New and Interesting Developments

As I said yesterday, the forecast was incredibly likely to change, and it has! Over the past several model runs, the models have trended to a much more amplified ridge developing over the area, which seems likely, given the strength of the jet streak which will amplify the Northern Plains trough, introducing what I like to call the "teeter totter" effect.  What happens is that when a jet streak or a strong trough moves into the West, usually strong height falls (equivalent to falling pressure over time) accompany them, causing a deepening of the trough.  This strong trough then progresses eastward, "squeezing" the ridge, eventually causing it to amplify.  The reason I call it the "Teeter Totter" effect, is because usually when there are height falls in the west, there are usually height rises occurring in the East, kind of like a kid sitting on the end of a teeter totter, causing the other end to go up.  Even with the ridge developing, I do expect that a weakening shortwave will move north of the area into Canada.  This will cause a cold front to approach to the area, but not pass through.  The good news about this front is that it COULD produce rain (even if it does it will probably occur west of here), given enough moisture and lift, which will not be in good supply over the area.  If any of you ever happen to look at recent model runs, you will notice that these models are forecasting that dew points into the lower 70's by Sunday afternoon. Do not believe this for one minute, because most models have well known moisture biases, which can cause major problems with convective feedback.  When models forecast more moisture than there actually will be, and since instability is related to the low level moisture profile, this will create a bias towards higher instability and thus more widespread thunderstorm activity.  In actuality, the models are having a problem with this insane drought, due to the fact that they are overestimating evapo-transpiration from crops such as corn, soybeans, and wheat.  The ground is so dry and the plants are so dry right now, that the models moisture parameterization schemes implement this into the  model, causing an extreme overestimation in moisture.  Therefore, I do not believe that thunderstorm activity will be very widespread, if there are thunderstorms that develop.  My second reason for not anticipating thunderstorms, is the fact that a strong cap will still be located over the region (even though it could be effectively reduced depending on where the shortwave tracks).  This will effectively block most thunderstorm activity.  If there is widespread thunderstorm activity it will be to the northwest of here in Illinois and Wisconsin on Sunday afternoon and evening.  The third reason is for the fact that over the past few weeks and months, models have consistently overdone convective potential.  There are a multitude of other reasons, but those are based on my opinions on how the situation is going to develop, not on actual facts. For these reasons, I don't think we will have as much cloud cover on Sunday, allowing temperatures to reach the lower 90's
     As for most of next week, the ridge appears to be stronger than what I thought yesterday.  Ridging will begin to build back in by Monday, sending temperatures back into the low to mid 90's.  On Tuesday through at least Thursday, temperatures could soar into the middle 90's to near 96 (according to the HPC and other guidance) with nighttime lows in the lower 70's. By Friday, the ridge will break with the approach of an upper level trough, as blocking breaks down in the Atlantic. After a few cooler days in the 80's looks likely, with highs returning to the 90's soon after.