000 AXNT20 KNHC 081148 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 AM EST THU MAR 08 2007 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...METEOROLOGICAL ANALYSIS... WEATHER OBSERVATIONS...AND RADAR. BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1100 UTC. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 7N11W 3N18W 2N29W 1N41W EQ50W. SCATTERED MODERATE CONVECTION IS WITHIN 60 NM EITHER SIDE OF THE AXIS BETWEEN 19W-21W AND FROM 1S-1N BETWEEN 30W-33W. ISOLATED MODERATE IS WITHIN 120 NM EITHER SIDE W OF 36W. ...DISCUSSION... GULF OF MEXICO... MAINLY QUIET WEATHER CONTINUES IN THE GULF THANKS TO A WEAK SFC RIDGE THAT STRETCHES ACROSS THE AREA. SHIP/BUOY OBS AND NIGHT CHANNEL VIS IMAGES SHOW LIGHT VARIABLE WINDS AND SCATTERED PATCHES OF LOW-MID LEVEL CLOUDS BETWEEN 85W-95W. AN EXTREMELY WEAK SFC TROUGH MAY BE FORMING ALONG 87W FROM 26N-29N BUT THIS WAS NOT SHOWN ON THE 09Z MAP DUE TO ITS VERY FEEBLE STRUCTURE. IN THE MID AND UPPER LEVELS...THE FLOW IS MAINLY FROM THE WNW BENDING AROUND AN UPPER RIDGE THAT EXTENDS NWD FROM THE TROPICAL EPAC INTO THE BAY OF CAMPECHE. SWLY FLOW ON THE W PERIPHERY OF THIS RIDGE IS SPREADING HIGH LEVEL MOISTURE FROM THE EPAC INTO CENTRAL MEXICO AND THE WRN GULF...W OF 90W FROM 23N-27N. MODESTLY DRY AIR EXISTS ELSEWHERE AIDING IN THE TRANQUIL WEATHER. OVER THE NEXT COUPLE OF DAYS...LITTLE PATTERN CHANGE IS ANTICIPATED BOTH AT THE SFC AND ALOFT KEEPING WINDS LIGHT AND THE WEATHER CONDITIONS MAINLY FAIR ACROSS MOST OF THE AREA. CARIBBEAN... THE WEAK LOW THAT WAS DRIFTING W IN THE NW CARIB APPEARS TO HAVE OPENED INTO A TROUGH ANALYZED ALONG 87W FROM THE COAST OF HONDURAS TO THE NE YUCATAN. THE MAIN EFFECT OF THIS WEAK SYSTEM IS AN AREA OF LOW TO MID LEVEL CLOUDS WHICH LIE ACROSS NRN CENTRAL AMERICA AND THE COASTAL WATERS FROM 15N-22N W OF 85W. THE MOIST ONSHORE FLOW IS RUNNING UPSLOPE SOME OF THE HIGH TERRAIN LIKELY PRODUCING ISOLATED SHOWERS OVER HONDURAS ...GUATEMALA AND THE YUCATAN PENINSULA. ELSEWHERE FAIRLY TYPICAL CONDITIONS EXIST WITH MODERATE TO STRONG ELY TRADES AND THIN PATCHES OF LOW-LEVEL MOISTURE STREAMING W ACROSS THE SEA. ALOFT...THERE IS SLIGHT TROUGHING EXTENDING SWD FROM ATLC ACROSS THE WINDWARD PASSAGE AND JAMAICA TO 15N81W. THIS TROUGH IS ENHANCING THE WIDESPREAD DRY STABLE AIR PREVENTING THE MOISTURE PATCHES FROM ACQUIRING MUCH VERTICAL DEPTH. THE WEAK SFC TROUGH ALONG THE CENTRAL AMERICAN COAST WILL DRIFT INLAND AND LIKELY DISSIPATING LATER TODAY. TRADE WINDS MAY RELAX LATE FRI AND THIS WEEKEND AS THE STRONG RIDGE IN THE E ATLC RETREATS AND LOW PRES DEVELOPS N OF THE REGION. OTHERWISE LITTLE CHANGE IS EXPECTED OVER THE NEXT FEW DAYS. WESTERN ATLANTIC... SLIGHT MID TO UPPER LEVEL TROUGHING COVERS THE MAJORITY OF THE ATLC W OF 50W EXTENDING SWD FROM A LARGE STRONG POLAR LOW. AN ASSOCIATED WEAKENING FRONTAL BOUNDARY IS LINGERING IN THE REGION ANALYZED STATIONARY ALONG 32N46W 26N55W THEN DISSIPATING TO 26N66W. BROKEN TO OVERCAST LOW AND MID LEVEL CLOUDS WITH EMBEDDED ISOLATED SHOWERS ARE WITHIN 180 NM BEHIND THE FRONT. THICKER CLOUD COVER LIES FURTHER W ACROSS THE BAHAMAS WHERE A SFC TROUGH HAS FORMED. SCATTERED SHOWERS ARE EMBEDDED IN THIS CLOUD COVER AS DEPICTED BY DOPPLER RADAR FROM THE BAHAMAS. THIS TROUGH IS LIKELY A RESULT OF ENERGY THAT BROKE OFF FROM THE WEAKENING FRONT AND ENHANCED BY AN UPPER SHORTWAVE. SE OF THE FRONT...SKIES ARE MAINLY FAIR UNDER THE INFLUENCE OF SFC HIGH PRES RIDGING FROM THE NE AND DRY STABLE AIR ALOFT. LOOKING AHEAD A COUPLE OF DAYS...THE LARGE POLAR VORTEX WILL GRADUALLY PULL EWD BUT THERE STILL SHOULD BE SOME SUPPORT FOR THE WEAK SFC TROUGH IN THE BAHAMAS. GFS SHOWS THIS FEATURE MERGING WITH A COLD FRONT CURRENTLY OFF THE SE U.S. ON FRI. THIS WILL LIKELY CONTINUE TO PRODUCE SOME UNSETTLED WEATHER FOR PORTIONS OF THE W ATLC. EASTERN ATLANTIC... A STRONG 1035 MB HIGH PRES SYSTEM LOCATED A COUPLE HUNDRED NM E OF THE AZORES IS DOMINATING THE SFC PATTERN ACROSS THE ATLC E OF 45W. THIS HIGH IS PRODUCING MODERATE TO STRONG TRADE WINDS ACROSS A GOOD PORTION OF THE DISCUSSION AREA PARTICULARLY E OF 30W WHERE A TIGHT PRES GRAD EXISTS BETWEEN THIS HIGH AND LOW PRES IN THE MEDITERRANEAN. THE ONCE VIGOROUS UPPER LOW HAS OPENED INTO A TROUGH ALIGNED ALONG 34W. SWLY UPPER LEVEL FLOW AND DIFFLUENCE TO THE E OF THE TROUGH AXIS IS STILL GENERATING PATCHY MID-HIGH LEVEL MOISTURE FROM 16N TO BEYOND 32N BETWEEN 23W-34W. THIS MOISTURE PLUME IS SUBSTANTIALLY THINNER THAN IT WAS YESTERDAY AT THIS TIME AND THIS TREND IS EXPECTED TO CONTINUE AS THE TROUGH PULLS NWD AND DISSIPATES LATER TODAY OR FRI. FAIR WEATHER LOOKS TO BE THE THEME FOR MOST OF THE REGION THIS WEEKEND AS STRONG DEEP LAYER RIDGING BECOMES WELL ESTABLISHED. $$ CANGIALOSI