Turn up the Thermostat

November has been warm across much of the Midwest compared to what is "normal". I'd be willing to bet your electricity bill reflects the milder temperatures. I know mine has!

Temperature departure from normal across the Midwest.

Indiana:

• Bloomington +4.4°
• Indianapolis +4.6°
• Lafayette +4.6°

Illinois:

• Carbondale +3.0°
• Chicago +3.5°
• Moline +1.8°

Kentucky:

• Louisville +2.3°
• Paducah +2.9°

Missouri:

• Cape Girardeau +3.6°
• Chesterfield +3.9°
• Poplar Bluff +3.8°
• St. Louis +4.8°

We're getting close to the end of Meteorological Fall (September 1 - November 30) and the start of Meteorological Winter (December 1 - February 28). Temperatures in Fall 2011 will go in to the books above normal for just about everyone in the Midwest. But it appears that Mother Nature is aware that meteorological winter is just around the corner as it looks like colder air is on the way.

Forecast models are hinting at a change in the weather pattern starting as early as this weekend. The change in the pattern should bring a prolonged period of colder air to much of the country.

Before we get too excited about the cold air coming for the weekend, let me say that Thanksgiving and the day after Thanksgiving look to be nice. Winds will begin to turn out of the south Friday (it will be breezy) and temperatures will climb under mainly sunny skies.

A strong cold front is projected to move through the central United States starting Friday. Along the front, showers and thunderstorms will develop. Some of the rain could be heavy at times Saturday/Sunday (depending on where you live).

Once the front passes, winds will shift and temperatures will plunge. Here's a view of the weather setup for Sunday evening as advertised by NOAA's global forecast computer model (GFS).

According to the GFS, cold air will dive all the way to the gulf coast by Sunday evening. (Hint: Look at the blue 540 line.) This also indicates an upper-level low will develop and center over Missouri by Sunday.

With the low, low clouds will hang around. The clouds are indicated by the gray shading. Along with the clouds notice the model keeps some precipitation around Illinois, extreme eastern Missouri and western Kentucky. IF this precipitation lags behind the cold front and IF the temperatures drop as much as advertised much of this moisture would fall in the way of light snow.

The European Forecast Agency's computer forecast model is also hinting at something very similar. (See above) The slight difference in the European model holds off the moisture until Monday afternoon/evening. At this point, it is splitting hairs between the two models. The key is to see the trend of what the two models are showing and the trend is very similar.

At this point I'm not concerned with the amounts as it should be relatively light. But yes, there could be snow flurries and snow showers Sunday night through Tuesday morning. Again, this is nothing to get excited about. My "Freak-Out-Meter" is pretty low, less than a 1 (on a scale of 1-10).

The models keep the cold air in place all next week. Yes, the temperatures might warm up a little but I think we will likely be below normal during the stretch. This would make sense with my belief in the "Law of Averages". November was very mild, relatively speaking, so we are due for some below normal temperatures.

Let's have some fun now... Look waaaay out in to the future. The GFS allows us to look 384 hours in to the future (16 days). At the end of the forecast run it is hinting at a decent storm developing along the gulf coast.

Over running the storm is a moisture plume that extends as far north as Kansas City. The model also brings down some colder air on the back side of the storm that would likely interact with the moisture plume spreading north. IF this storm were to pan out this way, that's a BIG IF, southeast Missouri, southern Illinois and western Kentucky would likely start out as rain December 7 and eventually change over to a rain and/or snow mix by that night or early December 8. This would definitely bare watching if the model is right.

I should say that the model is not very good at depicting what is going to happen that far out in its run. The model is likely to take the storm out of the equation over the next several runs. In fact, what usually happens is the storm will show up once and then go away on all subsequent model runs. I just wanted to give you a "behind the scenes" look at some of the data meteorologists look at but don't always mention because we know it isn't likely to happen. But, as I like to say, "Stay tuned..."

A Few Storms Possible

The Storm Prediction Center is monitoring southeast Missouri, southern Illinois, western Kentucky and northeast Arkansas for the need of issuing a tornado watch.


According to SPC the threat appears to be isolated. It will depend on how many storms can get fired up in the next couple hours as to whether a watch will be issued.

A Tornado Watch is currently in effect for most of Indiana. That watch is in effect until 9pm ET.


- Posted from my iPhone

Storms Tonight

The Storm Prediction Center has placed all of southeast Missouri and portions of southern Illinois, western Kentucky and Arkansas in a "Slight Risk" area for severe thunderstorms in their latest outlook.


It appears the best chance for severe storms in southeast Missouri and southern Illinois would be later tonight.

There are still a few question mark for severe thunderstorms to develop.

