Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
Probability of hail 1" or larger within 25 miles of a point. Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point.
Day 2 Hail Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
No Risk Areas Forecast
SPC AC 011726
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1226 PM CDT Tue Sep 01 2020
Valid 021200Z - 031200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHEAST/MID-ATLANTIC INTO THE OHIO VALLEY/MID-SOUTH...
...SUMMARY...
Isolated strong to severe thunderstorms may occur Wednesday from
parts of the Northeast/Mid-Atlantic into the Ohio Valley/Mid-South.
...Northeast into the Mid-Atlantic...
An upper trough over Ontario/Quebec and the Great Lakes is forecast
to develop across the Northeast and Quebec on Wednesday. The
strongest mid-level flow should remain confined to parts of northern
NY and New England, although modestly enhanced winds (around 30-35
kt) at mid levels will likely extend as far south as the
Mid-Atlantic. At the surface, a weak low initially over southern
Ontario should develop northeastward through the day, with a
trailing cold front moving southeastward across the Northeast and
Mid-Atlantic. A warm front is also forecast to lift northward across
parts of these regions through Wednesday evening.
Poor mid-level lapse rates will be present across the warm sector,
which should temper updraft strength to some degree through much of
the day. Still, 500-1000 J/kg of MLCAPE should develop ahead of the
cold front across parts of PA/NY into far western New England owing
to diurnal heating of an increasingly moist low-level airmass.
Greater instability (1500-2000 J/kg of MLCAPE) may be realized
across parts of the Mid-Atlantic to the east of the Blue Ridge
Mountains, where rich low-level moisture should be present and
stronger diurnal heating will likely occur. Around 30-40 kt of
effective bulk shear should act to organize storms as they form
along/ahead of the cold front, and along a lee trough extending
southward near/east of the Appalachians. A mix of multicells and
marginal supercell structures will be possible.
Isolated strong/gusty downdraft winds capable of producing some
damage may occur as storms move eastward through early Wednesday
evening given the enhanced mid-level flow. A tornado or two also
appears possible with any of the more discrete storms, as low-level
winds should be strong enough to support 100-150 m2/s2 of 0-1 km
SRH. An upgrade to Slight Risk may be needed for parts of the
Mid-Atlantic if current model trends continue, but confidence in
overall storm coverage/intensity was not high enough to introduce
greater severe probabilities just yet.
...Ohio Valley into the Mid-South...
Clusters of thunderstorms will likely be ongoing across parts of the
southern Plains into AR Wednesday morning in association with a weak
upper trough. A convectively enhanced, small-scale mid-level
perturbation may move northeastward across parts of the Mid-South
and OH Valley through the day. There appears to be some potential
for a small thunderstorm cluster to move northeastward over these
areas in tandem with the mid-level perturbation. Isolated strong to
damaging winds appear to be the main severe threat with this
activity, as mid-level southwesterly flow should be modestly
enhanced (around 25-30 kt) and sufficient destabilization is
anticipated downstream. A surface cold front over the OH Valley will
likely serve as a northern delimiter to any appreciable severe
threat Wednesday afternoon.
..Gleason.. 09/01/2020
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NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0600Z
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