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  • Tim McGill

Cooling Off After A Very Warm Start To October

Cooler For A Couple Of Days

Friday's high of 62° was only one degree below the average high for the middle of October but compared to the first two weeks of the month, it felt downright chilly. We just saw the second warmest first two weeks to October on record. Since the low Friday was 6° above average, overall the day ended up above average for O'Hare. Yesterday marked the 20th straight above average day.

It was a cold and crisp start to Saturday as we woke up to the coldest temperatures since late May. Aurora dropped to 38° this morning. Morris dipped to 39°. The cold spot was Rochelle with a low of 36°. O'Hare's low was 44°.

Today's highs may fail to get out of the 50s in some spots. If we don't make it to 62°, it will be the coolest day in over four months.

Average highs for today's date are around 62°. The GFS Model has our highs today topping out in the upper 50s to near 60° even with wall to wall sunshine.

The average low for this time of the year is around 45°. The GFS Model has our temperatures tumbling again tonight with lows falling into the lower to middle 40s for most of the area. It isn't out of the question for a few spots well northwest of Chicago to drop into the upper 30s.

Sunday should be sensational. A lot of sunshine with milder temperatures will make it a fantastic day for football at Soldier Field. The GFS Model has our highs bouncing back into the middle 60s.

The warm up continues through early next week. Our highs will climb to near 70° with the help of plenty of sunshine according to the GFS Model.

We may even warm a degree or two more by Tuesday. The GFS Model temperature anomaly forecast pushes our temperatures up between 12° or more above average. With an average high for Monday of 62° that would mean highs in the lower to middle 70s.

After highs today just a bit below average we recover tomorrow with highs just a bit above. Another seasonably cold night with lows in the lower to middle 40s for most of us but a few upper 30s possible well northwest of the city.

Winds will be breezy this weekend with gusts today near 30 mph and near 20 mph Sunday.

Wall to wall weekend sunshine with no chance of any rain.

Warming Through Wednesday

We should warm through the middle of next week before a possible dramatic drop in temperatures. The National Blend Of Models has our highs soaring into the middle 70s by Wednesday. It then has our highs falling into the upper 40s by a week from today.

Our longer range temperature outlooks suggest near normal temperatures overall at first then shifting back above average towards the end of the month. The 6-10 day outlook has us favored for about average temperatures overall from October 21st through October 25th. The longer range 8-14 day forecast favors us for above average temperatures from October 23rd through October 29th. Average highs for this period are in the upper 50s to lower 60s.

Despite anticipating a few periods with cooler than average temperatures, the even longer range forecast keeps us milder than average overall through the middle of next month. The longer term 35 day temperature anomaly forecast still has most of the Midwest warmer than average overall for the next five weeks. We are outlooked to be between 1° to 3° above average overall for the period from October 13th through November 17th. The Global Ensemble Forecast System (GEFS) is a weather forecast model made up of 21 separate forecasts, or ensemble members The model tries to give an idea of the amount of uncertainty in a forecast by running an ensemble of multiple forecasts which are each tweaked a bit with their initial conditions.

Drying Out

O'Hare now has a surplus of .46" of rain above average for the month of October after .02" of rain fell there yesterday. O'Hare is still down 1.5" of rain below average since the start of September.

13 of the first 15 days of the month have recorded rainfall. After an active pattern the last several days it appears we will dry out for at least the next four days.

The most recent US Drought Monitor analysis was released Thursday. It reflects the benefit of our recent rainfall. Here is a recap from Friday's post:

The ongoing drought in northern Illinois was dealt a blow over the past week or so. Some serious rain put a significant dent in the drought. I have more details on the status of the drought further down in my post. The drought started back in the middle of April and arguably had two peaks. One was in the middle of June when nearly 3% of the state was in at least an extreme drought (level 3 out of 4). The second peak occurred just last week when the worst level of drought actually decreased but nearly 16% of the state was in at least a moderate drought, the highest point so far this year.

The areas in at least a moderate drought (level 1 our of 4) dropped nearly 28% while the area in an at least a severe drought (level 2 out of 4) decreased a whopping 86% from last week's analysis. We no longer have any part of the state in an extreme or exceptional drought (levels 3 and 4 out of 4).

The side by side comparison of this week's Illinois drought map next to last week's helps to visualize the improvement we have seen in just seven days time.

Here is a summary of the impacts the ongoing drought is having on northern Illinois from the National Weather Service:

Volunteer observers across far northern Illinois indicate much lower then typical stream flows on area creeks and rivers, particularly along Beaver Creek and the Kishwaukee River.

Reports also indicate that lawns have gone dormant and there has been some stress to the trees. Few impacts to agriculture have been received recently, though the dry conditions and stressed crops have resulted in an early start to the harvest season across northern Illinois. Data available from the Illinois State Water Survey, USGS, and NCEP indicate that soil moisture, groundwater, and surface water levels remain below normal.

The drought news for the entire Midwest was good too. The areas in every level of drought decreased since the last update.

The drought rainfall deficit has diminished over the past week or so. Most of northern Illinois has received between 150% to 300% of average rainfall during the period with a few spots getting as much as 400% to 600% of average.

The GFS model's meteogram for O'Hare keeps us dry through the middle of next week. The next decent chance of rain doesn't come until late Wednesday into Thursday.

It may have been a moist start to the month but models are now hinting that are pattern will become more dry. The GFS model's total precipitation forecast through next weekend only squeezes out about two tenths of an inch to a quarter of an inch of rain.

The longer range precipitation outlooks suggests rainfall might not be as abundant for the end of this month. The latest 6-10 day forecast has the Chicago area favored for below normal rainfall from October 21st through October 25th. The longer range 8-14 day forecast has us outlooked for below average precipitation from October 23rd through October 29th too.

Here is my 7 day forecast:

Today: Mostly sunny, breezy & cooler High: 60

Sunday: Sunny skies Low: 44 High: 67

Monday: Mostly sunny & mild Low: 48 High: 71

Tuesday: Mostly sunny Low: 53 High: 72

Wednesday: Partly to mostly sunny Low: 54 High: 71

Thursday: Partly to mostly cloudy, sct. showers possible Low: 48 High: 64

Friday: Partly to mostly sunny Low: 47 High: 59


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