000 AXNT20 KNHC 171755 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT WED OCT 17 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... LARGE TROPICAL WAVE IS ALONG 39W/40W S OF 21N MOVING W 10-15 KT. A RECENT ASCAT PASS DEPICTED THE AXIS WELL WHICH LINES UP NICELY WITH THE ANALYZED POSITION...EXCEPT THE N PORTION WHICH SHOULD BE TILT TO THE E. STRONG SWLY SHEAR CONTINUES TO PROVIDE A VERY UNFAVORABLE ENVIRONMENT STRETCHING CLOUDINESS WELL TO THE NE OF THE WAVE. DEEP CONVECTION IS MOSTLY CONFINED TO THE INTERSECTION OF THE ITCZ...ESPECIALLY IN DIFFLUENT ZONES ALOFT. TROPICAL WAVE IS APPROACHING THE LESSER ANTILLES ALONG 60W S OF 15N MOVING W 10-15 KT. THE PLACEMENT OF THE WAVE AXIS IS BIT CHALLENGING AS THERE IS SOME CONFLICTING EVIDENCE. VISIBLE IMAGERY SHOWS AN AREA OF LOW LEVEL CYCLONIC TURNING ALONG 55W/56W. WHILE THIS REGION IS PRONOUNCED THERE WAS A FAINT LOW-LEVEL INVERTED V-SHAPE SEEN EARLIER CLOSER TO 60W. BASED ON THIS DATA DECIDED TO HOLD CONTINUITY AT 12Z. HOWEVER...THIS WILL BE EVALUATED AGAIN AT 18Z. REGARDLESS...THIS WAVE IS VERY WEAK ONLY PRODUCING ISOLATED SHOWERS AND TSTMS E OF THE AXIS FROM 10N-12N BETWEEN 52W-56W. TROPICAL WAVE CURRENTLY ALONG 90W/91W IS MAINLY IN THE EPAC WATERS AND INLAND OVER GUATEMALA. FOR DETAILS REFER TO THE EAST PACIFIC TWD...MIATWDEP. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 9N14W 7N22W 9N37W 7N44W 8N59W. SCATTERED MODERATE CONVECTION IS FROM 4N-11N BETWEEN 24W-33W AND FROM 7N-10N BETWEEN 43W-48W. A VERY SMALL LOW TO MID LEVEL TROUGH OR LOW IS PRODUCING SCATTERED MODERATE CONVECTION JUST N OF THE ITCZ FROM 11N-13N BETWEEN 48W-50W. DISCUSSION... GULF OF MEXICO... THE AREA OF LOW PRES...ORIGINATING IN THE CARIBBEAN...HAS NOW MOVED INLAND OVER ERN TEXAS. A WEAK TRAILING TROUGH HANGS SWD ALONG 95W N OF 28N...BUT ALSO SHOULD LIFT N OF THE AREA LATER THIS AFTERNOON. THE MAIN STORY IN THE GULF TODAY IS THE STRONG WINDS S OF THE LOUISIANA AND E TEXAS COASTS. BUOY DATA SHOWS AN AREA OF 20-25 KT S TO SE WINDS. BUOY 42361 HAS BEEN REPORTING WINDS NEAR 50 KT...BUT THIS STATION IS WELL ELEVATED. THIS AREA OF STRONG WINDS IS EXPECTED TO DECREASE OVER THE NEXT DAY OR TWO AS THE LOW LIFTS FURTHER N. AN AREA OF SCATTERED MODERATE CONVECTION HAS DEEPENED AND EXPANDED OVER THE PAST FEW HOURS FROM 22N-25N BETWEEN 90W-93W. THIS ACTIVITY IS ASSOCIATED WITH DIFFLUENCE ALOFT BETWEEN AN UPPER HIGH SITUATED OVER CENTRAL MEXICO AND THE LARGER SCALE W TO SW FLOW. MOIST LOW-LEVEL SLY WINDS ARE ALSO PLAYING A PART. SCATTERED MID TO HIGH LEVEL CLOUDINESS AND ISOLATED SHOWERS AND TSTMS COVER THE NE GULF. CARIBBEAN SEA... AN UPPER LOW CONTINUES TRACKING NW CENTERED 