000
AXNT20 KNHC 212336
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST MON JAN 21 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 5N9W 4N25W 2N40W EQUATOR 50W. 
SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 150 NM N OF 
THE AXIS BETWEEN 24W-29W AND WITHIN 120 NM S OF THE AXIS BETWEEN 
30W-34W. SCATTERED MODERATE CONVECTION IS WITHIN 90 NM EITHER 
SIDE OF THE AXIS W OF 45W.

...DISCUSSION...

GULF OF MEXICO...
A LOW-LEVEL TROUGH HAS DEVELOPED IN THE MIDDLE GULF ANALYZED 
ALONG 88W/89W S OF 27N AT 21Z. VISIBLE IMAGERY SHOWS LOW-LEVEL 
TURNING IN THE CLOUD ELEMENTS AND BUOY 42001 INDICATES WINDS 
BACKING TO THE N JUST W OF THE BOUNDARY. A FAIRLY DENSE LOW TO 
MID LEVEL CLOUD DECK AND EMBEDDED SCATTERED SHOWERS ARE WITHIN 
180 NM E AND 60 NM W OF THE TROUGH AXIS. A LONG-TERM SAT LOOP  
SHOWS THIS TROUGH BREAKING OFF FROM THE TAIL END OF A STALLED 
FRONT IN THE FLA STRAITS AND TRACKING W WITH THE LOW-LEVEL FLOW. 
SPEAKING OF THE LOW-LEVEL FLOW...IT REMAINS STRONG THIS EVENING 
E OF 90W ESPECIALLY IN THE FL STRAITS WHERE 30 KT REPORTS HAVE 
BEEN COMMON. DENSE MULTILAYER CLOUD COVER...SCATTERED SHOWERS 
AND ISOLATED TSTMS ARE S OF 24N E OF 87W. SLIGHTLY LESS DENSE 
CLOUDS AND ISOLATED ACTIVITY IS BETWEEN 93W-97W ASSOCIATED WITH 
LOW-LEVEL RETURN FLOW ON THE SW PERIPHERY OF A VERY HEALTHY 1044 
MB HIGH OVER SE VIRGINIA. 

ALOFT...A SHORTWAVE IS PROGRESSING THROUGH THE CENTRAL 
GULF WITH THE FLOW BECOMING MORE ZONAL W OF IT. MODEST 
SUBSIDENCE LIES ABOVE THE MAJORITY OF THE REGION KEEPING MUCH OF 
THE SHOWER ACTIVITY MENTIONED FAIRLY SHALLOW. HOWEVER...THE 
UPPER LEVELS WILL LIKELY MOISTEN SOON IN THE W GULF AS A PLUME 
OF PACIFIC MOISTURE MOVES TOWARD THE REGION.

CARIBBEAN...
THE BASE OF THE NEWLY FORMED LOW-LEVEL TROUGH IN THE GULF OF 
MEXICO HANGS S INTO THE NW CARIB FROM THE YUCATAN PENINSULA TO 
HONDURAS ALONG 21N87W 16N86W. SFC WEATHER STATIONS IN ISLAS DE 
LA BAHIA IN THE GULF OF HONDURAS ARE REPORTING WLY WINDS 
...SUGGESTIVE OF THE TROUGH AXIS EXTENDING VERY NEAR THE 
ISLANDS. LIGHTNING DATA INDICATES SCATTERED TSTM ACTIVITY N OF 
20N BETWEEN 82W-86W LIKELY INFLUENCE BY THIS TROUGH AND ENHANCED 
FURTHER BY UPPER DIFFLUENCE TO THE E OF A SHORTWAVE ALONG 88W. 
ELSEWHERE W OF 72W IS EXPERIENCING A VERY NICE EVENING BROUGHT 
ABOUT BY ABUNDANT SUBSIDENCE UNDER WEAK UPPER RIDGING.

SCATTERED SHOWERS AND ISOLATED TSTMS ARE AFFECTING THE E CARIB 
CURRENTLY NW OF A LINE FROM THE SRN WINDWARD ISLANDS TO S HAITI 
ALONG 13N61W 18N72W. THIS MOISTURE SWATH IS ASSOCIATED WITH THE 
TAIL END OF A WEAKENING FRONTAL TROUGH AND POSSIBLY SOME WEAK 
MID-LEVEL INSTABILITY AS NOTED IN WATER VAPOR IMAGES. DRIER AIR 
APPEARS TO BE APPROACHING AS INDICATED IN THE MIMIC TPW 
ANIMATION REVEALING THE E EDGE OF THE MOISTURE FETCH OVER THE 
LESSER ANTILLES.  

ATLANTIC OCEAN...
THE W ATLC IS DOMINATED BY SWLY FLOW ALOFT WHICH IS PROVIDING 
LIMITED SUPPORT FOR THE COLD FRONT EXTENDING FROM 32N52W TO 
26N67W THEN STATIONARY THROUGH THE FLA STRAITS. DENSE MULTILAYER 
CLOUDS AND EMBEDDED SCATTERED SHOWERS ARE WITHIN 240 NM BEHIND 
THE FRONT. STRONG HIGH PRES HAS BUILT N OF THE AREA...ANALYZED 
1044 MB OVER SE VIRGINIA. TIGHT PRES GRADIENT BETWEEN THE FRONT 
AND THE HIGH IS PRODUCING STIFF NE WINDS PRODUCING HAZARDOUS 
MARINE CONDITIONS. 

DEEP LAYER RIDGE/TROUGH PATTERN LIES OVER THE CENTRAL AND 
EASTERN ATLC WATERS. COMBINATION OF ABUNDANT SUBSIDENCE 
ASSOCIATED WITH THE UPPER HIGH SITUATED NEAR 24N49W AND 1028 MB 
SFC HIGH NEAR 29N46W IS PROVIDING TRANQUIL WEATHER AND LIGHT TO 
MODERATE WINDS ACROSS THE MAJORITY OF THE CENTRAL ATLC. THE MAIN 
FEATURE IN THE E ATLC IS A DEEP LAYER OCCLUDED CUT OFF LOW 
ANALYZED 1009 MB AT THE SFC NEAR 32N30W. A WEAKENING COLD FRONT 
EXTENDS FROM 32N24W SWD THROUGH 20N26W THEN CURVES SW TO 11N40W 
AND CONTINUES FARTHER W AS A SFC TROUGH ACROSS THE LESSER 
ANTILLES. SCATTERED SHOWERS AND TSTMS ARE LIKELY E OF THE 
LOW...IN AN UPPER DIFFLUENT ZONE...N OF 25N BETWEEN 18W-27W AND 
WITHIN 240 NM S SEMICIRCLE OF THE LOW. AN UPPER JET STREAK WELL 
SE OF THE LOW IS ADVECTING MID-HIGH LEVEL CLOUDS ACROSS THE CAPE 
VERDE ISLANDS AND IS FUELING CONVECTION IN THE ITCZ.

$$
CANGIALOSI