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Tropical Storm BLAS Forecast Discussion Number 5
2016-07-04 04:36:14| National Hurricane Center (East Pacific)
Issued at 900 PM MDT SUN JUL 03 2016 000 WTPZ43 KNHC 040236 TCDEP3 TROPICAL STORM BLAS DISCUSSION NUMBER 5 NWS NATIONAL HURRICANE CENTER MIAMI FL EP032016 900 PM MDT SUN JUL 03 2016 The satellite presentation of Blas has not changed much since the previous advisory, with the cyclone featuring large convective bands and a developing CDO feature. A GCOM/AMSR-2 image from 2042 UTC showed a mid-level eye feature displaced about 30 n mi southwest of the low-level center, consistent with about 10 kt of northeasterly shear. Satellite classifications remain T3.5/55 kt from TAFB and SAB, and that is the initial intensity. The intensity forecast reasoning remains unchanged, as Blas should continue to strengthen at a steady rate for the next 48 hours over warm SSTs and in a low to moderate shear environment. After 48 hours the SSTs cool steadily along the forecast track, especially at days 4 and 5, and quick weakening is forecast by then. The NHC intensity forecast is close to or a bit above the SHIPS model at the high end of the guidance through 48 hours, and trends toward the weaker LGEM late in the period. Its worth noting that the HWRF and GFDL models are much weaker with Blas compared to the statistical models for this cycle. The initial motion estimate is 285/10. The dominant steering mechanism through the forecast period is a mid-level ridge centered over northern Mexico and extending westward across the eastern Pacific. This feature should steer Blas on a general westward to west-northwestward track through the forecast period. The track model guidance is in very good agreement with small spread through day 4, but the spread increases a bit at day 5. By then the GFS shows more of a poleward turn as the ridge is eroded by a closed mid/upper-level low northeast of the Hawaiian Islands, while the ECMWF and UKMET show less influence from the upper low. The new NHC forecast is close to a blend of the GFS and ECMWF solutions and is in the middle of the guidance envelope. FORECAST POSITIONS AND MAX WINDS INIT 04/0300Z 12.4N 112.2W 55 KT 65 MPH 12H 04/1200Z 12.9N 113.9W 65 KT 75 MPH 24H 05/0000Z 13.5N 116.4W 80 KT 90 MPH 36H 05/1200Z 14.0N 118.8W 90 KT 105 MPH 48H 06/0000Z 14.5N 121.2W 100 KT 115 MPH 72H 07/0000Z 15.9N 125.7W 105 KT 120 MPH 96H 08/0000Z 17.3N 129.5W 85 KT 100 MPH 120H 09/0000Z 19.1N 132.9W 60 KT 70 MPH $$ Forecaster Brennan
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