000 AXNT20 KNHC 072350 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SUN OCT 07 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. ...SPECIAL FEATURE... A BROAD 1003 MB LOW PRESSURE AREA IS OVER THE NW CARIBBEAN NEAR 17N85W. THIS SYSTEM IS GENERATING SCATTERED SHOWERS AND TSTMS BETWEEN BELIZE...HONDURAS...AND THE CAYMAN ISLANDS. SURFACE PRESSURES CONTINUE TO FALL IN THE AREA...BUT THERE IS NO WELL-DEFINED CIRCULATION CENTER. UPPER-LEVEL WINDS ARE GRADUALLY BECOMING MORE FAVORABLE AND SLOW DEVELOPMENT OF THIS SYSTEM IS POSSIBLE OVER THE NEXT FEW DAYS AS THE LOW REMAINS NEARLY STATIONARY. ANOTHER AIR FORCE HURRICANE HUNTER MISSION IS SCHEDULED TO INVESTIGATE THE AREA ON MONDAY...IF NECESSARY. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 55W S OF 20N MOVING W TO NW NEAR 10 KT. A 1010 MB LOW IS LOCATED ALONG THE WAVE AXIS NEAR 17N. THE CIRCULATION REMAINS AN EXPOSED LOW LEVEL SWIRL...WITH MOST OF THE LIMITED SHOWER/TSTM ACTIVITY E OF THE CENTER FROM 15N-18N BETWEEN 50W-54W. DEVELOPMENT OF THIS SYSTEM IS NOT ANTICIPATED DUE TO UNFAVORABLE UPPER LEVEL WINDS. THE SOUTHERN END OF THE WAVE IS ENHANCING SOME SHOWER/TSTM ACTIVITY OVER FRENCH GUIANA AND SURINAME. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 11N14W 6N30W 8N40W 10N52W. THE ITCZ REMAINS FAIRLY ACTIVE THIS EVENING. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS OVER THE TROPICAL ATLANTIC FROM 3N-11N BETWEEN 23W-50W. THE UW-CIMSS TPW PRODUCT SUGGESTS THAT A WEAK TROPICAL WAVE IS PROBABLY NEAR 36W WHERE THERE IS A SMALL BULGE OF MOISTENED AIR. THIS TROPICAL WAVE MAY BE ADDED TO THE 0000 UTC SURFACE MAP. DISCUSSION... THE GULF OF MEXICO... A SFC RIDGE DOMINATES THE SE U.S. AND THE NORTHERN GULF WATERS. PRES GRADIENT BETWEEN THIS RIDGE AND A SFC LOW OVER THE NW CARIBBEAN CONTINUES TO PRODUCE MODERATE TO FRESH ELY SFC WINDS OVER FLORIDA AND THE NE QUADRANT OF THE GULF. THESE WINDS ARE ADVECTING MOSTLY SHALLOW SHOWERS FROM THE ATLC ACROSS FLORIDA AND INTO THE E GULF WATERS. SCATTERED SHOWERS AND TSTMS ARE A LITTLE MORE CONCENTRATED BETWEEN THE YUCATAN PENINSULA AND WRN LOUISIANA. THIS ACTIVITY IS ASSOCIATED WITH DEEP LAYER INVERTED TROUGH WHICH EXTENDS NWD FROM THE LOW IN THE NW CARIBBEAN THROUGH THE YUCATAN PENINSULA INTO THE GULF TO 29N95W. THE TROUGH IS WELL DEFINED IN THE WIND SHIELD. A LARGE CLUSTER OF MODERATE TO STRONG CONVECTION HAS DEVELOPED OVER THE YUCATAN PENINSULA. W OF TROUGH...MOSTLY CLEAR SKIES PREVAIL UNDER THE INFLUENCE OF A MODERATE SUBSIDENT ENVIRONMENT SUPPORTED BY AN UPPER HIGH LOCATED OVER CENTRAL MEXICO. MODERATE TO FRESH ELY WINDS WILL CONTINUE TO BLOW ACROSS THE E AND CENTRAL GULF OVER THE NEXT DAY