000 AXNT20 KNHC 290157 AAA TWDAT TROPICAL WEATHER DISCUSSION...UPDATED NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 957 PM EDT SAT MAR 28 2009 ...UPDATED GULF OF MEXICO SECTION TO ADD NEW CONVECTIVE ACTIVITY...ALSO UPDATED ITCZ CONVECTION... 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. ...ITCZ...UPDATED ITCZ AXIS IS CENTERED ALONG 4N9W 2N20W DIPPING TO S OF THE EQUATOR NEAR 22W...AND EXTENDS WSW FROM THERE TO INLAND THE COAST OF NE BRAZIL NEAR 3S41W. SCATTERED STRONG CONVECTION IS ALONG AND WITHIN 150 NM N OF THE ITCZ BETWEEN 21W-28W. SCATTERED MODERATE TO STRONG CONVECTION IS S OF THE AXIS BETWEEN 12W-27W. ...DISCUSSION... GULF OF MEXICO...UPDATED A LARGE DEEP UPPER LEVEL LOW MOVING E ACROSS MISSOURI EXTENDS A BROAD TROUGH S ACROSS TEXAS AND NOW ENTERING THE FAR WRN GULF. THE ASSOCIATED SURFACE COLD FRONT ENTERS THE AREA FROM THE FAR WRN FL PANHANDLE JUST W OF PENSACOLA SSW TO 26N88W TO 23N90W ...AND INTO THE ERN BAY OF CAMPECHE. THE FRONT IS MOVING E ABOUT 20-25 KT. A SQUALL LINE IS OBSERVED WITHIN 130 NM E OF THE FRONT N OF 27N. NWS DOPPLER RADAR AND RADAR IMAGERY ARE SHOWING SCATTERED SHOWERS AND TSTMS E OF THE FRONT...MORE NUMEROUS JUST INLAND N FL. A DIFFLUENT PATTERN TO THE E OF THE TROUGH OVER THE SE UNITED STATES AS SEEN ON SATELLITE WATER VAPOR IMAGERY IS SUPPORTING THIS ACTIVITY. PATCHES OF BROKEN LOW AND MID CLOUDS WITH EMBEDDED LIGHT RAIN AND ISOLATED SHOWERS ARE MOVING N ACROSS THE FAR SE WATERS AND STRAITS OF FL TO OVER AND ALONG THE FL KEYS. LATEST SURFACE ANALYSIS SHOWS HIGH PRES FILTERING IN ACROSS THE GULF BEHIND THE FRONT. NW TO N GALE WINDS BEHIND THE FRONT ARE IN THE 30-45 KT RANGE OVER THE SW GULF. THESE WINDS WILL DECREASE TO LESS THAN GALE FORCE LATE TONIGHT AS THE HIGH SHIFTS TO E OF THE GULF THROUGH MON. THE PRES GRADIENT OUTSIDE TSTM ACTIVITY IS RESULTING IN SE TO S WINDS OF 20-25 KT ACROSS MUCH OF THE MIDDLE AND ERN GULF SECTIONS AS NOTED IN LATEST BUOY OBSERVATIONS. THIS IS SERVING AS IN FLOW INTO STRONG TSTM WELL AHEAD OF THE FRONT OVER N FL. ADDITIONAL TSTM ACTIVITY HAS JUST RECENTLY DEVELOPED OVER THE NORTHERN YUCATAN PENINSULA DUE TO SURFACE CONVERGENCE WHICH IS FURTHER AIDED BY A SURFACE LOW OF 1006 MB OVER SE THE PART OF THE PENINSULA NEAR 19N89W AND THE UPPER TROUGH APPROACHING THE YUCATAN PENINSULA. THIS ACTIVITY IS MOVING RAPIDLY NE ACROSS THE SOUTHERN PORTION OF THE MIDDLE GULF...HOWEVER ALTHOUGH THEY ARE