000 AXNT20 KNHC 281108 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 AM EST TUE NOV 28 2006 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN 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...WEATHER OBSERVATIONS...RADAR... AND METEOROLOGICAL ANALYSIS. BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1100 UTC. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 8N13W 7N26W 6N35W 4N45W 3N52W. THE ITCZ IS RATHER QUIET WITH ONLY ISOLATED MODERATE CONVECTION WITHIN 180 NM S OF THE AXIS E OF 19W AND BETWEEN 37W-45W. ISOLATED MODERATE IS WITHIN 180 NM N OF THE AXIS BETWEEN 27W-36W. ...DISCUSSION... THE GULF OF MEXICO... THE WEATHER ACROSS THE GULF HAS CHANGED LITTLE OVER THE PAST FEW DAYS AS SFC HIGH PRES CONTINUES TO DOMINATE THE AREA. BREEZY 15-20 KT ELY WINDS IN THE ERN AND CNTRL GULF IS ADVECTING PATCHES OF LOW-LEVEL CLOUDS AND EMBEDDED ISOLATED TO SCATTERED SHOWERS ACROSS CENTRAL AND SOUTH FLORIDA ON THE BREEZE. SOME OF THIS LOW-LEVEL MOISTURE IS BEING DRIVEN ACROSS THE GULF AND TOWARDS THE SE TEXAS COAST BY S TO SELY RETURN FLOW AROUND THE 1028 MB SFC HIGH CENTERED JUST OFFSHORE OF THE MID-ATLANTIC STATES. IN THE UPPER LEVELS...A STRONG RIDGE IS CENTERED IN THE CENTRAL GULF NEAR 24N88W WITH RIDGING EXTENDING ACROSS THE FL PANHANDLE AND THE SOUTHEAST. WIDESPREAD STRONG SUBSIDENCE EXISTS EVERYWHERE ABOVE THE GULF. THIS STRONG CAP IS PREVENTING THE LOW-LAYER MOISTURE TO ACQUIRE MUCH DEPTH. GFS SHOWS THE SFC AND UPPER RIDGE SLIDING E IN RESPONSE TO A DIGGING UPPER TROUGH CURRENTLY OVER THE ROCKIES. THIS WILL ALLOW TEMPS TO REMAIN SLIGHTLY ABOVE NORMAL VALUES OVER THE NEXT COUPLE DAYS BEFORE A STRONG COLD FRONT MOVES OFF THE TX COAST LATE THU. GALE FORCE CONDITIONS AND A MUCH COLDER/DRIER AIRMASS WILL BE IN STORE FOR THE WRN GULF LATE THIS WEEK AND THIS WEEKEND. LESS OF AN AIRMASS CHANGE IS ANTICIPATED IN THE E GULF AS MUCH OF THE MODEL GUIDANCE STALLS THE FRONT OVER N FLORIDA. THE CARIBBEAN SEA... A WELL-DEFINED HIGHLY ELONGATED UPPER LEVEL TROUGH STRETCHES ACROSS HISPANIOLA AND JAMAICA TO NEAR 17N80W. THE TAIL END OF AN ASSOCIATED COLD FRONT IS DISSIPATING FROM 20N62W TO THE MONA PASSAGE. MULTILAYER CLOUDINESS AND SCATTERED SHOWERS ASSOCIATED WITH THE TROUGH/FRONT IS MAINLY CONTAINED N OF 18N BETWEEN 64W-72W WHICH INCLUDES PORTIONS OF HISPANIOLA...PUERTO RICO AND THE VIRGIN ISLANDS AS INDICATED ON SAN JUAN'S 88-D. A VERY BROAD FLATTENING UPPER LEVEL RIDGE LIES S AND E OF THE TROUGH CENTERED OVER