:: Like a Monsoon
After a summer of drought, the prayers and exhortations of many MN residents are finally being realized as a very stubborn frontal boundary and active upper level system has brought soaking - and unfortunately flooding - rains to southern MN. Albeit to late for this rain to arrive for many farmers and gardeners, this rain will finally true-up the area's rainfall totals to normal. 1.2" have fallen Saturday alone, bringing our total to 4.97" for August (so far).
The synopsis lies in a warm front now lined up along, or just north of, I-80 in Central IA. South of and near this boundary in IA, highs soared into the upper 80's today, while cloud cover and showery precip over southern MN up towards the TC Metro kept the atmosphere cooled into the 60's. Across the front is a steady low level moisture flow borne on southerly H85 winds. Moderate shortwave impulses moving through the H70 and H50 layers of the atmosphere along the front are giving enough vorticity to produce a continual train of showers and thunderstorms along and just north of the front, and this is what threatens southern MN through the morning hours.
Lakeville sits on the northern periphery of the bulk activity, so we can expect passing showers and thunderstorms through at least 4am Sunday. A slight break may occur during church hours of the morning, and then more TSRA will develop mainly mid-afternoon. At this time, only decent modeling avail is 00Z NAM which nailed tonights training storms across srn MN. GFS also blobbed precip max's over srn MN, but with more trending for SE'rn MN...which is fine as flash flooding is a major concern over that part of the state and along the MS River and its tributaries in that region. 00Z GFS also seems to trend a bit of an MCS signature tomorrow afternoon in SE MN/NE IA. That might be a stretch, but 50/50 pops in MOS seem pretty fair for both models. Wind profiles suggest a bit more vorticity might be on tap later Sunday as well.
After this front sags a bit further south and then translates into a stationary boundary Monday afternoon across MO, eyes of WFO's in the area have also turned to the mid-week period when two major weather-affecting events affect the North American continent: Hurricane Dean bound for the Yucatan, and possibly affecting srn TX, and a unseasonably deep Pac-NW cyclone bound for the intermountain west. GFS paints the latter more like a spring storm, dropping out of Alberta along the front ranges, and into the high plains of CO and NE as it triggers off a short-wave cold front to push across the area sometime Wednesday night. As for Dean, if the NHC forecast holds, landfall will be about 100 miles south of TX on Wed night...however Gulf moisture will pump more rapidly up the LLJ ahead of the system we will experience as a result of Dean's influence. If Pwats and DT's rise as a result, we could see quite another potent round of thunder and rain mid week.