WEAKENING SOME STRONG GUSTY WINDS MAY OCCUR IN AND NEAR THIS ACTIVITY. LATEST MODEL GUIDANCE SUGGESTS THAT THE COLD FRONT WILL REACH A LINE FROM TAMPA BAY TO NE YUCATAN PENINSULA EARLY SUN...AND TO THE FAR SE WATERS BY EARLY SUN EVENING AS THE UPPER TROUGH EXITS THE GULF...AND IS REPLACED BY ZONAL FLOW THROUGH MON WHILE THE SURFACE HIGH SLIDES E. EXPECT STABLE CONDITIONS TO PREVAIL THROUGHOUT UNDER SUBSIDENCE IN THE WAKE OF THE TROUGH THROUGH EARLY NEXT WEEK. CARIBBEAN SEA... THE AREA OF BROAD ANTICYCLONIC FLOW THAT WAS EVIDENT OVER MUCH OF THE CENTRAL AND ERN GULF THE PAST COUPLE OF DAYS HAS SHIFTED EWD AHEAD OF THE GULF OF MEXICO COLD FRONT AND PRESENTLY COVERS THE MAJORITY OF THE SEA...EXCEPT FOR THE FAR ERN PORTION. ITS ASSOCIATED MEAN RIDGE AXIS ROUGHLY EXTENDS ALONG 76W. ABUNDANT SUBSIDENCE RESULTING IN RATHER STABLE CONDITIONS IS RESULTING IN ABUNDANT MODERATE SUBSIDENCE SEEN THROUGHOUT JUST ABOUT THE ENTIRE SEA...AND IS FURTHER ENHANCED OVER THE NE PORTION WHERE CONFLUENT FLOW INTO THE BASE OF THE CENTRAL ATLC DEEP LAYER TROUGH MENTIONED BELOW UNDER ATLC OCEAN. ONLY VERY NARROW LINES OF LOW CLOUDS WITH POSSIBLE ISOLATED SHOWERS MOVING QUICKLY TO THE NW ARE NOTED OVER THE MIDDLE AND WRN CARIBBEAN W TO 84W. A JET STREAM BRANCH...WITH WINDS IN THE RANGE OF 40-60 KT ...EXTENDS FROM NORTHERN COLOMBIA NE INTO THE BASE OF THE CENTRAL ATLC UPPER TROUGH MENTIONED BELOW. THE JET IS TRANSPORTING BROKEN TO SCATTERED HIGH LEVEL CLOUDS NE TO ACROSS THE FAR ERN CARIBBEAN SEA. PATCHES OF LOW-LEVEL IN THE FORM OF SCATTERED TO BROKEN LOW CLOUDS MOVING W WITH ISOLATED SHOWERS ARE OVER THE FAR ERN CARIBBEAN S OF 15N E OF 70W. THIS MOISTURE IS GREATLY ATTRIBUTED TO THE WEAKENING ATLC FRONTAL TROUGH E OF THE LESSER ANTILLES. THE TROUGH IS FORECAST TO DRIFT N AND DISSIPATE OVER THE NEXT 48 HOURS...DIMINISHING THE CHANCES OF PRECIPITATION OVER THE WINDWARD ISLANDS AND ERN CARIBBEAN SEA. WITH RESPECT TO MARINE CONDITIONS...STRONG SE WINDS IN THE RANGE OF 20-30 KT ARE BEING OBSERVED OVER THE NW CARIBBEAN W OF ABOUT 84W DUE TO THE TIGHT PRES GRADIENT BETWEEN HIGH PRES CENTERED N OF THE SEA OVER THE ATLC NEAR 30N61W...AND LOWER PRES OVER THE ERN GULF OF MEXICO DUE TO THE COLD FRONT ADVANCING EWD. ATLANTIC OCEAN... OVER THE W ATLC...DEEP LAYER RIDGING IS KEEPING HOLD OF THE WRN PORTION OF THE ATLC AS IT GRADUALLY TRANSLATES EWD. AN UPPER LEVEL RIDGE AXIS MOVING E EXTENDS FROM 32N68W