SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0248 PM CDT Fri Jul 02 2021 Valid 022000Z - 031200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF THE NORTHEAST STATES... ...SUMMARY... A few locally strong wind gusts and hail remain possible with the stronger storms across a portion of the northeast states through early evening. ...Discussion... Primary change to previous outlook has been to remove the MRGL risk category across the eastern Carolinas. Widespread clouds in wake of earlier thunderstorms have resulted in limited potential for substantial destabilization in pre-frontal warm sector. Therefore any thunderstorms that redevelop along the cold front should remain sub-severe. Otherwise, a few storms developing in association with an upper low circulation over the Northeast States might produce a few instances of hail and locally strong wind gusts. Any remaining severe threat should quickly diminish with loss of surface heating this evening. ..Dial.. 07/02/2021 .PREV DISCUSSION... /ISSUED 1119 AM CDT Fri Jul 02 2021/ ...Carolinas... Focused along convective outflow, bands of showers and thunderstorms persist at midday across the coastal Carolinas parallel to an upstream southeastward-moving cold front. A moisture-rich air mass precedes the front while the strongest insolation is occurring along the immediate coast, roughly to about 35 miles inland from the coast as of 16Z. The primary concern for isolated severe thunderstorm development would be in this near-coastal zone this afternoon where stronger destabilization is expected coincident with 30-35 kt effective shear. However, while appreciable cloud cover will persist near the front much of the afternoon, there is some potential that additional thunderstorms could develop near the front later this afternoon into evening. Although overall destabilization should remain weak, a few stronger storms could occur across Piedmont areas pending near/pre-frontal air mass recovery later today. Overall, some multicellular clusters capable of localized wind damage are possible this afternoon through early evening. ...Northeast States... Relatively cool mid-level temperatures (near -18C at 500mb as per this morning's observed Buffalo NY sounding) will accompany an east-southeastward-moving upper low centered over Pennsylvania/southern New York. As additional cloud breaks/heating occur, semi-steep lapse rates and 500-1000 J/kg MLCAPE should support some strong to locally severe low-topped thunderstorms this afternoon. Quasi-long hodographs accentuated by strong anvil-level southwesterly winds will support the potential for hail, particularly across north-central/eastern Pennsylvania and nearby southern New York. Gusty winds and isolated tree damage could also occur. ...North-central High Plains... A few strong storms may develop late this afternoon and early evening across eastern Wyoming/southeast Montana into western South Dakota/southwest North Dakota. These storms will be in proximity to a weak and slow east/northeastward-moving mid-level impulse, coincident with a modestly moist air mass to the east of a surface trough/front. While steep lapse rates and upwards of 1000-1500 J/kg MLCAPE could support stronger storms, weak effective shear (20-25 kt or less) and warm mid-level temperatures/high freezing levels are expected to limit the potential for consequential hail and overall storm organization/sustenance. For these reasons, severe probabilities do not appear to be currently warranted. Read more LIVE: spc.noaa.gov
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