Weather or Not

All indicators are pointing towards a very significant rain event the first part of this week.  This is all rain...no snow...but a lot of rain will fall.  The key players include a large and very slow moving...mostly positively tilted upper level trough that will pump a continuous feed of moisture from both the Pacific and the Gulf of Mexico into the Midwest.  At the same time, a strong pocket of upper level winds (jet max) will remain nearly stationary from IA into the northern Great Lakes.  This will put much of MO and IL into a very favorable region of sustained lifting in the atmosphere starting Monday night and lasting into Tuesday.  This lifting will help to focus a low level jet stream into a slow moving cold front. 

The precip will likely be focused on two phases.  First will be Monday morning with the initial surge of moisture and low level instability.  This will be pushed north with the rapidly intensifying low level jet and the developing warm front.  Once the warm front punches north of I-70 around noon...thunderstorm chances will quickly diminish into Monday afternoon.  This trend will be short...as the main upper dynamics will then begin to unfold with a prolonged push of heavy rain and thunderstorms.

Rainfall totals will easily reach 3" over a large part of MO and IL by Tuesday evening with isolated 6" totals not out of the question.  The result will be widespread stream and river flooding developing.

Severe weather is also possible on Monday...mainly in the form of large hail since most of the storms will be elevated north of the warm front.  However, any storms that root close to the surface layer Monday afternoon...along the surface warm front will need to be watched for high winds and isolated tornadic potential.  This will become more likely IF clouds break and we see sunshine.  Most likely area to watch will be along I-70 into metro STL Monday afternoon or evening.