Monday, October 20, 2014

Indian Summer on Tap for the Weekend

Public weather briefing

Clear and chilly conditions are in store for tonight, with lows dipping into the lower 30's; make sure to bundle up when watching in the Orionid Meteor Shower. A chance of rain moves in for Thursday, as a warm front will approach the area from the west. Warm weather is on tap for the latter half of the week as high temperatures will approach and surpass the 70 degree mark. A cold front will push in by the start on next week, relaxing temperatures to near average.


Tonight. Clear and cool, patchy frost possible.  Low in the lower 30's.

Wednesday. Sunny and warmer. Light winds. High 60. Low around 38.

Wednesday night. Increasing clouds and light winds, Low around 40.

Thursday. Increasing Clouds, slight chance of rain. Highs in the mid 50's.

Friday. Mostly sunny, Highs around 64.

Outlook for Saturday through Monday. After a partly cloudy start on Saturday, temperatures should rebound well with highs to around 70. Much of the same for the tail end of the weekend with temperatures in the low 70's and ample sunshine on Sunday.  [CONFIDENCE: HIGH]

Forecast Discussion

A broad region of warm air advection clips the area Wednesday, but since it is not localized, vertical motion and precipitation will not be associated with this feature.  On Thursday a chance of precipitation associated with an area of positive vorticity advection exists at 500hPa. The NAM pinpoints the largest maximum in advection in southern Wisconsin, giving Madison a chance a showers. The GFS puts down roughly a tenth of an inch of rain during this time period; a region in Iowa will see between a half inch and an inch.  The GFS model brings 850hPa temperatures to around 14 or 15 during the weekend. With an addition of around 10 (according the recent days) degrees Celsius for parcels brought down adiabatically, highs could reach the mid 70s by the weekend.

The alternating periods of cold and warm air advections through the weekend could lead to discrepancies in when 850hPa temperatures will be a their peak, during the day or during the night. The timing of a strong cold front on Monday will certainly play a role in the tail end of the weekend and forecast period. 


  1. Our biggest issue with our forecast was the persistent clouds that hung around on Tuesday 21 October 2014. We had optimistic high temperatures that did not pan out because the clouds prevented diabatic warming. Our low temperature forecasts were more accurate; we called for cool conditions, and potentially frost, which panned out. We did not, however, consider the formation of fog, which was a feature that appeared multiple times last week. Our long-range forecast from the weekend was nearly accurate, clear conditions and warmer than normal temperatures occurred as expected. Highs did not surpass the 70 degree mark, but they approached it. Cold air advection behind a front pushed in for Sunday, and cooled us down, which was one of our concerns in the forecast. During our next forecast, we will consider all types of weather (including fog) and lower our confidence if there might be a chance for clouds (or other unknowns) to affect our temperature forecasts.

  2. Tanner and Joe - Overall, I think you guys did a particularly nice job for this first round of blog posts. You were well suited in your public weather briefing to describe some of the major features that were moving through during the forecast period. Make sure to include whether or not the cold frontal passage is accompanied by precipitation, however! As for your forecast discussion, I also enjoyed how you integrated some of the dynamical mechanisms responsible for both precipitation (and the lack of it) during the period. My only advice would be to work on composing a more effective narrative that accompanies your diagnostics. For example, the prose that accompanies your description could be cleaned up a little bit so that it reads a little easier. This will come with practice, though, and is something that will undoubtedly get better. Also, in your reflection, I am glad to see you discuss some of the forecast busts and successes, but it would be great if you could integrate a little bit more of the dynamical details into the discussion (i.e. what allowed for the frost formation). Nevertheless, a real solid first effort here.


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