958
ACUS02 KWNS 200545
SWODY2
SPC AC 200544

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1244 AM CDT Thu Jun 20 2024

Valid 211200Z - 221200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE
NORTHERN PLAINS...

...SUMMARY...
Scattered strong to severe storms will be possible from the northern
High Plains into the upper Mississippi Valley on Friday, with a few
strong storms over parts of the Northeast. A few severe gusts are
also possible over parts of the eastern Great Basin.

...Synopsis...
On Friday, and upper high will be centered over the OH/TN Valleys,
and will gradually build westward across the southern Plains. To the
north, the tail end of a broad, low-amplitude trough over eastern
Canada will skirt the Great Lakes and Northeast, with 30-50 kt
midlevel winds and slight cooling aloft.

Farther west, the upper trough over the Great Basin will eject into
the Rockies by 00Z, and amplify Friday night as it moves into the
northern Plains enhancing large-scale ascent. Steep lapse rates and
over parts of the Four Corners states will favor strong gusts with
storms.

At the surface, high pressure will extend from the mid MS Valley to
the Mid Atlantic, with southerly winds across the Plains. Low
pressure will develop over the central High Plains, and will move
into SD overnight. A warm front will extend east of the low, across
northern NE and into southern MN/WI Friday morning, moving north
into SD and central MN by Saturday morning. The combination of
increasing lift and moisture advection will favor areas of strong to
severe storms mainly over far eastern WY, SD, MN, and parts of NE.

To the east, a weak surface trough will remain from the lower Great
Lakes into parts of the Northeast, again providing a focus for
scattered daytime storms as the air mass remains unstable.

...Northern High Plains to the upper MS Valley...
Early day thunderstorms are expected over southern parts of MN and
perhaps into WI, north of the warm front. Lapse rates appear to be
poor at that time, with minimal hail potential. However, as the
warmer air lifts north, storms along the zone from northeast SD
across southern MN see an uptick in storm intensity with hail threat
initially. With time, and as the low develops, an MCS will be
possible, with risk of damaging winds.

Farther to the southwest, diurnal storms will form over the high
terrain of eastern WY into north-central CO, and likely produce hail
and wind as they move across western and into central NE. Ample
instability will remain overnight ahead of High Plains activity to
support a hail and wind risk as it persists all night across SD and
into MN.

...Lower Great Lakes into the Northeast...
A moist air mass and heating will again result in several daytime
thunderstorms over the area, from eastern OH into southern New
England. Forecast soundings indicate perhaps poorer midlevel lapse
rates overall compared to the previous day, with more of a
subsidence inversion around 700 mb. However, heating will easily
support at least isolated development by early afternoon along the
weak front. Isolated to scattered strong to damaging gusts will be
the primary concern.

...UT...northern AZ...western CO into WY...
Thunderstorm probabilities will be quite high on Friday over this
region, owing to cool air aloft with the upper trough and plentiful
midlevel moisture with PWAT of 0.75-1.00 inches. This should favor
scattered afternoon development over a large area, with strong to
severe outflows possible.

..Jewell.. 06/20/2024

$$