[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 232353
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON APR 23 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...
CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...
NORTHEASTERN 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.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 7N12W 2N30W 1N40W EQ50W. CLUSTERS OF
SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE WITHIN 60-70
NM N OF AXIS BETWEEN 14W-22W. SIMILAR CONVECTION IS OVER NE
BRAZIL. SCATTERED MODERATE CONVECTION IS FROM EQ-4N WEST OF 28W.
BETWEEN 26W-29W.

...DISCUSSION...

THE GULF OF MEXICO...
AS OF 21Z...A 1026 MB HIGH LOCATED NEAR 32N73W EXTENDS A RIDGE
SW TO THE BAY OF CAMPECHE...COVERING ALSO THE STATE OF FLORIDA.
UNDER THE INFLUENCE OF THIS SYSTEM...MOSTLY FAIR WEATHER
PREVAILS. 10-20 KT SELY RETURN FLOW COVERS THE ENTIRE GULF OF
MEXICO. ONSHORE FLOW OVER TEXAS AND E MEXICO IS PRODUCING BROKEN
LOW CLOUDS WITH EMBEDDED SHOWERS W OF 96W TO THE FOOTHILLS OF
THE SIERRA MADRE MOUNTAINS. ALOFT...AN UPPER LEVEL RIDGE
DOMINATES THE GULF AND THE FLORIDA PENINSULA. A SUBTROPICAL JET
IS TRANSPORTING ABUNDANT UPPER LEVEL MOISTURE FROM THE EPAC INTO
N-CENTRAL MEXICO AND TEXAS. HIGH PRES WILL SHIFT E ALLOWING THE
RETURN FLOW TO INCREASE TO 25 KT ON WED.

THE CARIBBEAN SEA...
THE TAIL END OF AN ATLC STATIONARY FRONT EXTENDS SW TO THE
VIRGIN ISLANDS. FROM THERE...A SURFACE TROUGH CONTINUES SW TO E
PANAMA. THE SAN JUAN DOPPLER RADAR SHOWS SCATTERED TO NUMEROUS
SHOWERS WITH ISOLATED TSTMS OVER THE VIRGIN ISLANDS AND PUERTO
RICO...WHERE A FLASH FLOOD WATCH IS NOW IN EFFECT UNTIL TUESDAY
MORNING. SCATTERED SHOWERS/TSTMS ARE WITHIN 35 NM EITHER SIDE OF
THE TROUGH...MAINLY BETWEEN 70W-76W. CLUSTERS OF MODERATE TO
ISOLATED STRONG CONVECTION ARE AFFECTING NORTHERN COLOMBIA AND E
PANAMA.  A DIFFLUENT PATTERN ALOFT IS HELPING THIS CONVECTIVE
ACTIVITY. PATCHES OF LOW LEVEL CLOUDS WITH MAINLY LIGHT
RAIN/SHOWERS ARE OVER HISPANIOLA AND JAMAICA. EARLIER QUIKSCAT
PASS SHOWED 20-25 KT NELY WINDS FLOW THROUGH BOTH THE MONA
PASSAGE AND THE WINDWARD PASSAGE. THESE WINDS WILL PERSIST
TONIGHT. LIGHTER ELY WINDS ARE OVER THE E CARIBBEAN E OF THE
SURFACE TROUGH. IN THE UPPER LEVELS...A POSITIVELY TILTED TROUGH
EXTENDS FROM AN UPPER LOW NEAR 31N61W TO CENTRAL CUBA INTO THE
NW CARIBBEAN. AN UPPER LEVEL E/W RIDGE AXIS IS OVER NRN SOUTH
AMERICA ALONG 10N FROM TRINIDAD/TOBAGO TO COSTA RICA. MOSTLY WLY
UPPER LEVEL FLOW COVERS THE CARIBBEAN SEA N OF THE RIDGE AXIS.
UPPER DRY AIR...RESULTING IN STRONG SUBSIDENCE COVERS THE BASIN
W OF 75W WITH THE DRIEST AIR OVER CENTRAL CUBA. THE SURFACE
TROUGH IS FORECAST TO REMAIN NEARLY STATIONARY ENHANCING THE
SHOWER ACTIVITY FROM PUERTO RICO AND THE VIRGIN ISLANDS TO
PANAMA DURING THE NEXT 24 HOURS.

THE ATLANTIC OCEAN...
A 1026 MB HIGH IS OVER THE W ATLANTIC NEAR 32N73W. A STATIONARY
FRONT ENTERS THE FORECAST AREA NEAR 31N34W THEN CONTINUES SW TO
THE VIRGIN ISLANDS. COMPUTER MODEL ANTICIPATES THE DEVELOPMENT
OF A WEAK SFC LOW ALONG THE FRONTAL BOUNDARY NEAR 26N55W LATE
TONIGHT. THIS LOW WILL MOVE NE EXITING THE DISCUSSION AREA TUE
NIGHT. A WIDE BAND OF MULTILAYERED CLOUDS WITH EMBEDDED SHOWERS
IS ASSOCIATED WITH THE STATIONARY FRONT. A 1023 MB HIGH IS OVER
THE E ATLANTIC NEAR 32N22W.  THE UPPER TROUGH MENTIONED ABOVE IN
THE CARIBBEAN SECTION SUPPORTS THIS FRONT. AN UPPER RIDGE
ANCHORED ON A HIGH NEAR 20N40W IS OVER THE CENTRAL ATLANTIC
COVERING N OF 10N BETWEEN 20W-50W. STRONG SWLY WINDS BETWEEN
THESE TWO UPPER FEATURES ARE ADVECTING UPPER LEVEL MOISTURE FROM
THE NE CARIBBEAN ALL THE WAY NE TO BEYOND 32N40W. AN AREA OF
BROKEN TO OVERCAST LOW/MID CLOUDS COVERS FROM 14N-25N BETWEEN
28W-45W. ANOTHER TROUGH IS OVER WEST AFRICA WITH AXIS CROSSING
NEAR THE CAPE VERDE ISLANDS.

$$
GR


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