** Severe weather tonight across northwest Oklahoma **
** Early round of storms possible in central OK, then severe in eastern OK Thursday **
Models not in good agreement this morning. GFS and NAM disagree on frontal timing. I used HPC guidance which correlates well fairly well with GFS and previous forecast. NAM has proved to be an unreliable model in the weather patterns as of late. CAPE around 1200 j/kg and lifted index around -4 expected to be in place around sunset across northwest Oklahoma. A sagging lee slipper cold front will nudge into the area near Buffalo by sunset with a trailing dry line back into the eastern Texas panhandle. An upper level storm should effectively remove the cap by sunset. However, models do not show any development along the dry line and keep it all with the cold front. Thunderstorms may move across the northern two rows of counties overnight but the majority of the activity should stay in Kansas. Helicity is significant after sunset, but directional sheer is such that storms may rotate but I have some doubts of tornadic weather.
4 KM WRF indicates there may be an outflow boundary somewhere along a line from roughly Altus - Clinton - Enid around sunrise and thunderstorms may redevelop along this outflow boundary around sunrise Thursday after most storms have moved into Kansas. MOS temperature profiles would support this theory as the spread between the low and the high in many areas tomorrow is quite small. New 12Z WRF keeps it quiet though. HPC and models suggest actual front may not arrive until around 7 pm in OKC. Storm line may effectively shift the actual front eastward however. If the 12Z run is correct, storms may fire across south-central OK along the front Thursday. The low connecting the dry line and cold front is forecast to move east-northeast from west-central or southwest OK to northeast of OKC during the day. There could be wrap-around storms forming behind the low across northern Oklahoma behind the front. These storms would of course be elevated with a possible risk of hail, despite being outside the slight risk area tomorrow.
System clears out for Friday with lots of sun. Winds should start off out of the northwest then shift southwest as the day goes along. This should prevent temperatures on Friday from being significantly cool. I am going upper 60s in OKC right now, slightly above MOS guidance.
On Saturday, a warm front lifts up from the red river during the afternoon. Saturday morning should start off cool but a rapid warm-up is expected to near 80 during the afternoon as the warm front lifts into northern Oklahoma. Right now I do not see any reason to think the front will not make it that far north. However, with previous fronts this year the front did not make it as far north as model projections. So far GFS has been consistent so I will keep the front near the Kansas border during the afternoon.
As mentioned yesterday, it is nearly impossible to time out the shortwaves associated with the next system. A large upper level storm will sit across the northern Rockies and periodically send out shortwaves. There is some variance run to run on timing so it is best to shotgun 20% pops every day east of the dry line, with higher pops Tuesday and Wednesday when there is more model consistency.
The low level jet kicks in Sunday morning. On Sunday the dry line looks to set up near US highway 183 and deep moisture should be in place. GFS shows CAPE of 1000 j/kg and lifted index around -4. There may be a weak shortwave around 1 p.m. but it's hard to tell. Dry line looks to be between US highway 83 and US highway 183 on Monday. GFS shows CAPE of 2000 j/kg during the afternoon and another weak wave passing around 1 p.m. We'll probably be mostly cloudy. GFS shows a shortwave passing to our north and it is questionable if it will cause enough mid-level cooling to break the cap. Low level jet looks weak so I am questioning stratus coverage during the morning, and that would effectively increase mixing.
According to 0Z GFS, a weak low level jet will be in place Tuesday morning. Plenty of stratus should overspread the area. CAPE should climb up to 2000 j/kg during the afternoon. GFS indicates there may be yet another weak wave pass around 1 p.m. I have the highest pops this day as the GFS has consistently developed precip this day the past several days of runs. 0Z GFS pulls the front through by 10 a.m. on Wednesday, effectively ending the show with storms in the morning.
6Z GFS has a totally different story. 6Z GFS pulls the front through early Tuesday effectively making Monday the last severe threat day. However, it brings the front back as a warm front on Wednesday with more storms. Therefore, this leaves credence to high pops remaining on Wednesday.
12Z GFS has the front coming through Tuesday evening with some overrunning. It does stall it across the area on Monday. We'll have to see what happens as models continue to resolve this time period. The 12Z is about 12 hours faster than the 0Z run.
Beyond the 7 day I have used the 0Z GFS as guidance through the following week.
OKC 76 57/62 42/67 44/78 57/80 60/82 65/83 58/70 45/62 40/68 49/73 55/70
Windy Wednesday, Breezy Thursday and Saturday, Windy Sunday, Breezy Monday and Tuesday, the following Friday and Windy the following Saturday.
Pops: Thursday 70%, Sunday 20%, Monday 20%, Tuesday 40%, Wednesday 40%, Thursday 10%, the following Sunday 20%.
State forecast and 7 day at www.okcfox.com
Greg
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