Stormy at First, then Spring

I have good news and some bad news.  For the bad news, current data suggests the potential for thunderstorms tomorrow, mainly south of the Michigan/Indiana border.  If the thunderstorm threat persists longer into the day, then I highly doubt that temperatures will make it much past the lower 60's and upper 50's.  The initial waves of showers look to arrive in late afternoon for areas west of here such as Northern Illinois and possibly even Northwest Indiana, while the initial waves of showers for Indiana and Ohio will not arrive until about 10 p.m. to midnight.  A more solid line of convection will make its way to the Ohio Valley and lower Great Lakes by the early morning hours, with the NAM suggesting these showers and possibly thunderstorms will arrive by 4 or 5 a.m., and the GFS suggesting a much faster solution of arrival around 3 a.m.  Rainfall amounts will likely be near a half inch, with higher amounts of rainfall farther west near Chicago and Illinois.  After the initial warm front passes through the region, temperatures will warm quite nicely from the overnight lows of the mid to upper 40's, into the lower 60's.  If enough diurnal heating takes place tomorrow,  (aka. sunshine) then it is possible that any weak instability that forms do to the heating, will cause the scattered development of thunderstorms, with some taking on severe characteristics, especially with the wind profile that is suggested by the NAM.  This would be supportive of small hail, and a few damaging wind gusts.  Right now, this is only small possibility as the best lifting from the upper level system will have moved out of the region by the time that conditions would be conducive for severe weather.

GFS forecast of the 500 millibar closed low at 5 a.m. tomorrow morning

Conditions will then clear for Monday night, with temperatures dropping into the upper 40's.  Through most of the upcoming week, expect sunny conditions and very warm weather, with highs likely hitting the 70's for several days in a row.  There are some thunderstorm chances coming up, especially Wednesday night into Thursday and next Saturday night, but these rain chances will be rather small, and will not affect temperatures much.  In fact, the latest GFS is forecasting this warmth to last even into the next week, and it really isn't showing much of an end to the warmth even 16 days into the future!  According to the WFO IWX (Northern Indiana's National Weather Service office), they would be not surprised to see the lower 80's by the week after this week, that's how warm this pattern is going to be!  Enjoy!