000 AXNT20 KNHC 101122 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 AM EST SAT MAR 10 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 1115 UTC. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 7N12W 4N25W 2N42W CROSSING THE EQUATOR NEAR 48W INTO NE BRAZIL. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM SOUTH OF THE AXIS BETWEEN 31W-41W AND WITHIN 90 NM N OF THE AXIS W OF 45W. SIMILAR CONVECTION EXISTS OVER NE BRAZIL. SCATTERED SHOWERS AND TSTMS ARE WITHIN 90 NM EITHER SIDE OF THE AXIS BETWEEN 18W-22W. ...DISCUSSION... GULF OF MEXICO... STRONG ZONAL MID TO UPPER LEVEL PATTERN HAS SET UP IN THE GULF SANDWICHED BETWEEN A DIGGING SHORTWAVE TROUGH OVER THE CENTRAL/EASTERN U.S. AND WEAK RIDGING OVER CENTRAL AMERICA. THIS STRONG FLOW ALOFT IS SPREADING A PLUME OF MOISTURE ACROSS CENTRAL/SOUTHERN MEXICO AND THE GULF S OF 27N. MOST OF THIS IS ONLY IN THE FORM OF BROKEN/OVERCAST MID TO HIGH LEVEL CLOUD DECK AND A POSSIBLE ISOLATED SHOWER IN THE BAY OF CAMPECHE. IN THE LOWER LEVELS...WEAK HIGH PRES RIDGING IS THE THEME EXTENDING SW FROM A STRONG HIGH WELL OFF THE MID-ATLANTIC COAST. A VERY WEAK SFC TROUGH...DEPICTED BY A SLIGHT WIND SHIFT OR PERTURBATION IN THE LIGHT ELY FLOW IN QSCAT AND SHIP OBS...IS NEARLY STATIONARY ALONG 89W FROM 25N-30N. SCATTERED LOW TO MID LEVEL CLOUDS AND MAYBE A FEW EMBEDDED LIGHT SHOWERS ARE WITHIN 180 NM E OF THE TROUGH AXIS. LOOKING AHEAD THROUGH THE WEEKEND...THE WEAK TROUGH WILL GRADUALLY DISSIPATE AS STRONG HIGH PRES BUILDS N OF THE REGION. THE PRES GRADIENT ON THE S SIDE OF THE HIGH WILL INCREASE THE SFC EASTERLIES SLIGHTLY ON SUN AND INTO EARLY NEXT WEEK. CARIBBEAN... QUIET WEATHER PERSISTS ACROSS MUCH OF THE BASIN THIS MORNING WITH PLENTY OF DRY STABLE AIR ALOFT IN PLACE. WEAK UPPER RIDGING GENERALLY DOMINATES THE REGION AS THE SHORTWAVE TROUGH HAS NOW PULLED E INTO THE CENTRAL ATLC. THERE ARE ONLY A COUPLE OF AREAS OF NOTABLE CLOUDINESS. ONE IS OVER COLOMBIA...PANAMA...COSTA RICA AND THE COASTAL WATERS WHERE THERE ARE SMALL PATCHES OF WEAKENING SHOWERS MOSTLY ASSOCIATED WITH CLIMATOLOGICAL LOW PRES AND THE ITCZ. THE OTHER AREA OF CLOUDINESS IS OVER THE ISLAND OF HISPANIOLA WHERE INFLUENCE FROM A SFC TROUGH TO THE N AND LOCAL UPSLOPING CONDITIONS IS LIKELY PRODUCING A FEW SHOWERS OVER THE HIGH TERRAIN...BUT THIS ACTIVITY HAS JUST ABOUT TURNED OFF OVER THE PAST FEW HOURS. OTHERWISE MAINLY FAIR WEATHER AND TYPICAL ISOLATED TRADE WIND SHOWERS ARE