000 AXNT20 KNHC 202359 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST SUN JAN 20 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 4N8W 4N30W EQ50W. SCATTERED MODERATE CONVECTION IS WITHIN 60-80 NM EITHER SIDE OF AXIS WEST OF 30W. UPPER DIFFLUENCE IS ENHANCING THIS CONVECTIVE ACTIVITY...AND IS ALSO HELPING THE DEVELOPMENT OF STRONG CONVECTION NE BRAZIL. ...DISCUSSION... THE GULF OF MEXICO... STRONG HIGH PRES OVER THE EASTERN CONUS EXTENDS A RIDGE OVER THE ENTIRE GULF OF MEXICO USHERING A COLD AIR MASS. THIS FEATURE WILL MOVE EWD ACROSS THE SE U.S. THROUGH MONDAY. BROKEN TO OVERCAST COLD AIR STRATOCUMULUS CLOUDS COVERS MOST OF THE AREA WITH PATCHES OF SCATTERED SHOWERS OVER SOUTH-CENTRAL FLORIDA AND THE SE PORTION OF THE GULF. AN EARLIER ASCAT PASS SHOWED NLY WINDS OF 20 TO 30 KT OVER THE EASTERN GULF. SOME OBSERVATIONS ACROSS SOUTH FLORIDA INDICATE SUSTAINED WINDS OF 25-30 KNOTS. THE WESTERN GULF HAS 15-20 KT NE TO E WINDS. IN THE UPPER LEVELS...A SHORT-WAVE TROUGH IS OVER THE E GULF WITH AXIS ALONG 85W. SIGNIFICANT UPPER LEVEL MOISTURE IS AHEAD OF THIS TROUGH AFFECTING FLORIDA AND WEST-CENTRAL CUBA. AS HIGH PRES MOVES EWD...RETURN FLOW WILL DEVELOP ACROSS THE WESTERN GULF INCREASING THE CHANCES OF SHOWERS ALONG THE COASTS OF TEXAS AND NE MEXICO. THE CARIBBEAN SEA... AS OF 2100 UTC...A COLD FRONT FROM THE WESTERN ATLC ENTERS THE CARIBBEAN SEA THROUGH CENTRAL CUBA...THEN CONTINUES SW AND SOUTH ACROSS THE GULF OF HONDURAS INTO HONDURAS. LIGHTNING DATA REVEALS SOME TSTM ACTIVITY OVER CENTRAL CUBA WITH SCATTERED SHOWERS ALONG THE FRONTAL BOUNDARY OVER THE BASIN. AN ASCAT PASS FROM AROUND 16Z SHOWED NLY WINDS OF 20-25 KT OVER THE NW CARIBBEAN JUST BEHIND THE COLD FRONT. ELSEWHERE...MODERATE TO STRONG TRADEWINDS ARE BLOWING ACROSS THE AREA WITH THE STRONGEST WINDS ALONG THE COAST OF N COLOMBIA. PATCHES OF BROKEN TO OVERCAST LOW CLOUDS WITH EMBEDDED SHOWERS ARE AFFECTING FROM WESTERN PANAMA TO HONDURAS LIKELY RELATED TO LOW LEVEL CONVERGENCE. AN OLD FRONTAL BOUNDARY IS PRODUCING A BAND OF CLOUDS AND SHOWERS FROM THE N LEEWARD ISLANDS TO DOMINICAN REPUBLIC. IN FACT...THE SAN JUAN DOPPLER RADAR SHOWERS SCATTERED SHOWERS AND ISOLATED TSTMS OVER THOSE ISLANDS AND COASTAL WATERS...INCLUDING THE ANEGADA AND MONA PASSAGES. THE GFS MODEL HAS MOISTURE FROM THIS OLD FRONT AFFECTING THE NE CARIBBEAN DURING THE NEXT 24 HOURS OR SO. IN THE UPPER LEVELS...A RIDGE IS OVER THE CARIBBEAN WITH AXIS ALONG 75W. VERY STRONG SUBSIDENCE COVERS THE BASIN EXCEPT OVER THE YUCATAN CHANNEL AND W CUBA WHERE CONSIDERABLE MOISTURE IS NOTE DUE TO THE PRESENCE OF THE ABOVE MENTIONED COLD FRONT. ACCORDING TO THE GFS MODEL...THIS FRONTAL SYSTEM AND ITS ASSOCIATED MOISTURE FIELD WILL SURGE BACK NORTH ACROSS SOUTH FLORIDA TOMORROW KEEPING THE RISK OF SHOWERS...PARTICULARLY ON MONDAY NIGHT. THE ATLANTIC OCEAN... AS OF 21Z...A COLD FRONT IS OVER THE W ATLANTIC FROM 31N68W TO CENTRAL CUBA NEAR 23N80W. LATEST VIS IMAGERY FROM THE DAY SHOWS A WELL-DEFINED BAND OF CLOUDS WITH EMBEDDED SHOWERS AND ISOLATED TSTMS ASSOCIATED WITH THE FRONT. BROKEN TO OVERCAST COLD AIR STRATOCUMULUS CLOUDS ARE W OF THE FRONT. A 1027 MB HIGH IS OVER THE CENTRAL ATLANTIC NEAR 32N44W. THIS SYSTEM IS FORECAST TO MOVE INTO THE FORECAST REGION DURING THE NEXT 6-12 HOURS THEN WILL BE ABSORBED BY ANOTHER HIGH PRES CENTER EXITING THE EASTERN COAST OF THE UNITED STATES ON MONDAY EVENING. THE LEADING EDGE OF THIS HIGH IS A COLD FRONT WHICH EXTENDS S THEN W FROM A 1009 MB SFC LOW LOCATED NEAR 34N28W TO THE NE CARIBBEAN. SATELLITE PHOTOS ALSO SHOW A WELL-DEFINED BAND OF CLOUDS AND SHOWERS RELATED TO THE FRONT. ALOFT...A TROUGH/RIDGE/TROUGH PATTERN DOMINATES THE DISCUSSION AREA. A DEEP-LAYERED TROUGH OVER THE EASTERN SEABOARD MAINLY N OF 30N SUPPORTS THE FRONT THAT LIES OVER THE W ATLC. A RIDGE CENTERED ON A HIGH NEAR 24N56W COVERS MOST OF THE W-CENTRAL ATLC BUT MAINLY BETWEEN 45W AND 70W. ANOTHER UPPER-LEVEL TROUGH IS OVER THE E ATLANTIC AND EXTENDS SW FROM A CUT-OFF LOW LOCATED NEAR 32N28W TO NEAR 17N53W. AROUND THE BASE OF THIS TROUGH...A STRONG JET STREAM BRANCH WITH CORE WINDS OF 90-110 KT IS TRANSPORTING ABUNDANT UPPER-LEVEL MOISTURE/ HIGH CLOUDS FROM NORTHERN SOUTH AMERICA ALL THE WAY NE TO THE WEST COAST OF AFRICA...PASSING THROUGH THE CAPE VERDE ISLANDS. $$ GR