Joe’s Weather Blog: Focusing on ice potential this weekend (MON-1/9)
I’m thinking the rumblings about the weekend ahead are starting to pick up a bit of steam. This blog will mainly talk about the upcoming weekend…mostly in very broad ways because it’s too early for many specifics but there are some trends to write about. Before we get to the weekend…a series of ups and downs will play out from a temperature standpoint. In some aspect that’s what’s setting the stage for this weekend. I’ll try and keep this blog a bit “tighter” compared to yesterday’s derailment.
Tonight: Variable clouds this evening with mostly steady to perhaps rising temperatures thanks to south winds. Lows in the 30s but by daybreak closer to 40°. Becoming cloudy though later this evening as a moisture surge comes in from the south.
Tuesday: Cloudy AM then variable clouds in the afternoon. Temperatures may push to near 50° before leveling off in the afternoon. Temperatures may be warmer south of the KC metro.
Wednesday: A warmer day is likely with highs into the 50s. A strong cold front will arrive either late in the day or in the evening crashing the temperatures.
The satellite picture this afternoon shows moisture surging in from the south. It’s moving due northwards…and you can see it towards AR and NE OK
Here is a close up of the moisture…
So we have more or less upper level moisture streaming through our skies now…and soon low level moisture will be coming into the region. I wouldn’t be shocked if there is some mist or drizzle out there overnight.
Tomorrow and Wednesday will be milder. The arctic front arrives sometime later Wednesday…temperatures on Thursday>Saturday are likely in the 20s at the surface…and that’s a key phrase…at the surface. Above us though…it’s not going to be as cold. That’s the rub for Friday>Sunday
Now about the next storm.
Cold air is dense and heavy compared to the lighter and less dense warm air. As a result…like oil and vinegar…the cold air is like oil and the warm air like vinegar. The cold air stays closest to the ground while warm air is above it…like vinegar. When cold air at the ground is being reinforced by a cold air mass to the north or northeast of KC…it’s tough to scour out. When warm air is getting warmer above us thanks to a SW flow aloft…it’s tough to chill that air down. So we have a mess on oour hands.
Warm air also flows over cold air…we call it overrunning. This leads to rain above us not snow. When the rain drops fall into the cold near surface air…the rain drops either change into ice pellets (IF the cold air is thick enough…or remain liquid until they hit something on the ground when they freeze up…leading to ice. IF the air above us isn’t cold enough…snow can’t form. It appears for the most part, that will be the case heading towards the weekend based on the latest information. So we’re not talking snow storm, at this point. Sometimes, the final piece of an upper level storm creating this mess can move through the area, removing the warm layer aloft and allowing snow to form. This may happen as well but it’s not worth the effort to write about as of yet.
Ice storms in KC have a bad history behind them. Many remember the ice storm on 1/30/2002. It left 100s of thousands without power for upwards of 2 weeks in some cases. It was a mess and brought down thousands of tree limbs. If you want to remember some of the sights…FOX 4 has a gallery for you to look at. This was put together for the 10 year anniversary.
So where is this “storm” now? Well really it doesn’t exist although IF I do a back trace of where the forecast storm ends up going over the weekend and back track from there…it is a tiny(!) little piece of this broader circulation wrapping in the NE Pacific Ocean off the coast of Washington
A tiny piece of that storm is going to spin around a break off. Eventually it will strengthen and close off into an upper level low in the SW part of the country near Los Angeles on Friday. Then it moves towards Tuscon, AZ on SAT…then potentially opens up in the Plains (somewhere) into Sunday. There may be another piece of the storm hanging back in the SW part of the US as this occurs…we’ll worry about that later.
Model trends off the EURO are negligible at the surface in terms of cold air…essentially 22-28° from Friday AM into Sunday AM. Aloft (around 5000′) we run from about 32° to eventually almost 50° on the south side of the metro by Sunday AM. That is a recipe for mostly ice in my opinion.
There is a difference though in ice storms…below 28 or 29°…it’s bad. When the surface temperature though is closer to 31-32° it’s NOT as bad. This is possible on Sunday and it’s also possible that by Sunday the ice is departing as well. Strangely when the temperatures aloft are so warm…45-50°(?) the warm raindrops come to earth and can stay above freezing longer when the surface temperature is near 32°. They don’t lose their heat as quickly which makes sense…that’s why we typically don’t have as many issues when the surface temperatures are around 32° in these scenarios.
Ice accumulations are also important, when combined with wind. The more wind that is out there combined with more of an ice accumulation…leads to more issues with the power lines. Many lines can handle up to 1″ or so of ice on them with light winds…after that all bets are off…and should there be some wind involved…problems develop faster. Remember while there may be lighter winds at the surface…IF you go up 50-150’+ there typically is a bit more wind.
This graphic is via the Omaha Public Power District…
This system has the look of something that will generate waves of ice and/or sleet as it moves through over the course of several days. It won’t be a continuous phenomena based on the current data. Heaviest days may be later Friday then a bit of a break at some point Saturday…then more Saturday night into Sunday(?). This is PURE SPECULATION in terms of timing at this point.
Is this guaranteed? Gosh NO! Let’s remember that we’re not even really seeing a storm yet…confidence won’t increase a lot till at least Wednesday afternoon or Thursday. Ice storms being predicted from so far out are tricky deals.
Why am I talking/writing about this now and over the past weekend? Well I want this to be on your “radar” screen because there is potential for this to be significant.
Can this turn into a snow storm? Technically yes it could BUT I think there is a better chance of nothing happening (low chance right now) than a snow storm happening this weekend if that helps you out at all.
Can this turn into a sleet (ice pellet) storm? This reduces the power line issues a lot. Since ice pellets don’t really stick to power lines. IF we don’t get ice we may end up with more of this. This wouldn’t be as bad but enough sleet will have big road impacts. What make that a tough forecast is the “depth” of the cold air closest to the surface. This depth may and will change during the event which complicates things more + it won’t be uniform in the region. Some areas could have more sleet while others get more freezing rain.
The bottom line is that it’s just to early to get into a lot of specifics. In a nutshell the atmosphere may be trying to set up for a wintry mix scenario this coming weekend…starting sometime on Friday. The risk of a snow storm appears lowest at this point. The risk of some sort of winter freezing rain/sleet combo appears highest at this point. Again all this MAY change.
That’s it for today.
The feature photo today is from @stormchaser111 in Leavenworth Co.. It was the sunrise from this morning