000 AXPZ20 KNHC 170932 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC SUN SEP 17 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 STORM MIRIAM IS CENTERED NEAR 19.1N 113.9W AT 0900 UTC MOVING NNE OR 015 DEG AT 4 KT. MAXIMUM SUSTAINED WIND SPEED IS 40 KT WITH GUSTS TO 50 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1002 MB. SCATTERED STRONG WITHIN 60 NM SE QUADRANT OF CENTER. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP4/WTPZ24 KNHC FOR MORE DETAILS. ...TROPICAL WAVES... A TROPICAL WAVE ALONG 82W N OF 4N MOVING W 10-12 KT. AN AREA OF CYCLONIC ROTATION NOTED IN THE MID CLOUDS WAS NEAR 12N84W OVER SE HONDURAS MOVING NW 10 KT. OTHERWISE CONVECTION REMAINS ISOLATED WITH THIS WAVE. A TROPICAL WAVE ALONG 91W N OF 5N MOVING W 10 KT. A CLUSTER OF STRONG CONVECTION LOCATED ABOUT 100 NM SW OF EL SALVADOR MOVING W 15 KT. HIGH LEVEL WIND SHEAR PRECLUDES ANY DEVELOPMENT. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 9N80W 10N88W 7N100W 9N109W 17N114W 10N140W. SCATTERED MODERATE CONVECTION WITHIN 30 NM OF A LINE FROM 5N78W TO 7N110W. ISOLATED MODERATE NEAR 12N123W AND 10N128W. OTHER CONVECTION NEAR THE CENTRAL AMERICAN COAST AT 6N79W 13N91W 15N93W 21N107W AND 24N108W. ...DISCUSSION... IN THE MID LEVELS TONIGHT A LARGE UPPER TROUGH LIES OVER THE WRN US AND EXTENDS S TO NRN MEXICO. THE TROUGH IS MOVING SLOWLY ENE. A CUTOFF LOW WAS LOCATED NEAR 29N34W WITH A DRY SLOT ON THE S SIDE AND HIGH LEVEL MOISTURE ON THE N SIDE ACCORDING TO THE WATER VAPOR IMAGERY. A MID LEVEL RIDGE OVER MEXICO LAST NIGHT HAS MOVED EWD OVER THE GULF OF MEXICO. ON THE SURFACE TONIGHT TROPICAL STORM LANE HAS MOVED INLAND OVER WRN MEXICO AND CONVECTION IS SLOWLY DECREASING. TROPICAL STORM MIRIAM WAS LOCATED ABOUT 500 NM SW OF LOWER BAJA MOVING SLOWLY N AND NE. HER STIRRING CURRENTS ARE WEAK..CAUGHT BETWEEN THE TROPICAL EASTERLIES AND WEAK WESTERLIES N OF 25N. THE PACIFIC RIDGE OVER THE NW CORNER OF THE AREA TONIGHT WAS UNDER A LARGE ANTICYCLONE BETWEEN 20N AND 30N AND SHOWS SOME SIGNS OF STRENGTHENING. NE TRADES TO 20 KT WERE EVIDENT FROM SSMI N OF 15N AND W OF 120W. GAP WINDS REMAIN LIGHT AND CROSS EQUATORIAL SLY WINDS ARE MOSTLY 10 TO 15 KT WITH SLY SWELL TO 8 FT. LATER DAY 1 LITTLE CHANGE TO THE MID LEVEL FEATURES. ON THE SURFACE WHATS LEFT OF LANE WILL CONTINUES MOVING NE OVER CENTRAL MEXICO AS IT SLIDES ALONG THE W SIDE OF THE MID LEVEL RIDGE OVER THE GULF OF MEXICO. MIRIAM WILL DRIFT N AND NE STILL INFLUENCED BY WEAK STIRRING WINDS ALOFT. THE CUTOFF LOW WILL DRIFT E TO NEAR 29N133W. MIRIAM IS FORECAST TO APPROACH THE LOWER BAJA PENINSULA AND INTERESTS ALONG THE LOWER BAJA COAST SHOULD MONITOR HER PROGRESS. LITTLE CHANGE TO THE PACIFIC RIDGE WITH NE TRADES REMAINING ABOUT THE SAME. GAP WINDS REMAIN LIGHT AS DOES CROSS EQUATORIAL SLY WINDS. FOR DAY 2 THE GFS MODEL SHOWS THE CUTOFF LOW AT MID LEVELS BEING PICKED UP BY THE WESTERLIES TO THE N. THE LOW MOVES TO NEAR 28N127W. MID LEVEL RIDGING WORKS IT'S WAY BACK ACROSS MEXICO TO NEAR 115W. A SECOND MID LEVEL RIDGE BUILDS IN BEHIND THE CUTOFF LOW TO NEAR 135W. ON THE SURFACE THE PACIFIC RIDGE GETS SOME SUPPORT FROM THE SECOND RIDGE BUT STAYS MAINLY W OF 125W AND N OF 12N. NE TRADES TO 20 KT SHOULD BE THE RULE. MIRIAM IS FORECAST TO MOVE TO NEAR 21N114W THEN SLOWLY TURN MORE TO THE NW OVER THE NEXT TWO DAYS BUT REMAIN WEAK WITH BARELY TROPICAL STORM STATUS. GAP WINDS W OF HONDURAS COULD PICK UP TO 15 KT AS HIGH PRESSURE STRENGTHENS SLIGHTLY OVER THE CARIBBEAN. CROSS EQUATORIAL SLY WINDS WILL REMAIN MOSTLY LIGHT EXCEPT FOR S OF 4N E OF 87W WHERE THEY COULD INCREASE TO NEAR 20 KT WITH SEAS TO 8 FT. $$ RRG