Day 1 Severe Weather Outlook

Valid 282000Z – 291200Z


No severe storms are expected through tonight.


Only minor adjustments have been made to previous forecast. A few
thunderstorms remain possible from the middle to lower MS Valley and
TN Valley this afternoon into early evening and along the Pacific NW
coast tonight.

..Dial.. 02/28/2020

.PREV DISCUSSION… /ISSUED 1016 AM CST Fri Feb 28 2020/

…Mid-South to Southern Appalachians…
A shortwave impulse over the Lower MO Valley will progress
southeast, aiding in scattered shower development during the late
afternoon across the Mid-South. Despite surface dew points only in
the low to mid 30s, steep lapse rates through a combination of
boundary-layer heating and very cold 500 mb temperatures near -32 C
may support scant buoyancy (SBCAPE up to 250 J/kg). Here, convection
could become sufficiently deep and cloud tops sufficiently cold to
support mixed phase and charge separation, with a threat for
isolated thunderstorms containing small hail and gusty winds.
Farther east, shallow convection is expected during the late
afternoon across the southern Appalachians with a leading shortwave
impulse, but even less buoyancy and shallower convective depths
suggest that thunderstorm probabilities are below 10 percent.

…Coastal WA/northern OR…
An offshore shortwave trough near 48 N and 132 W will move inland
near the WA/BC border area by evening. Cooling mid-level
temperatures and steepening lapse rates in the post-frontal
environment should be sufficient for scant buoyancy near the coast,
and an associated threat for isolated lightning flashes after 03Z.


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