:: Wet Start to Week
The sun did come out again this weekend...Saturday was excellent, today was nice as well, although cloudiness rolled in around 10am. That was expected, as a thrust of moist and warm air in the mid to lower atmosphere moved up from around Omaha to Lakeville. Looking ahead now to the work week, rain will be coming, and soon.
Right now, a nice line of thunderstorms has formed up from Jamestown, ND, to Pierre, SD. This line is moving east at a leisurely pace...around 20 mph. Some cells have prompted severe t-storm warnings, but only for wind and dime-size hail...nothing tornadic. But as these storms move east through sundown, they will hold on to their shape some, as they overrun the moist airmass that has parked now over MN. The lighning will persist, but the hail certainly will not. The complex should resolve into a line of showers that I think may affect us here in Lakeville around rush hour tomorrow AM.
Some of the computer models are struggling with the aftereffects of this line of weather, because as it dissipates, it will leave a good stretch of clouds from central MN, stretching to about Eau Claire, WI. This may keep some temps moderated tomorrow here. However, I think western MN will be the focus of a good dryline by 3pm tomorrow. The 18Z runs of the NAM and GFS models are at odds of timing, and the NAM seems to "rush" the precip activity through the mid day to late afternoon. The GFS pays a little closer attention to the affects of a progged surface low shipping in from NE to west-central MN by around dinnertime tomorrow. It is this feature that has caught my interest.
Should conditions dry up significantly before the sfc low arrives, there could be enough spark for some good springtime thunderstorms. CAPE (Convective Available Potential Energy) predictions are looking to be around 2000 J/kg again from Sioux Falls to Granite Falls (as it was with the convection predicted last week). The "push" for all of this is the surface cold front that is right now drifting past Dickinson, ND...by 3 pm tomorrow it will be on a line about Fargo, ND-Watertown, SD-Scottsbluff, NE. Ahead of the front warm moist surface winds will stream in plenty of instability, augmented by the secondary rouge low pressure center.
Models show 30-50% chance for Lakeville to see rain after 5pm. So for now, I say expect some showers around dawn, giving way to partly cloudy skies, 70 degrees by 3pm with a line of thunderstorms developing in southwest-west central MN, arriving in Twin Cities between 6pm and 8pm.
I should have a busy afternoon and evening tomorrow outside of the weather world, so I may not to give updates after 5pm, but I will try to get some more certainty into this forecast before then!