|Tropical Storm Alvin||Winds: 55 kt|
|Pressure: 997 mbar|
|Advisory 12 / June 28, 2019|
Tropical Storm Alvin Discussion Number 12
Wiki-Hurricanes Forecast Center
8:00 AM PDT Fri Jun 28 2019
Alvin continues to weaken as it quickly traverses the East Pacific thermocline, and analyses suggest that it has moved over sub-25C waters. As the storm is now running into southwesterly flow from a nearby upper-trough, wind shear is increasing north of 20 kt, resulting in the displacement of the low-level circulation center to the southwest of convection - decoupling is expected throughout the day today as conditions become increasingly hostile. SAB estimates T3.5/55 kt, though final values have fallen further to T2.5/35kt. CIMSS-ADT values show concordance with these estimates. Based on these values, Alvin's intensity is estimated at 55 kt.
Weakening should proceed as forecast with Alvin now firmly over cooler waters. Water vapor imagery shows a large expanse of dry and stable air immediately west of Alvin. As Alvin moves west-northwest, it will track into a core of stronger southeasterly upper-level flow, resulting in the mid- to upper-level convective content to shear towards the northeast and stream into southern California in two or so days. The remaining low-level circulation will become fully entrenched within the stable air regime as it shallows and pulls west under the influence of the subtropical ridge the Central Pacific after two days - there probably won't be much left of Alvin by that time. The intensity forecast shows aggressive deterioration of Alvin's winds before transitioning to a post-tropical system in two days, though I may be a little generous with the lonegivity of this resulting system.
INIT 28/1500Z 55 KT 65 MPH
12H 29/0000Z 35 KT 40 MPH
24H 29/1200Z 25 KT 30 MPH
36H 30/0000Z 20 KT 25 MPH
48H 30/1200Z 20 KT 25 MPH...POST-TROP/REMNT LOW72H 01/1200Z...DISSIPATED