Wednesday, October 15, 2014

Alternating Periods of Sun, Clouds, and Rain

Public weather briefing

We will remain dry tonight, however a chance of rain returns on both Friday night and Sunday night. Periods of sunny skies will make welcomed appearances Thursday and Saturday, and full sun is expected Tuesday and Wednesday. We will see typical mid-October temperatures for most of the week, except for a chilly Saturday with a chance of frost in the morning.


Tonight. Skies will remain clear. Low in the mid 40s. 

Friday.Skies becoming cloudy later in the day. High around 60.

Friday night. A chance for rain early in the evening. Low around 40.

Saturday. Cloudy skies with clearing later in the day. High in the lower 50s, low in the lower 30s.

Sunday. Some clouds. A small chance for rain very late. High in the upper 50s, low in the mid 30s.

Outlook for Monday through Wednesday. Dry except for a chance of rain early Monday. Highs in the mid to upper 50s with lows in the lower 40s. [CONFIDENCE=MEDIUM]

Forecast Discussion

High pressure will remain over our area tonight. Weak positive vorticity advection Friday night will force weak vertical motion that may lead to some precipitation. Winds from west to north Friday night, bringing significant cold air advection into the region on Saturday. Positive vorticity advection will work its way into the region Sunday night into Monday, producing vertical motion and our best chance for precipitation.

The main issue affecting our forecast confidence is the track of the cyclone that comes into our area Sunday night. If it were to track further to the north, our chance for precipitation diminishes significantly.

Joshua Weber
Brandon Lipp


  1. Looks like there was considerably more precipitation this morning in southern Wisconsin (Saturday) than you guys anticipated in your forecast discussion on Thursday. What factors do you think contributed to this?

  2. We were expecting localized cold air advection to "cancel out" any of the vertical motion that was associated with the positive vorticity advection. It looks like that cold air advection came a little later in the day, allowing for undamped vertical motion in the morning hours.

  3. Our temperature forecasts were pretty solid, both highs and lows consistently fell in the ranges we predicted. We also did a fairly good job with clouds, we saw clearing about when we expected it, particularly the sunny skies during the afternoon Saturday. Our most significant error was the rain we expected early Friday night actually fell early Saturday, and had more precipitation than we expected. This is most likely due to either stronger vorticity advection than we expected or a weaker or delayed maximum in cold air advection.

  4. Brandon and Josh - This is a nice first effort at your blog posts for the semester. I really enjoyed your integration of dynamical processes into your forecast discussion and I think you discussed the complexity of what may have allowed for precipitation over the weekend well. However, I think I'd encourage you to include more details in your discussion as this will sharpen up the overall analysis you provide as part of your forecast. For example, within your discussion, you discuss weak positive vorticity advection over the area on Friday night. What is this positive vorticity associated with? An upper-level trough? A jet streak? Furthermore, what causes the winds to shift during that same time period? These types of details are important to those who are interested in the dynamics that are pertinent to the forecast in our area and should be included in order to elevate the quality of your discussion. Furthermore, while you don't have to go into the dynamics in your briefing, don't be afraid to say that an approaching cold front or high pressure, etc, will be impacting the area. Overall, though, I think you guys are well suited by your ability to integrate the dynamics into your discussion. Inclusion of these details will not only position you well for round 2, but will help immensely in the way you think about the case studies and map discussions.


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