000 AXNT20 KNHC 070533 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 52W S OF 21N MOVING W 10 KT. A 1009 MB LOW IS LOCATED ALONG THE WAVE AXIS NEAR 15N. BUOY 41040 HAS BEEN VERY HELPFUL IN ANALYZING THIS LOW...CURRENTLY REPORTING VERY LIGHT WSW WINDS AND A PRESSURE NEAR 1010 MB. THIS LOW PRES SYSTEM REMAINS IN AN UNFAVORABLE ATMOSPHERIC ENVIRONMENT WITH WATER VAPOR IMAGERY AND DERIVED WINDS SHOWING STRONG SWLY FLOW BLOWING ACROSS THE LOW. THIS SHEAR HAS STAGGERED ALL OF THE DEEP CONVECTION...SCATTERED MODERATE IN NATURE...WITHIN 180 NM TO THE E OF THE EXPOSED LOW-LEVEL CIRCULATION. ...THE ITCZ... AXIS IS CENTERED ALONG 10N13W 7N28W 10N44W 11N49W 8N61W. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM N AND 90 NM S OF THE AXIS BETWEEN 29W-44W. SIMILAR CONVECTION IS WITHIN 90 NM EITHER SIDE OF THE AXIS BETWEEN 20W-24W. DISCUSSION... THE GULF OF MEXICO... THE SFC FLOW IS ON THE BRISK SIDE IN THE E GULF IN RESPONSE TO A TIGHTENED PRES PATTERN BETWEEN LOW PRES TO THE S IN THE NW CARIBBEAN AND HIGH PRES OVER AND OFF THE MID-ATLANTIC COASTLINE. THIS STIFF FLOW IS BLOWING ISOLATED STREAMS OF SHOWERS FROM THE ATLC ACROSS FLORIDA AND INTO THE E GULF WATERS. THE SFC FLOW SIGNIFICANTLY SLACKENS W OF 90W AS THE GRADIENT RELAXES. SCATTERED SHOWERS AND TSTMS ARE EXPANDING SOME IN THE CENTRAL GULF FROM 25N-29N BETWEEN 88W-92W. THIS ACTIVITY IS ASSOCIATED WITH DEEP LAYER INVERTED TROUGHING WHICH EXTENDS NWD FROM THE AFOREMENTIONED LOW IN THE NW CARIB. SKY CONDITIONS ACROSS THE W GULF ARE FAIR TO MOSTLY CLEAR UNDER A MODERATE SUBSIDENT ENVIRONMENT SUPPORTED BY A SOMEWHAT CONFLUENT UPPER PATTERN. LOOKING AHEAD A DAY OR SO...WINDS ARE EXPECTED TO REMAIN MODERATE TO FRESH IN THE E GULF AND THE MOISTURE PLUME IS ANTICIPATED TO PIVOT WWD SLIGHTLY. THE CARIBBEAN SEA... THE MAIN SYNOPTIC FEATURE IN THE REGION IS A 1005 MB LOW CENTERED NEAR 18N84W. SFC OBSERVATIONS IN THIS VICINITY REVEAL A BROAD LOW PRES TROUGH COVERING THE WRN HALF OF THE CARIB SEA. THIS LOW IS NOT VERY WELL DEFINED ON NIGHT CHANNEL IMAGERY...AS ITS TOUGH TO SEE ANY WELL DEFINED CYCLONIC TURNING IN THE CLOUD FIELD. CONVECTION REMAINS VERY SPREAD OUT AND RATHER SPARSE WITH SCATTERED MODERATE FROM 18N-20N W OF 86W...N OF 18N BETWEEN 77W-80W AND FROM 15N-18N BETWEEN 70W-76W. HOWEVER...A GLANCE AT WATER VAPOR IMAGERY SUGGESTS THAT MUCH OF THIS IS SUPPORTED BY MID-UPPER LEVEL FEATURES. THE PATTERN CONSISTS OF BROAD INVERTED TROUGHING W OF 75W AND WLY FLOW E OF 75W ON THE S SIDE OF AN UPPER LOW CENTERED JUST N OF HISPANIOLA. WIDESPREAD MID TO HIGH LEVEL CLOUDINESS COVERS THE BULK OF THE AREA. THE TYPICAL TRADE WIND FLOW IS INTERRUPTED IN THE WRN CARIB DUE TO THE PRESENCE OF THE BROAD LOW. ELY TRADES ARE STILL FAIRLY LIGHT...10-15 KT IN THE E CARIB DUE TO ANOTHER SFC LOW PRES TROUGH LOCATED TO THE N OF THE REGION. LOOKING AHEAD A COUPLE OF DAYS...THE MAIN FEATURE TO WATCH IS THE LOW PRES SYSTEM IN THE NW CARIB AS ENVIRONMENTAL CONDITIONS APPEAR TO SUPPORT FURTHER DEVELOPMENT. THE ATLANTIC OCEAN... ACTIVE WEATHER CONTINUES N OF PUERTO RICO ASSOCIATED WITH A STRETCHED OUT SFC TROUGH...ANALYZED ALONG 26N48W 24N61W 21N73W... AND AN UPPER LOW CENTERED ABOVE THE N SHORE OF HISPANIOLA. IR IMAGERY SHOWS GOOD ROTATION TO THE SCATTERED MODERATE TO STRONG CONVECTION FROM 19N-23N BETWEEN 64W-67W. THIS AREA IS BEING MONITORED FOR FURTHER DEVELOPMENT. ANOTHER BLOB OF SIMILAR CONVECTION IS LOCATED FROM 21N-25N BETWEEN 49W-54W. THIS CLUSTER IS BEING ENHANCED BY THE SAME SFC TROUGH COUPLED WITH DIFFLUENCE ALOFT ON THE E SIDE OF A SHORTWAVE MID TO UPPER TROUGH. THE TIGHTENED PRES GRADIENT BETWEEN THIS FAIRLY HORIZONTAL SFC TROUGH AND A HIGH PRES RIDGE N OF BERMUDA IS GENERATING AN AREA OF 20-25 KT ELY WINDS ROUGHLY N OF 25N W OF 48W. SCATTERED QUICK MOVING SHOWERS ARE POSSIBLE JUST ABOUT ANYWHERE UNDER THIS STRONG LOW-LEVEL FLOW REGIME. MUCH QUIETER WEATHER EXISTS E OF 45W. THE MAIN MID TO UPPER LEVEL FEATURE IS A HIGH PRES AREA CENTERED NEAR 14N37W. THIS SYSTEM IS HELPING TO SINK THE AIR ACROSS MOST OF THE TROPICS KEEPING CONVECTION CONFINED TO THE ITCZ. IN THE SUBTROPICS...THE UPPER FLOW IS QUITE STRONG OUT OF THE SW TO W ON THE N SIDE OF THE TROPICAL RIDGE AND ENHANCED E OF A TROUGH WHICH EXTENDS TO 27N28W. THIS SWIFT FLOW IS SPREADING DEBRIS MOISTURE ACROSS MUCH OF THE AREA N OF 25N W OF THE CANARY ISLANDS. THE SFC PATTERN IS RATHER TRANQUIL GOVERNED BY A 1021 MB HIGH CENTERED NEAR 27N27W. THIS IS KEEPING WINDS LIGHT IN THE SUBTROPICS AND MODERATE IN THE TROPICS...EXCEPT SLIGHTLY STRONGER NEAR THE AFRICAN COAST FROM 18N-26N WHERE THE GRADIENT IS TYPICALLY TIGHT BETWEEN THE SUBTROPICAL RIDGE AND INVERTED TROUGHING OVER THE CONTINENT. $$ CANGIALOSI