Christmas facts

This dataset shows that the most frequent range of high temperatures on Christmas is in between 30 and 39 degrees. The normal high for Christmas at Chicago is 32 degrees, which falls in the most frequent range. The highest temperature recorded on Christmas is 64 degrees set in 1982. The coldest high temperature on Christmas is -5 degrees which occurred in 1983. Last year, the high temperature was 42 degrees, which is in the 3rd most common range of high temperatures.



This dataset shows that the most frequent range of low temperatures on Christmas is in between 20 and 29 degrees. The normal low temperature on Christmas in Chicago is 17 degrees. The lowest temperature recorded on Christmas is -17 degrees which occurred in 1983. The highest low temperature for Christmas was 46 degrees in 1936. Last year, the low temperature was 21 degrees, which is in the most common range of low temperatures.

A Major Winter Storm on the way

Nam 12Z 850mb heights, temp. and wind

Nam 12Z Precipitation (by midnight), 850mb temps. and MSLP




After dumping a record 3-6 inches in Las Vegas yesterday, a major winter storm with snow, ice and thunder is on the way. They say what happens in Las Vegas stays in Las Vegas, but unfortunately this storm is headed east bound and we are right in its track. Major forecast challenges continues as whether we will see a major snow storm or a major ice storm. Either way its going to be a mess especially for Friday's morning commute. It seems the axis of major snow/ice is along the I80 corridor. North of I80 will see more snow than frezing rain. South will see more freezing rain than snow. A Winter storm warning has been posted for the Chicagoland area. However, our neighbors just to our south in Kankakee are under an Ice storm warning. Upwards to 8-14 inches is expected along the Illinois/Wisconsin border. 5-9 for the city and west suburbs, 3-8 for the south suburbs (south of I80 3-6 inches), and 0-3 inches Kankakee and south where ice storm warnings are posted where they could see ice accumulations exceed 0.5 inches. The line of heavy snow and ice will be very sharp. The energy from this system will have enough for some convection meaning thunder snow/freezing rain. 1-2 inch per hour snow rates will fall overnight. This is all due the surfacebeing below 32 degree farenheit. This storm system will provide winds fron the south to warm the mid levels of the atmosphere to above freezing. This setup is for a classic freezing rain/ice storm event. The further south the more warm air advection. This is why there is an ice storm warnign for the counties south of us. Now, there is great concern that the towns along, just north and just south of I80 could see an overlapp of snow and ice. This means that there could be ice accumulations of 0.25-0.5 inches then snow accumulations of 3-8 inches on top of that.

2008; Chicago's 2nd wettest year.

After a record breaking September that totaled 13.63 inches of rain for the month, a record single day rainfall total of 6.64 inches on from September 13 to September 14, December 9th with precip of nearly an inch and a half (1.47") pushed us into the second wettest year on record. The wettest year on record was set in 1983 with 49.35 inches. So far this year (our 2nd wettest year) we have 47.11. You have to think with 3 weeks in December still left that number likely will increase.

Below is a list of the top 10 wettest years!

Rank Year Precipitation
1 1983 49.35
2 2008 47.11
3 1970 46.09
4 1954 45.92
5 1883 45.86
6 2001 45.77
7 1993 44.90
8 1982 44.68
9 1885 44.37
10 1957 44.29

First snow

Well here it is November 29, 2008. Our first significant snowfall of the season is upon us. After last weeks Winter Weather Preparedness week, our first winter weather advisory has been issued for the Chicago area. A general 3-6 inches of snow is expected by Monday morning. With tomorrow and Monday expected to be the biggest travel days, hundreds of cancellations and delays are anticipated affecting hundreds acroos the country. Behind the system, temps will fall into the mid 20s by Monday evening with low tuesdy morning in the upper teens. With a brisk NW wind 15-20 mph wind chills will feel like the lower teens. Blowing and drifting snow will also be a concern.

Reporting and Weathercasting

Chroma-Keying.

Chicago stats for Thanksgiving

Below is a frequency distribution of high and low temperatures in Chicago. Note: The temperatures are a 136 yr data set from 1873 to last year (2007).



The most frequent range of high temperatures on Thanksgiving is in between 40 and 49 degrees. The highest temperature recorded on Thanksgiving is 69 degrees set on November 24th, 1966. The coldest high temperature on Thanksgiving is 14 degrees which occurred on November 27th, 1930 which also is the last time we were below 20 degrees. Because Thanksgiving doesn’t always occur on the same day, there is really no normal high, but the normals for around this time of year is in lower 40s (Highs) and the upper 20s (Lows). Last year, the high temperature was 33 degrees which is in the 2nd most common range of high temperatures. This Thanksgiving is forecasted to fall in the 40-49 range (the most frequent range).



