Historical Chances of a White Christmas

Courtesy: IL State Climatologist

If you're wondering what the odds of a white Christmas are across the Stateline and the entire state of Illinois, at left is a map that will give you some insight. (With this graphic, a white Christmas is defined by having at least 1" of snow on the ground on December 25th.)

From 1971 to 2000, the average chance of a white Christmas in Rockford was 43%. In Freeport, it is significantly higher at 56%. For more information, see this article by Dr. Jim Angel.

Near-Record High Today!

You wouldn't know it if you were outside during the daylight hours today, but we nearly tied a record high temperature in Rockford this morning! Just before a cold front reached the area in the wee hours of the morning, the Rockford airport's temperature hit 56 degrees. (The record high for this date is 58 degrees, set back in 1971.) Of course, temperatures dropped from there as that cold front continued eastward and gusty west-northwest winds bought more seasonable air into the Stateline.

What a difference a year makes

If you were to look at a U.S. snow cover map from December 2010 and compare it to the current U.S. snow cover you would notice quite a difference.  This time last year we were dealing with several inches of snow and this year...none!  Places in New Mexico still have snow on the ground from recent storms.  While we have entered into another La Nina pattern the colder outbreaks have not been as frequent because the major storm track has been, for the most part, positioned from southwest to northeast.  This has left us on the 'mild' side of the jet stream.  Sure, we've had a few cold spells but temperatures have been running above average for awhile.  A big factor as to why it's been fairly mild and quiet is the fact that the NAO (North Atlantic Oscillation) has been positive - read more on the NAO here.  Last year, as with previous years, the NAO was negative which allowed more cold air to move south, keeping the storm track south and giving us the colder and snowier December.  This year the NAO has remained positive which keeps the jet stream further north not allowing the cold air to invade the southern states.  Unfortunately, it doesn't look like this pattern will break any time soon.

Temperatures continue to fall into the afternoon

Hard to believe temperatures around midnight were in the middle 50s!  "Not so bad" you may be thinking to yourself, but don't get too excited.  West winds and thick cloud cover will keep the temperatures falling through the 40s this morning and eventually into the low to mid 30s later today.  Wind gusts today could reach 30-35 mph keeping wind chills in the 20s. 

Rain Totals So Far

Here are some rain totals from across the Stateline so far through this evening. As you can see most of the heavy rain fell in areas to the south of Rockford, with even higher totals to the south and east of our viewing area.

Tonight we'll have to deal with some patchy drizzle and fog until a cold front pushes through the area sometime around 3am. This front will bring drier air into the region. Although a few more rain showers are developing in eastern Iowa immediately along this approaching cold front, additional rain totals should only amount to a tenth of an inch or less.

Dense fog will likely become more common this evening

A Dense Fog Advisory has been issued for Jo Daviess county until 6pm. 

Visibility less than a quarter mile will be common across parts of southern Wisconsin and northern Illinois.  Locally dense fog and scattered showers will continue tonight.  Expect the fog to last into the overnight and early on Thursday. 

Slow travel this morning: Rain and fog continue

Copious amounts of moisture have been pulled north this morning leading to anywhere between a half an inch to over an inch and a half of rainfall since the rain started late yesterday evening.  Heavier showers now passing through the Rockford Metro will continue east into Boone county with another band of heavier rain south of Dixon.  There have been a few thunderstorms noted south of Davenport this morning but those will continue east and not have an impact on us in the near term.

Low pressure will continue to develop in response to a strong upper level trough in the southwestern part of the U.S.  That low will lift out of Kansas and into Iowa by later this afternoon.  As it does, it will pull a warm front closer keeping the rain threat going - even though we may get a break from the rain here and there.  Also of note is a dry-slot just to our southwest which may aid in further development of rain and embedded thunderstorms.  While storms, should they develop, are not expected to reach severe limits they could produce small hail especially since they would remain elevated. 

Another issue this morning is the fog.  With all the moisture streaming northward the dew points have become very close to our temperature readings.  Dew points will continue to rise along with the temperature through the afternoon so the fog will likely stick around into tonight and some of it may become locally dense.  Be careful when driving this morning as the heavier rain showers have likely caused ponding on some of the roadways.

Here are a few rainfall totals so far from earlier this morning:
Rockford: 0.50"
Freeport:  1.05"
Rochelle:  1.64"
Dixon (weather watcher 6am): 1.2"