Good morning bloggers,
An Arctic Blast Watch continues to be in effect for the next two weeks! Kansas City is about to be thrust into around a two week stretch of true winter weather. The weather will be quite mild today, and it is a good day to begin planning for a series of Arctic Blasts. The first blast of cold air will arrive Thursday, and it may come with some snow. Let's take a look.
Upper Level Flow Valid Thursday Morning:
These first two maps show the flow aloft at around 18,000 feet up. This is the 500 mb level, which is half way up in the atmosphere in weight. The top of the atmosphere has no weight, and at the surface the average sea level pressure is 1013.25 mb. So, the 500 mb level is right down the middle, and a great level to find storm systems that will affect the surface weather. This map shows a trough that is slightly positively tilted. Look at what happens just 9 hours later on Thursday afternoon, below:
The trough is becoming negatively tilted as it approaches KC. It is really isn't negatively tilted yet, but as it passes over the KS/MO state line Thursday evening it will have a negative tilt, from northwest to southeast, and this is an intensifying storm. The maximum vorticity is shown in that red area with the X. This is called a "vort max". This is intensifying, and conditions will be favorable for snow along and north of the track of this strong wave of energy. Quite simply, if it tracks south of us it will snow hard on Thursday. But, it is so fast moving it may be just two to three hours of snow and then out. As it passes by, a blast of cold air will be moving in with temperatures crashing into the 20s or low 30s Thursday. This is not the Arctic Blast. That is still organizing.
Thursday's Fast Moving Storm:
By Noon tomorrow, the cold blast will have arrived with 30 mph winds or stronger. And, rain and snow is possible:
This is a very fast moving storm. There will likely be a sharp cut off line to where snow is falling and to where no snow falls. As discussed above, this storm intensifies as it passes by us, and this makes the forecast difficult. Nothing is easy in Kansas City. The latest data just came out with the front moving through around 6 AM and snow before noon, but then ending. The temperature and timing of Thursday's snow chance will be critical to whether there are any problems. I do know it will be windy!
Kansas City Weather Time-Line:
- Today: Incredibly nice, as it won't be this nice again until late February. Try to get out there and enjoy the 55 to 60 degrees. Sunny, breezy, and mild. High: 56°
- Tonight: Increasing clouds. Southeast winds 10-20 mph with temperatures staying in the 40s.
- Thursday: Cloudy, windy, and turning much colder. A blast of cold will arrive just after sunrise or earlier. Temperatures crashing into the 20s with a 60% chance of rain changing to snow. Some sleet is possible. The window opens up for this precipitation mix between 8 AM and noon and then ends. The wind may gust to 50 mph.
- Friday: Partly cloudy and warming up a bit to near 40°
- Saturday: A 60% chance of snow developing and/or moving in from the northwest. Accumulations are possible, and right now I am thinking in the dusting to 2" range. We will be able to firm this forecast up by tonight.
I talked about the average sea level pressure being 1013.25 mb (milibars). Well, that is equivalent to 29.92 inches of mercury. Very rarely does the pressure go above 31" of mercury. Well, look at the Arctic High Pressure area that has formed north of Alaska. The pressure is up to a very high level of 1056 mb, or 31.18". A large and expansive Arctic air mass is building in response to blocking (see yesterday's blog). The conditions are now highly favorable for the Arctic air to be unleashed onto the United States.
Saturday's Snow Chance:
This is one of the forecast models showing the snow chance on Saturday. This shows it moving in around noon. Yesterday, the models had barely a few flurries, and now most of the models are showcasing a small snowstorm with a dusting to up to 4" on some models. As I just stated, I am going with a dusting to 2".
Snow Forecast Next 10 Days:
When you look at these maps there are two big takeaways: 1) Kansas City has had one 6" of snow so far this winter and the models have predicted 20" of snow in our area, so these models are to be taken more seriously when we are within a day of a storm. 2) There is a big gradient across Kansas with not much snow southwest to a lot northeast and there are solid reasons for this. Where will that southwest edge be located. Okay, here are the European and American models that came out last night:
The European Models shows 4 to 6 inches of snow in these next ten days and the American Model shows 6 to 10 inches of snow. The first chance is Thursday and the second chance is Saturday. As I showed in yesterday's blog, the chances are increasing.
The bottom line: We have time to prepare for this sudden change to pure winter. It will likely last for around two weeks, and by the time the Arctic air retreats, it will be getting close to March and spring will be on the way.
Thank you for spending a few minutes of your day reading the Action Weather Blog featuring the LRC. Enjoy today's nice weather as some major changes are just a day away. Have a great Wednesday. Watch 41 Action News, & we'll keep you advised.
Gary
