000 AXPZ20 KNHC 280925 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC SUN MAY 28 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 FEATURE... TROPICAL STORM ALETTA NEAR 15.4N 101.0W AT 0900 UTC. ALETTA IS NEARLY STATIONARY. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1002 MB. MAXIMUM SUSTAINED WIND SPEED IS 40 KT WITH GUSTS TO 50 KT. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP1/WTPZ21 KNHC FOR MORE DETAILS. THE STORM HAS BEEN MAINTAINING A BALL OF CONVECTION ON IT'S E SIDE WITH VERY COLD TOPS. THERE IS EVIDENCE OF AN ANTICYCLONIC FLOW PATTERN ABOVE THE STORM WHICH IS CONDUCING TO MAINTAINING STRONG CONVECTION. ...TROPICAL WAVES... A TROPICAL WAVE ALONG 91W N OF 2N HAS BEEN MOVING W 10 KT THE PAST 48 HOURS. THERE IS AN AREA OF SCATTERED MODERATE TO STRONG CONVECTION WITHIN 120 NM W OF THE AXIS WHILE ACTIVITY E OF THE AXIS IS MOSTLY ISOLATED. THERE IS SOME INDICATION OF A WEAK CYCLONIC CIRCULATION ABOUT THE AXIS BASED ON CLOUD MOTION. ..ITCZ... ITCZ AXIS IS CENTERED ALONG...9N77W 10N91W 14N100W 11N110W 8N120W 6N140W. SCATTERED MODERATE AND STRONG CONVECTION FROM 4N TO 10N E OF 89W. NUMEROUS STRONG WITHIN 90 NM OF 8N94W. ISOLATED MODERATE WITHIN 60 NM OF A LINE FROM 14N110W TO 10N113W TO 8N117W TO 8N121W. ISOLATED MODERATE NEAR 6N140W. ...DISCUSSION... UPPER LEVEL FEATURES... UPPER TROUGH OVER THE WRN PORTION OF THE N AMERICAN CONTINENT EXTENDS S BETWEEN 110W AND 120W TO NEAR 20N. A SHORTWAVE TROUGH IS DIVING SE IN THE BASE OF THE TROUGH TONIGHT ACCORDING TO THE LATEST WATER VAPOR AND IN GOOD AGREEMENT WITH THE 06Z RUN OF THE GFS MODEL. A UPPER RIDGE W OF 140W HAS DRIFTED WWD DURING THE PAST 24 HR. A WEAK SHORTWAVE TROUGH WAS IN THE BASE OF THE LARGE TROUGH NEAR 22N120W MOVING EWD. LATER TODAY THE UPPER PATTERN CHANGES LITTLE..ALTHOUGH SOME TROUGHING AT MID LEVELS BEGINS TO APPEAR NEAR 20N140W ACCORDING TO THE GFS MODEL. A WEAK RIDGE WILL HOLD FIRM OVER CENTRAL AMERICA. FOR DAY 2 LOOK FOR THE LARGE UPPER TROUGH TO REMAIN BETWEEN 110W AND 120W WITH WEAKENING INFLUENCE AS HEIGHTS RISE ABOUT 30 METERS. THE WEAK SHORTWAVE NEAR 22N120W WILL MOVE EWD TO NEAR 22N112W BEFORE HEADING NE OVER MEXICO. THE UPPER RIDGE W OF 140W APPEARS WEAKER DAY 2 WITH THE WESTERLY FLOW N OF 30N BECOMING MORE ZONAL. SURFACE FEATURES... THE MID PACIFIC RIDGE HAS A CENTER NEAR 32N137W AT 1026 MB TONIGHT WITH AN AXIS EXTENDING SE TO 15N110W. BOTH SSMI AND QUIKSCAT SHOW NE TRADES BETWEEN 10N AND 25N W OF 130W OF 20 TO 25 KT. ANOTHER AREA OF CONCERN IS ALONG THE UPPER BAJA COAST WHERE BOTH MICROWAVE IMAGES SHOW NW WINDS 20 TO 25 KT..SOMEWHAT STRONGER THAN THE GFS MODEL. SWELL IN BOTH AREAS IS ROUGHLY 8 TO 11 FT. LATER TODAY EXPECT LITTLE CHANGE IN THE WIND PATTERN. THE RIDGE CENTER DRIFTS SLOWLY EWD BUT REMAINS ABOUT THE SAME STRENGTH. THE GFS MODEL SHOWS SOME INCREASE IN SWLY WINDS E OF 90W S OF 5N TO 20 KT AND SOME SELY WINDS TO 20 KT S OF 8N BETWEEN 105W AND 120W. FOR DAY 2 THE MID PACIFIC RIDGE REMAINS IN ABOUT THE SAME PLACE WITH 1026 MB STRENGTH AND NE TRADES REMAIN ABOUT THE SAME. WINDS ALONG THE BAJA COAST DECREASE SOME AS WELL AS THE NW SWELL. THE REASON BEING THAT SURFACE PRESSURES INLAND RISE REDUCING THE PRESSURE GRADIENT ALONG THE COAST. CROSS EQUATORIAL SE AND S WINDS WILL CONTINUE TO 20 KT BETWEEN 110W AND 130W WITH SLY SWELL OF 8 FT MOVING INTO THE AREA. SW WINDS E OF 90W S OF 5N DECREASE AS LOW PRESSURE WEAKENS NEAR PANAMA. $$ RRG