The GFS’ track of the late week low-pressure system.

Point Forecast:

O’Hare

Today:  38/28, Snow ending, clouds breaking during overnight hours.

Tomorrow:  48/36, Partly sunny.

Wednesday:  61/47, Partly cloudy, possible rain shower overnight.

Thursday:  68/48, Partly sunny, possible rain shower overnight.

Friday:  70/50, Cloudy to partly cloudy, thunderstorms possible.

Rockford

Today:  38/28, Snow ending, clouds breaking during overnight hours.

Tomorrow:  46/33, Partly sunny.

Wednesday:  58/43, Partly cloudy, possible rain shower overnight.

Thursday:  66/45, Partly sunny, possible rain shower overnight.

Friday:  68/44, Cloudy to partly cloudy, thunderstorms possible.

Quad Cities

Today:  41/28, Snow ending, clouds breaking during overnight hours.

Tomorrow:  47/34, Partly sunny.

Wednesday:  62/44, Partly cloudy, possible rain shower overnight.

Thursday:  68/51, Partly sunny, possible rain shower overnight.

Friday:  69/50, Cloudy to partly cloudy, thunderstorms possible.

Discussion:

Mother nature needs to get her months right.

As most of you saw, snow graced us last night.  Ratios were rather impressive given the amount of liquid, and in areas we saw it fluff up to over 2”.  The snow at least should be rather temporary as we see temps get above freezing this afternoon.  And, the best news of this abysmal spring, temps should warm considerably thanks to strong warm air advection due to a strengthening low-pressure system in the Plains.  After high pressure moves off to our south tomorrow morning, we will begin to see WSW winds take over, and temps tomorrow appear to be heading for the mid-upper 40’s.  During the overnight hours tomorrow, temperatures don’t appear to drop much, thanks to some cloud cover and warm air advection.  During the day Wednesday, we should see the warm front push into southern WI, and temps should jump nicely into the high 50’s and lower 60’s.  There will be a weaker low-pressure system approaching the Midwest during the overnight hours on Wednesday and into Thursday morning, and we could see some light rain in the most northern portions of the state, but for the vast majority, it will likely be dry.  Even though the attendant cold front will pass through, temperatures will not be affected, as another low-pressure system in the plains follows closely.  Warm air advection with the next system appears to be even stronger, as thermal profiles indicate 35kt SSW winds at 850mb south of the warm front in south-central IL.  On Thursday, we should see temperatures in the mid-upper 60’s for the vast majority of northern IL.  The true warm front does not appear to advance beyond I-80 until later Friday at some point.  Guidance differs some on the speed at which this low-pressure system ejects into the plains.  The GFS is quicker than the GEM, and Euro with regards to this.  Friday appears to make it into the lower 70’s.  And Saturday will continue the trend of warmth, aside from more robust surface winds as the low-pressure system moves into/near Iowa.

For the long-range:  it does appear that we have entered a pattern more reminiscent of Spring.  But, I would not discount the possibility of a colder pattern re-establishing itself in May.

Arctic Oscillation (AO) depicting a change in high-latitude blocking, but also showing a trend to a towards a more negative solution later in the month.