Nov 16, 2010

Diurnal Temperature Variation & The Northwoods Snowstorm

Late this past week our mild temps took a dive back to seasonal. It was getting out of hand as our overnight minimum temperatures hovered around our average maximum temperatures. The cooler temperatures boost our chances for our first measurable snowfall to take place soon. The average date for OSNW3's first accumulating snowfall is Nov 20. That said, a trend that continues here at OSNW3 for the month of November is the lack of precipitation. We've received just 0.22 inches. 2010 marks our 5th season observing and of the four preceding Novembers all have failed to reach the average monthly precipitation total. As for what lies ahead, the forecast is calling for below average temperatures with equal chances of precipitation.

(OSNW3 Weather Brief)
(OSNW3 November Observations)

(OSNW3 November 2010 Summary)

(click on graph for the month summary data - it will open a new tab/window)


Diurnal Temperature Variation
It is the variation in temperature that occurs from the highs of the day to the cool of nights (wiki). Specific things pop out when analyzing a monthly summary graph and as I was overlooking RangerBob's I noticed a sizable difference between his daily hi/lo averages for the month of November. WxWatcher then joined the communication as he noticed the differences as well and quickly ran his data. Both WxWatcher and RangerBob did a great job describing multiple reasons their regions have their range through the seasons. Instead of reiterating their words, I will just link their blog entries in the previous sentence. All of their reasons are true for the variations at OSNW3. However, they all work together a bit differently in each of our regions, which is great fun for each of us to document and share.

I compared diurnal temperature variations of the 30 year average (1971-2000) for Oshkosh and the 3 year average (2007-09) for OSNW3, graph located below. After analyzing the data it is evident that RangerBob's variation during the summer and winter months is more extreme. Much wider of a span during summer and a slightly tighter span during winter. Overall for WxWatcher, his variations are a bit wider, spanning 5 degrees more on average as the seasons transition. Oshkosh's biggest drop occurs from autumn to winter as one would expect with the waning strength of the afternoon sun and the cool night that follows.

(Oshkosh & OSNW3 - Diurnal Temperature Variation)

Included with the annual summary for each year at OSNW3 is a newly created diurnal temperature variation graph. I particularly like the data presentation as one can quickly see long lived weather events or short lived extreme events that occurred throughout the year. An OSNW3 annual summary for 2007, 2008, and 2009 can be viewed by clicking the links.


Northwoods Snowstorm
While Derek, Nathan, and Tim were all involved with the latest snowstorm in the northwoods I wanted to pay tribute to their post storm reports. I've looped together the radar of the three days it spun around the region. Please visit each of their blogs for their recaps. Links are below.

NW Wisconsin Weather (Derek)
Northern Wisconsin Weather (Nathan)
Northeast Minnesota and Northwest Wisconsin (Tim)

(Regional Radar Loop - Nov 12-15, 2010)

(click on radar image for the actual radar loop - it will open a new tab/window)


Front Of House
As the days become shorter and weekends become busier I have a sneaky feeling I'll be finishing the autumn clean up duties by moonlight. Due to the FOH being practically the same as last week I've decided to remember a more bountiful time. Like Feb 19, 2008 when the snow depth was 16 inches out back at OSNW3, the deepest depth recorded in our short history. For the folks that enjoy predicting winter climatology at OSNW3, the list of predictions can be found by clicking here.

(OSNW3 - Feb 19, 2008)