Archive for November, 2008

Light Snow Still Looks Likely, If You Have Travel Plans To Chicago Beware.
November 30, 2008

All of the computer models are still on board with the potential for light snow for your Sunday afternoon and evening. In fact the storm system is developing even further west than originally thought. This shift isn’t dramatic enough to put us in a heavy snow band, but if you have travel plans north and east look out. Kansas City has already picked up on some light snow from this system and St. Louis to Chicago and even Detroit look to pick up several inches of snowfall. Some areas could pick up 8″ of snowfall.

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South Bend, IN northward to Grand Rapids, MI could then pick up another 4″+ of lake-effect snow on Monday for a total close to a foot. For here at home we are just on the edge of this storm system. We shouldn’t see any heavy snowfall but some light accumulations are possible. Here is the latest.

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The slushy accumulations will be on the grassy surfaces and cold elevated objects and surfaces such as parked vehicles. The roads and soil temperatures remain 10 to 15 degrees above freezing which should help to melt some of the snow showers as they hit the ground.

Blustery Sunday – Warm Tuesday
November 29, 2008

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The roller coaster of temperatures gets back on track over the next several days.  A potent trough of low pressure will send temperatures tumbling on Sunday; however, the trough will exit quickly, and temperatures will then rebound throughout the middle of next week.

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Wrap-around moisture will exist on Sunday evening, and with temperatures aloft below freezing, the wrap-around will likely fall as light snow.  No major accumulations are expected, but plan on a cold Sunday with winds between 10 to 20 mph, and wind chills at times in the 20’s!

Don’t get too scared away by the cold.  By Tuesday the temperatures will spring back into the 60’s!  850 mb temperatures will warm near 10 degrees Celsius as compressional heating develops along the Lee of the Rocky Mtns.  We may have to push high temperatures up even more as we get closer to Tuesday.  Stay tuned.

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Sunday’s Winter Blast
November 28, 2008

The computer models are still showing the winter blast for Sunday into early Monday. The upper level disturbances and wind field will be the main reason for the upcoming changes. Below is the latest 500 mb vorticity map.

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The potent upper level low will deepen as it moves across the area on Sunday. Even though temperatures at the surface will be very cold, it will be much colder aloft and allowing for upward motion to take place. As a result the models have been consistent in showing the snow chances over the past 2 days. A surface low pressure will rapidly develop due to the dynamics. However, it appears that will develop to far east to produce any significant snowfall, so only light snow is in the forecast. On the other hand, the snow is only the beginning of the story. The cold temperatures and windy conditions are the rest of it. 850 mb temperatures drop to -10 degrees Celsius on Monday which with clouds could easily keep temperatures in the 30s. The winds will make it feel even colder than that. Here are the 850 mb wind direction and speeds for late Sunday into early Monday morning.

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Wind speeds are racing out of the northwest at over 40 knots (46 mph) making it very plausable to see wind gusts up to 30 mph. A 30 mph wind at 30 degrees produces a wind chill of 15 degrees, the same wind speeds at 25 degrees produces a wind chill of only 8 degrees. Yikes! While grabing the Christmas decorations from the attic this weekend, make sure you have the winter coats as well. Old man winter is on the polar express and he’s making a stop in Arkansas by late weekend.

Light Snow for Sunday…
November 27, 2008

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Well, get your Christmas lights up soon; otherwise, you’ll be dealing with a blast of cold air, and likely some light snow on Sunday.  A trough of low pressure will usher in unseasonably cold air late Saturday night.  Wrap around moisture from a surface low near the Great Lakes could materialize as light snow for our area.

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Temperatures aloft will be cold enough to support snow; however, don’t be getting out the shovels just yet; this will be a quick moving system with light QPF amounts.

