000 WTPZ41 KNHC 072245 TCDEP1 TROPICAL STORM FAUSTO SPECIAL DISCUSSION NUMBER 1 NWS NATIONAL HURRICANE CENTER MIAMI FL EP062014 330 PM PDT MON JUL 07 2014 The area of low pressure located about 1000 nmi southwest of the southern tip of Baja California has acquired enough organized convection near the well-defined low-level circulation center to be classified as a tropical cyclone. Although convection has been waxing and waning over the past 12 hours or so, a new burst of deep convection with cloud tops as cold as -83C have developed near and just south of the center. The system is being designated as Tropical Storm Fausto based on wind data from two earlier ASCAT passes at 1704 UTC and 1757 UTC that indicated reliable wind speed of 35-38 kt in the southeastern quadrant. Upper-level outflow is good and continues to expand in all quadrants. The initial motion estimate is 275/11 kt and is based primarily on microwave satellite data. Fausto is expected to move westward for the next day or so and then turn toward the west-northwest after that as the cyclone moves along the southern periphery of a deep-layer subtropical ridge to its north. By Days 4 and 5, a weakness is forecast by all of the global models to develop between 140W-150W longitude, which should allow Fausto to turn more toward the northwest. Although some of the models show the cyclone turning into the ridge and beginning to recurve, the official forecast only shows a slight stair-step in the track since the GFS and ECMWF models show the ridge building back westward at the end of the Day 5 period. The official advisory track is a blend of the GFS and ECMWF models since they have a better depiction of the small tropical cyclone. Fausto is expected to remain in a favorable environment consisting of low vertical wind shear, a moist mid-level regime, and over sea-surface temperatures in excess of 28C for at least the next 72 hours. These conditions should allow for at least some gradual strengthening to occur, and the official forecast closely follows a blend of the GFS-based SHIPS and LGEM models. However, those intensity forecasts are based on the medium BAM model, which takes the cyclone well north of the official forecast track and into strong shear conditions and over colder water by Days 4 and 5. If Fausto fallows a low-latitude track as indicated by the NHC forecast, then strengthening rather than weakening could occur in the latter periods. FORECAST POSITIONS AND MAX WINDS INIT 07/2230Z 9.5N 120.1W 35 KT 40 MPH 12H 08/0600Z 9.7N 121.5W 40 KT 45 MPH 24H 08/1800Z 10.0N 124.1W 45 KT 50 MPH 36H 09/0600Z 10.7N 127.0W 50 KT 60 MPH 48H 09/1800Z 11.5N 130.4W 55 KT 65 MPH 72H 10/1800Z 12.6N 136.0W 55 KT 65 MPH 96H 11/1800Z 14.7N 140.9W 45 KT 50 MPH 120H 12/1800Z 16.0N 146.0W 35 KT 40 MPH $$ Forecaster Stewart