High wind event in progress. 69 mph peak wind gust at 10am CDT in Dodge City. I have already had to clean up torn off shingles off my roof as well as one of the downspouts to my gutter that came off. The sun is beginning to make an appearance and as a result, deeper mixing will ensue resulting in likely more aggressive gusts, and perhaps more frequent gusts exceeding 55 knots. The RUC Wind Gust field has done a fairly good job in its prediction of the magnitude of wind gusts. Below is a 9 hour forecast of Surface Wind Gust valid 15z (10am) with the verifying observations overlayed:
Frequent wind gusts are expected to remain in the 50 to 55 knot range…and perhaps a few gusts approaching 60 knots…through 22z (5pm CDT), as is shown by the 14z run of the RUC model:
Winds already getting underway over northwest Kansas and eastern Colorado. Observations at 7pm CDT indicated 40 to 45 knot wind gusts at Springfield and La Junta, CO as well as Goodland, KS. The image below shows the RUC 2-hour forecast for wind gust valid 00z (7pm) with 7pm observations of wind barb and gusts (red values, knots) overlayed:
The image below is the 18-hr forecast from the April 14th 22z run of the RUC valid 16z April 15th…showing 54-58 knot gusts (62-67 mph) all across Southwest Kansas by this time with a very deep 825mb low to the east:
It’s always windy in Dodge, but… What we have coming our way on Friday, April 15th will likely be a wind event the likes of which we haven’t seen in several years around Southwest Kansas. To complicate matters — it has been so dry so far this year, and if we don’t get anything more than sprinkles with this storm later on today and this evening, then there will likely be a substantial amount of blowing dust. I wouldn’t be blogging about this storm if there wasn’t some component of it that is fascinating to me and impacting western Kansas to some degree. A major cyclogenesis event will be occurring today over Kansas. As of the time of this writing, the surface low was located southeast of Dodge City, which will deepen substantially as it tracks northeast through central Kansas today.
Strong northwest winds will develop behind the low by early this evening which will strengthen substantially as the low wraps up tonight. The 12z RUC model valid 18 hours out at midnight tonight is already showing 60 mph gust potential developing along the Colorado-Kansas border to the west of the mature cyclone:
The strongest winds will begin impacting Dodge City after midnight tonight. The wind fields in all the models are extremely impressive with wind magnitudes about as high as I’ve seen for Southwest Kansas behind a mid latitude cyclone like this. The NAM has been persistent in showing 65 to 75 knots in the 800-700mb layer from 12z to 21z Friday. The ECMWF model has also shown a very similar signal in the strength of winds. NAM Boundary Layer (BL, 0-15mb AGL mixed depth) winds are expected to be around 45 knots sustained during the day on Friday. This is as high as I’ve ever seen BL winds for Southwest Kansas behind a low with deep vertical mixing. These are all strong signals of a prolonged, significant wind event last a good 12 to perhaps 18 hours! Below is the time sequence of this morning’s NAM model showing the development of high winds in the 0-15mb AGL mixed layer:
Lastly, here is a text output from the NAM12 model for Dodge City. Highlighted in red is the mixed layer. Typically, the mean wind in the lower third of the mixed layer in the NAM model translates well to surface sustained winds on the high plains. Peak wind gusts at the surface are typically the wind speed at the top of the mixed layer that have mixed all the way down to the surface due to both the mechanical mixing (by the wind) and the more traditional mixing due to insolation. The NAM model would suggest a prolong period of gusts in excess of 60 mph during the day tomorrow, withe a potential peak gust of 68 mph during the early to mid afternoon hours when the mixing height increased to about 775 mb:
Sleet showers continued through the night. Warm advection centered around 850mb prevailed through the night, keeping the warm layer aloft in-check, and keeping the precipitation type sleet all through the night (after it had changed back over from the first snow band late last evening). As of the pre-dawn hours this morning, the highest snowfall totals were 3 to 4 inches from Syracuse to Scott City (see Figure 1 below). The initial potential vorticity (PV) max (‘x’ #1 in Figure 2) was lifting out into central Kansas as of 1100 UTC (5:00am CST), yielding subsidence now across southwest Kansas, including Dodge City (outside of a few widely scattered sleet showers along and south of the Arkansas River). The next mid level PV anomaly, anotated ‘x’ #2 i Figure 2, will move south of southwest Kansas later on today, providing another shot at light accumulating precipitation, which will most likely be in the form of snow with cold advection finally prevailing at around 850mb eroding the warm layer aloft.
Major FAIL?!?! Wow. Leave it to me to start blogging about a potential winter storm to bring the possible failure modes of this system to light. This is not looking good AT ALL. That first band of precipitation did produce 0.4″ of snow at my place, but has since ended as of about 10:45pm. The figure below explains the major failure mode with this system for Dodge City. I still think a few inches of snow are possible, but significant accumulations appear unlikely, and if it does occur, precipitation will need to reform again to the southwest of Dodge City.
