000 AXNT20 KNHC 121755 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT THU OCT 12 2006 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN 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...WEATHER OBSERVATIONS...RADAR... AND METEOROLOGICAL ANALYSIS. BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...SPECIAL FEATURE... SHOWERS AND THUNDERSTORMS OVER THE EASTERN CARIBBEAN SEA AND WESTERN ATLANTIC OCEAN ARE ASSOCIATED WITH A WEAK AREA OF LOW PRESSURE BETWEEN PUERTO RICO AND THE NORTHERN LEEWARD ISLANDS. THIS SYSTEM HAS NOT BECOME ANY BETTER-ORGANIZED THIS MORNING AND ENVIRONMENTAL CONDITIONS ARE FORECAST TO BECOME LESS FAVORABLE FOR DEVELOPMENT THANKS TO THE PRESENCE OF AN UPPER TROUGH LOCATED JUST WEST OF PUERTO RICO. THE CHANCE FOR A TROPICAL DEPRESSION TO FORM IN THIS AREA IS DECREASING. LOCALLY HEAVY RAIN AND GUSTY WINDS WILL CONTINUE TO SPREAD ACROSS THE NORTHEASTERN CARIBBEAN SEA AND ADJACENT LAND AREAS TODAY AND TONIGHT AS THE SYSTEM MOVES WEST-NORTHWESTWARD BETWEEN 10 TO 15 MPH. LATEST SATELLITE IMAGERY SHOWS THAT THE CLOUD TOPS ARE WARMING UP. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FOUND 12N-22N BETWEEN 60W-64W. LATEST SATELLITE PICTURES SUGGEST THAT A NEW CIRCULATION SEEMS TO BE FORMING FARTHER NORTH NEAR 22N65W. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 36W S OF 18N MOVING W 10 KT. A 1010 SURFACE LOW HAS FORMED ALONG THE WAVE AXIS NEAR 13N THIS MORNING. DEVELOPMENT IS NOT ANTICIPATED DUE TO STRONG UPPER-LEVEL WINDS. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS SEEN FROM 12N-15N BETWEEN 31W-36W. A LARGE TROPICAL WAVE IS ALONG 64W S OF 22N. A 1010 MB SURFACE LOW IS ALONG THE WAVE AXIS NEAR 18N. SEE SPECIAL FEATURE FOR MORE DETAILS. TROPICAL WAVE IS ALONG 77W S OF 20N MOVING W 10 KT. BROAD LOW LEVEL INVERTED-V STRUCTURE IS NOTED ON SATELLITE IMAGERY. THIS SYSTEM IS GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS VERY CLOSE TO THE COLOMBIAN COAST. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 1ON14W 8N25W 8N34W 8N45W 10N60W WIDELY SCATTERED MODERATE CONVECTION IS WITHIN 100/120 NM ON EITHER SIDE OF THE AXIS WEST OF 30W. SIMILAR CONVECTION IS FOUND MAINLY NORTH OF THE AXIS BETWEEN 38W-48W. CLUSTER OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE INLAND OVER AFRICA FROM 8N-13N BETWEEN 10W-16W. ...DISCUSSION... GULF OF MEXICO... DEEP LAYERED TROUGH IS MOVING RAPIDLY EASTWARD ACROSS THE EASTERN US. THE ASSOCIATED FRONTAL BOUNDARY IS INLAND AND EXTENDS FROM NORTHERN GEORGIA TO TEXAS. THE COLD FRONT WILL MOVE INTO THE NW GULF OVERNIGHT AND EXTEND FROM NEAR TAMPA BAY THROUGH 27N90W TO THE DEEP SOUTH LATE FRI. A WEAKENING