WHAT A DIFFERENCE.....
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THEN VS. NOW
What a difference a year makes. Tuesday temperatures were in the low to mid 70s under sunny skies. One year earlier, much of my central counties experienced snow and record cold temperatures. This picture was taken by my friend and KGAN TV meteorologist Nick Stewart in downtown Cedar Rapids October 19, 2020.
The quick moving intense band of snowfall tracked across the central third of Iowa, bringing the first accumulating snow of the season to areas along and north of I-80. Snowfall amounts mainly between 2-5 inches fell in a line from Des Moines, to Belle Plaine, to Cedar Rapids, and on to Anamosa. Around Des Moines, some 10-11" amounts were reported near Ankeny.
Here's a larger perspective. The snow rapidly diminished in Illinois as it moved out of Iowa.
All the dots below indicate records for snowfall that were tied or broken during October 2020.
The last half of the month was quite cold too. Many records for low maximum temperatures were established. In Cedar Rapids the high the 19th was 35 and on the 26th just 32. Average highs would have been in the low 60s.
So here we are in 2021 and so far, so good. No freezing temperatures yet and readings that are averaging 7-9 degrees above normal per day. You can see why in the graph below. At the NWS station in Davenport, only 2 of the months 19 days have had highs below normal. 8 days have been 80 or above and another 12 have been in the 70s. The coldest low just 38.
I do see signs that winter may be stirring and I will get to that in a minute. First, let's focus on Wednesday's system that should bring a few showers to be followed by much cooler temperatures. On the satellite Tuesday night you can see the energy centered in Nebraska. Some good dynamics are evident but there are fatal limitations to rain production in my area. First, the best forcing and warm advection remains north of the area. Second, notice the absence of clouds over the central Plains into Missouri and Arkansas. That means moisture is lacking along the trailing cold front that arrives late Wednesday. The timing is actually good but the lack of instability and moisture will hinder the development of showers and storms.
Proof of the lack of surface moisture are the dew points at 7:00am Wednesday morning. They are running in the upper 40s. By the time the richer moisture arrives the brief forcing along the cold front is pretty much passed ending the threat of any worthwhile rains
As such, only light widely scattered showers are anticipated. Some spots may not even see much more than sprinkles. Most amounts should be a few hundredths at best. The most likely window to see any showers would be in the morning and perhaps again toward evening. With mixed sun and clouds and SW winds in the warm sector it will be another mild day with highs most spots in the lower 70s. Here are the projected rain totals through Wednesday night.
The 3k NAM
The 12k NAM
Behind the front a cooling trend commences that carries into the weekend. Dry conditions are anticipated through Saturday. As for temperatures, readings may not reach 60 Thursday beginning a run of 4 consecutive days where highs remain in the 50s. Another concern is frost. The potential is there both Friday and Saturday morning. With very dry air and what should be light winds the only thing that could hold readings back is cloud cover. The 12 and 3K NAM are very bullish on frost and freezing temperatures both mornings. The EURO and GFS suggest frost, especially Saturday morning but are generally showing mid 30s. I could certainly see 30-32 but that will require a cloud free sky. I'll be monitoring that trend closely in the next 24-48 hours. The worst case scenario for cold Friday morning is the 3K NAM which indicates lows that look like this. Clouds will tell the tale in the end.
That brings us to Sunday and today both the GFS and EURO are in better agreement that a chilly damp day is in the offering. The GFS sniffed this out well before the EURO so a nice victory for it. The challenge now is the track. The GFS is further NW and that makes a difference. Here's what the GFS shows for rain compared to the EURO. I would split the difference at this point. Either way, it looks like most areas are in for another good rain.
Sunday temperatures will also be dependent on the track. The GFS being further NW would bring a range of highs in the low 50s north to the low 60s south. If the southern route of the EURO pans out, it could be a very chilly day with 40s north and low 50s south. No doubt, the second half of the weekend looks pretty poor and will be a focus in coming days.
Okay, I mentioned winter waking up. I'm seeing the MJO (Madden Julien Oscillation) moving into phase 1 by the beginning of November. That's important going forward as the cold phases of winter 8, 1, and 2 lend themselves to cold and active weather. As you can see in the phase diagram, the EURO is going to 1 as I mentioned. In November its corresponding analogs point to below normal temperatures and above normal precipitation.
At least for now, both the GFS and EURO long range 500mb jet stream pattern shows blocking over Canada and a mean trough below it centered on the Midwest. Cold air would be drawn into the trough which would be slow to move if it indeed cuts-off as shown. It would also be unsettled and not very pleasant. This could be in response to the sudden stratospheric warming which is projected to be at its peak around Halloween.
The GFS 500mb jet November 4
The EURO 500mb jet November 3rd
I think the bottom line is that our endless summer is about ready to wrap it up. I still see another warm up next week but chilly before than and then cooling down again towards the start of November, a period to watch in the longer range. Well, that's all I have to say. Thanks for your time and if you appreciate the site please consider a donation by clicking the link below. The future of TSwails is in your kind and caring hands. Roll weather...TS