[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 281146
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST MON JAN 28 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1100 UTC

...THE ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 5N10W 4N25W 2N35W EQ41W INTO NE
BRAZIL NEAR 2S46W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE
WITHIN 70-100 NM EITHER SIDE OF AXIS MAINLY BETWEEN 20W-37W.
WIDELY SCATTERED MODERATE CONVECTION IS ALONG THE EQUATOR
BETWEEN 40W AND 49W.

...DISCUSSION...

THE GULF OF MEXICO...
HIGH PRES IS BUILDING ACROSS THE GULF WITH NLY WINDS AND COOLER
TEMPERATURES. AS OF 09Z...A 1025 MB SFC HIGH IS LOCATED OVER SE
LOUISIANA EXTENDING A RIDGE SW TO THE BAY OF CAMPECHE. THIS
FEATURE ALSO COVERS FLORIDA AND WESTERN CUBA. THE LEADING EDGE
OF THIS SFC HIGH IS A COLD FRONT THAT HAS PUSHED DOWN TO EASTERN
CUBA AND THE NW CARIBBEAN. SCATTERED COLD AIR STRATOCUMULUS
CLOUDS ARE MAINLY OVER THE EAST-CENTRAL GULF WHILE LOW LEVEL
CLOUDS ARE POOLED AGAINST THE SIERRA MADRE MOUNTAINS. HIGH PRES
WILL SLOWLY SLIDE SE AND WILL BE JUST EAST OF THE BAHAMAS TUE
MORNING. SLY RETURN FLOW WILL DEVELOP ACROSS THE WESTERN GULF
LATER TODAY AND TONIGHT AND THE NEXT COLD FRONT IS FORECAST TO
MOVE OFF TEXAS COAST TUE EVENING. IN THE UPPER LEVELS...A RIDGE
ALONG EASTERN MEXICO/TEXAS DOMINATES THE GULF GIVING THE AREA
NWLY WIND FLOW. A SUBTROPICAL JET IS DRAWING ABUNDANT UPPER
LEVEL MOISTURE FROM THE EPAC ACROSS NW MEXICO...TEXAS AND THE NW
QUADRANT OF THE GULF.

THE CARIBBEAN SEA...
MAIN FEATURE IN THE CARIBBEAN SEA IS A COLD FRONT THAT TRAILS
ACROSS EASTERN CUBA...THE CAYMAN ISLANDS AND THE NW CARIBBEAN.
THE FRONT HAS DISSIPATED OVER THE YUCATAN PENINSULA AND THE BAY
OF CAMPECHE AS HIGH PRES BUILDS IN. THIS FRONTAL SYSTEM IS
PRODUCING SCATTERED TO BROKEN LOW LEVEL CLOUDS AND ISOLATED
SHOWERS OVER CUBA AND THE CAYMAN ISLANDS. HOWEVER...THE FRONTAL
BOUNDARY BECOMES MORE ACTIVE OVER THE W ATLC DUE TO A DIFFLUENT
PATTERN ALOFT. ACCORDING TO THE GFS MODEL...THE FRONT WILL
CONTINUE TO PUSH EWD AND WILL BE EXTENDED FROM HISPANIOLA TO
HONDURAS THIS AFTERNOON WITH SCATTERED RAIN AND SHOWERS. THE
SAME FRONT IS FORECAST TO AFFECT PUERTO RICO LATE TONIGHT
THROUGH TUESDAY WITH AN INCREASE IN SHOWER ACTIVITY. THE TAIL
END OF A WEAKENING FRONTAL BOUNDARY CONTINUES TO PRODUCE PATCHES
OF LOW LEVEL CLOUDS AND ISOLATED SHOWERS OVER THE WINDWARD
PASSAGE AND HISPANIOLA. THE REMAINDER OF THE CARIBBEAN SEA AND
CENTRAL AMERICA HAS MODERATE TRADEWINDS. POCKETS OF LOW LEVEL
CLOUDS WITH EMBEDDED SHOWERS DOT THE AREA MORE CONCENTRATED IN A
BAND EXTENDING OVER THE EASTERN CARIBBEAN FROM THE NORTHERN
LEEWARD ISLANDS TO ISLA MARGARITA OFFSHORE VENEZUELA. THIS BAND
MAY PRODUCE LIGHT RAIN OVER THE UK/US VIRGIN ISLANDS TODAY.
PATCHES OF LOW LEVEL CLOUDS ARE ALSO AFFECTING FROM WESTERN
PANAMA TO NICARAGUA WHERE THE LOW LEVEL FLOW IS SLIGHTLY
CONFLUENT. IN THE UPPER LEVELS...THE BASIN REMAINS UNDER THE
INFLUENCE OF A SHORT-WAVE TROUGH OVER THE NW PORTION AND A
MODEST MID/UPPER LEVEL RIDGE ELSEWHERE. WV IMAGERY SHOWS
MODERATE TO STRONG SUBSIDENCE ACROSS THE ENTIRE REGION.

