000 ACUS02 KWNS 310527 SWODY2 SPC AC 310526 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1226 AM CDT Fri Mar 31 2023 Valid 011200Z - 021200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SATURDAY ACROSS PARTS OF EASTERN OHIO...MUCH OF PENNSYLVANIA...SOUTHERN INTO CENTRAL NEW YORK STATE AND PARTS OF NORTHWESTERN NEW JERSEY... ...SUMMARY... Strong thunderstorms may develop and organize east of the lower Great Lakes into the Hudson Valley and northern Mid Atlantic region Saturday, accompanied by a risk for severe wind gusts. ...Synopsis... While another significant short wave trough begins to dig within the main branch of mid-latitude westerlies, near/offshore of the Pacific Northwest coast, downstream flow is forecast to become less amplified into and through a confluent regime to the east of the Canadian Prairies and U.S. Great Plains during this period. To the south of a lingering vortex of Arctic origins (initially centered over southern Hudson Bay), models suggest that a vigorous short wave perturbation will dig to the southeast of James Bay and come in phase with an initially more substantive perturbation within this regime. The consolidating mid-level troughing may shift across New England into the Canadian Maritimes by 12Z Sunday. Associated forcing for ascent is forecast to support strong secondary surface cyclogenesis across the St. Lawrence Valley vicinity, while an initial occluded low over lower Michigan weakens. A conglomerating trailing cold front appears likely to advance east of the Appalachians and offshore of much of the Atlantic Seaboard into the Gulf coast vicinity by the end of the period. A narrowing pre-frontal plume of higher precipitable water content may advect across much of New England and Mid Atlantic coastal areas by mid afternoon, and the southern Atlantic coast later in the day. Within this regime, weak lapse rates and/or lingering convective cloud cover and precipitation may limit appreciable destabilization Saturday, particularly to the north of the southern Atlantic Seaboard. Strongest mid-level cooling and height falls are forecast to overspread the upper Ohio Valley/lower Great Lakes region through the northern Mid Atlantic and western New England by early Saturday evening. This may provide the focus for the primary severe weather potential for this period. ...Lower Great Lakes into Hudson Valley/northern Mid Atlantic... Lower/mid-tropospheric subsidence/warming likely will be in the process of overspreading the upper Ohio Valley and lower Great Lakes region at 12Z Saturday, before nosing east-northeastward through the day. This is expected to allow for appreciable surface heating and boundary-layer mixing to contribute to low-level destabilization prior to the arrival of the mid-level forcing for ascent and cooling, which is expected to provide support for low-topped thunderstorm development. This may impact areas to the east and south of Lakes Erie and Ontario Saturday morning into midday, with convection possibly consolidating into an organizing convective system. Given the shear and the strength of the mean flow (40-50+ kt in the lowest 6 km), coupled with the steepening low-level lapse rates, activity may support severe wind gusts while spreading east-northeastward across southern New York and Pennsylvania through the afternoon, perhaps as far east as the Hudson Valley vicinity by early Saturday evening. Farther east, in areas not impacted by the cool Atlantic marine layer, a gradually waning risk for strong wind gusts may continue into the evening hours. ...South Atlantic Seaboard... Strong deep-layer mean flow and shear will be at least conditionally supportive of organized severe weather potential on Saturday, given sufficient destabilization. At least widely scattered strong to severe thunderstorm development still appears possible. It remains unclear whether instability and mid/upper support will become sufficient for anything more widespread, but higher severe probabilities could still become more apparent and introduced in later outlooks for this period. ..Kerr.. 03/31/2023 $$