FRONTAL TROUGH IS AHEAD OF THIS FRONT AND ENTERS THE AREA NEAR 31N80W... 28N83W 25N88W. A NARROW BAND OF SHOWERS WITH EMBEDDED TSTMS IS RELATED TO THE TROUGH AND IS APPROACHING NOW TO THE TAMPA BAY AREA. A VERY LARGE MID/UPPER ANTICYCLONE CENTERED OVER CENTRAL MEXICO NEAR 20N98W COVERS THE ENTIRE GULF...THE FLORIDA PENINSULA... CUBA...THE WESTERN CARIBBEAN AND CENTRAL AMERICA GIVING THE AREA DRY AIR AND A SUBSIDENCE PATTERN. THIS FRONT PROMISES TO BRING THE COLDEST AIR OF THE SEASON SO FAR ACROSS THE CENTRAL AND EAST PARTS OF THE U.S. THE FRONT WILL MODE ACROSS SOUTH FLORIDA LATE SATURDAY INTO SUNDAY. TEMPERATURES MAY DROP A FEW DEGREES BELOW NORMAL. CARIBBEAN SEA... THE MAIN WEATHER FEATURE TODAY ACROSS THE BASIN IS THE WEAK AREA OF LOW PRESSURE LOCATED BETWEEN PUERTO RICO AND THE NORTHERN LEEWARD ISLANDS. SEE SPECIAL FEATURE. AN UPPER TROUGH IN THE W ATLC EXTENDS S INTO THE CARIBBEAN ACROSS HISPANIOLA. THIS UPPER TROUGH WILL CONTINUE TO MOVE EASTWARD TODAY AND TONIGHT AND MAY INTERACT WITH THE TROPICAL WAVE LOCATED CURRENTLY ALONG 64W...BRINGING THE POTENTIAL OF HEAVY RAIN TO PUERTO RICO AND THE VIRGIN ISLANDS FRIDAY TROUGH SATURDAY AND PROBABLY BEYOND. THE RISK OF FLASH AND RIVER FLOODING AND POSSIBLE MUD SLIDES OVER MOUNTAINOUS TERRAIN WILL INCREASE. BROAD RIDGE ANCHORED IN THE TROPICS NEAR 16N58W COVERING MOST OF THE CENTRAL ATLC INCLUDES THE FAR E CARIBBEAN. UPPER DRY AIR DOMINATES THE CARIBBEAN SEA WEST OF 67W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE FROM NORTHERN COLOMBIA TO COSTA RICA DUE TO THE PRESENCE OF THE ITCZ AXIS. UNUSUAL LIGHT TRADE WINDS OF 10 KT DOMINATES THE SOUTHERN CARIBBEAN. ATLANTIC OCEAN... A LINE OF SHOWERS WITH EMBEDDED TSTMS...PREVIOUSLY ASSOCIATED WITH AND OLD FRONTAL BOUNDARY EXTENDS FROM 30N68W TO THE NORTHERN BAHAMAS INTO SOUTH FLORIDA. DOPPLER RADAR IS SHOWING MORE SHOWERS AND TSTMS APPROACHING SOUTH FLORIDA UNDER A WLY WIND FLOW. AN UPPER TROUGH ENTERS THE AREA NEAR 31N70W THEN CONTINUES S INTO THE CARIBBEAN SEA ACROSS HISPANIOLA. UPPER DIFFLUENCE AHEAD OF THIS TROUGH IS ENHANCING THE CONVECTIVE ACTIVITY ASSOCIATED WITH THE TROPICAL WAVE/LOW LOCATED OVER THE EASTERN CARIBBEAN. RIDGE DOMINATES THE CENTRAL ATLC ANCHORED IN THE TROPICS NEAR 16N58W COVERING THE AREA FROM 48W-65W. UPPER TROUGH IS OVER THE E ATLC WITH THE AXIS EXTENDING ALONG 22/23W. THE BASE OF THIS TROUGH REACHES THE CAPE VERDE ISLANDS. AN UPPER RIDGE COVERS WESTERN AFRICA. AT THE SURFACE A BROAD SURFACE RIDGE COVERS THE ATLC E OF 55W WITH A 1020 MB HIGH LOCATED NEAR 29N48W. AN AREA OF SCATTERED SHOWERS IS FROM 20N-24N BETWEEN 30W-41W AHEAD OF A SHORT WAVE TROUGH THAT LIES ALONG 43W. $$ GR