SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0224 AM CDT Sun Aug 04 2024
Valid 061200Z - 071200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS TUESDAY INTO
TUESDAY EVENING ACROSS PARTS OF EASTERN ILLINOIS...NORTHERN AND
CENTRAL INDIANA...MUCH OF OHIO...CENTRAL AND SOUTHERN
PENNSYLVANIA...NEW JERSEY...SOUTHEASTERN NEW
YORK...CONNECTICUT...RHODE ISLAND AND ADJACENT PORTIONS OF
MASSACHUSETTS...LONG ISLAND...NORTHERN PORTIONS OF
DELAWARE...MARYLAND AND WEST VIRGINIA...COASTAL GEORGIA AND SOUTH
CAROLINA...MUCH OF CENTRAL AND EASTERN MONTANA...NORTHEASTERN
WYOMING...AND PARTS OF THE WESTERN DAKOTAS...
...SUMMARY...
Strong storms posing at least some risk for severe weather may
impact coastal Georgia and South Carolina, a corridor across the
Ohio Valley into northern Mid Atlantic, and parts of the northern
Rockies into adjacent Great Plains Tuesday into Tuesday evening.
...Synopsis...
After reaching peak amplitude, models suggest that northwestern
Canadian mid-level ridging may continue elongating eastward, while
evolving troughing to its south digs toward the western and central
Canadian/U.S. border vicinity. This may begin to suppress the
expansive western into central U.S. ridging, but flow may remain
broadly anticyclonic across much of the northern U.S. Rockies and
Great Plains through this period.
Downstream, it appears that the persistent/slow moving northern
Quebec mid-level low will redevelop eastward offshore, to the south
of Greenland, by early Wednesday, as a significant short wave
impulse accelerates east of the Canadian Maritimes and contributes
to cyclogenesis. However, trailing troughing is forecast to linger
across the eastern Canadian provinces and much of the Northeast, as
another embedded perturbation digs to the southeast of Hudson/James
Bays.
In lower-levels, an initial cold front is forecast to advance slowly
southward into the Ohio Valley and northern Mid Atlantic, and more
rapidly through the middle Mississippi Valley and central into
southern Great Plains. However, within weak steering flow between
the ridging in the southern mid- and subtropical latitudes, the
remnant circulation of what is forecast to at least briefly become
Hurricane Debby may only very slowly migrate into and across coastal
southeastern Georgia Tuesday through Tuesday night.
...Coastal Georgia/South Carolina...
Forcing for ascent, boundary-layer buoyancy and low-level shear
conducive to convection with potential to produce tornadoes seem
likely to largely continue slowly spreading east of Georgia coastal
areas early Tuesday. However, it is possible that this regime could
continue to impact areas perhaps as far north as South Carolina
coastal areas into the day.
...Ohio Valley into Mid Atlantic...
Westerly mid-level flow is forecast to begin to weaken Tuesday, and
there may be a tendency for the front to advance south of the
stronger lingering flow. However, it is possible that low-level
moisture along the front may still contribute to sufficient
instability, with daytime heating, to support scattered organizing
thunderstorm activity with potential to produce locally damaging
wind gusts Tuesday afternoon and evening.
...Northern Rockies and adjacent Great Plains...
Forcing for ascent associated with low-level warm advection,
downstream of the approaching mid-level troughing, might contribute
to one or two consolidating clusters of convection spreading off the
higher terrain late Tuesday afternoon. As this propagates into a
more strongly heated and deeply mixed boundary layer, in the
presence of strong shear (beneath 40-70+ kt flow in the 500-300 mb
layer), there may be potential for this activity to organize and
produce strong to severe outflow winds, despite relatively modest
potential instability.
..Kerr.. 08/04/2024
Read more
