- Day Three
acus03 kwns 230715
Storm Prediction Center ac 230715
Day 3 convective outlook
National Weather Service Storm Prediction Center Norman OK
0215 am CDT Sat may 23 2015
Valid 251200z - 261200z
..there is a slight risk of severe thunderstorms across much of Texas...
..There is a marginal risk of severe thunderstorms from the lower MS valley to the
upper Great Lakes...
Scattered-numerous thunderstorms will develop from Texas into the
middle south region on Memorial Day. Scattered thunderstorms will also
be noted across much of the interior west into the upper Great Lakes
and Ohio Valley. Greatest risk for severe will be across Texas with
isolated severe extending north into the upper Great Lakes.
Northern stream middle-level speed maximum is forecast to dig southeastward along the
Pacific coast into northern Mexico during the day2 period before ejecting
into The Big Bend region of Texas early Memorial Day. While deep
layer shear is not forecast to be particularly strong...sufficient
surface-6km shear will be present for organized convection and perhaps
supercell structures if larger convective clusters/line segments do
not disrupt discrete development. Tropical plume of high
precipitable water...1.75-2 inches...will persist along a corridor from the western Gulf
basin into the middle MS valley region. As large scale forcing spreads
into Texas convection should easily develop...likely early in the
period then spread toward the arklatex. Given the lack of
meaningful inhibition numerous storms...clusters and mergers are
expected. Forecast soundings suggest multi-faceted storm modes and
sufficient buoyancy for at least a threat of large hail and
wind...perhaps even a few tornadoes if supercells evolve. Given the
high precipitable water values these storms will likely produce very heavy rainfall.
..upper MS valley/Central Plains...
Day2 short-wave trough is expected to eject north-northeastward into the middle-upper
MS valley early in the period in response to speed maximum approaching
The Big Bend. Convection should develop ahead of this feature early
with large scale ascent likely spreading into northwest Ontario by early
afternoon. Weak short-wave ridging is expected along the trailing
frontal zone into the Central Plains during peak heating. Given the
weak large scale support will only introduce 5 percent severe probs
across this region for isolated supercells that evolve during the
late afternoon and linger into the evening hours.