120 NM W OF JAMAICA NEAR 18N81W. FAIRLY STRONG S TO SE WINDS ALOFT ON THE E SIDE OF THE LOW IS ADVECTING ABUNDANT TROPICAL MOISTURE INTO THE REGION BETWEEN 67W-77W. MUCH OF THIS MOISTURE IS IN THE FORM OF MID-HIGH LEVEL CLOUDINESS...THOUGH AN AREA OF SCATTERED SHOWERS AND TSTMS EXIST FROM 16N-19N BETWEEN 71W-76W AND FROM 12N-14N BETWEEN 73W-75W. THE MIMIC TPW ANIMATION SUGGESTS THAT A WEAK TROPICAL WAVE MAY BE IN THIS AREA ENHANCING THIS SHOWER ACTIVITY...BUT DECIDED NOT TO ADD IT TO THE SFC MAP DUE TO LACK OF GOOD HISTORY AND CLEAR CUT EVIDENCE. MUCH DRIER MID TO UPPER LEVEL AIR IS OVER THE LESSER ANTILLES AND THE CARIB WATERS E OF 66W ADVECTED BY N-NE UPPER FLOW AROUND A SW ATLC RIDGE. THE WRN CARIB IS FAIRLY TRANQUIL EXCEPT FOR AN AREA OF DISTURBED WEATHER IN THE SW PORTION FROM 10N-13N BETWEEN 81W-84W...ASSOCIATED WITH THE UPPER LOW AND LOW-LEVEL CONVERGENCE IN THE ITCZ. ATLANTIC OCEAN... A LOW PRES SYSTEM FORMED EARLY TODAY OR LAST NIGHT OFF THE S CENTRAL E COAST OF FLORIDA...ANALYZED 1014 MB. DOPPLER RADAR DATA SHOWS ROTATING BANDS OF SHOWERS AND TSTMS CONFINED WITHIN 45 NM OF THE CENTER. EVEN THOUGH THIS LOW IS SMALL IT PRODUCED VERY HEAVY RAINFALL OVER ERN PALM BEACH COUNTY IN S FLA LAST NIGHT. TROPICAL DEVELOPMENT IS UNLIKELY DUE TO AN UNFAVORABLE UPPER ENVIRONMENT AS IT MOVES N-NE. FARTHER E...A STRONG COLD FRONT IS DIGGING SOUTH JUST PASSING BERMUDA. WHILE MOST OF THIS BOUNDARY LIES N OF THE AREA...A PREFRONTAL TROUGH IS IN THE REGION ALONG 32N40W 26N59W 28N62W THEN BECOMES SOMEWHAT THERMAL TOWARD THE CAROLINA COAST. ISOLATED SHOWERS ARE POSSIBLE WITHIN 45 NM OF THE FRONTAL TROUGH. THE UPPER LEVEL FLOW IS FAIRLY STRONG N OF AN UPPER HIGH IN THE ERN BAHAMAS ASSOCIATED WITH LARGE SCALE TROUGHING...WITH A SERIES OF EMBEDDED SHORTWAVES. SFC WINDS ARE LIGHT TO THE S OF THE FRONT WHILE STRONG NWLY WINDS ARE BUILDING BEHIND THE BOUNDARY. THE SFC PATTERN IN THE CENTRAL AND E ATLC IS MOSTLY CONTROLLED BY RIDGING EXTENDING S/SW FROM A 1021 MB HIGH SITUATED W OF THE CANARY ISLANDS NEAR 29N21W AND A 1020 MB HIGH NEAR 24N28W. THIS IS PRODUCING MAINLY LIGHT WINDS OVER THE SUBTROPICAL ATLC ...WHILE MODERATE TRADES PERSIST IN THE TROPICS ESPECIALLY NEAR THE LARGE TROPICAL WAVE. THE UPPER PATTERN OVER THE E ATLC CONSISTS OF A LARGE SCALE RIDGE WITH THE AXIS RUNNING FAIRLY N-S ALONG 28W. HOWEVER...A STRONG CUT OFF UPPER LOW IS INTERRUPTING THE RIDGING LOCATED NEAR 18N40W. A SWLY JET BRANCH ORIGINATES ON THE SE SIDE OF THE LOW AND EXTENDS NE ALONG 12N42W 24N28W. THIS JET IS PROVIDING ENERGY BUT SHEARING THE TROPICAL WAVE ALONG 39W/40W AND SPREADING HIGH LEVEL CLOUDINESS ACROSS BETWEEN 25W-40W. $$ CANGIALOSI