000 AXNT20 KNHC 161758 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST WED JAN 16 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC ...THE ITCZ... THE ITCZ AXIS IS CENTERED ALONG 8N13W 4N20W ALONG THE EQUATOR BETWEEN 30W AND 35W TO 2S45W. SCATTERED MODERATE CONVECTION IS WITHIN 170 NM N OF AXIS BETWEEN 27W-40W. ...DISCUSSION... GULF OF MEXICO... STRONG UPPER-LEVEL DIVERGENCE...RIGHT REAR QUADRANT JET DYNAMICS...AND POSITIVE VORTICITY ADVECTION ASSOCIATED WITH A SHORTWAVE TROUGH MOVING INTO THE TENNESSEE VALLEY HAVE HELPED IN THE FORMATION OF A GALE CENTER LOCATED NEAR 27N 92W...WHICH IS MOVING RAPIDLY ENE AT 25-30 KTS. SURFACE OBSERVATIONS INDICATE A BROAD AREA OF GALE FORCE WINDS IN THE NORTHERN SEMICIRCLE...WITH A PEAK WIND OF 49 KTS GUSTING TO 53 KTS AT BUOY FGBL1 AT 13Z. SATELLITE AND RADAR IMAGERY REVEALS A WELL-ORGANIZED COMMA HEAD OF CLOUDS AND PRECIPITATION MOVING ONSHORE THE UPPER TX/LA COASTS NEAR AND NORTH OF THE SFC CYCLONE...WHILE A WELL-DEVELOPED CONVECTIVE BAND AHEAD OF THE ASSOCIATED COLD FRONT IS SHIFTING EWD INTO THE CENTRAL GULF OF MEXICO. FARTHER EAST...OVERRUNNING LOW/MID-LEVEL MOISTURE ARE CONTRIBUTING TO A LARGE SHIELD OF CLOUDS AND LIGHT TO MODERATE RAINS AHEAD OF THE ASSOCIATED WARM FRONT OVER THE CENTRAL AND EASTERN GULF OF MEXICO. WINDS OVER THE NORTH CENTRAL AND NORTHEASTERN GULF ARE ALSO APPROACHING GALE FORCE IN RESPONSE TO THE STRONG PRESSURE GRADIENT BETWEEN HIGH PRESSURE CENTERED OVER THE NORTHERN APPALACHIANS AND LOW PRESSURE OVER THE GULF. GLOBAL MODELS INDICATE THAT THE GALE CENTER SHOULD BEGIN WEAKENING AS ITS UPPER-LEVEL SUPPORT OUTRACES IT...AND THE CENTER SHOULD COME ASHORE FLORIDA PANHANDLE THURS MORNING BEFORE RE-EMERGING ALONG THE SE CONUS COAST LATER IN THE DAY. IN THE WAKE OF THIS SYSTEM...STRONG COLD-AIR ADVECTION ON A N TO NE WIND SHOULD OVERTAKE MOST OF THE GULF OF MEXICO BY FRIDAY...AS HIGH PRESSURE FROM THE ROCKIES BUILDS INTO THE SOUTHERN PLAINS. CARIBBEAN SEA... A MID-LEVEL HIGH LOCATED JUST NE OF DOMINICAN REPUBLIC CONTINUES TO DOMINATE MOST OF THE CARIBBEAN SEA WITH A VERY DRY AND STABLE AIR MASS WHICH IS LIMITING THE DEVELOPMENT OF DEEP CONVECTION. HOWEVER...THERE ARE SOME POCKETS OF LOW-LEVEL CLOUDS WITH EMBEDDED SHOWERS MOVING WWD ACROSS THE AREA UNDER THE INFLUENCE OF A PREVAILING ELY FLOW. IN FACT...THE SAN JUAN DOPPLER RADAR SHOWS SHOWERS CROSSING FROM THE N LEEWARD ISLANDS TO THE UK/US VIRGIN ISLANDS AND PUERTO RICO. STREAKS OF CLOUDS AND A FEW SHOWERS COVER PARTS OF THE CENTRAL AND WESTERN CARIBBEAN SEA...LIKELY RELATED TO THE SHEAR OF THE LOW-LEVEL WIND/SPEED CONVERGENCE. THE SPEED CONVERGENCE OVER THIS REGION IS A RESULT OF STRONG TRADE WINDS OVER THE CENTRAL CARIBBEAN SEA TO THE COLOMBIA COAST...WITH WEAKER TRADES TO THE WEST. ELSEWHERE...A DYING FRONTAL BOUNDARY LIES OVER NORTH CENTRAL CUBA AND IS GENERATING SCATTERED CLOUDINESS AND SOME LIGHT SHOWERS. THE NEXT COLD FRONT IS FORECAST TO REACH THE YUCATAN CHANNEL/WESTERN CUBA LATE SAT WITH STRONG NORTHERLY WINDS BEHIND IT. FINALLY...TO THE EAST...A BROAD UPPER-LEVEL RIDGE DOMINATING NRN SOUTH AMERICA IS ADVECTING MOISTURE/HIGH CLOUDS INTO THE SE CARIBBEAN AND THE TROPICAL ATLC. ATLANTIC OCEAN... A COLD FRONT STRETCHES FROM A DEVELOPING STORM OVER THE WESTERN ATLC NEAR 39N58W TO 28N68W THEN CONTINUES AS A STATIONARY FRONT LYING ACROSS THE CENTRAL BAHAMAS/CUBA. A BROKEN BAND OF MAINLY LOW CLOUDS AND POSSIBLE SHOWERS ARE ASSOCIATED WITH THE FRONT...MAINLY NE OF THE BAHAMAS. FARTHER EAST...A WWD-MOVING SFC TROUGH IS LOCATED OVER THE TROPICAL ATLC ALONG 47W/48W FROM 10N-17N WITH SCATTERED SHOWER AND THUNDERSTORMS EAST OF THE N END OF THE TROUGH AXIS. FARTHER NORTH...A 1030 MB SURFACE HIGH CENTERED NEAR 33N25W CONTINUES TO DOMINATE MUCH OF THE ERN ATLC. MODERATE TO STRONG EASTERLY TRADES SOUTH OF THIS FEATURE CONTINUE TO PRODUCE A REGION OF FAIRLY DENSE STRATOCUMULUS CLOUDS GENERALLY N OF 20N AND EAST OF 40W. FINALLY...AT UPPER LEVELS...A RIDGE/TROUGH/RIDGE PATTERN DOMINATES THE ERN PART OF ATLC. WITHIN THE BROAD LONGWAVE TROUGH ALONG 40W...A CUT-OFF LOW IS LOCATED IN THE CENTRAL ATLC NEAR 22N56W WITH A TROUGH EXTENDING SW TO ANOTHER DEVELOPING UPPER-LEVEL LOW WHICH CENTERED NEAR 13N50W. A STRONG 70- TO 90-KT JET DIGGING INTO THE BASE OF THE TROUGH MEETING ANTICYCLONIC FLOW TO THE SOUTH IS CREATING STRONG UPPER-LEVEL CONVERGENCE FROM THE LESSER ANTILLES EWD TO ABOUT 40W. THE RESULT IS LITTLE IN THE WAY OF ORGANIZED LOW CLOUDS...THOUGH A STREAM OF THIN CIRRUS CONTINUES TO FLOW FROM NORTHERN SOUTH AMERICA TO THE NW COAST OF AFRICA. $$ TK/GR