We need to see the atmosphere destabilize. Right now the air mass in place is relatively stable. As the surface low currently over Texas/Oklahoma tracks northeast the low will deepen (become stronger). Ahead of the low, southerly winds should tap in to more humid air to the south.

Forecast models are indicating instability should move back north and allow the atmosphere to become unstable by tonight.

If the air mass can become unstable there will likely see a few thunderstorms moving east across Arkansas and Missouri.

The main threat appears to be damaging wind. I can't rule out the chance of a quick spin up tornado, especially close to the track of the surface low. The good news is that if there is a tornado it won't be like the long lived tornadoes seen in Oklahoma yesterday.

A couple things bother me about the setup... Cloud cover. Missouri is pretty well socked in with cloud cover. This is going to limit instability somewhat.

Timing... The storms would likely move in well after sunset. This will take away some of the spark in the atmosphere. That's not to say we couldn't see something after dark, I just think that storms will be on the downward trend of severity.

Bottom line...

• Will there be thunderstorms? Probably.
• Will there be a watch? Possibly.
• Will there be a severe weather outbreak? No.
• Could there be warnings? Yes, there could be a few.
• Should you freak out? No. Just keep an eye on the situation. Make sure you have your NOAA weather radio plugged in. Have a way to be alerted if a warning is issued for your location.

- Posted from my iPhone

Threat of Storms

We are less than 25 days from the start of meteorological winter but we need to be thinking about spring... spring storms.

I have talked about the chance for colder air moving south out of the arctic in the next week and a half. Ahead of the colder air it appears we will have a chance for strong thunderstorms across the middle United States.

The Storm Prediction Center has included parts of Missouri, all of Arkansas and places further south in a "Slight Risk" for severe weather 7am Tuesday through 7am Wednesday.


An area of low pressure is going to develop over New Mexico and Texas over the next two and a half days.


Strong winds in the jet stream will rotate around and provide lift in the atmosphere. By mid to late afternoon Tuesday I expect to see thunderstorms developing over eastern Oklahoma, western Arkansas and western Missouri. The thunderstorms should develop in to a line of storms that will move east across Missouri, Arkansas and further south.

I have been looking over the morning run of the GFS and NAM computer models. There are a few subtle differences between the models but both appear to be pointing at diverging winds at the 300mb level over southeast Missouri by Tuesday evening/night. The NAM keeps winds a little more divergent over Arkansas and the GFS keeps winds a little more divergent over southern Illinois.

Here is a look at one of the computer models. This indicates winds at 300mb (approximately 30,000 feet) 7pm CT Tuesday.


I look for divergent winds at 300mb because that gives an indication if there will be lift in the atmosphere. Diverging winds create a void and wind from below lift in to fill the void.

All of the above said, it looks to me there could be strong to severe storms along the line of storms as it moves through Arkansas and Missouri. It is still a little early to nail down the main threat from the storms but it damaging winds, isolated tornadoes and hail all could be possible.

Stay tuned...
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Daylight Saving has come to an end. Hopefully you remembered to change the times on your clock this morning.

Fire departments across the country use the time change as an opportunity to remind everyone to replace the batteries in your smoke detectors. This is good practice. I want to suggest you take it a step further and use the time change as an opportunity to replace the batteries in your NOAA weather radios.

ISS Sighting Tonight

There is another opportunity to see the space station tonight for part of the midwest. Unfortunately, it looks like areas in southeast Missouri, western Kentucky, Tennessee and Arkansas will have cloud cover obscuring the view.

The details:

Chicago:

• When: 6:42pm (local) - The space station will be visible for 5 minutes.
• Where: Look to the WNW sky. The space station will travel across the sky and exit to the SE. It will reach a height of 55° above the horizon.

Columbus, IN:

• When: 7:42pm (local) - The space station will be visible for 6 minutes.
• Where: Look to the NW sky. The space station will travel across the sky and exit to the SE. It will reach a height of 73° above the horizon.

Indianapolis:

• When: 7:41pm (local) - The space station will be visible for 6 minutes.
• Where: Look to the WNW sky. The space station will travel across the sky and exit to the SE. It will reach a height of 68° above the horizon.

Moline:

• When: 6:40pm (local) - The space station will be visible for 6 minutes.
• Where: Look to the WNW sky. The space station will travel across the sky and exit to the ESE. It will reach a height of 79° above the horizon.

St. Louis:

• When: 6:41pm (local) - The space station will be visible for 6 minutes.
• Where: Look to the NW sky. The space station will travel across the sky and exit to the ESE. It will reach a height of 65° above the horizon.

Skies will be clear for the areas listed above so it should be perfect conditions to see the ISS as it passes overhead.

