Aug 10, 2010

Early August Heat & La Niña Trends

August begins as expected for what the 2010 summer has been known for. Hot, humid, and wet. Things will continue this way for the next week or so until a change in the overall patten takes shape. Slightly below average temperatures are forecast for the period starting Aug 16 thru Aug 24. Above average precipitation will accompany the moderate temps. It is likely OSNW3 will surpass the wettest summer (Jun/Jul/Aug) in Oshkosh history total of 20.80". To date we are second with a total summer precipitation amount of 19.37". The data set for the precipitation rankings can be found here. Click here for the temperature rankings.

(OSNW3 Weather Brief)
(OSNW3 August Observations)

(OSNW3 August 2010 Summary)

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

----

La Niña Conditions In Pacific
The NWS Duluth put together a great entry about the current La Niña and what it means for the winter in the Northland. Below is the opening statement. Please click here for the entire entry.

On the August 5th ENSO Diagnostic Discussion, the Climate Prediction Center declared that La Niña conditions had developed in the Pacific Ocean through the month of July. They have issued a La Niña Advisory which means that La Niña conditions have developed and are expected to persist.

Now the question is... What Does It Mean For Northeast Wisconsin winters? I did some digging and documented the results for Oshkosh in similar fashion as the NWS Duluth. Results are below.

Oshkosh Climate Stats
Since the winter of 1949-50, Oshkosh:

* In La Niña winters: averages 48.1" of snow
* In all other winters: averages 38.6" of snow
* Overall: averages 42.0" of snow




On the bottom graph, you can see a running total trend for snowfall for the winter months in Oshkosh. Through December, snowfall in La Niña months tends to be pretty close to overall averages. However, from January through March is when the snowfall tends to be above normal.

If you consider a winter snowfall within 7 inches of the mean to be "average", then only 4 of the 20 La Niña winters saw below average snowfall, with 5 average, and 11 above average. When the Oceanic Nino Index (ONI, sea-surface temperature anomalies in the Nino 3.4 Region) has been -1.0C or lower - indicating a moderate or strong La Niña - half of those winters saw 49 inches or more of snow in Oshkosh.

The last 4 winters have seen above average snowfall in Oshkosh. The winter of 2005-2006 saw 32.0 inches of snow. Oshkosh ended below 30 inches for winters of 2002 through 2005 when the totals were 23.0, 27.2, 26.2 inches respectively. Data set located here.

The NWS in Milwaukee has also done a comprehensive report on La Nina. See full article here.

----

Front Of House

I am anxious to trim my property this Autumn. Except for the garden, things are growing out of control. We are on mow 8 looking for 9 very soon. Speaking of Autumn, it gets me in the mood to hike, as did this site, Great Lakes Waterfalls.

(FOH - Aug 10, 2010)