ZCZC MIATCDEP1 ALL TTAA00 KNHC DDHHMM TROPICAL STORM ANDRES DISCUSSION NUMBER 3 NWS NATIONAL HURRICANE CENTER MIAMI FL EP012015 300 PM MDT THU MAY 28 2015 The satellite presentation of Andres continues to improve, with a band of convection now wrapping about three-quarters of the way around the center. A recent ASCAT pass revealed maximum winds of about 50 kt, so the initial intensity has been increased accordingly. The scatterometer data also provided a better estimate of the size of the tropical cyclone wind field, and the tropical-storm-force wind radii have been adjusted outward. The satellite data indicate that the center is located a bit southwest of the previous estimate, but the overall initial motion remains west-northwest or 295 degrees at 10 kt. The track forecast reasoning is unchanged from before. Andres should move west- northwestward to northwestward around the southwestern portion of a mid-level ridge extending westward over the eastern Pacific from central Mexico. The 1200 UTC global models show more ridging to the north of Andres late in the period than previous runs, which has resulted in a westward shift in the track guidance. The NHC forecast has been adjusted westward, but it lies along the right side of the guidance envelope. Environmental conditions consisting of warm water and low shear should allow for continued steady strengthening during the next couple of days. Although the latest SHIPS RI index shows a lower chance of rapid strengthening during the next 24 hours than this morning, it would not be surprising if rapid intensification occurred. The NHC forecast is near the upper end of the intensity guidance and is closest to the SHIPS model. After 72 hours, Andres should begin to weaken when it encounters slightly cooler sea surface temperatures and a drier and more stable airmass. FORECAST POSITIONS AND MAX WINDS INIT 28/2100Z 11.6N 112.5W 50 KT 60 MPH 12H 29/0600Z 12.3N 113.6W 65 KT 75 MPH 24H 29/1800Z 13.1N 114.7W 75 KT 85 MPH 36H 30/0600Z 13.9N 115.3W 85 KT 100 MPH 48H 30/1800Z 14.9N 116.0W 90 KT 105 MPH 72H 31/1800Z 16.5N 117.7W 85 KT 100 MPH 96H 01/1800Z 17.5N 120.0W 70 KT 80 MPH 120H 02/1800Z 18.0N 122.5W 55 KT 65 MPH $$ Forecaster Brown NNNN