000 AXNT20 KNHC 202334 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST TUE NOV 20 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS IN THE W CARIBBEAN ALONG 81W S OF 19N MOVING W 10-15 KT. THE MIMIC TPW ANIMATION SHOWS SOME CONTINUITY SUPPORTING THE ANALYZED POSITION. THERE IS A GOOD AMOUNT OF CLOUDINESS...WITH EMBEDDED SCATTERED SHOWERS/ISOLATED TSTMS OVER THE W CARIB S OF 17N W OF 75W. AN UPPER DIFFLUENT PATTERN SEEN IN WATER VAPOR IMAGES IS LIKELY THE MAIN CULPRIT FOR THIS UNSETTLED WEATHER BUT THE WAVE MAY BE AIDING IN SOME OF THE ACTIVITY. NRN PORTION OF A TROPICAL WAVE EXTENDS INTO THE BAY OF CAMPECHE ALONG 94W/95W S OF 22N MOVING W 10-15 KT. VISIBLE IMAGES SHOW A WWD SURGE OF LOW CLOUDS AND POSSIBLE SHALLOW ISOLATED SHOWERS WITHIN 60 NM OF THE WAVE AXIS. THIS LIGHT ACTIVITY WILL LIKELY SPREAD ACROSS SOUTHEASTERN MEXICO LATER TONIGHT OR TOMORROW. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 11N15W 8N26W 9N36W 8N53W 7N62W. SCATTERED MODERATE CONVECTION IS FROM 9N-14N BETWEEN 29W-38W ...ENHANCED BY AN EMBEDDED LOW-LEVEL TROUGH AND AN UPPER JET. DISCUSSION... GULF OF MEXICO... SFC HIGH PRES CENTERED JUST OFF THE SOUTHEAST COAST CONTROLS THE PATTERN. TIGHTENED PRES GRADIENT BETWEEN THE HIGH AND LOWER PRES IN THE CARIB IS PRODUCING AN AREA OF 20 KT ELY WINDS IN THE SE GULF AS NOTED IN A RECENT ASCAT PASS. LIGHTER E TO SE WINDS EXISTS ELSEWHERE. THIS FLOW IS ADVECTING PATCHES OF LOW-LEVEL CLOUDS...WHICH LIKELY CONTAIN ISOLATED SHOWERS...ACROSS THE REGION. THE CLOUDS APPEAR THICKEST IN THE FLA STRAITS...WHERE DOPPLER RADAR IS DETECTING SOME SHOWER ACTIVITY...AND N OF 26N BETWEEN 88W-91W. IN THE MID AND UPPER LEVELS...FAIRLY AMPLIFIED PATTERN EXISTS CONSISTING OF RIDGING CENTERED ALONG 83W/84W AND A SHARP SHORTWAVE OVER NRN MEXICO. FAIRLY STRONG SUBTROPICAL JET BETWEEN THESE FEATURES IS ADVECTING A PLUME OF MID-HIGH LEVEL MOISTURE FROM THE EPAC ACROSS CENTRAL/SRN MEXICO AND INTO THE WRN GULF. NEXT COLD FRONT EXPECTED TO MOVE OFF THE TEXAS AND LOUISIANA COASTS TOMORROW NIGHT. NLY WINDS WILL INCREASE SIGNIFICANTLY BEHIND THE BOUNDARY...BUT NO LONGER EXPECTED TO BE GALE FORCE. CARIBBEAN SEA... ABUNDANT CLOUDINESS...SCATTERED SHOWERS AND ISOLATED TSTMS COVER A GOOD PORTION OF THE W CARIB S OF 17N W OF 75W. THIS MOISTURE IS ASSOCIATED WITH A DIFFLUENT UPPER PATTERN ALONG AN ELONGATED UPPER RIDGE AXIS STRETCHING NW