[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 161750
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON APR 16 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 8N10W 3N20W EQ35W 2S45W. CLUSTERS OF
MODERATE/ISOLATED STRONG CONVECTION ARE ALONG THE COASTLINE OF
SIERRA LEONE AND LIBERIA. WIDELY SCATTERED MODERATE CONVECTION
IS WITHIN 40-60 NM SOUTH OF THE AXIS BETWEEN 18W-20W AND 32W-36W.

...DISCUSSION...

GULF OF MEXICO...
A MUCH COLDER AND DRIER AIRMASS IS GRIPPING THE GULF AND THE
STATE OF FLORIDA THANKS TO A 1025 MB HIGH PRES SYSTEM LOCATED
OVER SE LOUISIANA. A FAIRLY TIGHT PRES GRADIENT BETWEEN THIS SFC
HIGH AND A POWERFUL LOW PRESSURE OVER THE NORTHEAST UNITED
STATES IS PRODUCING MODERATE TO STRONG NLY WINDS OVER THE E GULF
AND THE FLORIDA PENINSULA. BROKEN COLD AIR STRATOCUMULUS CLOUDS
COVERS MOST OF THE GULF. SOME LOW CLOUDS ARE POOLED AGAINST THE
SIERRA MADRE MOUNTAINS SOUTH OF TAMPICO MEXICO. VIS IMAGERY
SHOWS CLEAR SKIES OVER THE SE U.S. AND THE NE CORNER OF THE
GULF. ALOFT...A RIDGE IS BUILDING OVER THE GULF WHILE A SHARP
SHORTWAVE TROUGH IS OVER THE SW US AND N BAJA. THIS TROUGH WILL
SUPPORT THE NEXT COLD FRONT THAT IS FORECAST TO MOVE OFF TEXAS
COAST EARLY WED. A PLUME OF UPPER LEVEL MOISTURE ASSOCIATED WITH
THE EPAC JETSTREAM EXTENDS NEWD ACROSS N MEXICO AND W TEXAS.
WINDS AND SEAS WILL SUBSIDE OVER THE GULF DURING THE NEXT FEW
DAYS AS HIGH PRES MOVES SLOWLY EWD.

CARIBBEAN SEA...
THE STRONG COLD FRONT THAT ENTERED THE NW CARIBBEAN YESTERDAY
CONTINUES TO MOVES SEWD. AS OF 15Z...THE FRONT ENTERS THE
FORECAST AREA NEAR 31N67W THEN CONTINUES SW ACROSS THE CENTRAL
BAHAMAS AND E CUBA. HAVANA REPORTED GUSTY SOUTH WINDS UP TO 47
KT (87 KPH) AHEAD OF THE FRONT AND 31 KT (57 KPH) BEHIND THE
FRONT. A WELL DEFINED BAND OF LOW/MID CLOUDS WITH EMBEDDED
SHOWERS AND ISOLATED TSTMS IS ASSOCIATED WITH THE FRONT.
TEMPERATURES TONIGHT WILL BE UNSEASONABLY COOL FOR THIS TIME OF
YEAR OVER SOUTH FLORIDA AND PROBABLY OVER PARTS OF W-CENTRAL
CUBA AS A TONGUE OF COLD AIR PUSHES SWD OVER THE STRAITS OF
FLORIDA. THIS FRONT HAS ALSO BROUGHT MUCH COOLER AIR TO THE
YUCATAN PENINSULA AND N CENTRAL AMERICA. THE REMAINDER OF THE
BASIN CONTINUES UNDER THE INFLUENCE OF A STRONG UPPER HIGH
CENTERED MIDWAY BETWEEN JAMAICA AND CABO GRACIAS A DIOS WITH
ABUNDANT DRY AND STABLE AIR ALOFT. THE TRADES ARE LIGHT TO
MODERATE ACROSS MUCH OF THE AREA DUE TO THE WEAK PRES GRADIENT.
HOWEVER...BEHIND THE COLD FRONT NLY WINDS OF 20-25 KT ARE
BLOWING ADVECTING IN THE COOLER AIRMASS. THE COLD FRONT IS
EXPECTED TO PUSH E AND SLOWLY WEAKEN REACHING THE E TIP OF CUBA
AND EASTERN HONDURAS THIS EVENING. A FAIR AMOUNT OF LOW-LEVEL
MOISTURE WILL LIKELY LINGER IN THE VICINITY OF THE FRONT
BRINGING SOME INCREASE IN SHOWER ACTIVITY OVER HISPANIOLA
TOMORROW AND OVER PUERTO RICO TUESDAY NIGHT THROUGH WEDNESDAY.

WESTERN ATLANTIC...
THE AFOREMENTIONED STRONG COLD FRONT IS PRODUCING GALE FORCE
WINDS AND HAZARDOUS MARINE CONDITIONS OVER THE W ATLC. EARLIER
QUIKSCAT PASS SHOWED WINDS OF 25 TO 35 KT AHEAD AND BEHIND THE
FRONT. THIS COLD FRONT IS ASSOCIATED WITH A STRONG LOW PRES
SYSTEM THAT IS NOW BATTERING THE NE US WHERE SEVERAL WATCHES AND
WARNINGS HAVE BEEN ISSUED. A DEEP LAYERED TROUGH OVER THE FAR
WEST ATLC IS SUPPORTING THIS FRONTAL SYSTEM. THE MID/UPPER LEVEL
RIDGE OVER THE CARIBBEAN EXTENDS NE INTO THE W-CENTRAL ATLC
THROUGH PUERTO RICO AND THE VIRGIN ISLANDS. AT THE SURFACE...A
1018 MB HIGH IS NEAR 30N55W EXTENDING A RIDGE TO THE NE
CARIBBEAN. A TROUGH/RIDGE PATTERN COVERS THE REMAINDER OF THE
ATLC OCEAN. A COLD FRONT/SFC TROUGH ARE ASSOCIATED WITH THIS
UPPER TROUGH. THE SFC TROUGH RUNS FROM 30N36W TO 20N53W. A
NARROW LINE OF LOW CLOUDS IS RELATED TO THIS FEATURE. ANOTHER
RIDGE DOMINATES THE E ATLC ANCHORED ON A 1019 MB HIGH LOCATED
NEAR 30N26W. THIN HIGH CLOUDS EXTENDS FROM N SOUTH AMERICA
ACROSS THE OCEAN AND ARE ASSOCIATED WITH STRONG WLY WINDS.

$$
GR








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