000 AXNT20 KNHC 071120 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 AM EST WED MAR 07 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 7N10W 5N20W 2N30W EQ40W EQ50W. SCATTERED MODERATE CONVECTION IS WITHIN 60 NM EITHER SIDE OF THE AXIS E OF 18W AND FROM 1S-3S BETWEEN 30W-38W. ISOLATED MODERATE IS WITHIN 180 NM N OF THE AXIS BETWEEN 36W-44W. ...DISCUSSION... GULF OF MEXICO... A 1028 MB SFC HIGH PRES SYSTEM REMAINS ESTABLISHED ACROSS THE AREA CENTERED OVER THE NE GULF NEAR 30N88W. LATEST QSCAT DATA AND SFC OBS SHOW LIGHT ELY WINDS ACROSS THE E AND MIDDLE GULF VEERING TO THE S IN THE W GULF ON THE WRN PERIPHERY OF THE RIDGE. IN THE MID AND UPPER LEVELS...THE FLOW IS MAINLY FROM THE WNW BETWEEN EXTENSIVE ZONAL FLOW OVER CENTRAL AMERICA AND WELL DEFINED TROUGHING OVER THE ERN U.S. ASSOCIATED WITH A LARGE POLAR VORTEX. BROKEN MID AND HIGH CLOUDINESS IS LOCATED N OF 27N ESPECIALLY IN THE NE GULF CLOSER TO THE BASE OF THE DEEP TROUGH. ABUNDANT DRY SINKING AIR EXISTS ELSEWHERE KEEPING SKIES FAIR TO MOSTLY CLEAR. OVER THE NEXT COUPLE OF DAYS...THE HIGH PRES SYSTEM MAY WEAKEN SLIGHTLY KEEPING WINDS LIGHT TO MODERATE. THE MID AND UPPER PATTERN WILL LIKELY REMAIN NEARLY ZONAL BUT MAY INCREASE IN MAGNITUDE AS SMALL IMPULSES/VORT MAXES MOVE ACROSS THE SRN U.S. CARIBBEAN... REMNANT PATCHES OF LOW TO MID LEVEL CLOUDS...LEFT OVER FROM THE DISSIPATED TROUGH/FRONT...ARE STILL LINGERING IN THE NW CARIB STEERED BY MODERATE TO STRONG NELY FLOW. THIS FLOW IS POOLING MOISTURE OVER HONDURAS...BELIZE...GUATEMALA AND S MEXICO AND LIFTED OROGRAPHICALLY NEAR/OVER THE HIGH TERRAIN. SOME STATIONS IN THESE COUNTRIES ARE REPORTING LIGHT SHOWERS. A SIMILAR SETUP EXISTS OVER THE HIGH TERRAIN OF HISPANIOLA. ELSEWHERE MODERATE ELY TRADES ARE BLOWING WITH ONLY A FEW PATCHES OF LOW-LEVEL MOISTURE. ALOFT...THE FLOW IS RATHER ZONAL WITH A LARGE AMOUNT OF DRY STABLE AIR ...ESPECIALLY E OF 78W...KEEPING MOST OF THE MOISTURE PATCHES SHALLOW. NO BIG PATTERN CHANGES ARE EXPECTED IN THE NEXT DAY OR TWO SO SIMILAR TRADES AND WEATHER CONDITIONS ARE LIKELY. WESTERN ATLANTIC... DEEP LAYER TROUGHING COVERS THE MAJORITY OF THE ATLC W OF 50W EXTENDING SWD FROM A LARGE POLAR LOW. TWO FRONTAL BOUNDARIES ARE ASSOCIATED WITH THE TROUGH. ONE OF THESE HAS BEEN IN THE AREA FOR QUITE SOMETIME AND IS ANALYZED ALONG 32N52W 26N63W THEN STATIONARY ACROSS THE ERN BAHAMAS. BROKEN LOW AND MID LEVEL CLOUDS AND EMBEDDED SHOWERS ARE WITHIN 180 NM ALONG AND AHEAD OF THE COLD FRONT AND WITHIN 150 NM W OF THE STATIONARY PART OF THE BOUNDARY. A PREFRONTAL TROF LIES 150 NM E OF THE FRONT ALONG 25N59W 21N67W NOTED BY GENTLE LOW-LEVEL CONVERGENCE SEEN IN QSCAT DATA AND SAT IMAGES. THE OTHER FRONT IS RAPIDLY PROGRESSIVE ENTERING THE AREA NEAR 32N58W EXTENDING WSW TO 29N77W THEN STATIONARY TOWARD THE SE GEORGIA COAST. THIS FRONT IS CLEARLY MARKED BY A THIN ROPE LINE ON NIGHT CHANNEL VIS BUT BECAUSE OF THE STABLE LOW-LEVELS BEHIND THE FIRST FRONT...INDICATED BY COLD AIR STRATOCUMULUS CLOUDS...LIMITED MOISTURE IS ASSOCIATED WITH THIS ONE. HOWEVER WV IMAGES DO SHOW A PATCH OF MID-HIGH LEVEL CLOUDS N OF 27N W OF 60W ASSOCIATED WITH A CLIPPER SYSTEM EMBEDDED IN THE DEEP LAYER TROUGH. NWP MODELS SHOW THE LAYERED TROUGH HOLDING ON FOR THE NEXT DAY OR TWO BEFORE PULLING NE TOWARD THE END OF THE WEEK. GFS IS HINTING AT DEVELOPING A SFC TROUGH OR WEAK LOW IN THE BAHAMAS LATE THU/FRI WHICH MAY PRODUCE SOME UNSETTLED WEATHER. EASTERN ATLANTIC... A 1035 MB HIGH PRES SYSTEM LOCATED A FEW HUNDRED NM S OF THE AZORES NEAR 33N23W IS DOMINATING THE SFC PATTERN ACROSS THE ATLC E OF 50W. THIS HIGH IS PRODUCING MODERATE TO STRONG TRADES ACROSS A GOOD PORTION OF THE DISCUSSION ZONE. THE MAIN FEATURE IN THIS AREA IS IN THE UPPER LEVELS WHERE A FAIRLY VIGOROUS 300 MB LOW IS LOCATED NEAR 26N42W. THIS LOW IS EMBEDDED AND CUTTING OFF A LARGE UPPER RIDGE THAT COVERS MOST OF THE REGION. SWLY UPPER LEVEL FLOW AND DIFFLUENCE TO THE E OF THE UPPER LOW IS ADVECTING AND GENERATING A FAIR AMOUNT OF MOISTURE/SCATTERED SHOWERS FROM 10N-32N BETWEEN 25W-40W. MODELS SHOW THE UPPER LOW MOVING NWD AND OPENING INTO A TROUGH LATER TODAY OR TOMORROW. THIS WILL LIKELY REDUCE THE FETCH OF MOISTURE ACROSS THE REGION AS THE UPPER RIDGE GAINS CONTROL. $$ CANGIALOSI