The most frequent range of low temperatures on Thanksgiving is in between 30 and 39 degrees. The lowest temperature recorded on Thanksgiving is -1 which occurred on November 23rd, 1950 which happens to be the only time we had a temp. below zero and the last time we dropped below 10 degrees. The highest low temperature for Thanksgiving was 57 degrees in 1896. The last time our low temperature was over 50 degrees was November 24, 1966 with a low temp of 54. Last year, the low temperature was 25 degrees, which is in the 2nd most common range of low temperatures. This year, Chicago is expected to fall in the 30-39 category (also the most frequent).

**Winter Weather Preparedness Week!!!**

This week November 16 thru November 22nd is Winter weather preparedness week for Illinois and Indiana. Throughout this week as we get ready to prepare for the winter season, I will supply you with winter weather facts, tips, and terms.



Winter Weather Definitions:

Winter Storm Watch - Conditions are favorable for hazardous winter weather conditions including heavy snow, blizzard conditions, or significant accumulations of freezing rain or sleet. These watches are usually issued 12 to 36 hours in advance of the event.

Winter Storm Warning - Hazardous winter weather conditions that pose a threat to life and/or property are occurring, imminent or likely. The generic term, winter storm warning, is used for heavy snow of 6 inches or greater, heavy sleet of half inch or more, or a combination of two or more of the following winter weather events; heavy snow, freezing rain, sleet and strong winds. The following event-specific warnings are issued for a single weather hazard:
• Blizzard Warning - Sustained winds or frequent gusts of 35 mph or greater, considerable falling and/or blowing snow reducing visibility frequently to 1/4 mile or less for a period of three hours or more. There are no temperature criteria in the definition of a blizzard but freezing temperatures and 35 mph winds will create single digit wind chills.
• Lake Effect Snow Warning - Lake effect snowfall of 6 inches or more in 12 hours or less, or 8 inches or more in 24 hours or less.
• Ice Storm Warning - Accumulations of 1/4 inch or more of freezing rain.

Winter Weather Advisory - Hazardous winter weather conditions are occurring, imminent or likely. Conditions will cause a significant inconvenience and if caution is not exercised, will result in a potential threat to life and/or property. The generic term, winter weather advisory, is used for a combination of two or more of the following events; snow, freezing rain or drizzle, sleet, blowing snow.

Wind Chill Warning - Extreme wind chills of -30oF or colder.
A Wind Chill Warning is issued when the wind chill will be less than or equal to -30oF AND winds greater than or equal to 10 mph.

Wind Chill Advisory - Dangerous wind chills of -20oF to -30oF.
A Wind Chill Advisory will be issued when the wind chill is less than or equal to -20oF AND the winds are greater than or equal to 10 mph.

Lake-Effect clouds and showers today; More rain by the end of the week

North winds riding along a 30 mile stretch of lake plus warmer waters (60+ degree water temp.) brings lake-effect showers today. But with high pressure moving in and a fairly dry airmass in place, precipitation will be scatterred and light. With increased ridging and subsidence, the lake effect showers should turn off by late afternoon. However, the clouds will still linger until the winds finally diminish later on this evening.



Of increasing concern is the potential for a wet weekend and even a cooler start to the work week next week. We get a break from any wet weather later on tonight through Thursday, but Thursday night is when we can see some rain. High pressure takes over later tonight and for the next couple of days but there is an ever so slow moving low out to our west (in the Rockies) that is expected to makes its way here late Thursday/Friday. Once here, this low will bring rain lasting though the weekend. As far as temps. are concerned, Autumn has a pretty good grip on us for at least the next week. Highs will remain in the low to mid 50s for the week. Possibly even cooler temperatures early next week with forecasted highs in the upper 40s. This is the result of the buckling of the jet stream by weeks end forcing us in a northwest flow pattern.