MOVING WWD ACROSS THE REGION. TRANQUIL WEATHER IS EXPECTED TO CONTINUE THROUGH THE WEEKEND WITH CONDITIONS DOMINATED BY MODERATE TO STRONG TRADE WINDS. WESTERN ATLANTIC... A LARGE AREA OF MULTILAYER CLOUDINESS AND SCATTERED SHOWERS/TSTMS CONTINUE TO AFFECT THE REGION. THE SFC PATTERN CONTRIBUTING TO THIS UNSETTLED WEATHER HAS BEEN SOMEWHAT COMPLEX. LAST NIGHT...THE SETUP CONSISTED OF A LOW PRES SYSTEM N OF THE CENTRAL BAHAMAS WITH AN ASSOCIATED TROUGH EXTENDING SWD TO THE WINDWARD PASSAGE AND AN APPROACHING COLD FRONT NE OF THE LOW. OVER THE PAST SEVERAL HOURS...IT HAS BECOME APPARENT ON SATELLITE IMAGERY THAT THESE FEATURES HAVE MERGED TOGETHER AND AS OF 06Z A COLD FRONT ENTERED THE AREA NEAR 32N44W TO 29N55W THEN STATIONARY TO A 1012 MB LOW NEAR 26N72W. A TROUGH REMAINS FAIRLY DISTINCT FROM THE LOW SWD TO THE WINDWARD PASSAGE. ALL OF THESE ELEMENTS ALONG WITH STRONG W-SWLY UPPER LEVEL FLOW IS GENERATING AND ADVECTING MOISTURE MAINLY N OF 24N W OF 50W. HOWEVER...PRECIP IS NOT REACHING THE GROUND ACROSS THIS ENTIRE AREA. IR IMAGES SUGGEST THAT SCATTERED SHOWERS AND TSTMS ARE MOST LIKELY FROM 24N-29N BETWEEN 62W-70W WHERE LIFTING AND INSTABILITY IS GREATEST. IN ADDITION TO THE MOISTURE...ANOTHER CONCERN IS THE STRONG NELY WINDS AS A TIGHT PRES GRAD HAS NOW SET UP BETWEEN THE LOW AND A 1034 MB HIGH NEAR 38N64W. LOOKING AHEAD IN TIME...THE WEAK LOW IS EXPECTED TO INTENSIFY AND TRACK TO THE NE. THIS WILL INCREASE THE PRES GRAD FURTHER THROUGHOUT THE DAY AND FOR THAT REASON A GALE WARNING IS IN EFFECT FOR A PORTION OF THE FORECAST AREA. FOR DETAILS REFER TO THE HIGH SEAS FORECAST UNDER AWIPS HEADER MIAHSFAT2. EASTERN ATLANTIC... STRONG HIGH PRES RIDGING CONTINUES TO DOMINATE 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 N OF 20 E OF 25W WHERE THE TIGHTEST PRES GRAD EXISTS. IN THE MID AND UPPER LEVELS...STRONG RIDGING IS ALSO THE RULE WITH THE AXIS ALIGNED ROUGHLY ALONG 30W. ABUNDANT DRY SUBSIDENT FLOW ALOFT IS WIDESPREAD AIDING IN THE FAIR WEATHER ACROSS THIS REGION. OVER THE NEXT FEW DAYS...THE STRONG RIDGING WILL RETREAT NE ALLOWING THE TRADES TO RELAX SLIGHTLY TODAY ESPECIALLY IN THE E ATLC. HOWEVER THEY ARE SET TO PICK UP AGAIN FROM W TO E SUN AND INTO NEXT WEEK AS STRONG HIGH PRES REBUILDS E ACROSS THE ATLC OCEAN. THE UPPER RIDGE IS FORECAST TO SHIFT W AS A SHARP TROUGH DEVELOPS IN THE E ATLC N OF THE REGION...THIS SHOULD ALLOW FAIR WEATHER TO CONTINUE FOR THE BULK OF THE AREA. $$ CANGIALOSI