SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0229 PM CDT Wed Oct 07 2020 Valid 072000Z - 081200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR EAST-CENTRAL NEW YORK INTO PARTS OF SOUTHERN NEW ENGLAND... ...SUMMARY... Strong to locally severe wind gusts are possible this afternoon and perhaps persisting into the early evening from parts of the Hudson Valley into southern New England. ...Discussion... Have upgraded to 15-percent wind probabilities for parts of east-central NY eastward into southern New England ahead of a squall line quickly moving east across NY. Several NY Mesonet sites in Chenango, Montgomery, and Herkimer counties have observed gusts in the 50-56 mph range during the past hour. Water-vapor imagery shows a potent mid-level shortwave trough moving into the Northeast. The flow associated with this disturbance is quite strong (50 kt at 1.5 km ARL) as sampled by the KENX (Albany, NY) and KBOX (Boston, MA) 88D VADs. Although the earlier rain shield has progressed across southern New England, cloud breaks and peak heating in wake of these showers will enable at least some steepening of the low-level lapse rates and a few hundred J/kg SBCAPE to develop. Given the strongly forced squall line with adequate instability developing ahead/downstream of the convective line, it seems plausible strong to locally severe gusts (50-60 mph) via horizontal momentum transport, will continue or possibly increase in coverage over the next few hours and result in widely scattered wind damage. ..Smith.. 10/07/2020 .PREV DISCUSSION... /ISSUED 1101 AM CDT Wed Oct 07 2020/ ...Northeast... The current forecast area appears to be on track, with no changes made. A band of showers and thunderstorms is organizing from lake Ontario northeastward along the St Lawrence Valley. This activity will move quickly eastward across much of NY early this afternoon, and across much of New England through early evening. Widespread clouds are present ahead of the convection, which will limit low-level lapse rates and CAPE. It is likely that these fast-moving showers and storms will produce gusty and marginally damaging winds, but it is uncertain how prevalent the risk of 50 knot winds will be. Given the overall marginal thermodynamic environment, will maintain the ongoing MRGL risk area. Activity should move off the New England coast by mid-evening, ending the threat of gusty winds.
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