Severe Weather for Oklahoma City on Friday??

Currently, I am monitoring the latest information on the potential for a severe weathre outbreak in the southern plains on Friday. This includes OKC along and east of US-183 on Friday. The values used to predict severe weather are through the roof right now. Here is the latest Day 3 Convective Outlook from the Storm Prediction Center. This lays out the foundation for the severe weather threat.

Day 3 convective outlook
National Weather Service Storm Prediction Center Norman OK
0234 am CDT Wednesday Apr 06 2011

Valid 081200z – 091200z

..There is a slight risk of severe thunderstorms across part of the Ohio Valley…
..There is a slight risk of severe thunderstorms across part of the Southern Plains…

Models are in agreement showing height falls continuing over and west of northern Baja California as the southern extent of a deep western U.S. Trough develops south-southeastward on Friday from along and off the California coast to the lower Colorado valley and northern Baja California by 12z Saturday. Downstream…a ridge will build northward across the MS valley in the wake of a midlevel shortwave trough tracking through the Ohio Valley to the Middle Atlantic States.

..OH valley…
A surface low attendant to the Midwest/Ohio Valley shortwave trough initially located over Illinois…and an east-southeastward extending warm front… will shift eastward on Friday. The surface low should reach eastern Ohio by 09/00z. Low level southwesterly flow will advect moisture into the upper Ohio/Tennessee valleys beneath an eastward extending plume of steep midlevel lapse rates with surface dewpoints in the lower 60s reaching southern Ohio/western WV by Friday afternoon. This combined with surface heating is expected to support a moderately unstable warm sector. Forcing for ascent with the transient shortwave trough is expected to allow thunderstorms to develop from west-east across the Ohio Valley with effective bulk shear of 40-45 knots resulting in organized strong to severe storms.

..srn plains…
Model uncertainty exists with the exact placement of a north-south oriented dry line across the Southern Plains to Kansas on Friday afternoon. Despite this factor…increasing southerly low level winds will allow better moisture return along and east of the dry line from eastern Texas through central/eastern OK to eastern Kansas on day 3. Models suggest a weak midlevel impulse should track northeastward reaching North Texas/OK area by peak heating and aid in the development of thunderstorms along the dry line. Effective bulk shear strengthening to 50 knots and oriented perpendicular to the dry line should support isolated supercells.

By middle-evening increasing sbcinh should result in a diminishing trend for new surface based thunderstorm development. However…a veering low level jet into the lower MO/middle MS valleys Friday night is expected to support elevated thunderstorms across these areas. Moderate elevated instability may support a few stronger storms with hail…though weakening bulk shear should limit the severe threat with eastern extent.

.Peters.. 04/06/2011


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