LIVE MAP (ABOVE) ... SPC 0600Z Day 2 Outlook
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
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