:: Continued Mildness
The past 5 days or so since my last entry has been dry, pleasant, and cooler. It would seem that autumnal weather is knocking on Minnesota's doorstep...and all the typical indicators are in place. Our average temp in August so far has dropped to 72F from 77F in July. Likewise, average relative humidity has dropped precipitously from 61% in July to 28% in August. We received almost all of our precipitation in the beggining of the month after the polar jet decided to slide back south from a north-of-60 position in the end of July. This shift coincided with the seasonal setup of the desert SW monsoon, and that feature remains in place as a driving force in US weather today.
As the monsoonal ridge remains anchored over AZ and NM, the polar jet remains in a relatively fixed zonal flow. The jet core remains hovering over our latitudes, and the impulses that do get translated into other than fair weather are typically spawned of lee-side of the Rockies troughs. So long that the monsoon contiunues in the SW, we will remain in this pattern.
One of the impulses is forming up right now, and a couple preceeding short waves have spun downstream to contend with. Both the NAM/ETA and the GFS paint a jet max between 500MB and 300MB that sweeps ENE'ward over MN, allowing the first short wave to develop convection and best forcing over NW MN later today. The second shortwave will propogate the jet core more easterly over the Dakotas and should develop an MCS that will persist into EC MN for tomorrow AM's commute.
The main lee wave that is generating our mid-week break from the norm is currently progged to move into the eastern Dakotas by late Thursday into Fri AM. Models aim precip bulleyes over central MN, with some ESE propogation through Fri. Your mid-to-end-of-week forecast for Lakeville...
TUESDAY...Mostly cloudy in the morning, turning partly cloudy in the afternoon. High 84 with light NE winds. Low 60.
WEDNESDAY...Showers and a few rolls of thunder for the AM commute. Partial clearing by noon, and high of 82. SE winds 5-10 mph, chance of rain 40%.
THURSDAY...Partly cloudy and humid, 30% chance of showers and thunderstorms in the afternoon. Then a 50% chance of thunderstorms after dark. High 84, low 63.