LOW
LOCATED AHEAD OF THE WAVE AXIS NEAR 13N53W.

A TROPICAL WAVE IS OVER THE LESSER ANTILLES ALONG 61W GENERATING
SOME SHOWER ACTIVITY PARTICULARLY BETWEEN GUADELOUPE AND SAINT
VINCENT INCLUDING ALSO BARBADOS. ACCORDING TO THE GFS MODEL...
THE WAVE WILL SLOWLY MOVE WWD ACROSS THE EASTERN CARIBBEAN
TONIGHT AND TOMORROW CROSSING MAINLY SOUTH OF PUERTO RICO AND
THE VIRGIN ISLANDS.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 11N14W 8N24W 9N36W 9N45W 10N60W. A
SURFACE TROUGH IS EMBEDDED WITHIN THE ITCZ AND RUNS FROM 16N38W
TO 6N39W. A 1011 MB SFC LOW IS ALONG THE TROUGH AXIS NEAR 11N.
SHOWER ACTIVITY ASSOCIATED WITH THIS LOW REMAINS DISORGANIZED
AND UPPER-LEVEL WINDS ARE BECOMING LESS CONDUCIVE. THEREFORE...
ANY DEVELOPMENT OF THIS SYSTEM SHOULD BE SLOW TO OCCUR AS IT
MOVES SLOWLY WEST-NORTHWESTWARD OVER THE NEXT COUPLE OF DAYS.
ELSEWHERE...CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG
CONVECTION ARE FROM 7N-11N BETWEEN 21W-28W. SIMILAR CONVECTION
IS NEAR 8N33W.

...DISCUSSION...

GULF OF MEXICO...
A DEEP LAYERED TROUGH EXTENDS FROM THE NE CONUS TO THE NORTHERN
BAHAMAS WHILE A RIDGE IS BUILDING ALONG THE MEXICAN COAST/FAR
WEST GULF. UNDER THIS PATTERN...STRONG WLY FLOW PREVAILS ACROSS
MOST OF THE GULF REGION AND THE STATE OF FLORIDA. THE ASSOCIATED
COLD FRONT IS OUT OF AREA OVER THE W ATLC...EASTERN CUBA AND THE
NW CARIBBEAN. A SURFACE RIDGE CONTINUES TO BUILD IN BEHIND THE
FRONT ANCHORED ON A 1035 MB HIGH LOCATED NEAR THE TEXAS/
OKLAHOMA BORDER. BROKEN TO OVERCAST COLD AIR STRATOCUMULUS
CLOUDS COVER THE GULF SOUTH OF 26N. THE COOL AIR IS ALSO BAKING
UP AGAINST THE E SLOPE OF THE SIERRA MADRE AND A STATIONARY
FRONT IS INDICATED THERE. NLY WINDS OF 20 TO 25 KT ARE BLOWING
ACROSS THE GULF. AN UNSEASONABLY COLD NIGHT WITH RECORD LOW
LIKELY AT SOME LOCALES IS EXPECTED IN SOUTH FLORIDA UNDER MOSTLY
CLEAR SKIES AND DIMINISHING WINDS.

CARIBBEAN SEA...
A STRONG COLD FRONT OVER THE WEST ATLC AND THE SE BAHAMAS ENTERS
THE CARIBBEAN SEA THROUGH EASTERN CUBA THEN CONTINUES SW
CROSSING JUST SOUTH OF THE CAYMAN ISLANDS TO THE GULF OF
HONDURAS NEAR 16N88W. A REINFORCING COLD FRONT IS OVER CENTRAL
CUBA. A 100 NM WIDE BAND OF MULTILAYERED CLOUDS WITH SCATTERED
SHOWERS AND TSTMS IS ASSOCIATED WITH THE MAIN FRONT OVER THE
CARIBBEAN SEA PARTICULARLY SOUTH OF THE CAYMAN ISLANDS. THE
FRONT IS ALSO PRODUCING SOME SHOWER ACTIVITY OVER HONDURAS AND
EASTERN CUBA. COLD AIR STRATOCUMULUS CLOUDS NOTICED BEHIND THE
COLD FRONT IMPLY THAT A COOL AND DRIER AIR MASS HAS INVADED ALSO
THE NW CARIBBEAN AND WESTERN CUBA. A TROPICAL WAVE IS OVER THE
LESSER ANTILLES. SEE ABOVE. ALOFT...AN UPPER-LEVEL RIDGE
ANCHORED IN THE W ATLC NE OF PUERTO RICO DOMINATES THE AREA
GIVING THE CARIBBEAN E OF THE FRONT STRONG SUBSIDENCE AND DRY/
STABLE ATMOSPHERE. A WEAK SFC TROUGH IS BETWEEN THE ISLANDS OF
VIEQUES AND CULEBRA AND EASTERN PUERTO RICO. ONLY ISOLATED
SHOWERS ARE ASSOCIATED WITH THIS TROUGH. THE STRONG COLD WILL
CONTINUE TO MOVE SE AND STALL FROM THE WINDWARD PASSAGE TO THE
HONDURAN/NICARAGUAN BORDER LATE WED. N TO NE WIND OF 20-25 KT
ARE BLOWING W OF THE FRONT WHILE NE TO E WINDS OF 10-15 KT ARE
AHEAD OF THE FRONT. MODERATE TRADE WINDS DOMINATE THE REMAINDER
OF THE AREA REACHING 25 KT NEAR THE COLOMBIAN COAST.

ATLANTIC OCEAN...
THE DEEP LAYERED TROUGH THAT COVERS THE E US EXTENDS OVER THE W
ATLC W OF 70W TO THE NORTHERN BAHAMAS PRODUCING STRONG SWLY
FLOW. THESE WINDS ARE ADVECTING DEEP TROPICAL MOISTURE FROM THE
GULF OF HONDURAS THROUGH CENTRAL CUBA INTO THE W ATLC. THE UPPER
TROUGH SUPPORTS A STRONG COLD FRONT WHICH EXTENDS FROM THE
BERMUDA ISLAND SW TO EASTERN CUBA AND THE NW CARIBBEAN. A
SECONDARY FRONT IS BEHIND AND ENTERS THE AREA NEAR 31N68W THEN
CONTINUES SW TO CENTRAL CUBA. THIS FRONT HAS DISSIPATED OVER THE
CARIBBEAN SEA AND IS EXPECTED TO MERGE WITH THE MAIN FRONT
TONIGHT. MODERATE TO STRONG NWLY WINDS ARE NOTED BEHIND THE
SECONDARY FRONT. BROAD UPPER RIDGE COVERS THE REMAINDER OF THE W
ATLC AND INTO THE CENTRAL ATLC ANCHORED NE OF PUERTO RICO NEAR
24N62W. UPPER DIFFLUENCE BETWEEN THIS UPPER-LEVEL HIGH AND AN
UPPER-LEVEL TROUGH OVER THE CENTRAL ATLC IS HELPING TO INDUCE
SOME SHOWER ACTIVITY N OF 22N BETWEEN 48W-54W. AT THE
SURFACE...A TROUGH IS ANALYZED IN THIS AREA AND EXTENDS FROM
22N55W ALL THE WAY NE THEN N TO BEYOND 31N47W. A STRONG
UPPER-LEVEL RIDGE CENTERED JUST SOUTH OF THE CAPE VERDE ISLANDS
COVERS THE DEEP TROPICS EAST OF 45W AND IS ENHANCING CONVECTION
ALONG THE ITCZ.

$$
GR




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