[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 271746
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST TUE JAN 27 2009

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS
OF SOUTH AMERICA...AND 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 6N9W 3N17W 2N30W 1N47W CROSSING THE
ITCZ NEAR 50W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG
CONVECTION ARE WITHIN 120 NM N OF THE ITCZ FROM 34W-46W AND
WITHIN 90 NM S OF THE ITCZ FROM 33W-38W. SCATTERED MODERATE
CONVECTION IS S OF 6N W OF 47W TO INLAND OVER SOUTH AMERICA.

...DISCUSSION...

GULF OF MEXICO...
BROAD UPPER RIDGE CONTINUES TO DOMINATE THE GULF ANCHORED IN THE
E PACIFIC REGION GIVING THE ENTIRE GULF WESTERLY UPPER FLOW. A
SURFACE RIDGE ANCHORED IN THE W ATLC EXTENDS W ACROSS MUCH OF
THE GULF GIVING THE ENTIRE GULF SOUTHERLY SURFACE FLOW. THIS
COMBINED IS PRODUCING FAIR AND MILD CONDITIONS ACROSS THE AREA.
SCATTERED SHOWERS OVER THE FLORIDA STRAITS AND FAR SE WATERS
INCLUDING THE FLORIDA KEYS ASSOCIATED WITH WEAK TROUGH IN THE W
ATLC. THIS RATHER TRANQUIL PATTERN IS EXPECTED TO CONTINUE UNTIL
THE NEXT FRONT ENTERS THE NW WATERS LATE TONIGHT CROSSING THE
GULF BY FRI AS A SURFACE RIDGE BUILDS OVER THE PLAIN STATES.

CARIBBEAN SEA...
AN UPPER LOW IS OVER THE WINDWARD PASSAGE EXTENDING AN UPPER
TROUGH SW TO THE TIP ON NICARAGUA/HONDURAS. HOWEVER...STRONG
SUBSIDENCE AND DRY STABLE AIR ALOFT IS LIMITING ANY DEEP
SHOWERS/CONVECTION. A TIGHT SURFACE PRESSURE GRADIENT BETWEEN
THE RIDGE OVER THE ATLC AND LOWER PRESSURE OVER THE TROPICS IS
PRODUCING STRONG EASTERLY TRADE WINDS ACROSS THE CARIBBEAN WITH
GALE FORCE WINDS ALONG THE COAST OF COLOMBIA. THESE WINDS WILL
DIMINISH BY WED AS THE ATLC RIDGE BEGINS TO WEAKEN THROUGH FRI.
THESE WINDS ARE ALSO USHERING IN LOW LEVEL CLOUDS WITH ISOLATED
FAST MOVING SHOWERS ACROSS THE ENTIRE CARIBBEAN. A COLD FRONT
WILL MOVE INTO THE REGION OVER THE YUCATAN CHANNEL LATE FRI AND
WILL CONTINUE EASTWARD EXTENDING FROM CENTRAL CUBA TO THE GULF
OF HONDURAS FRI NIGHT AND HAITI TO EASTERN HONDURAS SAT NIGHT.

ATLANTIC OCEAN...
RELATIVELY TRANQUIL WEATHER CONTINUES ACROSS THE ATLC TODAY AS
THE ATLC HIGH PRESSURE RIDGE COVERS MUCH OF THE BASIN. NEAR
ZONAL WESTERLY UPPER FLOW DOMINATES THE ATLC W OF 30W WITH AN
UPPER TROUGH OVER THE REMAINDER OF THE FAR E ATLC. AT THE
SURFACE IS A WEAK COLD FRONT THAT EXTENDS FROM THE N/CENTRAL
ATLC THROUGH BERMUDA TO 31N70W. A SECOND COLD FRONT IS TO THE E
EXTENDING THROUGH 32N41W TO 31N44W CONTINUING AS A SURFACE
TROUGH TO 28N51W. ISOLATED SHOWERS ARE WITHIN 60 NM EITHER SIDE
OF THE FRONT/TROUGH. A REMNANT SURFACE TROUGH IS OVER THE SW
ATLC EXTENDING FROM 27N61W TO 22N69W GENERATING ISOLATED SHOWERS
WITHIN 180 NM W OF THE TROUGH. STRONG SUBSIDENCE AND DRY STABLE
AIR ALOFT IS LIMITING ANY DEEP SHOWERS/CONVECTION ACROSS THE
ENTIRE BASIN. THE SURFACE RIDGE THAT DOMINATES MUCH OF THE ATLC
EXTENDS FROM A 1029 MB HIGH JUST W OF THE MADEIRA ISLANDS SW
THROUGH 32N22W ALONG 27N30W THEN W TO A 1028 MB HIGH IN THE W
ATLC NEAR 30N75W AND CONTINUES TO OVER THE GULF OF MEXICO AND
THE FAR SE US WITH A WEAKNESS IN THE VICINITY OF THE SURFACE
TROUGHS MENTIONED ABOVE.

$$
WALLACE



This weather bulletin was brought to you by:
www.nashvilleweather.net