Thursday, October 2, 2014

Frigid Weekend in the Mix

Public weather briefing

The dreary Thursday we are currently experiencing will continue into the night, with cooler temperatures arriving early in the morning Friday. Winds will shift to out of the northwest overnight, making for a cool, breezy Friday. Highs tomorrow will not make it out of the 50s, and Saturday will be even colder, with a high around 46. Temperatures Saturday morning will dip into the mid 30s, with a chance for some cold rain or even snow (!) early. Sunday will be drier and cold as well; we do not begin to warm up until early next week, with highs Monday still in the 50s and a possible high of 60 by Tuesday.


Tonight. Quite rainy. Over half an inch of rain is possible. Low of 53.

Friday. Some lingering rain showers, especially in the morning. High of 54. Very windy; winds around 15 mph, gusting as high as 30 mph.

Friday night. Possible showers late. Cold. Low around 35. Windy conditions continue.

Saturday. Coldest day of the week. High around 46.

Sunday. Possible return of sun, but still mostly cloudy. Winds die down in the morning. High of 53.

Outlook for Monday through Wednesday. First part of next week looks to remain cool, with temps remaining in the mid-50s. Will be much clearer and drier than the weekend. Lows at night typically in the low 40s. Fall has arrived. 

Forecast Discussion

The cold front initiated by the low in southern Canada comes through later tonight, roughly around midnight. We will see widespread precipitation throughout tonight and early Friday morning. This precipitation was initially generated from convection in Missouri, and enhanced by a deep trough aloft. This deep trough exhibited significant PVA by the thermal wind over much of the central plains, further driving upward vertical motion. The genesis of the remaining precipitation was from the cold front, so we will likely see an end to the heaviest rain after midnight tonight. 

The very northerly flow on the other side of this front will bring cold temperatures for Saturday and much of the weekend, with the possibility for snow early Saturday morning. The MOS puts this probability at around 66 percent as of the 18Z forecast, but this is only if the atmosphere is precipitating. The flow over our area remains westerly/northwesterly through much of the weekend and early next week. Conditions will be much drier by Sunday, and continue through the early week, due to a surface low which will remain just north of the forecast area for several days.

Alex Haugstad
Conner Hardesty


  1. Nice job on the precipitation amount on Thursday night, guys! Looks like Madison got right around 0.64 in. during the overnight hours. It looks like most of the rain, though, didn't start until after midnight, which came as a surprise to me. I was wondering if, as part of your reflection, you could comment on why the precipitation may have had such a delayed onset?

  2. That also came as a surprise to us, Andrew. I think that cold front from the low in Canada was a little slower than we thought it was going to progress and the precipitation forced by that front was held off as well by that. I remember stepping out that night and clearly noticing crisper temps and a steady amount of rain starting at around 1 AM or so, but there definitely wasn't anything noticeable temperature-wise before that. The day on Friday was pretty uncomfortable, as we forecasted, with steady winds making it feel much colder than it actually was. Our forecast for Saturday was also very close to what was observed, but I don't believe there was any observed snow, which is good because I'm not sure if I'm ready for that yet.

  3. I can confirm that the front came through right around 1AM. I happened to be out walking when it happened, which was a less than ideal situation. As for why it was so delayed, it could be since the vertical motion due to the cold front wasn't quite as strong as initially predicted, meaning a slower formation of precipitating clouds. It also could have been that the motion of the cyclone itself was stagnated by something, but I don't know enough about what drives the propagation of cyclones to confirm that. On another note, I was surprised both by how little rain we got on Thursday, since the gfs also seemed fairly certain we would receive two big rounds of rain, if I remember correctly. In regards to what we did well, we were right on with, as you said, the precip amounts, as well as the windy Friday and cold weekend. It felt as though winter had come early for a while.

  4. Alex and Conner - Nice job with this first round of forecasts for the blog! I think where you both were successful was in your identification in some of the major features of interest and in your attempt to link to some of the dynamical processes that were in place to affect the production of sensible weather. However, I think you want to have a bit more of this discussion in the public weather briefing section. If you forecast a wind shift or precipitation, acknowledge what is causing that (e.g. a frontal passage, etc). You don't need to go into the details you do during the forecast discussion though. Also, while you do have a discussion of the pertinent dynamics during the period, I'd challenge you to continue working on making your discussion read as cleanly as possible. This will come with continued work on lab assignments and case studies. Finally, make sure to include a statement of uncertainty in your forecast somewhere (see previous posts). This could be something you could touch on further in your forecast discussion - particularly when you discussed the chances of snow. Your reflection shows some nice thoughts related to your period, but definitely include some more details on the things that you did righted (for example in the process of making your forecast or in the way the dynamics unfolded). Nevertheless, I think this was definitely a solid first effort and something worth building off of.


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