000 AXNT20 KNHC 191747 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT FRI OCT 19 2007 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 50W S OF 16N MOVING W 10-15 KT. FOR THE PAST FEW DAYS THERE HAS BEEN SOME CONFLICTING EVIDENCE ON THE POSITION OF THIS WAVE. WE HAVE MAINTAINED CONTINUITY FOR THE PAST COUPLE OF DAYS FOLLOWING A FAINT LOW-LEVEL INVERTED V-SHAPE IN THE LOW CLOUDS WELL AHEAD OF DENSER CLOUDINESS. HOWEVER... THAT WEAK LOW-LEVEL SIGNATURE HAS JUST ABOUT DISSIPATED AND THE DENSER CLOUDINESS HAS BECOME MORE PRONOUNCED WITH SOME WAVE LIKE STRUCTURE EVIDENT. A LONG-TERM SATELLITE LOOP AND THE MIMIC TPW ANIMATION ALSO SHOWS WWD PROPAGATION OF THIS CLOUD MASS. THEREFORE...THIS WAVE WILL LIKELY BE RELOCATED BACK FIVE DEGREES OR SO TO AGREE WITH THE SATELLITE SIGNATURE. SCATTERED MODERATE CONVECTION IS FROM 5N-13N BETWEEN 39W-47W. WEAK TROPICAL WAVE IS IN THE CENTRAL CARIBBEAN ALONG 72W S OF 17N MOVING W 10-15 KT. THIS WAVE HAS BEEN CHALLENGING TO TRACK OVER THE PAST COUPLE OF DAYS WITH THE CURRENT POSITION SOLELY BASED ON FORWARD CONTINUITY. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 9N13W 6N30W 8N46W 6N56W. THERE IS NO SIGNIFICANT CONVECTION BESIDES FOR THE ACTIVITY ASSOCIATED WITH THE TROPICAL WAVE. DISCUSSION... GULF OF MEXICO... A COLD FRONT...SUPPORTED BY A UPPER TROUGH OVER THE PLAINS...IS MOVING ACROSS THE GULF WATERS. AS OF 15Z...THE FRONT WAS ANALYZED FROM THE WRN FL PANHANDLE TO JUST N OF BROWNSVILLE TEXAS ALONG 31N87W 28N90W 27N98W. A PREFRONTAL TROUGH OR BROKEN SQUALL LINES LIE ABOUT 60 NM AHEAD OF THE FRONT. MOSAIC DOPPLER RADAR DATA DEPICTS NUMEROUS SHOWERS AND TSTMS MOSTLY ALONG AND TO THE E OF THE FRONT WITHIN 90 NM. THIS RAINFALL HAS PRODUCED SOME FLOODING ACROSS THE FL PANHANDLE. FOR DETAILS REFER TO PRODUCTS FROM YOUR LOCAL WEATHER OFFICE. BEHIND THE FRONT...MUCH DRIER AND SLIGHTLY COOLER AIR IS FILTERING IN WITH DEWPOINTS DROPPING INTO THE 40'S AND 50'S F. WELL AHEAD OF THE FRONT...DEEP LAYER SLY FLOW IS CREATING A WARM HUMID AIRMASS WITH A FAIR AMOUNT OF CLOUDINESS BUT ONLY ISOLATED SHOWERS AT THE MOMENT. MODEL GUIDANCE SHOWS THIS FRONT CONTINUING SE THRU TONIGHT THEN SLOWLY AND BEGINNING TO WASH OUT OVER THE WEEKEND. THE NEXT FRONT...WHICH WILL LIKELY BE STRONGER...SHOULD ENTER THE REGION EARLY NEXT WEEK. CARIBBEAN SEA... AN UPPER LOW IS TRACKING NW ACROSS THE CARIBBEAN CENTERED VERY NEAR COZUMEL