Wednesday Decreasing clouds; becoming mostly sunny
High 56
Low 40

Thursday Sun to clouds; Rain late
High 55
Low 47

Friday Rain likely
High 55
Low 45

Saturday Rain likely
High 54
Low 45

Sunday Decreasing clouds; Clouds to sun
High 50
Low 35

Monday Partly Cloudy
High 48
Low 34

Tuesday Partly Cloudy
High 51
Low 38

Midweek rain ahead of a late week warmup

Much of the area enjoyed highs in the upper 60s/lower 70s yesterday (an official high of 69 degrees at O'Hare 3 degrees above normal). Today similar conditions expected with forecasted highs in the mid to upper 60s. I'm forecasting for a high of 67. Our normal for this time of year is 66 degrees. However, there is rain with isolated thundestorms on the way. The rain should make its way here sometime early this afternoon from south to north lasting through early Wednesday. Heaviest rainfall should be just south of the city where there is a greater amount of moisture in the atmosphere. The heaviest shoudld fall between 6pm CDT thru mindnight tonight. With a weak cold front to advance, temperatures are not expected to fall much. In fact Wednesday we should see highs around normal. A ridge out west will follow surging temperatures into the 70s. Friday we should see the warmest weather in October with temperatures in the mid 70s (10 degrees above normal).

Temps. rebound; Wet weather on the way

After a quiet week with temperatures only in the 60s, the high today reached 72 today and for the remainder of the week temperatures will range from the upper 60s to the lower 70s. The remnants of a strong storm system that dumped 10-20 inches of snow in the mountains of Colorado (currently in the plains) will give us showers and storms Tuesday and Wednesday. Ahead of this storm system, winds are out of the south providing us with pretty mild weather.

Autumn's first cool push of air

Say goodbye to summer and hello to autumn as this week (our 2nd week into the season) will really have a fall like feel. It was just last week where we were talking about temperatures in the 80s. Now we're talking about waking up to temperatures in the 40s and highs struggling to make it out of the 50s. Our first major push of cold air comes in and comes in with a bang. With a trough locked in place, many cities across the upper Midwest and Northeast will certainly feel the effects.

Chicago forecast for the week

Want to start off by mentioning that today is officially our first day of Autumn. At least another week for us to enjoy tranquil summerlike weather here in Chicago. Sunny, dry, and warm conditions continue to prevail with temperatures in the upper 70s/lowers 80s for the week.

Chicago's Climate

For those of you that may or may not be into weather/climate and just want to check out some climate facts about the city of Chicago in general or maybe for a future visit...here are some facts about Chicago's climate.

Climate for Chicago, Illinois
Home : Climate Graphs: Illinois : Chicago
Average Temperatures for Chicago
Average Temperature for Chicago, Illinois

Month Low High
Jan 14.3°F 29.6°F
Feb 19.2°F 34.7°F
Mar 28.5°F 46.1°F
Apr 37.6°F 58.0°F
May 47.5°F 69.9°F
Jun 57.2°F 79.2°F
Jul 63.2°F 83.5°F
Aug 62.2°F 81.2°F
Sept 53.7°F 73.9°F
Oct 42.1°F 62.1°F
Nov 31.6°F 47.1°F
Dec 20.4°F 34.4°F

Chicago's coldest month is January when the average temperature overnight is 14.3°F. In July, the warmest month, the average day time temperature rises to 83.5°F.
Average Rainfall for Chicago
Average Rainfall for Chicago, Illinois

Month Precipitation
Jan 1.75in.
Feb 1.63in.
Mar 2.65in.
Apr 3.68in.
May 3.38in.
Jun 3.63in.
Jul 3.51in.
Aug 4.62in.
Sept 3.27in.
Oct 2.71in.
Nov 3.01in.
Dec 2.43in.

The driest month in Chicago is February with 1.63 inches of precipitation, and with 4.62 inches August is the wettest month.
Monthly Sunshine Hours
Percentage of Sunshine for Chicago, Illinois

Month Sunshine Hours
Jan 44%
Feb 49%
Mar 51%
Apr 50%
May 58%
Jun 67%
Jul 66%
Aug 62%
Sept 59%
Oct 55%
Nov 38%
Dec 43%

Sunshine hours refers to the amount sunshine there is during the hours of daylight. A higher percentage means there is more sunshine through the day and a lower percentage will indicate that it is probably cloudier. Sunshine hours are important when you are planning your vacation.

August 4th 2008 Tornado and High Wind Event

On the evening of Monday August 4 2008 a total of 5 tornadoes were confirmed by the National Weather Service. Below is a list of the tornadoes, where they hit, and how strong they were on the Enhanced Fujita (EF) scale.