TO 29N69W. THE ASSOCIATED 1024 MB SURFACE HIGH CENTER IS LOCATED NEAR 30N61W WITH A RIDGE SW TO S CENTRAL FL. A JET STREAM BRANCH WITH MAXIMUM WINDS OF 60 KT POKES SE INTO CENTRAL BAHAMAS FROM THE ERN GULF OF MEXICO. UPPER LEVEL MOISTURE IS BEING CHANNELED EWD INTO THE WRN ATLC BY THIS JET STREAM BRANCH. THE ABOVE GULF OF MEXICO COLD FRONT IS FORECAST TO MOVE OFF THE SE U.S. AND NE FL COAST SUN MORNING PRECEDED BY INCREASING SLY WINDS OF 20-30 KT FOLLOWED BY SHIFTING WINDS TO W ALSO AT 20-30 KT. EXPECT AN INCREASE OF SCATTERED SHOWERS AND TSTMS OVER THE THE NW PART TONIGHT THROUGH SUN AHEAD OF THE FRONT. THE FRONT IS FORECAST TO REACH FROM NEAR BERMUDA TO THE NORTHERN BAHAMAS TO STRAITS OF FL MON EVENING...THEN BECOME STATIONARY ALONG 26N TUE. OVER THE CENTRAL ATLC...A DEEP LAYER TROUGH EXTENDS FROM 22N58W NE TO 26N49W WHERE IT SHARPLY TILTS NE TO 28N41W TO NE OF AREA AT 32N39W. THE ASSOCIATED SURFACE COLD FRONT ENTERS THE AREA THROUGH 32N37W AND CONTINUES SW TO 24N42W WHERE IT BECOMES STATIONARY TO 19N49W...THEN A FRONTAL TROUGH TO NEAR 12N57W. LATEST SATELLITE IMAGERY SHOWS BROKEN MAINLY LOW AND MID LEVEL CLOUDS ALONG WITH SCATTERED HIGH CLOUDS. SCATTERED SHOWERS AND TSTMS ARE WITHIN THESE CLOUDS WITHIN ABOUT 90-200 NM E OF THE FRONT N OF 26N. OVERCAST TO BROKEN LOW AND MID LEVEL CLOUDS WITH SCATTERED SHOWERS ARE ELSEWHERE WITHIN 180 NM EITHER SIDE OF THE STATIONARY FRONT ...AND WITHIN 90 NM EITHER SIDE OF THE TROUGH. IN THE FAR ERN ATLC...ATLC COLD-AIR INSTABILITY IS BRINGING A SMALL AREA OF SCATTERED TSTMS JUST N OF THE FAR NE PART OF THE AREA. THIS ACTIVITY IS APPROACHING THE COAST. SCATTERED TO BROKEN STRATOCUMULUS CLOUDS MOVING S WITH SCATTERED SHOWERS ARE OVER THE NE PART OF THE AREA N OF 26N E OF 25W. FOR THE THIRD DAY IN A ROW...SATELLITE VISIBLE IMAGERY SUPPORTED BY THE CIMSS SAL ANALYSIS SHOWS AN AREA OF SAHARAN AFRICAN DUST THAT EMERGED OUT OVER THE FAR ERN ATLC S OF 17N AND E OF 37W. AN EXTENSIVE AREA OF DEEP HIGH PRES COVERS THE AREA S OF ABOUT 27N WITH A MEAN ANTICYCLONIC CENTER OBSERVED FAR S NEAR 7N23W WITH A RIDGE NW TO 15N31W...THEN TO 23N32W AND BECOMES RATHER WELL DEFINED TO NE OUT OF THE AREA AT 32N31W. THE RIDGE IS ENHANCING CONVECTION NEAR AND ALONG THE ITCZ W OF 38W WHERE SOME DIFFLUENCE IS NOTED ON THE SW PERIPHERY OF THE RIDGE AXIS. THE HIGH IS FORECAST TO SLIDE E OVER THE NEXT 48 HRS AS THE UPPER TROUGH TO ITS NW PRESSES EWD. $$ AGUIRRE