000 AXNT20 KNHC 170539 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 105 AM EST SAT FEB 17 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 5N9W 4N20W 2N31W...CROSSING THE EQUATOR NEAR 38W...1S40W INTO NORTHEASTERN BRAZIL NEAR 2S44W. CLUSTERS OF SCATTERED MODERATE CONVECTION ARE WITHIN 150 NM EITHER SIDE OF THE AXIS E OF 17W AND W OF 32W. ISOLATED MODERATE IS WITHIN 120 NM EITHER SIDE BETWEEN 24W-29W. ...DISCUSSION... THE GULF OF MEXICO... FAIR WEATHER IS THE RULE ACROSS THE GULF THIS EARLY MORNING AS MOST OF THE LOW TO MID LEVEL CLOUD DECK HAS THINNED AND PUSHED SWD WITH THE FRONT NOW IN THE NW CARIB. THE ONLY AREA OF THICK CLOUD COVER IS IN THE SW GULF NEAR A LINGERING WEAK STATIONARY FRONT ALONG THE SIERRA MADRE MOUNTAINS....BUT EVEN THESE CLOUDS ARE BEING ERODED AND PUSHED SWD. SCATTERED COLD AIR STRATOCUMULUS CLOUDS ARE SEEN ON IR IMAGES OVER MOST OF THE ERN HALF OF THE REGION. THE SFC FLOW IN THE W GULF HAS RELAXED A GREAT DEAL SINCE YESTERDAY AT THIS TIME AS THE HIGH PRES SYSTEM HAS WEAKENED AND BECOME CENTERED IN THE N CENTRAL GULF. NLY WINDS ARE MODERATE IN THE E GULF DUE TO THE TIGHTENED PRES GRADIENT BETWEEN HIGH PRES IN THE CENTRAL GULF AND LOW PRES IN THE ATLC. THESE NLY WINDS ARE ADVECTING IN A COLD AIRMASS WITH TEMPS ALREADY IN THE 20'S F IN N FLA. THE COLD AIR WILL BE REINFORCED BY A QUICK MOVING DRY COLD FRONT WHICH WILL BE PUSHING THRU THE ENTIRE REGION TODAY INTO EARLY SUN. THIS WILL RAMP UP THE NLY WINDS AGAIN IN ITS WAKE AS ANOTHER STRONG HIGH PRES SYSTEM BUILDS S. THE CARIBBEAN SEA... THE TAIL END OF A WEAKENING COLD FRONT EXTENDS FROM CENTRAL CUBA TO HONDURAS ALONG 22N78W 20N83W 15N87W. THE FRONT IS MARKED MOSTLY BY A SURGE IN NLY WINDS WELL INDICATED BY A QSCAT PASS NEAR 00 Z. A WEAK PRE-FRONTAL TROUGH IS ANALYZED FROM 20N79W TO 14N82W SHIFTING THE WINDS FROM E/NE TO NW PRIOR TO THE FRONTAL PASSAGE. LOTS OF LOW TO MID LEVEL CLOUDS LIE OVER CUBA AND PARTS OF THE NW CARIB...ALTHOUGH THERE ISN'T MUCH SHOWER ACTIVITY EMBEDDED IN THIS AS SUGGESTED BY DOPPLER RADAR IN CUBA. ELSEWHERE THE MAIN WEATHER FEATURE IS A VERY BROAD STRONG UPPER LEVEL RIDGE STRETCHING ACROSS THE REGION. THIS RIDGE IS SUPPLYING AN ABUNDANT AMOUNT OF DRY AIR/SUBSIDENT FLOW ALOFT SUPPRESSING ANY SIGNIFICANT TSTM ACTIVITY. THE DRIEST AIR IS IN THE UPPER CONFLUENT ZONE BETWEEN HISPANIOLA AND VENEZUELA/COLOMBIA. BENEATH THE STRONG MID LEVEL CAP...SMALL PATCHES OF LOW-LEVEL MOISTURE ARE BEING STEERED BY LIGHT TO MODERATE ELY TRADES E OF 78W. THE NLY WINDS ARE ANTICIPATED TO SLACKEN LATER TODAY IN THE NW CARIB BUT INCREASE AGAIN ON SUN BEHIND THE NEXT COLD FRONT. THE ATLANTIC OCEAN... A COLD FRONT ENTERS THE AREA NEAR 32N57W AND CONTINUES SW ALONG 26N68W TO THE COAST OF CUBA NEAR 22N77W. LOW LEVEL LIFT NEAR THE FRONT ALONG WITH A SUBTROPICAL JET RACING THRU THE AREA IS PRODUCING BROKEN TO OVERCAST MULTILAYERED CLOUDS WITH EMBEDDED SHOWERS WITHIN 400 NM NW OF THE FRONT. A SFC TROUGH ENTERS THE AREA NEAR BERMUDA AT 32N65W AND CONTINUES WSW TO 29N80W...ADDING A LITTLE CYCLONIC CURVATURE TO THE PREDOMINANT STRONG NW WINDS BLOWING OFFSHORE THE SE U.S. SWLY GALE FORCE WINDS ARE OCCURRING WITHIN 240 NM AHEAD OF THE FRONT N OF 29N. THE REMAINDER OF THE SFC PATTERN IN THE ATLC AREA IS DOMINATED BY THE SRN PERIPHERY OF A 1028 MB HIGH NEAR 35N28W. THIS IS SUPPLYING MOSTLY FAIR WEATHER AND MODERATE TRADES ACROSS A GOOD PORTION OF THE CENTRAL AND E ATLC. THE MID TO UPPER LEVEL PATTERN HAS AMPLIFIED A LITTLE...AS EXPECTED...DOMINATED BY A LARGE RIDGE OVER THE WRN AND CENTRAL ATLC W OF 40W AND A BROAD TROUGH E OF THERE. WHILE THE PATTERN IS MORE AMPLIFIED THERE IS LITTLE SIGNIFICANT MOISTURE BEING GENERATED OUTSIDE OF THE ITCZ. $$ CANGIALOSI