It will initially look like a dim star but it will be moving like an aircraft.

Check it out and let me know if you see it. Leave a comment here on my blog. Enjoy!

Cold Air Building

It is the time of year when I like to start looking further out in the computer models. What am I looking for? I'm looking for cold air marching south through Canada and I am also looking for storms taking shape that can interact with the cold air. When the two play together, "fun things" develop.

For the last couple of days NOAA's Global Forecast model (GFS) has been advertising some cold air building and marching south out of Canada for mid-November. The latest run of the GFS (12z) continues to hint at the cold air coming.

Right now it looks like the cold air would come down in two shots. The first would arrive in the Midwest/Ohio River Valley sometime around November 13/14.


The second shot, and most likely the colder of the two, would arrive in around November 16/17. (The image above depicts the morning of November 16.) If the above image were to hold true, then I might have to use the "s" word for the first time this season. Yes, snow.

I should also add that the European Forecast Agency's computer model is also hinting at a shot of colder air coming down around November 12. At this point, it is splitting hairs between the two models. However, it is interesting that both models are hinting at something similar around the same time.

Don't get too excited just yet. This is a LONG way out in the computer models. There is a likely climatological bias in the models trying to bring in cold air to keep in mind. If I were a betting person, I would say the above scenario is not likely to happen this far in advance. However, it is something to keep an eye on. Especially if you enjoy colder weather.

Stay tuned...

U.S. Winter Outlook

The National Oceanic and Atmospheric Administration (NOAA) has released its winter outlook for 2011-2012. According to the forecasters, another La Nina will influence winter for the second year in a row.

La Nina returned in August and is expected to gradually strengthen and continue through the winter. It is associated with cooler than normal water temperatures in the tropical Pacific Ocean.

Forecasters also say there will be a wild card in play that will allow dramatic short-term swings in temperatures this winter. The wild card is the Arctic Oscillation.

Here is an explanation of the Arctic Oscillation from the National Snow and Ice Data Center (NSIDC)...

The Arctic Oscillation refers to the opposing atmospheric pressure patterns in the northern middle and higher latitudes. The oscillation exhibits a "negative phase" with relatively high pressure over the polar region and low pressure at midlatitudes (about 45 degrees North), and a "positive phase" in which the pattern is reversed. In the positive phase, higher pressure at midlatitudes drives ocean storms farther north, and changes in the circulation pattern bring wetter weather to Alaska, Scotland and Scandinavia, as well as drier conditions to the western United States and the Mediterranean. In the positive phase, frigid winter air does not extend as far into the middle of Northn America as it would during the negative phase of the oscillation. This keeps much of the United States east of the Rocky Mountains warmer than normal, but leaves Greenland and Newfoundland colder than usual. Weather patterns in the negative phase are in general "opposite" to those of the positive phase, as illustrated below. Over most of the past century, the Arctic Oscillation alternated between its positive and negative phases. Starting in the 1970's, however, the oscillation has tended to stay in the positive phase, causing lower than normal arctic air pressure and higher than normal temperatures in much of the United States and northern Eurasia.

Effects of the Positive Phase | Effects of the Negative Phase

of the Arctic Oscillation of the Arctic Oscillation

(Figures courtesy of J. Wallace, University of Washington)

So what does all of this mean? Here is a look at NOAA's U.S. Winter Outlook for 2011-2012. Remember that winter is considered December through February.

Temperature Outlook:


Precipitation Outlook:


According to the outlook...

Ohio and Tennessee Valleys: Wetter than average with equal chances for above, near, or below average temperatures. Potential for increased storminess and flooding.
Great Lakes: Colder and wetter than average.

The outlook specifically points out "The seasonal outlook does not project where and when snowstorms may hit or provide total seasonal snowfall accumulations. Snow forecasts are dependent upon winter storms, which are generally not predictable more than a week in advance."

I don't know about you, but I am ready to start talking about snow. What about you? What would you like to see this winter? Weekly snow storms or calm and 55°? Let me know by leaving what you'd like to see for the winter in the comments section of this post.

First Frost and Freeze

Its getting to be that time of year. The time leaves are falling off the trees, heavier coats are coming out of the back of the closets and time to unpack the shovels. Ok, it might not be time for shovels just yet but that time is getting closer, albeit a few months off.

So when is the normal first frost and freeze? The Midwest Regional Climate Center has put together some nice maps to try and help show when dates of the average first 32° F and 28° F temperatures.

Average Date of 32° F Freeze:


Average Date of 28° F Freeze:


According to the National Weather Service office in Paducah the mean date of the first freezing temperatures over the last 30 years for Paducah, KY is October 25 and October 26 for Evansville, IN.