Friday, February 26, 2016

March 1, 2016 Oklahoma Severe Weather Discussion

This is a severe weather discussion for March 1, 2016 for Oklahoma.

Models Used: 2/26 00z GFS

Energy currently located out over the North Pacific, west of Alaska, will ride in on strong Pacific jet stream (over 190 knots as of 06z 2/26) into the Gulf of Alaska by 12z 2/28. Storm system will then drop to the southeast on lee side of a ridge just offshore of the West Coast of North America by 2/29. Slight interaction with energy immediately north of Montana/Canada border will aid to wrap system to a negative tilt by the day of the event. Vorticity max will be located over western Kansas by morning of 3/01 as system pushes east and severe weather event commences.

Similar to severe weather event on 2/23 and 2/24, a negatively-tilted trough will move into Central/Southern Plains on the morning of 3/01. Mid-level jet streak in excess of 110 knots will wrap around base and lee side of trough in the morning of March 1, providing anomalously supportive dynamics for a severe weather event. Unimpressive jet streak at 250-millibar level (90 knots) should be negated by the aforementioned mid-level dynamics. Lower-level wind fields also impressive, with nocturnal lower-level jet streak at 700-millibars nosing into southern Kansas by 09z 3/01 AOA 80 knots. 925-millibar wind field generally broad-brush 40 to 50 knots across Oklahoma out of the south, with temperatures up to +20ยบ C in this warm sector. Surface temperatures in excess of 60 degrees F being advected northward by sub-990 millibar surface low centered in northwest Kansas combines for southerly surface winds AOA 25 knots.

Severe weather set-up not enticing from current model guidance, despite anomalous mid and lower level features. Primary factor looks to be the mere factor that it will be the morning when this event may occur (06z - 15z 3/01), and as such an inversion will be in place. Current guidance suggests favorable mid-upper level lapse rates but anemic lower-level lapse rates with CINH progged to exceed 200 j/kg in the morning hours, particularly in western and central Oklahoma. Forecasted soundings from KOUN indicate excessive CINH, as well as somewhat dry lower levels. Narrow corridor of uncapped instability forms in central Oklahoma by 12z 3/01, with just below 1000 j/kg MUCAPE available in the midst of CIN AOB 20 j/kg. LCLs around 700 meters, combined with 0-3km SRH exceeding 200 m2/s2 and surface-6km shear nearing 50 knots, do foretell a possible supercell threat with any storms that do manage to form amidst this rather stable environment. Wind profile generally veering on forecasted soundings, save for a slightly backed look around 700-millibars.

All in all, expect that the environment will not be conducive to anything more than scattered severe thunderstorms on the morning of March 1st. Any storms that do manage to form will have the potential to be severe, thanks to impressive lower and mid-level wind fields and sufficient helicity and shear. Current thinking is while there is a marginal tornado threat with this environment (SARS-indicated, in addition to favorable LCL and sufficient wind profile), isolated nature of storms in a more or less unfavorable instability-related environment should suppress any threat of a larger-magnitude severe weather event.