Figure 1 (Illustrating/discussion potential major failure mode for a significant precip event for Dodge City):
Figure 2 (08/00z run of the GFS valid hours 6, 12, and 18):
NOTE: As I publish this post, precipitation is trying to form southwest of Dodge City back to the northwest of the major area highlighted in red in Figure 1. All is not lost…yet! Precipitation forecasting on the western plains is very sensitive to the little sub-synoptic scale nuances thanks to the “Rock Pile” just west of us.
Sleet has commenced at my house, 5 N Dodge City. The initial band of precipitation (see Figure 1) began to move in around 8:30pm. It has been pretty much all sleet up to this point through the time of this writing around 9:30pm. It’ll be interesting to see how long the precipitation type will be sleet. There is a disagreement with respect to the warmth of the warm layer aloft over Dodge between the RUC and the NAM. The RUC is about 1 to 1.5 degrees C warmer and keeps the zero line at 850mb quite a ways northwest of Dodge, whereas the NAM keeps the zero line quasi-steady right over Dodge (see Figure 2).
Significant, much needed precipitation event headed for southwest Kansas! For the better part of the last week or so, it appeared a major winter storm would affect the western Plains. Mid to late last week, all of the global spectral model solutions (and to a large degree their associated ensemble members) were focusing on western/central Nebraska…into southern South Dakota for this storm. By Friday and Saturday (March 4-5), the models were beginning to suggest a more southern track to the storm. It then became apparent that northwest Kansas into south-central South Dakota would see the brunt of the storm. Now that the storm is now within striking distance, all models are locked in on a solution with the mid level PV anomaly and evolution, and it really does favor Southwest Kansas for substantial precipitation. While the placement in the models was always in question, what was a near-constant was precipitation potential with the storm. 36-hr storm total precipitation from the GFS as well as the Canadian GEM consistently showed potential for 1.0 to 1.5″ of storm total precipitation within the “sweet spot”. Late last night and early this morning’s model runs showed this 1.0 to 1.5″ storm total QPF shifting south to generally a Lakin-Dighton-Wakeeney line… continuing northeast to north-central Kansas and southeast Nebraska. 18z runs of both the GFS and the NAM have continued this southward shift of the 1.0 to 1.5″ axis even further… to roughly a Ulysses to Garden City to Jetmore corridor. Both the 07/18z NAM and the GFS show 1.0″+ storm total QPF for Dodge City. It stands to reason now that Dodge City will be included, if not VERY close, to the sweet spot of the storm.
Now precipitation type. Today, a shallow arctic cold wedge was moving south and was more aggressive in its movement south than any of the models from last night were suggesting. This isn’t a surprise (early last week’s arctic cold wedge event in southwest Kansas is a classic example). As I type, the temperature in Dodge City 33 degrees (See Figure 1), and advection on north winds 15-20 mph will continue to lower the temperature through the evening into the upper 20s.
Precipitation in Dodge City will likely commence as some light freezing drizzle later on this evening with more widespread precipitation in the form of freezing rain/sleet sometime around midnight or thereafter. Huge questions regarding how shallow the cold wedge will be in Dodge City and whether it will be deep enough for the warm layer aloft to be pinched off enough to support all snow (entire sounding below zero Celsius). I think we will see several hours of accumulating sleet overnight with a change over to snow probably 4-7am or so tomorrow morning. I took a look at the 12-hour QPF from the 18z run of the GFS ending 09/00z and it showed about a half inch of QPF during this time frame… this would suggest as much as 4-6″ snowfall after the sleet/freezing rain. Below are some figures I put together
Figure set 2 (18z NAM model depiction of 700mb RH/Omega, 850mb Temperature):
Figure set 3 (18z NAM model depiction of 400mb Potential Vorticity/Wind Speed, 500mb Heights):
7.8″ total snowfall (10:30pm) at my house 5 N Dodge City. As of the time of this blog post, at around 11:40pm CST, light snow continued, but it was beginning to wind down (see radar figure below). We have been getting roughly 2 to 5 tenths of an inch of snow, per radar analysis, since the last time I measured the snow. I went out and measured again, but compaction has set in from the prolonged strong northeast winds, so simply measuring snow depths doesn’t really mean the same thing as “snowfall”. At 6:25pm, I called it 6.3″, so another 1.5″ in that four hour time span is reasonable. It’s going to be fun photographing these drifts in the morning! In the meantime, I have attached some nighttime images of some of the drifting between my house and the neighbor’s house on my south side. The northeast winds caused fairly substantial drifting in through there.