[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 182342
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT FRI APR 18 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 2315 UTC.

...THE ITCZ...

ITCZ AXIS IS CENTERED ALONG 5N9W 2N20W 1N27W CROSSING THE
EQUATOR NEAR 33W CONTINUING WSW TO 1S47W. THE AXIS IS FAIRLY
QUIET THIS EVENING WITH WIDELY SCATTERED MODERATE CONVECTION
CONFINED FROM THE EQUATOR TO 4N W OF 36W.

...DISCUSSION...

THE GULF OF MEXICO...
A DEEP LAYER LOW PRES SYSTEM OVER THE MIDWEST IS SUPPORTING A
COLD FRONT FROM SE LOUISIANA TO S MEXICO ALONG 30N92W 26N95W
22N97W THEN INLAND ALONG THE E SLOPES OF THE SIERRA MADRE
MOUNTAINS IN MEXICO. DOPPLER RADAR AND LIGHTNING DATA DEPICT
SCATTERED TSTM ACTIVITY AHEAD OF THE FRONT OVER LOUISIANA AND
MISSISSIPPI...BUT THERE DOES NOT APPEAR TO BE MUCH SPREADING
INTO THE GULF. SCATTERED SHOWERS AND POSSIBLY AN ISOLATED TSTM
IS LIKELY WITHIN 60 NM OF THE FRONT OVER THE GULF WATERS. A WEAK
SMALL-SCALE LOW HAS DEVELOPED AHEAD OF THE FRONT BUT IS QUICKLY
DISSIPATING AS IT TRACKS SE. BEHIND THE FRONT...N WINDS ARE
INCREASING TO 20-25 KT BUILDING SEAS TO 8 FT...AS INDICATED BY
BUOY 42020 OFF THE S TX COAST. ELSEWHERE E OF THE FRONT...A 1023
MB HIGH SITUATED OFF THE NE FLA COAST IS STILL IN CONTROL
PROVIDING LIGHT TO MODERATE SE WINDS AND AIDING IN PRODUCING
MAINLY FAIR WEATHER. THE FRONT IS EXPECTED TO CONTINUE PUSHING
SE THROUGH SAT NIGHT THEN STALL AND WEAKEN ON SUN AS THE
ASSOCIATED UPPER TROUGH BECOMES CUT OFF AND A MID-UPPER RIDGE
BUILDS IN.

THE CARIBBEAN SEA...
MAINLY ZONAL MID-UPPER FLOW LIES OVER THE CARIB BASIN BETWEEN
BROAD FLAT RIDGING OVER SOUTH AMERICA AND TROUGHING N OF THE
AREA. MODESTLY DRY AIR IS ASSOCIATED WITH THIS PATTERN LEADING
TO MAINLY FAIR WEATHER REGION-WIDE. THERE IS ONE PATCH OF TSTM
ACTIVITY IN THE GULF OF HONDURAS FROM 17N-18N BETWEEN
82W-85W...LIKELY ENHANCED BY LOW-LEVEL CONFLUENCE AND POSSIBLY
BY WEAK UPPER DIFFLUENCE E OF SMALL SCALE SHORTWAVE.
OTHERWISE...TYPICAL LOW-LEVEL CLOUD STREAMERS ARE BEING STEERED
W ACROSS THE SEA BY STIFF TRADES. THE TRADES ARE STRONGEST
...25-30 KT...NEAR THE COAST OF COLOMBIA. THESE WINDS ARE
EXPECTED TO REMAIN THAT WAY FOR THE NEXT 24 HOURS.

THE ATLANTIC OCEAN...
A WEAKENING UPPER TROUGH LIES OVER THE W ATLC ALONG 65W
PROVIDING LIMITED SUPPORT FOR A STATIONARY OR SLOWLY LIFTING
BOUNDARY ANALYZED FROM 32N59W TOWARD THE SE BAHAMAS NEAR 20N72W.
UPPER DIFFLUENCE E OF THE TROUGH AXIS COMBINED WITH LOW-LEVEL
CONVERGENCE ALONG THE BOUNDARY IS PRODUCING SCATTERED SHOWERS
AND ISOLATED TSTMS WITHIN 120 NM E OF THE FRONT N OF 26N AND
WITHIN 60 NM EITHER SIDE S OF 26N. A 1023 MB HIGH CENTERED N OF
THE BAHAMAS NEAR 29N78W HAS BUILT W OF THE FRONT.

THE CENTRAL AND E ATLC IS DOMINATED BY A LARGE SCALE
RIDGE/TROUGH PATTERN. THE MID-UPPER RIDGE IS CENTERED NEAR
23N40W WITH THE ASSOCIATED 1029 MB SFC HIGH CENTER LOCATED NEAR
34N44W. THE LARGE UPPER TROUGH...SUPPORTED BY A STRONG DEEP
LAYER LOW WELL N OF THE REGION...COVERS THE NE PORTION OF THE
ATLC DISCUSSION ZONE SUPPORTING A COLD FRONT FROM THE CANARY
ISLANDS TO 27N27W THEN NW TO 32N38W. THE FRONT APPEARS FAIRLY
DRY IN NATURE...IN FACT MUCH OF THE REGION REMAINS FAIRLY
TRANQUIL N OF THE ITCZ.

$$
CANGIALOSI





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