OR SO. THE CARIBBEAN SEA... THE BROAD AREA OF LOW PRESSURE CENTERED BETWEEN BELIZE... HONDURAS...AND THE CAYMAN ISLANDS REMAINS THE MAIN FEATURE OF INTEREST ACROSS THE BASIN. THIS SYSTEM IS BEING MONITORED FOR SLOW DEVELOPMENT. SEE SPECIAL FEATURE FOR MORE DETAILS. SHOWERS AND TSTMS HAVE DEVELOPED AGAIN ACROSS CUBA. ACCORDING TO LIGHTNING DATA...TSTMS ARE MORE CONCENTRATED OVER THE WESTERN PART OF THE ISLAND. SIMILAR ACTIVITY IS SEEN OVER JAMAICA. A MOIST AND UNSTABLE SLY FLOW ON THE E SIDE OF THE BROAD AREA OF LOW PRESSURE CENTERED OVER THE NW CARIBBEAN IS ENHANCING THIS CONVECTIVE ACTIVITY. UPPER-LEVEL FLOW IS ALSO DIFFLUENT OVER THIS REGION BETWEEN TROUGHING OVER THE BAHAMAS AND RIDGING OVER THE CENTRAL CARIBBEAN. THE TRADE WINDS ARE EXPECTED TO REMAIN INTERRUPTED OVER THE WESTERN CARIBBEAN...W OF 70W DURING THE NEXT FEW DAYS. LIGHT TO MODERATE ELY WINDS ARE BLOWING ACROSS THE REMAINDER OF THE AREA. THE ATLANTIC OCEAN... AN ELONGATED SFC TROUGH PERSISTS ACROSS MUCH OF THE WEST AND CENTRAL ATLC EXTENDING FROM THE SE BAHAMAS ALONG 24N60W TO 29N42W. AN UPPER-LEVEL TROUGH WITH A SERIES OF EMBEDDED UPPER LOW IS SUPPORTING THIS SURFACE FEATURE. THERE ARE A COUPLE OF AREAS ALONG THE TROUGHING WHERE LOW LEVEL VORTICITY APPEARS TO BE MAXIMIZED. ONE IS LOCATED SEVERAL HUNDRED MILES NORTH-NORTHWEST OF PUERTO RICO NEAR 23N69W...WHERE THERE IS A DISORGANIZED AREA OF SHOWERS AND TSTMS. THE SECOND ONE IS NEAR 28N50W AND IS ALSO GENERATING SCATTERED MODERATE CONVECTION. UPPER-LEVEL WINDS REMAIN STRONG ENOUGH TO INHIBIT ANY TROPICAL DEVELOPMENT OF THESE SYSTEMS. ELY WINDS REMAINS MODERATE TO FRESH N OF THE TROUGHING DUE TO THE TIGHTENED GRADIENT BETWEEN THE TROUGH AND HIGH PRES OVER THE MID ATLC COAST. AS IS USUAL FOR THIS TIME OF THE YEAR...COMPUTER MODELS DEVELOP A SERIES OF LOW PRES AREAS ALONG THE TROUGHING OVER THE NEXT SEVERAL DAYS THAT MOVE MAINLY NE ALONG THE BOUNDARY...BUT CURRENTLY HAVE LOW CONFIDENCE IN THESE LOWS WITH FAIRLY WIDE DIVERGENCE BETWEEN THE GLOBAL MODELS. MUCH QUIETER WEATHER EXISTS E OF 40W UNDER THE INFLUENCE OF A SFC RIDGE WITH A 1022 MB HIGH NEAR 31N30W. THIS IS KEEPING WINDS LIGHT IN THE SUBTROPICS AND MODERATE IN THE TROPICS... EXCEPT SLIGHTLY STRONGER 20-25 KT NLY WINDS OFF THE COAST OF NW AFRICA WHERE THE GRADIENT REMAINS TIGHTER PER USUAL. THE MAIN MID TO UPPER LEVEL FEATURE OVER THE TROPICS IS AN UPPER HIGH LOCATED NEAR 12N37W. THE UPPER-LEVEL FLOW IS QUITE STRONG OUT OF THE W TO SW ON THE NORTHERN SIDE OF THE TROPICAL RIDGE. UPPER DIFFLUENCE BETWEEN THE AFOREMENTIONED UPPER-LEVEL TROUGH AND THIS RIDGE IS SUPPORTING THE SHOWER/TSTM ACTIVITY OVER THE CENTRAL ATLC NEAR 28N50W. $$ GR