Valid 021200Z – 031200Z
…THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM CENTRAL
KANSAS INTO CENTRAL OKLAHOMA…AND OVER MUCH OF WESTERN MONTANA…
…SUMMARY…
Isolated severe storms are likely from central Kansas into central
Oklahoma. Damaging wind gusts or marginal hail are the most likely
threats. A brief tornado is possible over north-central Oklahoma or
south-central Kansas. Strong wind gusts are possible over much of
western Montana.
…Synopsis…
An upper high will remain centered over the Four Corners states,
with modest northwest flow aloft across much of the Plains. To the
west, a shortwave trough will skirt across WA, northern ID and
northwest MT, providing increasing deep shear and cooling aloft
which will aid destabilization.
At the surface, mid to upper 60s F dewpoints will generally exist
from the central and southern Plains eastward to the Mid Atlantic,
with high pressure causing stable conditions from the Midwest into
the Northeast.
Low pressure will develop during the afternoon over western OK and
the TX Panhandle, with a north-south warm front from central KS into
northern OK. Hot conditions will be found over TX and western OK,
which will aid in storm development generally northeast of the
surface low.
…Central KS into central OK…
Thunderstorms are likely to be ongoing in the morning over much of
eastern KS, with scattered showers/storms into northeast OK as well.
Much of this activity is expected to thin out by early afternoon as
mass fields focus west toward the developing low. Strong heating
will result in an uncapped air mass from central KS into OK, with
MLCAPE averaging 2000 J/kg within the theta-e axis. Storm initiation
is expected near 21Z along the warm front in KS, and within the
low-level lapse rate plume into western OK which will also be near
the low.
The corridor near I-35 and along the warm front will have lower
LCLs, and a band of 200 m2/s2 SRH. Forecast hodographs are
sufficiently long to sustain south or even southwestward moving
cells, including a few supercells. Sporadic hail or a brief tornado
is possible. However, the most likely threat for the region is
expected to be a few damaging wind gusts as storms spread south and
into the steep low-level lapse rate environment. A small Slight Risk
cannot be ruled out in later outlooks should confidence in storm
coverage and positioning increase.
…Central ID into western MT…
Strong heating will occur over ID and MT, beneath strengthening
southwest flow aloft along the periphery of the upper ridge. At the
same time, cooling aloft will occur, and this will result in very
steep lapse rates from the surface through 500 mb. Given these
profiles, moisture will be sufficient for high-based thunderstorms
to form over central ID and into western MT during the afternoon.
Deep-layer shear in the cloud-bearing layer will favor both cellular
activity and small lines resulting in outflow, and a few wind gusts
may approach severe levels. Any cells will also be capable of mainly
small hail given the low moisture content.
..Jewell/Bentley.. 08/02/2019
$$