000
AXNT20 KNHC 172325
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST SAT JAN 17 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2315 UTC.

...THE ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 6N9W 1N25W 1N41W AND INTO NE 
BRAZIL NEAR 1S47W. SCATTERED MODERATE CONVECTION IS WITHIN 150 
NM ON EITHER SIDE OF THE AXIS BETWEEN 13W-28W. SCATTERED 
MODERATE/ISOLATED STRONG CONVECTION IS FROM 2S-4N BETWEEN 
34W-39W.

...DISCUSSION...

GULF OF MEXICO...
A SURFACE RIDGE OF HIGH PRESSURE EXTENDS FROM ACROSS THE SERN 
CONUS TO E/CENTRAL MEXICO ANCHORED ON A 1033 MB HIGH CENTERED IN 
SERN GEORGIA. SOUTHERLY RETURN FLOW OF 15-20 KTS IS OBSERVED 
ACROSS THE NW GULF AS THE RIDGE SLOWLY SLIDES E-SE. LIGHT NE 
WINDS OF 10-15 KT ARE ACROSS THE SE HALF OF THE GULF. A COLD 
FRONT IS EXPECTED TO FOLLOW THE RIDGE...ENTERING THE NW GULF 
EARLY SUN. ALOFT...NWLY FLOW ASSOCIATED WITH A TROUGH ACROSS THE 
W ATLC AND NW CARIBBEAN IS PROVIDING THE GULF WITH MODERATELY 
DRY MIDDLE TO UPPER LEVEL AIR WITH FAIR WEATHER STRATOCUMULUS 
CLOUDS OBSERVED IN THE LOW-LEVELS ACROSS THE CENTRAL GULF AND 
WRN GULF W OF 92W.

CARIBBEAN SEA...
A WEAKENING SURFACE TROUGH LINGERS IN THE NW CARIBBEAN...FROM 
THE GULF OF HONDURAS ACROSS CENTRAL CUBA AND INTO THE W ATLC 
GENERATING SCATTERED SHOWERS WITHIN 120 NM ON EITHER SIDE OF THE 
TROUGH. NE WINDS 20-25 KT COVER THE NW CARIBBEAN BEHIND THE 
TROUGH. THIS BOUNDARY IS EXPECTED TO BECOME DIFFUSE ON SUN. OVER 
THE ERN CARIBBEAN...A SURFACE TROUGH IS ANALYZED FROM ARUBA NE 
ACROSS WRN PUERTO RICO AND INTO THE W ATLC. A BROAD CIRCULATION 
SURROUNDING THIS TROUGH IS EVIDENT ON SATELLITE IMAGERY WITH SAN 
JUAN DOPPLER RADAR SHOWING SCATTERED SHOWERS MOVING OVER PUERTO 
RICO...THE MONA PASSAGE AND ERN HISPANIOLA THIS EVENING. 
ADDITIONAL SHOWERS ARE W OF THE TROUGH AXIS N OF 13N AND E OF 
74W. ALOFT...AN UPPER LEVEL TROUGH IS ACROSS THE NW CARIBBEAN 
WHILE AN UPPER LEVEL RIDGE IS ACROSS THE CENTRAL AND ERN 
CARIBBEAN WITH STRONG SUBSIDENCE AND DRY AIR OBSERVED E OF 73W.

ATLANTIC OCEAN...
A DEEP-LAYER TROUGH OVER THE EASTERN SEABOARD SUPPORTS A FRONTAL 
BOUNDARY ACROSS THE W ATLC. A COLD FRONT ENTERS THE DISCUSSION 
AREA NEAR 32N57W AND EXTENDS SW TO 25N69W WEAKENING TO A 
STATIONARY FRONT ACROSS THE SE BAHAMAS. MULTI-LAYERED CLOUDS AND 
SCATTERED SHOWERS FILL IN THE W ATLC BEHIND THE FRONT. MORE 
ENHANCED SCATTERED SHOWERS WITH POSSIBLE EMBEDDED TSTMS ARE 
AHEAD OF THE FRONT N OF 25N AND W OF 56W. FARTHER SOUTH...A 
SURFACE TROUGH EXTENDS FROM THE ERN CARIBBEAN ACROSS PUERTO RICO 
TO 21N65W. SCATTERED SHOWERS ASSOCIATED WITH THE TROUGH ARE N OF 
18N BETWEEN 60W-70W. A STRONG SURFACE RIDGE ANCHORED ON A 1034 
MB HIGH NEAR 32N32W COVERS THE REMAINDER OF THE ATLC. ALOFT...A 
DIFFLUENT PATTERN IN THE TROPICS IS ENHANCING CONVECTION ALONG 
THE ITCZ.

$$
HUFFMAN