097
ACUS01 KWNS 260556
SWODY1
SPC AC 260554

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1254 AM CDT Wed Jun 26 2024

Valid 261200Z - 271200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS TODAY INTO TONIGHT
ACROSS PARTS OF THE MID AND UPPER OHIO VALLEY INTO THE NORTHERN MID
ATLANTIC REGION...ACROSS PARTS OF THE OZARK PLATEAU INTO LOWER OHIO
VALLEY AND ACROSS THE FRONT RANGE INTO ADJACENT GREAT PLAINS...

...SUMMARY...
Clusters of thunderstorms accompanied by potentially damaging wind
gusts are possible today into tonight from the Ohio Valley into
northern Mid Atlantic, across parts of the Ozark Plateau into lower
Mississippi Valley, and to the lee of the Front Range and Sangre de
Cristo Mountains.

...Synopsis...
To the south of a broad vortex centered over the higher latitudes of
northeastern Canada, models indicate some further amplification of
large-scale mid-level troughing east of the upper Mississippi Valley
through the northern Mid Atlantic and Northeast during this period.
Upstream, a broad low embedded within larger-scale mid-level
troughing is forecast to progress inland across the Pacific
Northwest.  As it does, initially prominent ridging appears likely
to become suppressed from the northern into southern Rockies by late
tonight.

A number of smaller-scale perturbations, including some convectively
generated or enhanced, are embedded within the weaker flow around
the Western ridging, and on the southern periphery of the stronger
westerlies across the central Great Plains into Ohio Valley.  As
these progress through the evolving flow, they are expected to
provide the primary focus for developing clusters of thunderstorms
today into tonight.  The predictability of these features is still
relatively low at this forecast time frame, and it remains unclear
how outflow associated with ongoing convection across the central
Great Plains into lower Missouri and Ohio Valleys may impact
convective development later today through tonight.

Although a plume of elevated mixed-layer air emanating from the
Intermountain West is in the process of becoming suppressed to the
east of the Rockies, by late this afternoon it still appears that
boundary-layer moisture and daytime heating will still be sufficient
to contribute to moderate to large CAPE across parts of the central
and southern Great Plains, the lower Mississippi Valley into eastern
Gulf States, and across the Ohio Valley into Mid Atlantic.

...Ohio Valley into northern Mid Atlantic...
Ahead of digging mid-level troughing, one or more convectively
generated perturbations may contribute to increasing thunderstorm
development across the mid into upper Ohio Valley by this afternoon,
beneath modest west-southwesterly mid-level flow (on the order of
30+ kt).  Although lower-level wind fields may be initially more
modest, various model output suggests that convection could become
fairly widespread and contribute to strengthening conglomerate
surface cold pools accompanied by potentially damaging wind gusts.
Potential instability across and east of the Allegheny Mountains
remains a little more unclear, but it is possible that vigorous
convection may be maintained along the leading edge of the outflows
as they spread eastward into northern Mid Atlantic coastal areas by
early this evening.  While the magnitude of the convective surface
gusts may be mostly marginally severe in nature, one or more swaths
of potentially damaging gusts are possible, and severe wind
probabilities may still need to be increased once sub-synoptic
developments become more unclear.

...Ozark Plateau into and east of lower Mississippi Valley...
Potential convective evolution remains uncertain.  However, there is
a substantive signal within at least some model guidance that a
notable convective perturbation will be in the process of
progressing into the Ozark Plateau at the outset of the period.
This may still be accompanied by continuing vigorous convective
development and a southeastward propagating cold pool, which may
persist or contribute to renewed strong convective development
across Arkansas into Mississippi and adjacent portions of the Gulf
states by this evening.  If this occurs, it probably will be
accompanied by one or more swaths of strong to severe surface gusts.

...Front Range into adjacent Great Plains...
Beneath modest westerly to northwesterly mid-level flow,
destabilization may become supportive of scattered strong to severe
storm development off the higher terrain.  Models suggestive that
destabilization will become sufficient across the adjacent plains to
support considerable upscale growth and potential for strong to
severe gusts along strengthening cold pools late this afternoon into
this evening.

..Kerr/Barnes.. 06/26/2024

$$