A White Late Thanksgiving Weekend?
November 27, 2008

One thing is for sure and that is that some big changes weather wise will occur this weekend with a big cold blast lasting into next Monday. What is still unclear is if, and how much moisture will be available across the area on Sunday and Monday when the cold air moves in across the state. The computer models are showing different tracks this storm may take. Here are two possible tracks. If the storm takes the first track it would bring us some light snow. The second track would most likely keep us dry but very cold.

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The computer models are having a lot of trouble with a storm system that is expected to develop late this weekend. The reason is because two upper level waves will actually phase together on Sunday causing a complex storm system to develop. The two upper level waves will be forced together by a northern jet and a southern jet. So there is a lot of fine details for the models to pick up on including the two upper level waves, instead of just one. Here is the 500 mb vorticity. The two white circles highlight the two waves that are expected to phase together.

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Perhaps the biggest problem at this time is that both of these waves are just now moving on to land. This is important because the computer models need lots of high resolution data to create accurate projections of the weather. There is very limited weather data over the ocean and this forces the computer models to make assumptions about the current conditions and this can lead to big errors in the model’s forecast. It will be very interesting over the next couple of days to see how the models change as the two waves are now moving on to the west coast. Here is an image from the GFS computer model that shows some light snow breaking out by Sunday night.

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Mild Thanksgiving to a Cold Weekend!
November 26, 2008

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850 mb temperatures for Thursday continue to boast unseasonably mild temperatures at the surface.  We’ll expect another day with highs in the low to mid 60s for Thanksgiving with plenty of sunshine.

 

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The 850 mb temperatures by Sunday tell a completely different story.  The GFS is the most robust with the cold air compared to the other computer models.  The GFS is also introducing the chance for light precipitation on Sunday; if this cold air scenario plays out, the precipitation would fall as snow.

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The GFS is the odd man out at this point, so we’ll continue to see if it holds the light snow scenario in the next few runs.  Regardless, a cold snap of weather is a good bet for Sunday and Monday!

Sunset / Venus & Jupiter Time Lapse
November 26, 2008

I did this time lapse last night (November 25).  It shows sunset and a very bright Venus & Jupiter popping out of the still blue sky.  The high clouds caused halos around the planets thus making them appear much larger.  On December 1st there will be a spectacular conjunction involving Jupiter, Venus and a crescent moon in the southwestern sky.  These are the 3 brightest night sky objects and they will be close enough to cover up with your thumb held out at arms length!

Post by Brian Emfinger on November 26, 2008 at 5:25PM

SOME MORNING CLOUDS, BUT AFTERNOON SUNSHINE!
November 26, 2008

We had a little bit of cloud cover to begin the morning, but most of the clouds are now moving out.  This is great news if you want more sunshine across the area today!  Here is a look at the visible satellite from this this morning.  Notice the nice clearing trend for NE Oklahoma and NW Arkansas.

VISIBLE SATELLITE IMAGE

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The cloud forecast for this afternoon is looking very minimal and with some southwest winds our temperatures will warm up very nicely.

AFTERNOON CLOUD FORECAST

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2 Storm Systems, and a Cold Blast
November 26, 2008

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It’s turning out to be an active week in the upper level flow; that’s very typical heading toward the Winter months.  Our first storm system, which will impact us on Friday, is currently sitting over the Baja of California. 

The computer models were rather wet with this first system; however, that solution has now changed, and we’re expecting just a slight chance for showers for early Friday morning.  The heavy rainfall is now forecast to occur to our south.

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We’ll get a break Friday afternoon before the second storm system arrives.  This second system across the Pacific Northwest will not only provide us a chance for rain Saturday into Sunday, but the GFS is forecasting a surge of cold Canadian air as well.

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We’ll keep an eye on this cold trend; which could possibly create a little winter weather as well.  Stay tuned on that one!

Baby Brett’s Winter Thought…..
November 25, 2008

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Drew’s baby boy Brett can’t speak yet, but he wasn’t very happy to learn that the Climate Prediction Center’s forecasting an above average temperatures for the upcoming winter.  We’ll have to see if that holds true!