ACUS02 KWNS 080454
SWODY2
SPC AC 080452

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1152 PM CDT Wed Aug 07 2024

Valid 091200Z - 101200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FRIDAY INTO
FRIDAY NIGHT ACROSS PARTS OF SOUTHEASTERN NEW YORK STATE...PARTS OF
SOUTHERN VERMONT AND NEW HAMPSHIRE...WESTERN
MASSACHUSETTS...CONNECTICUT AND LONG ISLAND...NEW JERSEY...EASTERN
PENNSYLVANIA...CENTRAL MARYLAND AND THE EASTERN SHORE OF
MARYLAND...DELAWARE...PARTS OF EASTERN VIRGINIA AND THE DISTRICT OF
COLUMBIA...

...SUMMARY...
There may be at least some continuing risk for tornadoes in advance
of the remnant low of Debby, spreading across parts of the northern
Mid Atlantic and adjacent portions of New England.

...Synopsis...
It still appears that an initially prominent ridge will generally be
maintained over the higher latitudes of North America through this
period, though its mid-level height center may begin to become
suppressed to the east-southeast of the Canadian Northwest
Territories.  Some eastward redevelopment of a significant mid-level
low evolving to its southeast may also commence, as a couple of
embedded perturbations pivot around its circulation center near the
upper Great Lakes region.

In lower-levels, pattern developments to the northeast and east of
the Great Lakes region remain a bit more unclear.  A modest initial
cyclone, to the north/northeast of Lake Superior at 12Z Friday, may
gradually occlude, with varied model output then suggesting that
modest secondary cyclogenesis may ensue somewhere across southern
Ontario and the lower Great Lakes region into the upper St. Lawrence
Valley by 12Z Saturday.  At the same time, Debby's remnant low is
forecast to accelerate north of the Virginia Piedmont by early
Friday, before accelerating north-northeastward and passing
near/just west of the Poconos and Catskills vicinity by Friday
evening.  Eventually, it may interact with a frontal zone trailing
the evolving cyclone to the north, and perhaps merge into the
cyclone, but these details remain uncertain.

...Northern Mid Atlantic/New England...
Severe probabilities have been adjusted north-northeastward, based
on westward and accelerated adjustments to the official forecast
track.  Despite the weakening trends to Debby, models suggest that
the evolution of sizable clockwise-curved low-level hodographs and
appreciable boundary-layer buoyancy may be maintained at least
through the daytime hours Friday.

It appears that the most favorable environment for convection which
could become capable of producing tornadoes will be focused near the
stronger surface pressure falls, north through east of the
accelerating low-level circulation, and just ahead of the mid-level
warm core.  This may be in the process of overspreading the
Chesapeake/Delmarva vicinity as daytime heating contributes to
boundary-layer destabilization, before spreading northward across
eastern Pennsylvania and New Jersey, much of southeastern New York
and adjacent portions of western New England by early Friday
evening.

Even if the clockwise curvature to the low-level hodographs does not
remain as large as some forecast soundings indicate, downward mixing
of strong southerly ambient wind fields (including 40-50+ kt in the
850-700 mb layer) may still contribute to potentially damaging
surface gusts in the stronger convection.  While it seems that this
risk may wane overnight Friday, it is possible that low severe
probabilities may need to be extended northeastward in later
outlooks for this period.  Severe probabilities might also still
need to be increased across parts of the current marginal risk area,
if/when lingering uncertainties become better resolved.

..Kerr.. 08/08/2024

$$
--- SBBSecho 3.20-Linux
 * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (618:250/1)