000 AXPZ20 KNHC 051615 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC SUN OCT 05 2008 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1500 UTC. ...SPECIAL FEATURES... TROPICAL STORM MARIE AT 18.9N 122.3W AT 05/1500 UTC OR ABOUT 845 NM W-SW OF SRN TIP OF BAJA CALIFORNIA MOVING W OR 270 DEG AT 2 KT. ESTIMATED MINIMUM CENTRAL PRES 1001 MB. MAXIMUM SUSTAINED WIND SPEED 40 WITH GUSTS TO 50 KT. REFER TO LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP4/WTPZ24 KNHC AND INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPEP4/WTPZ34 KNHC FOR MORE DETAILS. DEEP CONVECTION ASSOCIATED WITH MARIE NOW RESTRICTED ONLY TO 75 NM IN SW QUADRANT AND FORECAST TO CONTINUE ITS DOWNWARD TREND TILL ITS DEMISE POSSIBLY WITHIN THE NEXT 48-72 HRS. DRY STABLE AIR MASS AND COOL SEA SURFACE TEMPERATURES HAVE WEAKENED MARIE FOR THE LAST 24 HRS. TROPICAL STORM NORBERT AT 14.6N 101.9W AT 05/1500 UTC OR ABOUT 215 NM S OF ZIHUATANEJO MEXICO MOVING W-NW OR 290 DEG AT 7 KT. ESTIMATED MINIMUM CENTRAL PRES 997 MB. MAXIMUM SUSTAINED WIND SPEED 50 WITH GUSTS TO 55 KT. REFER TO LATEST NHC FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP5/WTPZ25 KNHC AND INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPEP5/WTPZ35 KNHC FOR MORE DETAILS. SE WIND SHEAR OVER NORBERT HAS DIMINISH ALLOWING SYSTEM TO ORGANIZE LOW LEVEL DEEP CONVECTION AND INTENSIFY. CLOUDS HAVE NOW WRAPPED AROUND CLOSER TO CENTER AND OUTFLOW HAS TAKEN A WELL ROUNDED SHAPE INDICATING STRENGTHENING. IN ADDITION...NORBERT IS APPROACHING AREA OF FAIRLY STRONG UPPER LEVEL DIFFLUENCE WHICH COULD ACT AS A CATALYST TO INTENSIFY SYSTEM. AS CONDITIONS STAND NOW...NORBERT IS FORECAST TO ACQUIRE HURRICANE FORCE WINDS WITHIN 24 HRS. LOW PRES 1008 MB AT 11N90W MOVE W AT 7 KT. LOW-LEVEL CENTER DISPLACED TO THE E OF ITS DEEP CONVECTION DUE TO MODERATE E WIND SHEAR ALOFT...BUT SYSTEM MAINTAINS GOOD ORGANIZATION. CONDITIONS ARE NOT UNFAVORABLE FOR DEVELOPMENT ALTHOUGH QUESTIONS REMAIN ABOUT IMPACT OF A STRONGER NORBERT MIGHT HAVE IN THIS SYSTEM. GLOBAL MODELS DIVERGE IN THEIR SOLUTIONS...SO LITTLE CONFIDENCE PLACED IN A DEVELOPING FORECAST AND TRACK. ...ITCZ... ITCZ AXIS ALONG 11N86W TO 11N100W TO 07N110W TO 13N125W TO 10N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION WITHIN 90 NM N OF AXIS FROM 135W-138W. ...DISCUSSION... ATLC MID-UPPER LEVEL RIDGE CUTS ACROSS YUCATAN PENINSULA TO EXTEND INTO E PAC TO ANTICYCLONE AT 15N122W SADDLED BY WEAK UPPER LEVEL TROUGH ALONG 106W N OF 18N. ANTICYCLONE IS RESPONSIBLE FOR WIND SHEAR FLOW ABOVE LOW PRES SYSTEM MENTIONED ABOVE. IT IS ALSO THIS COMBINATION OF FEATURES THAT IS CAUSING THE UPPER DIFFLUENT FLOW EXPECTED AHEAD OF NORBERT AND INFLUENCING ITS DEVELOPMENT. FURTHER W...UPPER LEVEL TROUGH FROM SRN BAJA CALIFORNIA TO BROAD CYCLONE AT 25N136W PROVIDE ADVERSE CONDITIONS ALOFT FOR T.S. MARIE AS IT DISRUPT SYSTEM'S OUTFLOW AND MAINTAINS DRY AIR MASS ENVIRONMENT AHEAD. ELSEWHERE AT THE SURFACE... LOW PRES 1012 MB OVER YUCATAN PENINSULA HAS NOT DISSIPATED AS FORECAST AND CONTINUES FORCING WINDS ACROSS ISTHMUS OF TEHUANTEPEC...ALTHOUGH AT LESSENED RATE. CONDITIONS INDICATE LOW PRES SHOULD CONTINUE WEAKENING AND DISSIPATE WITHIN NEXT 24 HRS...SO GAP WINDS OVER TEHUANTEPEC OUGHT TO DIE OFF WITHIN THAT TIME. LARGE LONG PERIOD NW SWELL MOVING SE FROM HEALTHY HIGH PRES 1025 MB JUST NW OF BASIN HAVE BEGUN TO SUBSIDE BUT STILL REMAIN CLOSE TO 12 FT. NWW3 MAY HAVE OVER DONE INITIAL HEIGHTS BUT IS CATCHING UP WITH LOWERING SEAS IN 24-48 HR FORECAST. SIMILARLY...LONG PERIOD CROSS EQUATORIAL SWELLS HAVE LESSENED THEIR HEIGHTS AND ONLY REACH 7-8 FT FROM 95W TO 115W. CONTINUED SUBSIDING IS EXPECTED DURING NEXT 48 HRS. $$ WALLY BARNES