Monday, October 13, 2014

Rainy Week Ahead

Public weather briefing

After a lovely weekend and a foggy Monday afternoon, rainy conditions and typically cool fall temperatures are anticipated for the week ahead.  The rainfall will begin tonight and persist through Wednesday across southeastern WI.  Heavy rain and deep clouds will continue throughout the week, fully clearing up on Friday.  Daytime high temperatures will remain moderate to mild throughout the week and slightly decrease on the weekend.  Pleasant conditions will linger into the next week.


Tonight. Overcast with strong winds out of the northeast. Chance of thunderstorms overnight. Low around 55.

Tuesday. Continued showers with rain accumulating to around 1-2". High around 61.

Tuesday night. Clouds remain; rain begins to lighten up. Low in the mid 40s.

Wednesday.  Rain tapers off around mid-afternoon. High mid to upper 50s. Low around 45 in the early morning.

Thursday. Showers possible in the morning. Clouds continue. High near 65.

Outlook for Friday through Sunday. Partly cloudy Friday, small chance of rain on Saturday, partly sunny Sunday.  Highs in the low 60s Friday and around 55 Saturday and Sunday. Lows around 40. [CONFIDENCE: MEDIUM-HIGH]

Forecast Discussion

A surface cyclone will be moving through the central United States, south of Madison this week.  Strong overcast conditions will stifle radiational cooling overnight.  As the cyclone moves to the northeast, it will bring rain to Madison through the middle of the week. The strongest effects of the warm and cold fronts associated with thickness advection will largely avoid the Madison area, resulting in mild temperatures. As the cyclone moves eastward, conditions will begin to clear by the end of the week, and through the weekend (average daily high temperature for later in the week 60F; low 40F).

The chances and amount of precipitation expected in Madison through the week come from analysis of the MOS data from the GFS. The most significant amount of precipitation is expected throughout Tuesday and continues into Wednesday evening. We expect the precipitation to move through before the weekend, making way for pleasant conditions Friday to Sunday.

Rachel Down
Samuel Hartwick


  1. Hey guys,

    I'm not sure if you saw it today, but the NEXRAD radar loop hosted on the AOS page showed a very peculiar set up of precipitation, with a very long comma/frontal band from the Gulf up into Wisconsin, with more precipitation to the southwest of the surface cyclone. Did you know perhaps why that was occurring or what possible factors are at play in its origination?

    Other than, nicely written and job well done!

  2. Dan,
    I noticed that too. While the "comma" shape of the band moved east, there was precipitation that stayed pretty stationary in northwestern Missouri and northeastern Kansas. We noticed something similar last week on the NEXRAD, with almost a secondary band of precipitation to the west. Is this a common observation in cyclones? What causes this precipitation?
    Great job Rachel and Sam!

  3. Thanks for the observations, Liz and Dan! Just to add my two cents in to the discussion, sometimes that precipitation to the west and south of the cyclone center is associated with vertical motions forced by the upper-level trough or by Qs convergence in the vicinity of the cyclone center. In other cases, you can actually have a secondary cold frontal boundary that trails the initial one. These secondary boundaries typically have weaker precipitation (if any at all) given the air mass in the wake of the primary front is drier and cooler. Nevertheless, these secondary cold fronts can reinforce a shot of cold air that may accompany these cyclones, especially as we get into the late fall and winter season!


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