Severe Weather Likely for Oklahoma City the Next 2 Days

Looks like the sprinkles we saw earlier this afternoon might be the start of something bigger. The moisture is fast increasing, which means rain & storms. With the forcing of a front plus the dryline in the area, it equals severe weather. Here is the latest on what the Storm Prediction Center is saying for tomorrow on severe weather.

Day 2 convective outlook
National Weather Service Storm Prediction Center Norman OK
1211 PM CDT Thursday Apr 21 2011

Valid 221200z – 231200z

..there is a slight risk of severe thunderstorms from northwestern Texas/OK into the Ohio Valley…

..srn plains to Ohio Valley…

Strong shortwave trough and associated middle level speed maximum will eject across the central rockies/plains into the upper Great Lakes region Friday. This large scale flow regime will undoubtedly enhance low level warm advection/moistening beneath an intensifying and northeastward evolving low level jet as it shifts from eastern Kansas/OK early in the
period into Illinois/ind by 23/00z. This feature will force a substantial amount of elevated convection along/north of retreating warm front the entire forecast cycle…initially along/north of the I-70 corridor before height falls aloft induce large scale ascent to overspread the Great Lakes/upper Ohio Valley.

Given the very steep lapse rates that remain in place west of the MS river…any elevated storms that develop atop cooler airmass would pose at least a threat for large hail. Of more concern will be the possibility for surface based convective development along/ahead of the cold front across MO into IL/ind. Substantial moistening/destabilizing is expected across this region by 18z and latest indications are that modest instability will be in place by middle afternoon for robust thunderstorm development across MO within a strongly sheared environment for supercells…including the possibility for a few tornadoes…very large hail and damaging winds. This activity should spread downstream into the lower Ohio Valley into a recovering airmass in the wake of northward shifting warm front.

Farther SW…surface front will ease southward across northern OK to a position along I-44 from NE-SW across OK by 23/00z. Although large scale forcing will prove negligible across the Southern Plains…intense boundary layer heating west of the dryline will likely remove the cap by 21-22z. Deep layer shear is expected to be on the order of 45kt near the dryline/cold front intersection where SBCAPE values should be at or above 3500 j/kg. Latest thinking is scattered supercells will develop along the front/dryline within an environment conducive for very large hail and possibly even an isolated tornado. This activity is expected to propagate eastward across the remainder of OK into late evening as the low level jet increases and veers toward northern Arkansas. Southward extent of afternoon storms into northwestern Texas is possible…but with weak shear/convergence this activity will remain isolated.


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