[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 261750
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SAT APR 26 2008

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.

...THE ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 6N12W 2N20W...CROSSING THE
EQUATOR NEAR 40W...AND INTO NE BRAZIL NEAR 2S50W. SCATTERED
MODERATE TO ISOLATED STRONG CONVECTION IS WITHIN 180 NM N OF
AXIS EAST OF 38W.

...DISCUSSION...

GULF OF MEXICO...
SATELLITE IMAGERY AND DOPPLER RADAR SHOW AN AREA OF SHOWERS AND
TSTMS OVER THE NW CORNER OF THE GULF AHEAD OF A COLD FRONT THAT
LIES OVER NORTHERN LOUISIANA AND SE TEXAS. A DIFFLUENT PATTERN
ALOFT BETWEEN AN UPPER RIDGE COVERING THE ENTIRE GULF AND AN
UPPER TROUGH OVER THE CENTRAL CONUS IS ENHANCING THIS CONVECTIVE
ACTIVITY. A TROUGH WAS ANALYZED IN THIS AREA AT 12Z AND 15Z SFC
MAPS. A 1009 SFC LOW IS OVER THE BAY OF CAMPECHE NEAR 19N94W.
THIS LOW IS FORECAST BY THE COMPUTER MODELS TO REMAIN STATIONARY
DURING THE NEXT 24 HOURS. AFTERWARD...AN OPEN TROUGH WILL
PERSIST OVER THE SAME REGION WHILE A COLD FRONT IS EXPECTED TO
MOVE OVER THE WESTERN GULF. STRONG NORTH WINDS WILL FOLLOW THE
FRONT WITH GALE FORCE OVER THE SW PART LATE SUN AND MONDAY.
ELSEWHERE...A 1022 MB HIGH CENTERED NEAR 31N74W EXTENDS A RIDGE
OVER THE REMAINDER OF THE GULF PRODUCING 10-15 KT SELY SURFACE
WINDS DUE TO RETURN FLOW. PRES GRADIENT BETWEEN THIS RIDGE AND
THE ABOVE MENTIONED SFC LOW OVER THE BAY OF CAMPECHE WILL BRING
A SLIGHT INCREASE IN WIND SPEED OVER THE SOUTH-CENTRAL GULF
TONIGHT THROUGH SUNDAY.

CARIBBEAN SEA...
LIGHT TO MODERATE TRADEWINDS ARE OVER THE CARIBBEAN SEA WITH
MOSTLY FAIR WEATHER W OF 75W. BROKEN TO OVERCAST MULTILAYERED
CLOUDS WITH SCATTERED SHOWERS ARE OVER THE E CARIBBEAN MAINLY
E OF 70W. THIS ACTIVITY IS ASSOCIATED WITH A SFC TROUGH
EXTENDING ALONG 63/64W ON THE 12Z MAP AND A MID/UPPER LEVEL
TROUGH LOCATED OVER THE WEST-CENTRAL ATLC JUST N OF PUERTO RICO.
STRONG SW TO WLY UPPER LEVEL FLOW IS ALSO HELPING TO INDUCE THIS
SHOWER ACTIVITY. THE SAN JUAN DOPPLER RADAR DEPICTS A BAND OF
SHOWERS WITH EMBEDDED TSTMS VERY CLOSE TO THE UK/US VIRGIN
ISLANDS ON THE CARIBBEAN SIDE. LOW LEVEL MOISTURE GENERATED BY
THIS WEATHER PATTERN COMBINED WITH THE DIURNAL HEATING AND LOCAL
ISLAND EFFECTS WILL CONTINUE TO AFFECT THE NE CARIBBEAN
INCLUDING THE VIRGIN ISLANDS...PUERTO RICO AND PARTS OF
DOMINICAN REPUBLIC DURING THE NEXT FEW DAYS. SAN JUAN REPORTED A
24 HOUR RAINFALL AMOUNT OF 1.12 INCHES THIS MORNING. SHALLOW
MOISTURE EMBEDDED IN THE TRADE WIND FLOW IS ALONG THE NORTHERN
COAST OF JAMAICA AND WEST OF THE CAYMAN ISLANDS GENERATING SOME
SHOWER ACTIVITY. A 1010 MB LOW IS INLAND OVER N COLOMBIA NEAR
10N75W.  WIDELY SCATTERED MODERATE CONVECTION IS FURTHER E
AROUND LAKE MARACAIBO IN VENEZUELA.

ATLANTIC OCEAN...
A RIDGE/TROUGH/RIDGE PATTERN DOMINATES THE DISCUSSION AREA. A
MID TO UPPER LEVEL TROUGH IS OVER THE WEST-CENTRAL ATLC WITH THE
BASE OF THE TROUGH JUST NORTH OF DOMINICAN REPUBLIC AND PUERTO
RICO. THE ATTENDANT COLD FRONT EXTENDS FROM AN EXTRATROPICAL
CYCLONE OVER THE NORTH CENTRAL ATLC ALONG 32N50W 21N59W. AT THIS
POINT A SFC TROUGH CONTINUES SW TO THE NORTHERN LEEWARD ISLANDS.
MOST OF THE SHOWER ACTIVITY IS WELL AHEAD OF THE FRONT FROM 24N
TO BEYOND 31N BETWEEN 41W AND 46W. A 1022 HIGH PRES CENTERED
NEAR 31N74W ALSO ENVELOPS THE STATE OF FLORIDA...CUBA...THE
BAHAMAS AND THE WESTERN ATLC WITH MOSTLY FAIR WEATHER. ANOTHER
RIDGE EXTENDING FROM A SFC HIGH NEAR THE AZORES DOMINATES THE
EASTERN ATLC. IN THE MIDDLE...THE AFOREMENTIONED COLD FRONT. WV
IMAGERY AND CLOUD TRACKED WINDS INDICATE THE PRESENCE OF A LARGE
UPPER LEVEL HIGH CENTERED NEAR 7N52W. THIS FEATURE IS DOMINATING
THE TROPICAL BELT WEST OF 30W.

$$
GR








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