FROM AN ANTICYCLONE OVER SOUTH AMERICA. TSTM ACTIVITY IS MOST ORGANIZED OVER AND NEAR THE COASTS OF PANAMA AND COSTA RICA WHERE THERE IS SOME INFLUENCE FROM THE ITCZ. SCATTERED SHOWERS AND ISOLATED TSTMS ALSO COVER A PORTION OF THE CENTRAL AND ERN CARIB N OF 15N BETWEEN 64W-75W. THIS ACTIVITY IS ASSOCIATED WITH THE TAIL END OF A PRE-FRONTAL TROUGH. THE MAIN FRONT IS FAIRLY FAR S NOT FAR AWAY FROM PUERTO RICO AND HISPANIOLA. THE REMAINDER OF THE REGION IS TRANQUIL UNDER ZONAL MID AND UPPER FLOW AND MODERATE TO FRESH TRADE WINDS. ATLANTIC OCEAN... VIGOROUS 988 MB LOW PRES SYSTEM IS CENTERED WELL N OF THE AREA NEAR 39N53W. AN ASSOCIATED FAST MOVING COLD FRONT SWEEPS SWD INTO THE DISCUSSION AREA FROM 32N56W TOWARD THE N COAST OF HAITI. SECONDARY FRONT CLIPS THE AREA ENDING NEAR 30N59W. THIS STRONG LOW IS GENERATING WINDS TO HURRICANE FORCE...BUT THIS IS ALL N OF THE AREA. N TO NW WINDS NEAR GALE FORCE ARE OCCURRING N OF 27N BETWEEN THE MAIN FRONT AND ABOUT 72W. SCATTERED SHOWERS AND TSTMS ARE WITHIN 180 NM E OF THE FRONTS. MODEL GUIDANCE SHOWS THIS LOW OSCILLATING AROUND WITH A GENERAL MOVEMENT TOWARD THE SE OVER THE NEXT COUPLE OF DAYS. AN ILL-DEFINED PRE-FRONTAL TROUGH IS ANALYZED AHEAD OF THE FRONT ALONG 30N46W 17N69W AND THEN WWD INTO THE CARIB. THE NRN PORTION OF THIS TROUGH WILL LIKELY BE REMOVED FROM THE 00Z MAP AS THE FLOW HAS BECOME UNIFORM SELY AHEAD OF THE FAST APPROACHING FRONT. HOWEVER ...THERE IS STILL WEAK CONVERGENCE E OF THE LESSER ANTILLES AND ESPECIALLY IN THE CENTRAL CARIB SO PLAN ON KEEPING THAT REPRESENTED. ONLY PATCHY LOW LEVEL CLOUDS AND MAYBE AN ISOLATED SHOWER IS IN THE VICINITY OF THE TROUGH. THE SFC PRES PATTERN IN THE E ATLC IS VERY WEAK SUPPORTED BY A 1018 MB HIGH DISPLACED IN THE TROPICS NEAR 20N26W. THIS IS ALLOWING WINDS TO BE MAINLY LIGHT AND ANTICYCLONIC ACROSS THE REGION. A WEAK LOW-LEVEL TROUGH OR LOW AMPLITUDE TROPICAL WAVE IS PERTURBING THE ITCZ SLIGHTLY ALONG 34W S OF 13N. THE COMBINATION OF THIS LOW-LEVEL BOUNDARY AND DIFFLUENCE TO THE SE OF AN UPPER JET IS SUPPORTING CONVECTION IN THE ITCZ AND SPREADING DEBRIS CLOUDINESS TO AFRICA WITHIN 540 NM SE OF A LINE ALONG 13N38W 21N17W. A STALLED FRONT LIES JUST N OF THE AREA ALONG 33N/34N E OF ABOUT 35W. CONVERGENCE IN THE LOW-LEVELS NEAR THE FRONT ALONG WITH MID-UPPER LEVEL INSTABILITY IS GENERATING SCATTERED SHOWERS N OF 30N E OF 35W. $$ CANGIALOSI