UPDATE 6:35 P.M.
Flash flooding is ongoing in the Twin Cities. Full details here.
UPDATE 5:40 P.M.
The thunderstorm warning has been extended to include Minneapolis and St. Paul, which will be in place until 6:15 p.m.
There has been a constant rumble of thunder across the northern metro for about the past half-hour, while a tornado warning has been issued for an area including Waconia.
UPDATE 4:30 P.M.
Severe thunderstorm warnings are now being issued for the northwestern Twin Cities metro, including Maple Grove.
The National Weather Service says wind gusts of up to 50 mph and half-dollar sized hail is possible.
The system is expected to make its way through the metro during the rush-hour traffic, making for wet conditions on the roads.
As expected, the National Weather Service has issued a severe thunderstorm watch in advance of explosive storm development Monday afternoon and evening.
The watch, in effect until 10 p.m., does not include the Twin Cities, but it runs just north of the immediate metro area up through parts of central and northeast Minnesota.
Primary threats include scattered damaging wind gusts to 70 mph and isolated large hail up to 1.5 inches in diameter, which is about the size of a walnut or ping pong ball.
"Storms are expected to intensify along and ahead of a cold front where the atmosphere is moderately to strongly unstable. Damaging wind and hail should be the main threats through mid-evening," says the Storm Prediction Center.
The National Weather Service in the Twin Cities acknowledges that severe storms are possible south of the watch area, but the better ingredients are within the watch box.
The 2 p.m. run of the HRRR computer model shows more explosive development around the cities as a possibility during the evening. But remember, this is a simulation of what could happen, not precisely what will happen.
Keep an eye to the sky this afternoon and evening as conditions could rapidly change.