000 WTPZ41 KNHC 270231 TCDEP1 TROPICAL DEPRESSION ONE-E DISCUSSION NUMBER 1 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP012007 800 PM PDT SAT MAY 26 2007 CONVECTION ASSOCIATED WITH THE LOW PRESSURE AREA WELL SOUTHWEST OF MANZANILLO MEXICO HAS INCREASED SIGNIFICANTLY DURING THE PAST SEVERAL HOURS...WITH TOPS OF COLDER THAN -80C DEVELOPING OVER THE CENTER. SATELLITE INTENSITY ESTIMATES ARE 30 KT FROM TAFB AND 25 KT FROM SAB. BASED ON ALL THIS...ADVISORIES ARE INITIATED ON TROPICAL DEPRESSION ONE-E. THE INITIAL MOTION IS A SOMEWHAT UNCERTAIN 265/4. WATER VAPOR IMAGERY SHOWS A LARGE AND COMPLEX MID/UPPER-LEVEL TROUGH OVER MEXICO AND THE ADJACENT PACIFIC WATERS NORTH OF 20N EAST OF 115W... WITH A LARGE MID/UPPER-LEVEL RIDGE COVERING THE REGION WEST OF 115W. THIS LEAVES THE DEPRESSION IN AN AREA OF WEAK STEERING FLOW. THE LARGE-SCALE MODELS FORECAST THE TROUGH TO MOVE EASTWARD AND THE RIDGE TO SLOWLY BUILD NORTH OF THE DEPRESSION DURING THE FORECAST PERIOD. THIS SHOULD ALLOW A SLOW WESTWARD MOTION AS FORECAST BY THE GFDL...THE ECMWF...AND THE CANADIAN MODELS. THE OFFICIAL FORECAST FOLLOWS THIS SCENARIO...CALLING FOR A SLOW WESTWARD MOTION UNDER THE RIDGE THROUGH 120 HR. A POTENTIAL COMPLICATING FACTOR IS THE POSSIBILITY THAT ANOTHER TROPICAL CYCLONE WILL FORM EAST OF THE DEPRESSION...AS FORECAST BY THE GFS...NOGAPS...AND UKMET MODELS. SHOULD THIS OCCUR...THIS COULD CAUSE TROPICAL DEPRESSION ONE-E TO HAVE ERRATIC MOTION. THE DEPRESSION IS CURRENTLY IN AN ENVIRONMENT OF DIFLUENT SOUTHEASTERLY UPPER-LEVEL WINDS AND MODERATE VERTICAL SHEAR. THE DEPRESSION SHOULD REMAIN IN A LIGHT-TO-MODERATE SHEAR ENVIRONMENT OVER WARM WATER FOR 48-72 HR...WHICH SHOULD ALLOW STRENGTHENING. THE INTENSITY FORECAST CALLS FOR THE CYCLONE TO REACH 60 KT IN 72 HR...WHICH IS SLIGHTLY ABOVE THE SHIPS AND GFDL FORECASTS. AFTER THAT...THE FORECAST TRACK TAKES THE SYSTEM OVER GRADUALLY COOLING SEA SURFACE TEMPERATURES...WHICH SHOULD START A WEAKENING TREND. FORECAST POSITIONS AND MAX WINDS INITIAL 27/0300Z 12.6N 110.8W 30 KT 12HR VT 27/1200Z 12.5N 111.5W 35 KT 24HR VT 28/0000Z 12.4N 112.6W 45 KT 36HR VT 28/1200Z 12.3N 113.5W 50 KT 48HR VT 29/0000Z 12.3N 114.4W 55 KT 72HR VT 30/0000Z 12.5N 116.0W 60 KT 96HR VT 31/0000Z 12.5N 118.0W 60 KT 120HR VT 01/0000Z 13.0N 121.0W 55 KT $$ FORECASTER BEVEN