Enhanced Risk: 5/4/22

For the next six weeks, my attention is fully dedicated to severe weather and storm chasing.

Yesterday, the SPC showed no tornado reports. The storms that formed were largely wind events. From the tracks of the reports, it looks like a few embedded cells were responsible for the high winds.

The Storm Prediction Center (SPC) has issued an Enhanced Risk for the Ohio Valley today.

Associated with the Enhanced Risk is a 10% hatched tornado threat ring. This includes the dreaded “SigSevere” category.

To summarize the SPC:  The models are not in agreement with how far the warm front will advance. As such, there is a chance that storm coverage and severity will be higher than predicted, depending on the placement of the warm front. Dryline supercells with large hail and tornadoes are predicted. Later this evening, the supercells will morph into a Mesoscale Convective System (MCS).

The visible satellite imagery shows cloudy skies and some morning convection east of the threat area. I also like the linear feature near the Mississippi River, even though it isn’t part of today’s severe weather forecast.

The surface observations show cloudy conditions over the threat area. The surface winds are largely southeasterly, advecting Gulf of Mexico moisture northwest into Oklahoma.

The frontal boundaries are very hard to see on this chart. The dryline (black line) is over eastern New Mexico and that was easy to find. The warm front is much more subtle; I checked a few other sources until I could barely make out the boundary. The wind shift is every so slight, but there is a small temperature step between stations.

The surface pressure chart shows an elongated surface low over eastern New Mexico. The RAP shows this low will tighten and move northeast over the next six hours.

The 12Z Norman, OK, sounding shows that there is some Convective Available Potential Energy (CAPE) aloft. Currently, surface CAPE is low (1 J/kg), and the lapse rate is low (2.8 C/km) but both of those will improve with diurnal heating. The low-level shear is abundant (35 kts) and the deep-layer shear is at the threshold to support supercells (40 kts).

The Nested NAM simulated reflectivity shows showers and thunderstorms all morning. I kept looking for the radar image with the most discrete cells, but it never really materialized. The storm modes look to be clusters, ending with a squall line this evening.

High temperatures will rise into the lower 60s F, which isn’t very impressive. The temperature forecast chart shows the warm front as lingering near the Red River, never really reaching into the threat area.

The Nested NAM shows a plume of deep moisture halted by the stalling warm front, keeping dewpoints in the mid 50s F for Oklahoma City.

The Nested NAM CAPE/CINH plot is showing CAPE is peaking at around 4200 J/kg in the southern Texas panhandle, it never really reaches Oklahoma.

The Nested NAM shows that the supercell parameter will be highest in southern Oklahoma later in the afternoon (22 Z or so).

The Nested NAM shows that the SigTor parameter will also peak in very southern Oklahoma.

If I were targeting and chasing today, I would target somewhere in North Texas.

1.  Wichita Falls, TX
2.  Burkburnett, TX
3.  Waurika, OK

Meteorologically speaking, there is major variance between models. The NAM has high temperatures in Oklahoma City in the upper 50s and the HRRR has temperatures reaching the mid 70s. This is due in part their predictions of the warm front, and maybe also how much diurnal heating affects the area. With the surface temperature at 53 F, a sunny day would boost the temperatures in to the mid 70s, but it will remain cloudy over the area for most of the day. If the warm front moves north, the moisture will be right behind it, so the 50s dewpoints will quickly moisten.

I targeted northern Texas, as I think diurnal heating will not be as important as the location of the warm front. I tend to agree with the NAM’s solution, where the warm front stalls, just based on the fluid motion of the model as compared to the HRRR’s motion. Wichita Falls has a good road network, including nearby Red River crossings should the front surge a few miles farther north into Oklahoma.

Overall, it wouldn’t surprise me to see the threat shifted south from the SPC’s prediction during their mid-morning update. Plenty of people “bull’s eye” hunt and just go to the SPC threat area- some days it works out great. Today is going to be about finding the subtleties, even if it means chasing a lower SPC threat area.

Storm Prediction Center
College of Dupage – SATRAD

About highplainschasing

This blog is about my tales in storm chasing. My name is Seth Price and I am an instrumentation instructor at New Mexico Tech. My amateur radio call sign is N3MRA.
This entry was posted in Practicing Concepts, Predictions, Satellite Imagery, Severe Weather and tagged , , , , , , , . Bookmark the permalink.

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