SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0736 AM CDT Thu Aug 04 2022
Valid 041300Z - 051200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
FROM THE OH VALLEY INTO PARTS OF THE NORTHEAST...SOUTHERN OK TO THE
TX PANHANDLE...CENTRAL MT...AND IN WESTERN NE...
...SUMMARY...
Isolated damaging winds are possible this afternoon from the Ohio
Valley into parts of the Northeast, Oklahoma into the Texas
Panhandle, central Montana, and western Nebraska.
...Central MT this afternoon/evening...
A midlevel shortwave trough over southern BC and WA will progress
generally eastward to southern AB/SK/northern MT. A surface cyclone
will precede the midlevel trough across southern AB/SK, and a
trailing cold front will move southeastward across MT late this
afternoon into tonight. Low-level moisture will be limited in
advance of the front across MT, but deep mixing with strong surface
heating will likely be sufficient for weak surface-based buoyancy
with inverted-v profiles. Some increase in midlevel flow by
afternoon, coupled with the weak buoyancy and DCAPE of 1200-1500
J/kg, will support isolated strong-severe outflow gusts with
high-based convection in the zone of weak ascent along and just
ahead of the front for a few hours this afternoon/evening.
...OH Valley into NY/VT this afternoon...
In association with persistent overnight convection, an MCV will
likely emerge in the vicinity of the MO Bootheel. Outflow with this
convection will continue to move southward across AR today while
weakening, and the cold pool is less defined farther east toward the
lower OH Valley. The persistence of weak outflow and/or
differential heating from the lower OH Valley into NY/VT, where
MLCAPE will likely reach or exceed 2000 J/kg in an environment of
weak vertical shear, will help loosely focus thunderstorm
development (along with the Blue Ridge) and the potential for
isolated strong/damaging downbursts this afternoon.
...Southern TX Panhandle into OK late this afternoon/evening...
Proximal to the midlevel high over the Southern High Plains, another
hot day with deep mixing is expected from the southeast TX Panhandle
into central/southern OK. This corridor will lie along and just
south of an outflow-reinforced front that will sag southward across
OK through this evening. Weak lift along the wind shift, in
combination with both MLCAPE/DCAPE of 1000-1500 J/kg and minimal
convective inhibition, will support the threat for isolated
thunderstorms with strong-severe downbursts for a few hours late
this afternoon/evening.
...Western NE and vicinity this afternoon/evening...
Strong surface heating and deep mixing will occur along a surface
lee trough across western NE and vicinity, as a warm front develops
northward through the day from NE toward SD. Though moisture will
be somewhat marginal, MLCAPE could exceed 1000 J/kg with minimal
convective inhibition, and a couple of storms may form along the
surface trough. Inverted-v profiles and sufficiently long
hodographs with effective bulk shear of 30-35 kt could support
high-based supercells with a low-end threat for wind/hail.
..Thompson/Kerr.. 08/04/2022
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