000 AXPZ20 KNHC 180939 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC MON SEP 18 2006 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS. BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0845 UTC. ...SPECIAL FEATURES... TROPICAL DEPRESSION MIRIAM IS CENTERED NEAR 19.9N 113.7W...OR 300 NM SW OF THE SOUTHERN TIP OF BAJA CALIFORNIA...AT 18/0900 UTC MOVING N AT 6 KT. MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 40 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1001 MB. THE TOP PORTION OF MIRIAMS' CIRCULATION WAS SHEARED OFF AND MOVED RAPIDLY WSW LEAVING THE LOW LEVEL CIRCULATION AT THE ABOVE LOCATION. THERE IS NO CONVECTION AND FURTHER WEAKENING IS EXPECTED AS SHE MOVES N AND THEN NE. SEE LATEST NHC FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP4/WTPZ24 KNHC FOR MORE DETAILS. ...TROPICAL WAVES... TROPICAL WAVE ALONG 90W N OF 4N MOVING W 12 KT. SCATTERED CONVECTION MAINLY NEAR THE COAST OF EL SALVADOR WITH NO ORGANIZATION. STRONG UPPER LEVEL ELY WINDS EVIDENT IN SATELLITE PICTURES PRECLUDE ANY FURTHER DEVELOPMENT. TROPICAL WAVE ALONG 99W N OF 4N MOVING W AT 12 KT. SCATTERED WEAK CONVECTION WITHIN 3 DEGRESS OF THE AXIS WITH NO ORGANIZATION. STRONG HIGH LEVEL ELY WINDS EVIDENT OVER THE REGION PROBABLY WILL NOT ALLOW ANY DEVELOPMENT. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 9N79W 9N99W 8N105W 9N111W 13N118W 10N128W 11N140W. SCATTERED MODERATE CONVECTION WITHIN 45 NM OF A LINE FROM 8N79W TO 7N101W TO 11N121W. OTHER MODERATE TO STRONG CONVECTION NEAR THE COAST AT 13N89W 13N93W AND 16N95W. ...DISCUSSION... STRONG SHORTWAVE TROUGH DROPPING S OVER THE SW US TONIGHT PROBABLY WILL HAVE LITTLE AFFECT ON OUR REGION..EXCEPT TO DEPRESS THE MID LEVEL RIDGE SWD. THE RIDGE HAS BEEN OVER MEXICO THE PAST WEEK THEN SLID EWD OVER THE GULF OF MEXICO AND CONTINUES TO HANG ON OVER SRN MEXICO. ANOTHER SHORTWAVE TROUGH WHICH USED TO BE A CUTOFF LOW IS LOCATED ALONG 130W. WATER VAPOR IMAGERY SHOWS ONLY A VERY DRY CIRCULATION. THIS SYSTEM IS MOVING SLOWLY EWD. ON THE SURFACE TONIGHT WHATS LEFT OF MIRIAM IS NEAR 19N114W AND NEARLY STATIONARY. THE UPPER CIRCULATION OF MIRIAM HAS MOVED WSW TO NEAR 17N120W AND IS GRADUALLY DISSIPATING. THE PACIFIC RIDGE HAS REGAINED SOME STRENGTH THANKS TO INCREASING HEIGHTS AT MID LEVEL AS A MID LEVEL RIDGE MOVES INTO THE WRN PORTION OF THE AREA TONIGHT. NE TRADE TO 20 KT PREVAIL N OF 14N AND W OF 125W. GAP WINDS ARE LIGHT TONIGHT AND CROSS EQUATORIAL SLY WINDS ARE ALSO LIGHT BUT SLY SWELL TO 9 FT CONTINUES TO CROSS NWD TO 5N BETWEEN 105W AND 130W. LATER DAY 1 LOOK FOR THE SHORTWAVE ALONG 130W TO PICK A LITTLE STEAM AS IT MOVES TO 126W. THE TROUGH IS GETTING A LITTLE PUSH FROM THE WESTERLIES TO THE NW. MID LEVEL RIDGES WILL CONTINUE OVER MEXICO AND OVER THE W PORTION OF THE AREA. ON THE SURFACE LATER DAY 1 LOOK FOR MIRIAM TO CONTINUE TO WEAKEN AS IT DRIFTS N AND NE. THE PACIFIC RIDGE STAYS ABOUT THE SAME WITH LITTLE CHANGE TO THE NE TRADES. GAP WINDS REMAIN LIGHT AS WELL AS CROSS EQUATORIAL SLY WINDS AND SWELLS. FOR DAY 2 THE SHORTWAVE CONTINUES TO STRENGTHEN AS IT MOVES SLOWLY EWD TO 122W. MOVEMENT OF THE TROUGH HELPS THE MID LEVEL RIDGE OVER MEXICO BUILD NWD OVER THE SW US WHILE REMAINING CENTERED OVER MEXICO. LITTLE CHANGE TO THE MID LEVEL RIDGE OVER THE WRN PORTION OF THE AREA. ON THE SURFACE DAY 2 WHATS LEFT OF MIRIAM WILL GRADUALLY DISSIPATE NEAR 23N117W. SOME TIGHTENING OF THE PRESSURE GRADIENT OVER THE NW CORNER OF THE AREA WHERE THE PACIFIC RIDGE RESIDES THUS NE TRADES INCREASE TO 20 KT WITH GUSTS TO 25 KT. GAP WINDS REMAIN LIGHT AROUND THE COASTS OF MEXICO AND CENTRAL AMERICA. LITTLE CHANGE TO CROSS EQUATORIAL SLY WINDS ALTHOUGH THE GFS SHOWS SOME INCREASE TO 20 KT BETWEEN 95W AND 105W S OF 5N WITH S SWELL TO 9 FT. $$ RRG