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Hurricane BLAS Forecast Discussion Number 8
2016-07-04 22:39:14| National Hurricane Center (East Pacific)
Issued at 200 PM PDT MON JUL 04 2016 000 WTPZ43 KNHC 042039 TCDEP3 HURRICANE BLAS DISCUSSION NUMBER 8 NWS NATIONAL HURRICANE CENTER MIAMI FL EP032016 200 PM PDT MON JUL 04 2016 Blas' cloud pattern has not changed much in organization since this morning, except for the emergence of what appears to be a ragged, banding-type eye. The cyclone's central features are still not that well organized, although there are some recent signs that this may be changing. A dry slot of air has also been wrapping around the western half of the circulation. Dvorak classifications remain T4.0 and T4.5 from SAB and TAFB, respectively. A 1652 UTC ASCAT overpass indicates that Blas is a minimal hurricane at best, and the initial intensity estimate is held at 65 kt for this advisory. The latest fixes indicate that the initial motion is a little faster and has a bit more of a northerly component than yesterday. The best estimate is that the cyclone is moving 290/12. Overall, the forecast reasoning is unchanged. Blas should be steered on a west- northwestward course during the next several days to the south of a strong, deep-layer subtropical ridge extending westward from northern Mexico. A more northwesterly track is possible toward the end of the forecast period as the cyclone nears the western end of this ridge. The new NHC track forecast is adjusted a little to the north in the short term and lies on the northern side of the guidance envelope. The forecast does not deviate much from the previous forecast beyond day 2 and lies near the multi-model consensus. It is unclear as to why Blas has not strengthened much, especially since the large-scale environment appears conducive for intensification. The current interruption to the cyclone's strengthening could be related to a dry air intrusion from an unknown source and/or some northeasterly shear. Whatever the cause, additional strengthening is still indicated, and the new intensity forecast remains near the upper-end statistical guidance. On days 3-4, Blas will reach the 26-deg sea surface temperature isotherm and encounter substantially drier and more stable air. This should result in gradual weakening in an otherwise low-shear environment. By 96 hours, rapid weakening is expected to commence due to increasingly unfavorable environmental factors. The wind radii have been significantly adjusted based on the aforementioned ASCAT overpass. FORECAST POSITIONS AND MAX WINDS INIT 04/2100Z 13.7N 115.7W 65 KT 75 MPH 12H 05/0600Z 14.1N 117.5W 75 KT 85 MPH 24H 05/1800Z 14.6N 120.0W 95 KT 110 MPH 36H 06/0600Z 15.1N 122.5W 105 KT 120 MPH 48H 06/1800Z 15.6N 124.6W 100 KT 115 MPH 72H 07/1800Z 16.8N 128.6W 80 KT 90 MPH 96H 08/1800Z 18.2N 131.7W 60 KT 70 MPH 120H 09/1800Z 20.0N 135.1W 35 KT 40 MPH...POST-TROPICAL $$ Forecaster Kimberlain
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