CHANGING OF THE GUARD...
The atmosphere is in the process of realigning itself. That means the pattern is in flux. During times such as this the weather becomes unsettled and at some point, we typically see a significant change in the jet stream which generally results in a sharp temperature change. In this case, we are transitioning from record highs in the 90s last week to readings that will not get out of the 50s Saturday. More on the changing of the guard coming up.
Focusing on the present, unsettled weather has prevailed in the form of clouds and spotty showers since early Tuesday. Some lingering light showers or sprinkles will continue into Wednesday morning but in most case will be nothing more than a nuisance. Gradual clearing spreads in during the afternoon allowing enough sunshine to get highs into the upper 60s to low 70s (perhaps mid 70s south). Actually close to seasonal norms.
Thursday a warm front surges through the region allowing a quick burst of warmth, some humidity too (especially in the south). Highs are likely to reach the low to mid 80s. The EURO, my preferred solution shows this for highs.
Models go off the rails just a bit Thursday night when the GFS brings a cold front into the area much quicker than the EURO. That allows the front to work on the CAPE (instability) that builds up during the day.
As a result, the GFS brings some active storms into the far north later Thursday evening and night. Some are shown producing decent rains and perhaps a couple marginally strong storms, especially in my far northern counties. SPC shows a slight risk of severe storms just to the west Thursday afternoon and evening.
However, the EURO is much slower with the front bringing it in Friday morning. By then the instability is limited due to a lack of heating. So much so that the EURO doesn't scare up any showers or storms Thursday night or Friday and looks far different than the GFS, especially in the north. Here's the difference in rainfall totals between the two models.
The only way I could see the GFS being correct is if its faster speed is correct. However, most other models are slower and the consensus easily lends itself to the drier EURO solution. Therefore, I like what the EURO is advertising and I'm currently anticipating a dry frontal passage Friday.
The speed of the cold front also impacts temperatures Friday. With the cooler air arriving faster on the GFS, it's keeping temperatures in the low to mid 70s.
The EURO is significantly warmer, especially in the central and south where it pops mid to upper 80s before cooling late in the day. Again, since I'm siding with the slower EURO I think it ends up closer to reality.
THE BIG CHILL...
Once the cold front is through Friday night temperatures begin to nose dive allowing lows to reach the mid 40s NW to the mid 50s SE. Saturday starts frisky.
Saturday morning another surge of cold air arrives from the northwest where it merges with the elongated trough situated in Illinois. That provides the forcing for clouds and showers. During the day temperatures will move little and if the GFS has its way, highs may not get out of the 40s in the NW third of my area (that would challenge records for coolest maximum highs). Low to mid 50s are found elsewhere. Talk about an ugly day. Here's what the GFS shows.
The EURO is more in the mid to upper 50s which is still a very cool day. For perspective, the Saturday departures.
Sunday should at least see a mix of sun and clouds allowing highs to make it back into the upper 50s to perhaps low 60s south. Not a bad day if it were 2 months earlier!
Next week is the lead up to Memorial day weekend and I still think the signs are there for a good warm-up just in time for the holiday. Here's what the EURO see's for highs Saturday through Memorial Day itself.