This paragraph from the Storm Prediction Center this morning highlights what I’ve been saying the past few days:
SPECIFICS ARE STILL RATHER NEBULOUS. FORECAST CERTAINTY AND CLARITY OFTEN INCREASE AS EVENTS GET CLOSER -- BUT NOT ALWAYS. SOMETIMES MESOSCALE AND SMALLER-SCALE ISSUES WITH TIMING AND MODE...THAT ARE NOT APPARENT IN FAVORABLE-LOOKING PATTERNS OF SYNOPTIC MODELS 3-5 DAYS OUT...CAN COMPLICATE FORECAST SCENARIOS AND CAN MAINTAIN IMPORTANT LEVELS OF UNCERTAINTY. THAT IS TRUE IN THIS OUTLOOK. NEVERTHELESS...POTENTIAL REMAINS FOR VERY LARGE/DAMAGING HAIL...SEVERE GUSTS...AND TORNADOES FROM SRN NEB TO NRN AND PERHAPS CENTRAL TX THIS AFTN/EVENING.
This paragraph from the National Weather Service this morning highlights that long-lived violent tornadoes aren’t the big focus:
SECOND QUESTION IS TORNADO POTENTIAL. LOW-LEVEL AND DEEP-LAYER SHEAR CERTAINLY SUPPORT TORNADOES TODAY. BUT AGAIN LOOKING AT THE DETAILS... MOST FORECAST HODOGRAPHS SHOW A VEEING/BACKING/ VEERING PROFILE WITH HEIGHT WHICH IS NOT NECESSARILY CONDUCIVE TO LONG-LIVED TORNADIC STORMS
Computer models haven’t been much help up to this point, with a myriad of different solutions to choose from. What the SPC, NWS, and I do know, is that the overall pattern supports severe weather over a large geographical area. Earlier I said the devil is in the details on exact timing and location of not only storm formation, but also tornadoes. Typically those are revealed the day of. In this case, that still may hold true, as the latest models are finally coming around. The hi-res HRRR model has dug its heals for storm formation in W OK around 3pm. This means a late arrival into the OKC metro, around 7pm or so. Keep in mind other models develop them sooner and closer to the metro, so at this point anytime after 4pm is fair game, but I’m leading with the HRRR.
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Speaking of, here are some model images showing that the highest tornado threat with the best directional shear is actually in W OK early on (circled in red). The shear over C OK is mostly linear, one direction, as indicated by the forecast sounding for 7pm as the storms approach. This is good if you don’t want tornadoes. Tornadoes have a hard time developing with a linear shear profile, a very hard time.
Best shear according to the model in W OK early to mid afternoon.
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More of a linear shear profile (all southerly) with height in OKC at 7pm.
So the trend is to keep this mostly linear profile going into the evening which will allow these supercell clusters to merge into a squall line once they get to and east of I-35. Wind and hail the primary hazards, but a few tornadoes will likely still occur.
Supercell storms develop around 3pm in W OK along dryline. Image shown is for 5pm.
Squall line evolution beginning to take shape as storms approach I-35 at 8pm.
I’ll be standing by ready to stream live severe storm coverage later today. You can also watch live storm chasing from Oklahoma Storm Chasers through my live stream page. -AT
