Pop-up showers slid south through the region on Sunday, triggered by surface heating and a very cold pool of air in the mid-layers of the atmosphere.
I spent my Sunday afternoon thoroughly cleaning my car (inside & out) in the driveway and was wondering if I'd be drenched by a passing storm. All the rain missed me, but I'm curious as to why I was missed.
I grabbed a radar estimated precipitation total (to the right) after the showers diurnally died down. I might venture that something NWS Duluth calls 'lake aridification' may have played a role. In the past, NWS Duluth has observed a phenomenon between the water and the north shore's cliffs that dries air as it moves over the region. Since all the showers and storms dissipated as they moved southwards across the lake, I would guess they were robbed of their mositure. Downstream, in the second tier of counties (Washburn, Sawyer, Price) the storms fired back up and continued to produce precipitation. It's just something interesting to note.
Pleasant temperatures, but rain needed.
These two graphs (to the left) show measured temperatures and rainfall from the last 14 days. The solid lines indicated the high & low temperatures at my location, with the dashed lines displaying the date's average.
Friday (the 20th) reached 82.8 degrees, this marks the third day in 2008 that I've reached above 80.
I did measure a trace of precipitation on Saturday and Sunday from the pop-up showers, but it was only brief sprinkles each day.
Today marks the twelfth day since the last serious amount of rainfall (1.47" on the 12th). While everyone has been enjoying the sunshine and summer-like weather, we need some real rain. No problems so far, but we need some help keeping the vegetable gardens green.
Next weather-maker starting to organize. I found a cool site today from Penn State, with a suite of US satellite images. This one (to the right) is from early this evening and shows color enhanced infrared (Eh-IR) imagery of cloud tops. The color-scale is nice and it clearly shows something brewing along the front range of the Rocky Mountains.
Surface analysis shows two areas of low pressure emerging from the Rockies, currently located in Colorado (1008 mb) and Wyoming (1010 mb).
The HPC's seven day pressure & front forecast shows the northern low will swing along the Canadian border on Tuesday and Wednesday, bringing a series of weak fronts and instability across the region. The second low pressure will move northeast into the western Great Lakes on Thursday, bringing a warm front north into Wisconsin before the cold front sweeps through. It is this second system that we'll need to watch for possible measurable rain and possibly severe thunderstorms.
Storm chances the next several days.
I've clipped the convective outlooks from the SPC and added some narrative (to the left).
Tuesday could bring some storm chances, with a possibility of some strong storms across northern Minnesota. I'm holding my breath for Wisconsin to see much action.
Wednesday is the beginning of the interesting systems. Exact timing of what will happen and where are not yet clear, but will become more apparent by tomorrow evening.
The SPC's wording for Day 4 (Thursday) gets a little more interesting: all modes are possible. The wording indicates confidence that something convective will occur, so I'm actually getting my hopes up that we'll see some storms.