AUGUST WITH A CHILL...OR NOT!
The last few days the upper air pattern had been funneling fresh Canadian air into the Midwest. Gone is the heat and humidity that seared us the previous week. Many spots were treated to lows in the 50s and highs that held in the 70s for a day or two. This is the trough that brought the change.
Going into the weekend the upper level winds are expected to flatten allowing a seasonal brand of warmth to return.
Fortunately humidity levels will not be extreme as dew points peak in the upper 60s to near 70 making this a tolerable warm-up. These are the projected highs on the EURO for Saturday and Sunday.
Of interest is the long range trends in temperatures. While the EURO is relatively warm to open August, the GFS is in a different camp and significantly cooler. Look at the temperature departures the GFS is projecting August 4-9.
The EURO on the other hand is dramatically warmer for the same period, especially where the GFS is coolest.
Usually the EURO does well in leading the charge when it comes to trends and situations like this. However, it has had problems seeing cool air this summer and it got whipped by the GFS on the depth of the cool air that's currently departing the Midwest. I think the GFS may very well be on the right track and if so its idea of a cool start to August may have merit.
In fact, the EURO is not in sink with its own MJO (Madden Julien Oscillation) forecast. It shows the MJO in phases 3 and 4 to start the month of August. (see the dotted green lines)
Phase 3 and 4 both correlate to below normal temperatures in August similar to what the GFS is depicting.
Going forward it will be interesting to see which model wins this battle. Both the EURO and GFS show rising heights at 500mb creating blocking over higher latitudes near Greenland. That type of pattern is conducive to east coast troughing and the cooler solution of the GFS. It's odd that the EURO shows a similar upper air pattern but does not depict the cool air at the surface. I'm liking the cooler look and I think the EURO will come around to it in time. (below the GFS Aug 5th)
If the CFSv2 (U.S. climate model) is correct, the cool weather will be around all month. Here's its outlook for August temperatures. Man, so much for summer!
That brings me to the coming weekend. As I alluded to above, it will be a warm but uneventful until a front arrives Sunday night to generate some scattered storms. Some of you need the rain, others not so much. Hopefully the drops are most numerous where they are needed most. The EURO shows this for 24HR. rainfall totals noon Sunday to noon Monday. Hopefully these numbers go up a bit in coming runs.