VENEZUELA. S-SWLY UPPER LEVEL FLOW ON THE W SIDE OF THE BROAD RIDGE AXIS IS DRAWING SOME MOISTURE FROM THE ITCZ AND UPPER DIFFLUENCE IS PROVIDING ENOUGH INSTABILITY TO SPARK SCATTERED SHOWERS AND TSTMS S OF 14N BETWEEN 76W-84W. THE REMAINDER OF THE CARIB IS QUIET WITH VERY DRY AIR/STRONG SUBSIDENCE...DUE TO UPPER CONFLUENT FLOW...ABOVE THE NW CARIB AND MODERATELY DRY AIR ALOFT ELSEWHERE. THIS DRY AIR IS SUPPRESSING ANY DEEP CLOUDINESS IN THE AREAS NOT OUTLINED. TRADES ARE MODERATE AND WILL LIKELY REMAIN THAT WAY OVER THE NEXT DAY OR SO. LATER THIS WEEK...THESE WINDS WILL LIKELY INCREASE AS THE FRONTAL BOUNDARY PULLS NE AND STRONG HIGH PRES DEVELOPS TO THE N TIGHTENING THE PRES GRAD. THE ATLANTIC OCEAN... THE WRN ATLC IS DOMINATED BY VERY DRY AIR ALOFT...PRODUCED BY UPPER LEVEL CONFLUENCE BETWEEN A WELL-DEFINED UPPER TROUGH ALONG 32N55W 25N65W TO HISPANIOLA AND AN UPPER HIGH IN THE GULF. PATCHES OF LOW-LEVEL MOISTURE UNDERNEATH THE STRONG MID-LEVEL CAP ARE BEING DRIVEN TOWARDS THE BAHAMAS/FLORIDA BY MODERATE NELY FLOW. THE ONLY LOW PRES FEATURE IN THE DISCUSSION AREA IS IN THE CNTRL ATLC WHERE A COLD FRONT EXTENDS FROM AN OCCLUDED 1003 MB LOW NEAR 33N48W ALONG 24N55W 21N59W THEN DISSIPATING TO THE MONA PASSAGE. SWLY UPPER LEVEL FLOW...ON THE E SIDE OF THE MID/UPPER LEVEL TROUGH AXIS...AND LOW-LEVEL LIFT NEAR THE SFC BOUNDARY IS PRODUCING MULTILAYERED CLOUDS WITH EMBEDDED SCATTERED SHOWERS WITHIN 400 NM E AND 180 NM W OF THE FRONT N OF 28N AND WITHIN 240 NM EITHER SIDE OF THE FRONT S OF 28N. MODELS SHOW THE SFC LOW QUICKLY RACING TO THE NE WHICH SHOULD HELP TO SLOWLY THIN THE MOISTURE PLUME IN THIS AREA OVER THE NEXT DAY OR TWO. AN ELONGATED LOW AMPLITUDE MID/UPPER RIDGE LIES E OF THE TROUGH AND COVERS THE AREA BETWEEN 25W-50W N OF 20N. SLIGHT TROUGHING...REMNANTS OF AN UPPER LOW...EXISTS SW OF THE RIDGE BETWEEN 40W-55W. DEEP MOISTURE IS VERY LIMITED IN THE SUBTROPICAL E ATLC AND MUCH OF TROPICAL ATLC WATERS INCLUDING THE ITCZ...WHICH LOOKS PARTICULARLY QUIET THIS MORNING. PLENTY OF DRY STABLE AIR ALOFT IS LOCATED E OF 20W S OF 20N ENHANCED BY UPPER LEVEL CONFLUENT FLOW W OF AN UPPER TROUGH OVER AFRICA. AT THE SFC...WEAK TO MODERATE HIGH PRES RIDGING IS THE RULE ACROSS THE ERN AND WRN SUBTROPICAL ATLC SUPPORTED BY A 1027 MB HIGH NEAR THE AZORES AND A 1028 MB HIGH OFFSHORE OF THE MID-ATLANTIC U.S. A PRONOUNCED WEAKNESS IN THIS RIDGING LIES IN THE CNTRL ATLC DUE TO THE SFC LOW AND FRONTAL BOUNDARY MENTIONED. $$ CANGIALOSI