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ACUS02 KWNS 121713

SWODY2

SPC AC 121712



Day 2 Convective Outlook  

NWS Storm Prediction Center Norman OK

1212 PM CDT Fri Apr 12 2024



Valid 131200Z - 141200Z



...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS CENTRAL

OREGON...



...SUMMARY...

Isolated severe hail and strong gusts are possible across central

Oregon between about 2 to 8 PM PDT on Saturday.



...Oregon...



An upper low near the northern/central CA Pacific Coast will weaken

some as it shifts east/southeast over CA/NV on Saturday. Moderate

south/southeasterly low to midlevel flow on the northeastern

periphery of this system will overspread OR. Effective shear

magnitudes around 30-40 kt will overlap with a plume of midlevel

moisture and steep midlevel lapse rates. Forecast soundings show

temperatures warming into the 60s by afternoon, allowing for deep

boundary-layer mixing beneath the steep midlevel lapse rates. Modest

destabilization is forecast with generally 500-1000 J/kg MLCAPE

expected. Isolated to widely scattered thunderstorms are expected to

develop by mid to late afternoon and spread north/northwest into the

evening hours. Given ample shear and instability in conjunction with

cool temperatures aloft, isolated large hail is possible.

Additionally, inverted-v sub-cloud thermodynamic profiles may

support strong gusts with this activity as well. 



...Central Plains...



A weak shortwave impulse is forecast to spread across the central

Plains during the afternoon/evening. Thermodynamic profiles indicate

a nearly saturated profile in the 600-400 mb layer. A surface trough

extending south/southwest across the Plains from a surface low over

the northern Plains/Upper Midwest will result in some poleward

transport of Gulf moisture. However, deeper boundary-layer moisture

will remain confined to TX, with generally 40s F dewpoints into

KS/NE. Strong heating during the day will likely mix out this scant

moisture, limiting instability and overall thunderstorm chances.

Nevertheless, steep midlevel lapse rates amid the elevated moist

layer will foster weak instability (generally less than 500 J/kg

MUCAPE). Convection may try to develop by late afternoon/early

evening, though potential appears very conditional. If a storm can

develop, gusty winds are possible given the deeply mixed/dry

boundary-layer.



...Great Lakes...



Elevated thunderstorms are possible during the evening/overnight

hours in a northwest flow regime and as a weak shortwave impulse

develops southeast from the Canadian Prairies to the Great Lakes.

Elevated thunderstorms are expected to develop in a warm advection

regime ahead of a southeastward-advancing cold front and to the cool

side of a warm front draped across northern WI/MI. Weak elevated

instability (generally less than 400 J/kg MUCAPE over a shallow

layer) will preclude severe potential, though a stronger cell or two

could produce small hail. Overall potential/coverage appears too low

for severe probabilities.



..Leitman.. 04/12/2024



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