THE ATLANTIC OCEAN...
A COLD FRONT ENTERS THE FORECAST AREA NEAR 31N63W...THEN
CONTINUES SW ACROSS THE SE BAHAMAS AND EASTERN CUBA INTO THE NW
CARIBBEAN. SATELLITE IMAGERY AND LIGHTNING DATA SHOW SCATTERED
SHOWERS AND TSTMS WITHIN 120 NM AHEAD OF THE FRONT AND NE OF THE
SE BAHAMAS. SIMILAR CONVECTIVE ACTIVITY IS NOTED FROM 23N-26N
BETWEEN 61W-65W. UPPER DIFFLUENCE BETWEEN THE DEEP LAYERED
TROUGH THAT SUPPORTS THIS FRONT AND A RIDGE OVER THE CENTRAL
ATLC IS ENHANCING ALL THIS ACTIVITY. COLD AIR STRATOCUMULUS
CLOUDS ARE OBSERVED OVER THE W ATLC BEHIND THE FRONTAL ZONE. A
1013 MB SFC LOW IS NEAR 28N56W GENERATING SCATTERED SHOWERS AND
TSTMS. A STATIONARY FRONT EXTENDS SW FROM THE LOW TO HISPANIOLA
AND THE WINDWARD PASSAGE. A WARM FRONT ALSO EXTENDS E FROM THE
LOW TO 28N50W. AT THIS POINT...A COLD FRONT CONTINUES NE TO
BEYOND 31N38W. THE COLD FRONT OVER THE W ATLANTIC IS EXPECTED TO
MERGE WITH THE STATIONARY FRONT OVER THE CENTRAL ATLANTIC AND
MOVE TOWARD PUERTO RICO LATE TONIGHT. A SURFACE TROUGH CONTINUES
TO LINGER OVER THE EASTERN ATLC AND LIES ALONG 28W/29W FROM 25N
TO 32N. A QUIKSCAT PASS FROM AROUND 08Z SHOWS THE WIND SHIFT
RELATED TO THE TROUGH. ALOFT...A TROUGH/RIDGE/TROUGH PATTERN
DOMINATES THE REGION. A DIGGING UPPER-LEVEL TROUGH IS OVER THE
WESTERN ATLC SUPPORTING THE PREVIOUSLY MENTIONED COLD FRONT.
THE BASE OF THE TROUGH REACHES THE ISLAND OF GREAT INAGUA IN THE
BAHAMAS. THE CENTRAL ATLC IS UNDER THE INFLUENCE OF AN UPPER
RIDGE WHILE ANOTHER UPPER-LEVEL TROUGH PERSISTS OVER THE E ATLC
WITH A CUT-OFF LOW NW OF THE MADEIRA ISLANDS NEAR 31N23W. UPPER
LEVEL DIFFLUENCE E OF THE LOW CENTER IS PRODUCING A LARGE AREA
OF CLOUDS WITH EMBEDDED SHOWERS OVER THE CANARY/MADEIRA ISLANDS.
FURTHER SOUTH...A SWATH OF STRONG WLY UPPER LEVEL WINDS IS OVER
THE TROPICAL ATLANTIC S OF 20N FROM THE NE CARIBBEAN TO W AFRICA
CROSSING THE CAPE VERDE ISLANDS.

$$
GR






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