Royce Sheibal
EF3
THE BIG DAY! Prepare for a wall of text!
I know you're all excited. Friday will likely be an appetizer for what will probably be the best day of the year on Saturday. Multiple targets, good cape, good bulk shear, questionable hodographs? Let's talk models.
SPC's ensemble just came out for Saturday. My personal favorite probability they run is 1000 cape + 40 kts bulk shear + precip. 70% by 21z N KS and 50% from S OK to the SD border. These are good #'s. SPC's 30% on 4 day is going to be a Moderate tomorrow, most likely. Depending on morning convection, it could be more than just a moderate day. Keep an eye on ML LCL's, which are forecast to be below 750m! for the entire zone. Low bases mean more helicity from surface based flow and outflow interactions. We could see some really high 0-1km SRH in localized areas, even if forecasted hodo's aren't impressive. Also: HP's..Be Advised...
12Z NAM is not a fan of the central plains for Sat. Sig tor values are peaked in SW IA and OK, but most of KS and NE is covered with ongoing precip and cloud debris, as well as significant drying at the lower levels behind the MCS's. The models appear to be mixing in a lot of dry southwestern air behind the MCS's, despite hitting 70 Td in Nebraska on Friday. NAM is forecasting a full fledged outbreak on Friday in Nebraska as well, so it will be interesting to see how things pan out overnight. NAM 4km is not at Saturday yet, but it's been my baby the last 2 years, so we'll see what she says tomorrow.
12Z GFS has been predicting ongoing precip in the central plains region as well, which will continue to complicate things. The GFS has, however, shown areas of increased helicity in central KS along the dry line as well as another possible target out in IA/MO or even up north into Minnesota, for you easterners out along the warm front there is also some solid vorticity. Another possible target is down to the south in Wichita Falls where cape is bigger, but cap becomes more of a question. 850's are screaming outta the south everywhere.
So what does this all mean? Well, we are still 4 days out, and forecasts may diverge greatly, but the general placement of the front, moisture, and shear are all lining up pretty well. Hodograph's aren't great, and I'm seeing a lot of veer/back/veer shenanigans. But any area that can get some sun between the AM precip is going to be juicy.
Consider the following, and please do comment:
Super far north target: Central MN into W IA: 1500 cape, shear along the WF, and likely ahead of the AM precip
Middle of the road target: SC Neb: Cape may rebound in the dry slot behind morning precip, shear is good near the dryline as the low gets a little negative tilt, also NUTS DPVA.
South Target: Wichita, KS into NW OK: Better Cape, OK Shear, early convection is an issue
Super south target: Wichita Falls, TX: Best Cape, OK Shear, Strong cap may work to your advantage to keep convection down until it breaks after 21z. Meanwhile bases are still forecast to stay low enough for tors.
I know you're all excited. Friday will likely be an appetizer for what will probably be the best day of the year on Saturday. Multiple targets, good cape, good bulk shear, questionable hodographs? Let's talk models.
SPC's ensemble just came out for Saturday. My personal favorite probability they run is 1000 cape + 40 kts bulk shear + precip. 70% by 21z N KS and 50% from S OK to the SD border. These are good #'s. SPC's 30% on 4 day is going to be a Moderate tomorrow, most likely. Depending on morning convection, it could be more than just a moderate day. Keep an eye on ML LCL's, which are forecast to be below 750m! for the entire zone. Low bases mean more helicity from surface based flow and outflow interactions. We could see some really high 0-1km SRH in localized areas, even if forecasted hodo's aren't impressive. Also: HP's..Be Advised...
12Z NAM is not a fan of the central plains for Sat. Sig tor values are peaked in SW IA and OK, but most of KS and NE is covered with ongoing precip and cloud debris, as well as significant drying at the lower levels behind the MCS's. The models appear to be mixing in a lot of dry southwestern air behind the MCS's, despite hitting 70 Td in Nebraska on Friday. NAM is forecasting a full fledged outbreak on Friday in Nebraska as well, so it will be interesting to see how things pan out overnight. NAM 4km is not at Saturday yet, but it's been my baby the last 2 years, so we'll see what she says tomorrow.
12Z GFS has been predicting ongoing precip in the central plains region as well, which will continue to complicate things. The GFS has, however, shown areas of increased helicity in central KS along the dry line as well as another possible target out in IA/MO or even up north into Minnesota, for you easterners out along the warm front there is also some solid vorticity. Another possible target is down to the south in Wichita Falls where cape is bigger, but cap becomes more of a question. 850's are screaming outta the south everywhere.
So what does this all mean? Well, we are still 4 days out, and forecasts may diverge greatly, but the general placement of the front, moisture, and shear are all lining up pretty well. Hodograph's aren't great, and I'm seeing a lot of veer/back/veer shenanigans. But any area that can get some sun between the AM precip is going to be juicy.
Consider the following, and please do comment:
Super far north target: Central MN into W IA: 1500 cape, shear along the WF, and likely ahead of the AM precip
Middle of the road target: SC Neb: Cape may rebound in the dry slot behind morning precip, shear is good near the dryline as the low gets a little negative tilt, also NUTS DPVA.
South Target: Wichita, KS into NW OK: Better Cape, OK Shear, early convection is an issue
Super south target: Wichita Falls, TX: Best Cape, OK Shear, Strong cap may work to your advantage to keep convection down until it breaks after 21z. Meanwhile bases are still forecast to stay low enough for tors.