MEXICO. S TO SE FLOW ALOFT...BETWEEN THIS UPPER LOW AND A RIDGE OVER THE SW ATLC...IS DRAWING ABUNDANT TROPICAL MOISTURE NWD FROM THE ITCZ BETWEEN 76W-83W. THIS MOISTURE PLUME HAS BEEN PERSISTENT AND SHIFTING W WITH THE UPPER LOW OVER THE PAST FEW DAYS. THERE ALSO HAS BEEN SOME EVIDENCE OF LOW-LEVEL TROUGHING LIKELY ASSOCIATED WITH A TROPICAL WAVE WHICH HAS BEEN MOVING IN TANDEM WITH THE UPPER LOW. IR IMAGES SHOW A NARROW SWATH OF SCATTERED SHOWERS AND TSTMS FROM 11N-20N BETWEEN 77W-82W. MUCH DRIER MID TO UPPER LEVEL AIR IS OVER THE CARIB WATERS E OF 73W ADVECTED BY NLY UPPER FLOW AROUND THE AFOREMENTIONED RIDGE. SCATTERED CLOUDINESS AND SHOWER ACTIVITY IS OVER PORTIONS OF THE LESSER ANTILLES ASSOCIATED WITH DIFFLUENT AREAS BETWEEN A DEVELOPING CUT OFF JUST N OF THE AREA AND THE SW PERIPHERY OF A HIGH JUST TO THE E. THE FAR NW CARIB IS FAIRLY TRANQUIL WITH LITTLE SIGNIFICANT MOISTURE DIRECTLY UNDERNEATH THE UPPER LOW. ATLANTIC OCEAN... AN AMPLIFIED LONG WAVE RIDGE/TROUGH/RIDGE PATTERN IS WELL ESTABLISHED ACROSS THE SUBTROPICAL ATLC. THE WRN ATLC RIDGE IS CENTERED ABOUT 90 NM NE OF THE NRN BAHAMAS NEAR 28N76W. A VERY LARGE SHARPENING TROUGH LIES TO THE E OF THERE COVERING THE AREA BETWEEN 40W-63W N OF 20N. A LOW APPEARS TO BE TRYING TO CUT OFF NEAR THE BASE OF THE TROUGH JUST N OF THE LESSER ANTILLES. THIS TROUGH IS PROVIDING SOME SUPPORT FOR A SLOWLY DYING STATIONARY FRONTAL BOUNDARY WHICH ENTERS THE AREA NEAR 32N30W AND STRETCHES SW TO A 1016 MB LOW NEAR 29N43W CONTINUING TO 24N57W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE GENERALLY WITHIN 180 NM W OF THIS BOUNDARY SUPPORTED BY DIFFLUENCE ALOFT. MODERATE SFC RIDGING DOMINATES THE AREA TO THE W OF THE FRONT. THE SFC PATTERN IN THE CENTRAL AND E ATLC IS MOSTLY CONTROLLED BY WEAK HIGH PRES RIDGING ANCHORED BY A 1020 MB HIGH SITUATED NEAR 26N31W. THIS IS PRODUCING MAINLY LIGHT WINDS OVER THE SUBTROPICAL ATLC...WHILE MODERATE TRADES PERSIST IN THE TROPICS ESPECIALLY NEAR THE TROPICAL WAVE. THE UPPER PATTERN OVER THE E ATLC CONSISTS OF A LARGE SCALE RIDGE EXTENDING NWD FROM A HIGH CENTER NEAR 10N32W. THE STRONG CUT OFF LOW FROM A FEW DAYS AGO HAS RACED NE AND OPENED INTO A TROUGH BUT IS STILL INTERRUPTING RIDGING SLIGHTLY ALONG 27W/28W N OF 18N. CONVECTION IS MOSTLY CONFINED TO THE ITCZ SUPPORTED BY DIFFLUENCE ALOFT NEAR THE W PERIPHERY OF THE RIDGE. SEE ABOVE FOR DETAILS. $$ CANGIALOSI