* Griffith, IN, rated EF2
* Bloomingdale, IL, rated EF1
* Bolingbrook, IL, rated EF1
* Orland Park, IL, rated EF0
* Boswell, IN, rated EF0

The stage was set for a severe weather outbreak Monday. With a strong southerly flow out of the south, the mercury climbed into the 90s ranging from 90-95 degrees across Northern Illinois and Northwest Indiana. Combine that with dewpoints in the upper 60s/lower 70s and heat indices were ranging from 100-105. In fact some areas just to the south and west of Chicago were prompted heat advisories till 8pm CDT Monday evening. In addition, the atmosphere was very unstable as was confirmed by several severe weather indexes. With so much potential energy in the atmosphere, all needed was a lifting mechanism.

Around 6pm CDT that evening, thunderstorms started to form in far Northwest Illinois. This cluster of thunderstorms that effected us on Monday is described by many as a Multiple Convective System or MCS. This basically is a continuous line of long lived thunderstorms that can span many miles for several hours. This is characterized by upper level winds that orient themselves in a northwest flow pattern and allow waves of energy (disturbances) to travel the region. Once the storms reached Winnebago and Ogle counties, the line of storms started forming a bow shape (Bow Echo) to it. This signifies that there are strong winds developing from the storms. In addition with these storms was the presence of a low level circulation. These circulations are generally near the leading edge of a line of storms but north of the bow apex. They help to produce brief spin ups or non major tornadoes (anywhere from an EF0 to an EF2). The first image above is a radar image at 745 PM of the Mesoscale Convective System which was in its mature bow echo stage as it moved through Cook, Dupage, and Will counties. The second one is a radar Image at 758 PM displaying the very strong winds associated with the Bow Echo. Cool colors (green) represent inbound winds toward the radar and hot colors (red) represent winds away from the radar. Note the dark blue and purple colors in Kane county. Radar indicated possible winds near 90 MPH across this location at this time.

Now also to mention was the frequency of lightning as we reported over tens of thousand lightning strikes that evening. I have a video showing the spectacular display.

Chicago Flood 2008

On September 13th 2008, 6.64 inches of rain fell in Chicago. This broke the old record for the maximum rainfall in a day of 2.26 inches set back in 1936. This also breaks the amount of rainfall to fall in a 24 hour period in Chicago history dating back from when records started being recorded in 1871. The old record was 6.49 inches set back in August 14 1987. No one will forget anytime soon the three day rain event (from September 13 to September 15 2008) that flooded so many homes, roads, and rivers. By Sunday night, much of Northern Illinois including the Chicago metro area and Northwest Indiana received a total rainfall accumulation between 6 to 10 inches. Heres the doppler radar showing the storm estimates from the weekend flooding.

Not minor, but major flooding took place. Many of the main rivers shattered old records by several inches. Homes were completely destroyed and several roads had to be abandoned. Here is a list from NOAA of rivers that reached record levels.

***River Crests for Select Locations in northeast Illinois and northwest Indiana

The following is a list of preliminary crest data for select river locations. Some rivers have not yet crested. This data may be updated or corrected as new crest information is made available. To get more information on each data point, go to our Advanced Hydrologic Prediction Service (AHPS) webpage.

Last updated 9/16/08


Location

Flood Stage
Crest (ft) Remarks
HART DITCH
Dyer 15 16.76 9/14/2008 New record. Previous record was 15.66 on Aug 24, 2007
Munster 6 12.81 9/14/2008 New record. Previous record was 9.22 on Aug 24, 2007

LITTLE CALUMET RIVER
Munster 12 17.31 9/14/2008 Record crest. Previous record was 15.66 on Nov 28, 1990
South Holland 16.5 20.16

DES PLAINES RIVER
Des Plaines 5 10.00 9/14/2008 Second highest crest on record.
Riverside 7 9.86 9/14/2008 Second highest crest on record.

FOX RIVER
Dayton 12 21.55 9/15/2008

ILLINOIS RIVER
Morris 16 24.84 9/16/2008

Record crest. Previous record was 23.91 on July 14, 1957
LaSalle 20

33.64 9/16/2008


River still rising. Record crest. Previous record was 32.05 on Dec 5, 1982

KANKAKEE RIVER
Shelby 9 13.06 9/16/2008

Record crest. Previous record 12.98 on Mar 24, 1982. River still rising.
Mommence 5 7.00 9/15/2008
Wilmington 6.5 8.68 9/15/2008

VERMILION RIVER
Leonore 16 24.29 9/15/2008 Third highest crest on record.***