[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 251731
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON 25 APR 2005

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE
AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING
INFORMATION IS BASED ON SATELLITE IMAGERY...WEATHER
OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...THE ITCZ...

ITCZ AXIS IS CENTERED ALONG 7N12W 3N25W 2N40W 1N50W. WIDELY
SCATTERED MODERATE ISOLATED STRONG CONVECTION IS WITHIN 60-90
NM EITHER SIDE OF THE ITCZ FROM THE WEST COAST OF AFRICA TO 13W.
WIDELY SCATTERED MODERATE CONVECTION IS WITHIN 90 NM S OF THE
ITCZ BETWEEN 21W-24W....AND WITHIN 90 NM S OF THE ITCZ BETWEEN
35W AND 42W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS
FROM THE EQUATOR TO 3N BETWEEN 46W-49W.

...DISCUSSION...

GULF OF MEXICO...
1500 UTC SURFACE ANALYSIS INDICATED A 1017 MB SFC HIGH NEAR LAKE
OKEECHOBEE FLORIDA WITH SOUTHERLY RETURN FLOW AROUND THE WEST
SIDE OF THE HIGH CENTER OVER THE ENTIRE GULF OF MEXICO. RETURN
LOW LEVEL FLOW IS PRODUCING BROKEN TO OVERCAST LOW CLOUDS OVER
THE GULF NORTH OF 27N AND WEST OF 87W...WITH WIDELY SCATTERED
SHOWERS AND ISOLATED THUNDERSTORMS ALONG THE TEXAS AND LOUISIANA
COASTS IN ASSOCIATION WITH A DISSIPATING SFC TROUGH. THE MOST
SIGNIFICANT ACTIVITY IS OVER THE HOUSTON-GALVESTON AREA AND NEAR
THE MOUTH OF THE MISSISSIPPI RIVER. IN ADDITION THE ONSHORE FLOW
IS PRODUCING OVERCAST LOW CLOUDS ALONG THE FOOTHILLS OF THE
SIERRA MADRE ORIENTAL MOUNTAINS AND THE ADJACENT GULF WATERS
WEST OF 95W NORTH OF 21N. IN THE UPPER LEVELS...A BROAD FLAT
RIDGE WITH ZONAL FLOW COVERS THE GULF OF MEXICO WITH A WEAK
SHORT WAVE EMBEDDED WITHIN THE FLOW ALONG THE LOUISIANA COAST
AND MOVING E AT 25-30 KT. A MORE SIGNIFICANT SHORT WAVE OVER
W-CENTRAL TEXAS IS EXPECTED TOP MOVE INTO THE WRN GULF OF MEXICO
WITHIN THE NEXT 18-24 HOURS.

CARIBBEAN SEA...
SURFACE AND SHIP OBSERVATIONS AS WELL AS A 1022 UTC QUIKSCAT
PASS CONTINUE TO INDICATE LIGHT SURFACE WINDS OVER MOST OF THE
CARIBBEAN SEA WITH THE EXCEPTION OF INCREASING SOUTHEASTERLY
FLOW OVER THE FAR WESTERN CARIBBEAN NEAR BELIZE. WIDELY
SCATTERED SHOWERS ARE NOTED OVER THE CARIBBEAN S OF 15N BETWEEN
67W AND 75W EXTENDING SOUTHWARD TO THE COASTS OF COLOMBIA AND
VENEZUELA. WIDELY SCATTERED SHOWERS EXTEND NORTHEASTWARD TO NEAR
THE VIRGIN ISLANDS AND THE FAR NORTHERN LEEWARD ISLANDS. WSR-88D
DATA FROM SAN JUAN PUERTO RICO INDICATED WIDELY SCATTERED
SHOWERS OVER THE CARIBBEAN SE OF THE ISLAND AS WELL AS
INCREASING SHOWER ACTIVITY OVER PUERTO RICO WITHIN THE PAST HOUR
DUE TO OROGRAPHIC LIFT. IN THE UPPER LEVELS...A SHEARING TROUGH
OVER THE W ATLANTIC EXTENDS INTO THE NORTHEAST CARIBBEAN WITH
STRONG SUBSIDENCE COVERING HISPANIOLA...THE NORTHERN CARIBBEAN
AND PUERTO RICO. ELSEWHERE OVER THE CARIBBEAN...BROAD
ANTICYCLONIC SWLY FLOW DOMINATES. THIS SWLY FLOW IS ADVECTING
MID TO UPPER LEVEL MOISTURE NEWD FROM VENEZUELA TO THE CENTRAL
WINDWARD AND LEEWARD ISLANDS. SATELLITE DERIVED WINDS INDICATE
UPPER LEVEL WINDS ARE IN THE 35-40 KT RANGE.

ATLANTIC OCEAN...
COLD FRONT EXTENDS FROM 32N64W SOUTHWESTWARD TO THE CENTRAL
BAHAMAS NEAR 22N77W. BEHIND THE FRONT...W AND NW WINDS HAVE
BEGUN TO DECREASE TO 15 KT EAST OF 70W AND BECOME LIGHT AND
VARIABLE OVER THE AREA WEST OF 73W. A 1026 MB HIGH NEAR 34N30W
DOMINATES THE E ATLANTIC. IN THE UPPER LEVELS...A
TROUGH-RIDGE-TROUGH PATTERN PREVAILS OVER THE ATLANTIC WATERS
WITH A BROAD...BUT LIFTING TROUGH OVER THE E UNITED STATES AND
ATLANTIC W OF 60W. THIS TROUGH IS ROTATING NEWD N OF THE AREA
AND A RIDGE IS FORECAST TO BUILD IN THE WAKE OF THE TROUGH
WITHIN THE NEXT 24 HOURS. THE TROUGH ALSO APPEARS TO HAVE
FRACTURED WITH A SHEARED PORTION OF THE TROUGH EXTENDING THROUGH
32N54W TO 21N61W. SHARP RIDGE IS OVER THE CENTRAL ATLANTIC
EXTENDING FROM 32N44W TO AN EMBEDDED ANTICYCLONIC CIRCULATION
NEAR 10N53W. A TROUGH IS OVER THE E ATLANTIC E OF 35W WITH A
DEVELOPING CYCLONIC CIRCULATION NEAR 27N28W. BROAD SWLY FLOW
EXISTS OVER THE REMAINDER OF THE TROPICAL ATLANTIC AND IS
ADVECTING MID AND UPPER LEVEL MOISTURE FROM THE ITCZ OVER THE
WEST COAST OF AFRICA.

$$
COBB







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