New Post has been published on KSStorm.Info
New Post has been published on http://j.mp/1wU61gN
I’m going to start with the bottom line: while we will have a severe weather event tomorrow, and possibly some severe storms today, I’d certainly stop short of calling this an outbreak scenario. I’m seeing hail of 2″ or smaller and wind of 70 miles an hour or so as the primary risk. For unharvested farm fields that’s a pretty big deal. But I’m not seeing a life threat from these storms.
Here is the SPC Day2 probability graphic from this morning, effective 7am Wednesday to 7am Thursday.
First thing you’ll notice in comparing it to yesterday’s Day3 outlook for the same time period is the size and shape haven’t changed much. That’s an indication the models forecasters are using are in pretty good agreement on the large-scale details of tomorrow’s event. Much of Kansas east of a Hays to Greensburg line has a 15% probability of any severe weather report within 25 miles of a point.
There are two major challenges with tomorrow’s forecast. #1, as highlighted by SPC:
LEE SFC CYCLONE SHOULD DEVELOP OVER SWRN KS AND MOVE LITTLE THROUGH THE PERIOD
The emphasis is mine. A low-pressure area typically forms in southeast Colorado in response to systems clearing the Rockies. Once it does, the area typically moves east or northeast. The lack of movement on tomorrow’s system may steal an important ingredient from the afternoon and evening storms: a push from the west.
Challenge 2, Clearing and moisture return. We’re seeing the same challenges we ses in the early spring storms — will whatever happens tonight clear out of Central Kansas early enough tomorrow for several hours of sunshine, and will the moisture flow return from the southeast? The models are inconclusive at best on this particular detail.
Here’s what SPC says can happen IF things clear early enough and moisture returns in time:
IF DEW POINTS RISE INTO THE MID-UPPER 60S AS DEPICTED BY LATEST NAM THEN SUBSTANTIAL SBCAPE WILL EXIST ACROSS THIS REGION BY 21Z. ISOLATED SUPERCELLS SHOULD EVOLVE THEN SPREAD/DEVELOP EAST AND NORTH INTO SERN NEB. EARLY IN THE CONVECTIVE MODE DISCRETE SUPERCELLS ARE POSSIBLE WITH THUNDERSTORM CLUSTERS LIKELY EVOLVING DURING THE OVERNIGHT HOURS ALONG NOSE OF LLJ OVER THE MID MO VALLEY. LARGE HAIL…A FEW DAMAGING WIND GUSTS AND PERHAPS A FEW TORNADOES CAN BE EXPECTED.
Note that one model is saying the conditions will be right. However, that same model is showing some of the things I watch when trying to analyze tornado risk being out of sync with one another. Compare these images:
Comparison of NAM forecasts for Helicity and CAPE/CIN as of 7pm CDT Oct. 1
The helicity bullseye (left) is centered on Lawrence. However, the nice white bullseye of highest CAPE and no CIN is from Salina to north of Hays to about Marysville. To simplify: the location of best twist is displaced from the location where available energy is high/resistance to storms firing is low by about 100 miles. It’s kind of like trying to heat a pot of water that’s sitting on the back burner by turning on the front burner…or the stove.
Here is the same model’s simulated radar for 7pm tomorrow. While you can’t take the locations of the predicted rain as gospel, notice it has Kansas almost completely dry!
Simulated Radar, 7pm Wednesday.
For comparison, here is a simulated radar image from the GFS model for the same time:
GFS Simulated Radar, 7pm CDT Oct 1
Note the darkest green in a tiny area just northwest of Wichita? Based on some other parameters in the GFS forecast, if I were chasing tomorrow I think it would almost literally be a backyard chase. If this model plays out I’d expect some large hail in northwest Sedgwick and Harvey counties around this time of the evening.
I’ll end with the notes I used to do my radio forecasts today:
The developing low in eastern Colorado may provide the first energy to get some thundershowers going in west central Kansas tomorrow afternoon. Then look for a larger area of thundershowers to develop in central and south central Kansas, spreading into northern parts of the state during the evening. Some of these storms are expected to be severe, and while they remain discrete early in their life they could produce large hail, high wind and maybe a brief tornado. They’ll evolve into a storm cluster during the evening, it appears. By midnight, they’ll be ending from the northwest to the southeast as a strong cold front sweeps in. That front will push the storms into eastern Kansas by Thursday afternoon.
Finally, a note about today. I think Dodge City said it best in their discussion this morning (slightly edited):
A SURFACE TROUGH AXIS WILL EXTEND FROM ROUGHLY HAYS TO MEADE. EAST OF THIS LINE, CONDITIONS WILL BE SUPPORTIVE OF A FEW STRONG TO SEVERE THUNDERSTORMS…IF THEY DEVELOP. MAIN HAZARD IS WIND GUSTS UP TO 60 MPH AND HAIL UP TO THE SIZE OF QUARTERS.
Have a great day and feel free to share this with your friends!
