THE TRANSITION OF POWER....

The transition is underway to a much cooler weather pattern in the 6-10 day period. However, before the northwest flow is fully established one more significant piece of energy will round the bend bringing a couple days of unsettled weather.

All the models are consistent showing two rounds of precipitation. The first arrives early Friday and departs by evening. You can see that wave of energy and its rain on the GFS below.

With easterly winds, clouds and occasional rain Friday is going be a very chilly day by mid-May standards. The GFS has 40s for highs. Probably a bit low but at the very best only low to mid 50s for my local area.

So basically Friday is a worthless day for the time of year and I'll leave it at that.

Saturday things get more interesting. The latest trend in models is to take the surface low and warm front that was to the south Friday and bring it into Iowa Saturday afternoon. That brings a significant surge of warmth and moisture into the region. Highs will go up more than 20 degrees from Friday with readings surging into the 70s by late afternoon.

Dew points are pegged in the mid to upper 60s.

The new found warmth and moisture will contribute to respectable instability with CAPE values over 2,000j/kg.

Showers and thunderstorms will herald the arrival of the warm air late Friday and early Saturday. After a break mid-day a low pressure and cold front swings into the region late Saturday. With the instability in place the possibility of strong storms will exist from eastern Iowa into northern Illinois. You can see the set-up below at 7pm Saturday.

Just exactly where and how widespread the storms will be on Saturday is still in question. The track and timing of the surface low and cold front will play an important role in the eventual outcome. More on that in the next post.

With multiple rounds of precipitation rainfall totals have the potential to be generous. Between now and Sunday morning 1-3" rains are possible over much of the central Midwest. The EURO shows this for total precipitation.

The GFS has this.

Finally, the rain leaves the forecast for the second half of the weekend. With some passing clouds, highs on Sunday will hold in the 60s. That's just the beginning of a cool pattern that means no more 80s in my area until perhaps the beginning of June. Have a terrific Friday and role weather...TS