[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 172342
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT THU MAY 17 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.

...THE ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS ALONG THE LINE...6N10W
6.5N30W 3N521W. SCATTERED MODERATE CONVECTION IS JUST N OF THE
AXIS FROM 3N-6N WEST OF 45W. ISOLATED MODERATE CONVECTION IS
WITHIN 20-40 NM N OF THE AXIS BETWEEN 15W-42W. CLUSTERS OF
SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE OVER LIBERIA
AND SIERRA LEONE...AND OVER FRENCH GUIANA AND SURINAME.

...DISCUSSION...

THE GULF OF MEXICO...
A BROAD MIDDLE/UPPER LEVEL TROUGH DOMINATES THE EASTERN U.S. AND
THE FAR E GULF. THIS TROUGH SUPPORTS A COLD FRONT THAT EXTENDS
FROM SE GEORGIA TO NEAR BROWNSVILLE TEXAS. THE FRONT IS
WEAKENING WEST OF 90W. HIGH PRES IS BUILDING IN BEHIND THE FRONT
GIVING THE AREA MAINLY LIGHT TO MODERATE NLY WINDS. VIS SAT
IMAGERY SHOWS SCATTERED LOW CLOUDS ASSOCIATED WITH THE FRONTAL
BOUNDARY WHILE A DRIER AIRMASS IS INVADING THE NORTHERN GULF
WATERS. THE FRONT WILL CONTINUE TO MOVE SLOWLY SOUTH. AN UPPER
RIDGE IS OVER MEXICO AND THE W GULF INCLUDING ALSO THE YUCATAN
PENINSULA. DRY AIR/SUBSIDENCE COVERS THE AREA SOUTH OF 22N. A
WEAK SURFACE PRESSURE GRADIENT COVERS THE REST OF THE GULF OF
MEXICO AWAY FROM THE FRONT.

THE CARIBBEAN SEA...
AN UPPER LEVEL TROUGH FROM THE GULF OF MEXICO DIGS INTO WESTERN
CUBA AND THE NW CARIBBEAN. UPPER LEVEL NORTHWESTERLY-TO-WESTERLY
WIND FLOW DOMINATES THE BASIN. AN UPPER RIDGE REMAINS OVER
NORTHERN SOUTH AMERICA/CENTRAL AMERICA AND THE EPAC. AS OF
21Z...A 1011 MB SFC LOW IS ANALYZED NEAR 18N83W. A TROUGH
EXTENDS FROM THIS LOW TO THE COLOMBIAN COAST. THIS TROUGH
COMBINED WITH THE CLOSE PROXIMITY OF THE EPAC ITCZ AND A
DIFFLUENT PATTERN ALOFT IS GENERATING BROKEN TO OVERCAST
MULTILAYERED CLOUDS WITH EMBEDDED SHOWERS AND TSTMS OVER THE SW
CARIBBEAN...PANAMA AND COSTA RICA AS WELL AS OVER THE CARIBBEAN
PLAINS OF NICARAGUA. CLUSTERS OF MODERATE TO ISOLATED STRONG
CONVECTION ARE ALSO SEEN OVER N COLOMBIA AND THE LAKE MARACAIBO
AREA. ANOTHER SFC TROUGH CROSSES CENTRAL CUBA AND EXTENDS SW
FROM A 1011 MB LOW LOCATED NEAR GRAN ABACO IN THE NW BAHAMAS. A
SWIRL OF LOW CLOUDS DEFINES THIS FEATURE WITH AN EXTENSIVE AREA
OF CLOUDINESS JUST E OF THE SFC LOW. THE TROUGH OVER THE W
CARIBBEAN WILL REMAIN STATIONARY AND THE LOW IS FORECAST TO MOVE
ALONG THE TROUGH TOWARD CUBA. MODERATE TRADE WINDS ARE BLOWING
ACROSS THE CENTRAL AND EASTERN CARIBBEAN.

THE ATLANTIC OCEAN...
AS PREVIOUSLY MENTIONED...A 1011 MB SFC LOW NEAR THE GRAN ABACO
ISLAND IS GENERATING A LARGE AREA OF CLOUDINESS WITH EMBEDDED
SHOWERS AND TSTMS. A DIFLUENT PATTERN ALOFT...ASSOCIATED WITH AN
UPPER RIDGE OVER THE AREA...IS ENHANCING THIS CONVECTIVE
ACTIVITY. A TROUGH EXTENDS FROM NEAR 31N73W TO THE LOW AND
CONTINUES INTO CENTRAL CUBA/NORTHWESTERN CARIBBEAN. THE LOW IS
EXPECTED TO MOVE NORTH OF 31N IN 24 HOURS AND DEVELOP INTO A
GALE NORTH OF THE DISCUSSION AREA. A MIDDLE TO UPPER LEVEL
TROUGH EXTENDS FROM A CYCLONIC CIRCULATION CENTER NEAR 28N49W TO
19N50W. THIS TROUGH SUPPORTS THE ATLANTIC OCEAN STATIONARY
TROUGH THAT PASSES THROUGH 31N48W TO 21N54W. A WEAK SFC LOW HAS
DEVELOPED ALONG THE TROUGH AXIS NEAR 28N49W. THIS LOW IS
FORECAST TO MOVE N WITH LITTLE CHANGE. A SURFACE RIDGE EXTENDS
SOUTH INTO THE AREA ALONG 60W. ANOTHER RIDGE IS EAST WITH THE
AXIS ALONG 35W. ANOTHER MIDDLE TO UPPER LEVEL TROUGH IS FAR
EASTERN ATLANTIC N OF 20N. UPPER SWLY WINDS ARE ADVECTING UPPER
LEVEL MOISTURE ACROSS THE TROPICS E OF 40W INTO THE CAPE VERDE
ISLANDS AND WEST AFRICA.

$$
GR


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