Joe’s Weather Blog: Flooding rain + ice + sleet + cold! (THU-11/26)

This is an archived article and the information in the article may be outdated. Please look at the time stamp on the story to see when it was last updated.

Happy Thanksgiving! It’s going to be a day filled with changeable weather, here in KC and through the Plains states. Already temperatures are dropping rapidly out to the west and that same drop will move into KC during the afternoon. For those that are interested in the Winter Weather Forecast that was issued yesterday, here is the blog that I published on Wednesday.

Forecast:

Today: Mild through the middle afternoon in KC with temperatures into the lower 60s. Scattered showers and patches of drizzle will give way to a solid area of rain that will overspread the area in the afternoon as well. The cold front will move in between 11AM-3PM or so from the NW to the SE. About the only change in the forecast seems to be a slight speed-up of the front moving into the area. Temperatures will drop from 20-25° within 1-2 hours and continue then to slowly fall into tomorrow morning. Heavy rain is expected with a few rumbles of thunder.

Tonight: Rain, heavy at times, continues. Temperatures drop to 30-35° with nasty NW winds of 15-25 MPH creating wind chills in the teens. The Plaza lighting ceremony will be awful from a weather standpoint.

Friday: There may be a period of light to moderate sleet or some freezing rain during the morning. The main concern in KC would be keeping an eye out for slick spots especially on bridges and overpasses. At this point temperatures look to hover around 32° which typically doesn’t create widespread problems with the roads during the daytime hours because the daylight hours tend to “warm the pavement” just a couple of degrees. It’s something worth paying attention too especially through noon or so.

Discussion:

If you’ve been following the weather blog for the last week…you know that everything that is going to happen has been written about extensively. In the strangest way this forecast has been a VERY easy one to do for about 5+ days. I rarely put in 100% chance of rain 5 days out…I forecasted a high of 62° today with AM lows in the upper 50s…all working out nicely from last weekend.  Everything is playing out almost exactly as I expected. It’s not been complex at all. The only issues were 1) timing the front to the exact hour if possible and 2) the rainfall amounts…everything else has played out near perfect. Fortunately it was, to me at least, one of the easiest forecasts of the year. Unfortunately, the timing is just not going to work out for the lighting ceremony.

So let’s start with the rain…here is a look at radar from Pleasant Hill, MO…this radar will update for you automatically so you can always get the latest information.

 

The more solid area pf precip out west will move eastwards today as the cold front cuts through the Plains states as the day moves along…here is the regional radar.

 

That’s a huge area of rain/freezing rain and sleet with just a little snow in NE as I type this…impressive for sure and moving eastwards.

Now the temperatures…we’re mild this morning and will stay that way in KC proper through lunch. Then after 11AM or so the cold front will start moving through the northside and migrate southwards through the Metro. Temperatures will be in the 60-65° range ahead of the front and drop to around 40-45° immediately behind the front as the winds switch (that’s when you know the front has arrived) from the south to the N/NW at 5-20 MPH. As of 9AM the front has slipped through NW MO and parts of E KS…it seems to be running slightly (1-3 hours) ahead of schedule.

sfc

I’ve highlighted by the dashed lines the 32° line and the 20° line…the solid blue line is the cold front…ahead of the front, where KC is as I type this this morning…we’re solidly in the 60s.

You can see the run-up of the temperatures by looking at the temperature trends from KCI over the past couple of days…IF you’re looking at this in the afternoon, you’ll see a dramatic drop-off. In the image below, look for the red line on the top part of the graphic…that is the temperature. Notice we were steady to rising all night long and into this morning.

 

Now the winter-type weather. Again in the KC area it’s not going to be that bad. areas farther NW of KC and west and SW of KC will have more issues than the metro over the next couple of hours. Here are the latest warnings/watches from the NWS in Pleasant Hill and Topeka.

Capture

 

 

 

A lot of colors out there…

The worst of the ice storm itself will be towards central KS, OK and N TX where ice accumulations may be in excessive of 1/2″. This may create power line issues down there.

Here is a handy chart that combines the winds and the icing amounts to determine the power line vulnerability when an excessive amount of freezing rain is possible…

The reason why this storm is going to generate more ice than snow out west is that the air aloft just isn’t cold enough. Temperatures above the area tomorrow will be warmer than the temperature on the ground. So in reality snowflakes can’t form or if they do will melt well before they reach the ground in the KC vicinity. What can happen though is the melted snowflakes or the actual rain droops freeze when they get closer to the ground with the shallow cold air in place. This they creates sleet or ice pellets.

The image above shows what I’m talking about…the left side of the image represents and atmosphere that will be supportive of all snow…that would be for parts of NE NE this morning. The middle and right side would represent KC. That would be towards later tonight>tomorrow early AM for the middle image and then we may have some sleet in the region tomorrow or Saturday.

The overall snow component to this is not going to be overly impressive in terms of area affected.

The rain part of the storm though will be. Flooding rains are likely from the I-44 area of southern MO southwards through Dixie and especially into AR/OK and parts of TX. Rainfall amounts in the KC area will be closer to 3/4″-1.5″. Here is the latest NAM model…these totals represent the amount of rain/sleet and or freezing rain through tomorrow evening.

 

nam_total_precip_mc_13

Here is the HRRR model that goes out through the next 15 hours…showing the evolution of the precipitation through the region. This model will also update throughout the day…via IA State.

 

In terms of the weekend…there may be some sort of wintry mix on Saturday. At this point temperatures should be close enough or above freezing so that we don’t have issues for most of the daylight hours…we’ll need to watch for re-freezing on the pavement during the overnight hours into Sunday morning. Anything wet may turn to black ice in parts of the area,

Finally early next week the upper level storm will be moving through the area. It really won’t be till later Monday that the atmosphere above us will support the creation of snow…and by then the storm will be lifting away from the area..but some snowflakes are possible later Monday or Monday night. We’ll watch N MO especially for this potential.

A cold week is on tap for next week, but the longer term prognosis is looking milder, especially after the 1st week of December.

OK that’s it for the morning…I’ll be watching the evolution of things and, if needed, update the blog in the afternoon or evening. I’ll be filling in for MT for the next couple of nights so I’ll see you starting tonight at 5PM

Joe

 

 

 

 

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