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Tropical Storm Elida Forecast Discussion Number 6
2020-08-10 10:51:13| National Hurricane Center (East Pacific)
Issued at 300 AM MDT Mon Aug 10 2020 000 WTPZ44 KNHC 100851 TCDEP4 Tropical Storm Elida Discussion Number 6 NWS National Hurricane Center Miami FL EP092020 300 AM MDT Mon Aug 10 2020 After the earlier burst of deep convection and the development of a small 10-nmi-wide low- to mid-level eye noted in passive microwave satellite imagery, convection has waned somewhat and the eye feature has eroded in the northwestern semicircle due to entrainment of dry air, along with some modest northwesterly vertical wind shear. A 0314Z ASCAT-A overpass revealed peak winds of only 43 kt in the northeastern quadrant, along with a radius of maximum winds (RMW) of 10-15 nmi. Satellite intensity estimates range from T3.5/55 kt from TAFB to T4.0/65 kt from SAB, along with a UW-CIMSS SATCON estimate of 53 kt and an ADT estimate of 59 kt. An average of these intensity estimates, and allowing for some undersampling by the scatterometer instrument due to Elida's small RMW, supports maintaining an intensity of 55 kt for this advisory. The initial motion estimate remains west-northwestward or 300/13 kt. Both the forecast track and rationale remain straight-forward and basically unchanged from the previous advisory. Elida is expected to be steered west-northwestward by a deep layer ridge to the north for the next 72 hours or, followed by a westward motion on days 4 and 5 when Elida will be weakening over much cooler waters and becoming a shallower cyclone. The latest NHC track guidance remains tightly packed and, thus, the new official forecast is very similar to the previous advisory track, and lies near the TVCE and NOAA-HCCA consensus track models. The brief intensity hiatus that Elida is experiencing is expected to be short-lived due to the cyclone's small RMW and the vertical shear forecast to decrease to less than 10 kt in the 12-36 hour time frame. This should allow for Elida to strengthen -- possibly even rapidly -- during the next 24 hours, followed by a leveling off in the intensity due to the cyclone moving over sub-26C sea-surface temperatures (SST). By 48-60 h, SSTs less than 25C and modest southwesterly vertical wind shear will combine to induce steady weakening. By 96 h or so, Elida is forecast to degenerate into a post-tropical cyclone. The new official intensity forecast is a little lower than the previous advisory, but is a little above the consensus models IVCN and HCCA. FORECAST POSITIONS AND MAX WINDS INIT 10/0900Z 18.3N 108.8W 55 KT 65 MPH 12H 10/1800Z 19.1N 110.8W 65 KT 75 MPH 24H 11/0600Z 20.0N 113.5W 75 KT 85 MPH 36H 11/1800Z 20.8N 116.2W 80 KT 90 MPH 48H 12/0600Z 21.5N 118.6W 65 KT 75 MPH 60H 12/1800Z 22.2N 120.7W 55 KT 65 MPH 72H 13/0600Z 22.6N 122.6W 45 KT 50 MPH 96H 14/0600Z 22.2N 125.7W 35 KT 40 MPH...POST-TROPICAL 120H 15/0600Z 21.4N 128.8W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Stewart
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