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Weather Blog - Rain Is Likely On Saturday Afternoon

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Posted at 7:28 AM, Nov 20, 2020
and last updated 2020-11-20 11:32:59-05

Good morning bloggers,

The 41 Action News "Get Ready For Winter" special is less than two weeks away. Our weather team is working on the special now and I am working on that winter forecast. The LRC, which describes the cycling weather pattern in the river of air above us, is in the first cycle of this years pattern. It is just now coming into focus. Let's take a look beginning with our weather forecast time-line:

  • Today: Cloudy & cooler. Light east winds and a high of 60°
  • Tonight: Becoming mostly cloudy and staying dry. Low: 50°
  • Saturday: Cloudy with a 100% chance of some rain. Rainfall amounts will be in the 0.01" to 0.35" range. The best chance of rain is during the afternoon with temperatures dropping into the 40s.
  • Sunday: Mostly cloudy with a high of 47°. There is a slight chance of showers early in the day.

The developing weather pattern:
This forecast map shows a band of rain moving into our area tomorrow afternoon. There is around a six hour window for this rain the opens up late morning on Saturday.

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There is a weak storm approaching our area and this forecast for rain, above, is still somewhat suspect. Why are we so uncertain on Saturday's rain, even one day away? There is one good reason. Take a look at this forecast map of the upper level flow valid tomorrow morning:

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This map above shows the flow aloft valid tomorrow morning. Where is the storm that is going to produce our rain chance? The blue line drawn in that extends from the Pacific Ocean, across the USA, then into the northern Atlantic Ocean is pretty flat. We look at this level for upper level storm systems that are very important for our weather forecasts. There is no defined disturbance that I can see at this level over the USA, with the exception of one moving into northwestern Montana, and another one near the northern Great Lakes. The one moving into Montana will strengthen as it passes by early Sunday. There is enough of a surface set up for our chance of rain, but will it be organized? Will we get more than 1/4" of rain? I doubt it in most areas. A few spots may only have a few drops, especially over northern Missouri.

This next map below shows the flow aloft next Wednesday, Thanksgiving Day Eve! This shows a storm over Missouri as shown by the L plotted just east of KC. The flow is buckling and becoming a bit more active:

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The Arctic Oscillation (AO):

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The AO suddenly went high into positive territory around a month ago and it has stayed there. This is one of the biggest reasons we have had a fairly long mild stretch of weather after the winter surge we had in October. This AO influence is something we are monitoring closely. If it stays positive over the winter it will not be a cold winter. We do see some strong potential for it to dip negative at times this winter, but when? There is a dip forecast in that direction in the next two weeks. We will discuss this a lot more when we issue our winter forecast in a couple of weeks.

The LRC Model from Weather2020:

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This is very preliminary as our LRC computer model was run way before the first cycle of this year's pattern was finished. This forecast above shows the lowest temperature prediction for each of the United States. We will be running our model in a couple of weeks, and this will be adjusted. This shows Montana with the coldest low of the winter at below -40 degrees. I haven't checked yet, when that was predicted based on the preliminary LRC model, but that is signficant.

For now, it is a mild stretch that shows signs of cooling off in the next couple of weeks. Have you entered the snowflake contest? I have been saying on the air to pick a date between around December 5th and 10th, but we still need to learn more about this cycling pattern. Good luck! Go to www.kshb.com/contests to enter!

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Thank you for spending a few minutes of your day reading the Action Weather Blog. It's Friday! Have a great weekend.

Gary