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  • Tim McGill

A Fall Feel To Early May

Cool Pattern Continues

Meteorological summer is just a little over three weeks away but for the next several days it is going to feel more like fall. Average highs this time of the year are around 67° and by the middle of the month the average highs hit 70°. We will probably be below average at least through next Thursday.

Not only will we remain cooler than average well into next week there is even a chance for some light frost by Saturday morning.

Today's highs will fail to get out of the 50s. A northerly breeze will keep us around 10° to 15° below average. Look for highs away from the lake to top out in the middle 50s but just lower 50s along the lakefront.

A northerly breeze will kick in this afternoon after a cold front crosses through the area. The wind shifts a little more northwesterly Friday. These brisk breezes will keep us much cooler than average with highs today and Friday in the 50s.

There will be a couple of days within the next seven that see highs near 60° but we remain well below average through next Wednesday. The good news is that just beyond this forecast we should be warming up to at least near 70°.

There is a risk of frost Friday night into early Saturday morning. Skies should be clear Friday night and if the winds lighten up enough, we could see lows dip into the middle 30s north and west of the city.

Sorry Moms but Mother's Day will feel more like late March than early May. The temperature anomaly forecast for Sunday afternoon keeps us about 15° to 20° cooler than average. Highs Saturday may only reach into the lower 50s.

More May Rain Needed

Some light rain will fall at times today especially early but more significant rain is needed to put a real dent in the drought. We are now just under 5" below average for rainfall since the start of spring on March 1st. The GFS model shows a few chances for rain between today and this weekend. After our light rain this morning there could be a few showers redeveloping this afternoon. A few more instability showers may dot the area Friday afternoon. There is also a chance for rain mainly south of the city Saturday night into Sunday.

The GFS model total precipitation accumulation forecast for this first round of rain today and tomorrow suggests as little as about a tenth of an inch of rain south of the city to as much as a half inch north of Chicago in total. While this will be welcome rain, we will need much more to help with the moderate drought much of the area is experiencing.

The National Weather Service had this to say about our low soil moisture:

"Soil moisture values in northern Illinois, especially areas closer to the Chicago metro, have been dropping quickly over the last few weeks. Measured soil moisture in the 8 inches nearest the surface at Freeport and St. Charles, for example, has dropped from near average values in early April to very rare low levels by late May. South of the Chicago metro area, precipitation has kept near surface soil moisture slightly higher, but deeper soil moisture is much lower due to longer-term dry conditions."

Break From Cool Pattern Coming?

The longer range temperature probability forecasts signal our relatively cooler pattern could be coming to an end towards the middle of May. The latest 6-10 day forecast has us outlooked for cooler than average temperatures overall from May 11th through May 15th but there is hope for a warm up or at least a return to near normal just beyond that period. The 8-14 day temperature probability forecast has us favored for returning to about average temperatures overall from May 13th through May 19th. Average highs for the middle of May are around 70°.

The even longer range Subseasonal Experiment (SubX) temperature anomaly forecast is signaling a cooler than average pattern for the last two weeks of May. The temperature anomaly forecast for the week ending May 21st has us outlooked to be below average overall. The forecast for the following week ending on May 28th has Chicago below average overall too. Average highs for this period are in the lower to middle 70s.

More Active Pattern Later In May Possible

The longer range precipitation probability forecasts are a mixed bag. The first of the two longer range forecasts have us outlooked to see a continuation of the dry pattern we have been in recently. The latest 6-10 day has Chicago favored for below average precipitation from May 11th through May 15th. The longer range 8-14 day forecast though has us favored for above average precipitation overall from May 13th through May 19th.

Here is my 7 day forecast:

Today: Showers early then partly sunny with pm sct. showers High: 56 (52 lakeside)

Friday: Partly/mostly sunny, spotty pm shower possible Low: 42 High: 59 (cooler lakeside)

Saturday: Partly to mostly sunny Low: 38 High: 59 (cooler lakeside)

Sunday: Mostly cloudy, scattered showers mainly south Low: 43 High: 54

Monday: Partly to mostly sunny Low: 41 High: 57 (cooler lakeside)

Tuesday: Partly to mostly sunny Low: 40 High: 62 (cooler lakeside)

Wednesday: Partly to mostly sunny Low: 42 High: 64 (cooler lakeside)



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