[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 182335
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE MAR 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 6N10W 3N20W 1N27W CROSSING THE
EQUATOR NEAR 31W TO NE BRAZIL NEAR 3S40W. SCATTERED MODERATE TO
STRONG CONVECTION IS WITHIN 120 NM N OF THE AXIS BETWEEN
13W-17W. ISOLATED MODERATE IS WITHIN 240 NM EITHER SIDE OF THE
AXIS BETWEEN 23W-34W.

...DISCUSSION...

GULF OF MEXICO...
A TIGHT PRESSURE GRADIENT BETWEEN A 996 MB LOW PRES TROUGH OVER
S TEXAS AND MEXICO AND A 1033 MB HIGH OFFSHORE OF THE
MID-ATLANTIC COAST IS PRODUCING SLY GALE FORCE WINDS OVER A GOOD
PORTION OF THE WRN GULF. BUOYS AND SHIPS ARE REPORTING SEAS AS
HIGH AS 16 FT IN THAT AREA. THESE SE TO S WINDS ARE AHEAD OF A
STRONG COLD FRONT WHICH HAS JUST EMERGED OFF THE TEXAS COAST.
DOPPLER RADAR AND LIGHTNING DATA DEPICT A NARROW SWATH OF
SCATTERED TSTMS WITHIN 30 NM AHEAD OF THE FRONT. THIS BOUNDARY
IS EXPECTED TO PUSH E ACROSS MOST OF THE REGION AS IT WEAKENS
OVER THE NEXT COUPLE OF DAYS. IN THE MID AND UPPER
LEVELS...STRONG SWLY FLOW LIES OVER THE WRN GULF BETWEEN A SHARP
UPPER TROUGH (THE SUPPORT FOR THE FRONT) OVER SW TEXAS/N MEXICO
AND BROAD RIDGING OVER THE E GULF. THIS FLOW IS ADVECTING A
BROKEN SWATH OF MID-HIGH LEVEL CLOUDS W OF 94W.

CARIBBEAN SEA...
AN IMPRESSIVE COLD FRONT HAS SWEPT THROUGH THE NRN LEEWARD
ISLANDS...PUERTO RICO AND HISPANIOLA. THIS BOUNDARY IS STILL
WELL DEFINED FROM 18N63W TO 17N71W...NOTED AS A BROKEN ROPE
CLOUD WHICH CONTAINS SCATTERED SHOWERS WITHIN 60 NM AHEAD OF IT.
N TO NE WINDS ARE INCREASING BEHIND IT PULLING IN COOLER AIR.
THE LONG N FETCH OVER THE ATLC IS CREATING VERY ROUGH MARINE
CONDITIONS N OF THE ISLANDS. OTHERWISE...WIDESPREAD SUBSIDENCE
ALOFT IS BEING ENHANCED BY CONFLUENCE ASSOCIATED WITH A RIDGE
OVER THE W CARIB AND A HIGHLY ELONGATED TROUGH OVER THE EASTERN
HALF. THIS STABLE PATTERN IS CAPPING THE TYPICAL LOW-LEVEL CLOUD
STREAMERS STEERED BY STRONG TRADES. THE TRADES ARE EVEN TO GALE
FORCE NEAR THE COAST OF COLOMBIA...EXPECTED TO PERSIST FOR ABOUT
24-36 HOURS.

ATLANTIC OCEAN...
A STRONG COLD FRONT CONTINUES TO PUSH E ACROSS THE CENTRAL ATLC
ENTERING THE REGION NEAR 32N45W AND CONTINUING SW ACROSS THE NRN
LEEWARD ISLANDS ALONG 25N49W 18N63W. LIGHTNING DATA SHOWS
SCATTERED TSTM ACTIVITY WITHIN 120 NM E OF THE FRONT N OF 24N
AND SCATTERED SHOWERS WITHIN 60 NM OF THE FRONT S OF 24N.
SIMILAR SCATTERED SHOWER AND TSTM ACTIVITY IS OCCURRING N OF 28N
BETWEEN 50W-60W. WIDESPREAD BROKEN STRATOCUMULUS DECK BEHIND THE
FRONT CLEARLY INDICATES COOL STABLE AIR. A LONG N FETCH OF
WINDS...TO GALE FORCE IN OUR REGION...IS PRODUCING VERY HIGH
SEAS UP TO 27 FT. A 1033 MB HIGH PRES SYSTEM LOCATED OFF THE
MID-ATLANTIC COAST NEAR 37N73W IS BUILDING SE IN THE WAKE OF THE
FRONT.

THE EASTERN ATLC REMAINS TRANQUIL THIS EVENING LYING ON THE S
SIDE OF A 1026 MB HIGH OVER THE AZORES. A FAIRLY RELAXED
GRADIENT ON ITS S SIDE IS PRODUCING LIGHT TO MODERATE
TRADES...EXCEPT TO 20 KT NEAR THE COAST OF AFRICA WHERE THE PRES
GRADIENT IS TIGHTENED DUE TO INVERTED TROUGHING OVER THE
CONTINENT. ALOFT...THE FLOW IS MAINLY OUT OF THE W TO SW BETWEEN
PRONOUNCED TROUGHING OVER THE NRN SUBTROPICS/MID-LATITUDES AND A
FLAT UPPER RIDGE OVER AFRICA AND THE TROP E ATLC. DRY AIR IS
ASSOCIATED WITH THIS MID-UPPER PATTERN LIMITING CONVECTION IN
THE ITCZ.

$$
CANGIALOSI


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