Archive for November, 2009

VERY IMPRESSIVE COLD BLAST…
November 30, 2009

We have been talking about the slight chance for some light snow across the area on Wednesday, but the major weather story will be the major shot of “Arctic Air” that will be with us to end the week.  Once the cold front moves through Wednesday night, it will open the gates for all the cold air to move in.  Here is a look at the temperature forecast for this week.  The cold air will also be the major key to our snow chances…if it holds off long enough we could only see a few snow flurries late Wednesday night.

WEDNESDAY AFTERNOON

THURSDAY AFTERNOON

FRIDAY AFTERNOON

Keep in mind, these are the temperatures that we will have during the afternoon hours.  Everyone will have a hard time getting out of the 30s for high temperatures Thursday afternoon!

BLOG ENTRY BY: PATRICK CRAWFORD (11-30 8:00PM)

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Midweek Winter Blast
November 30, 2009

Sunshine returns to your forecast for Monday and most of Tuesday. However, our next weather maker is not far away. There are two weather systems that will impact the viewing area on Wednesday. The first is a sharp cold front dropping out of Canada. The second is a low pressure center that will take a southern track.

The two storm systems will meet over the natural state and bring rain for the first half of Wednesday before some of the rain will switch over to light snow Wednesday afternoon and evening. The final punch from this storm system will be an arctic blast that will drop temperatures into the low 20s on Thursday morning. This could bring about slick spots on the bridges and overpasses if any moisture remains.

The image below highlights the two storm systems that will be moving our way for Wednesday.

When it comes to snowfall the models are having a tough time agreeing on whether there will be much moisture left over once the cold air arrives. The image below is of the 500mb vorticity map on Wednesday evening. It shows a deformation zone which could be key to some snowfall. Deformation zones can occur on the northwest side of a surface low and it is a concentrated area of forcing.

Here is the latest on the model data, precipitation amounts, and on where the rain/snow line is lining up.

GFS model Wednesday 1pm

GFS model Wednesday 7pm

NAM model Wednesday 1pm

GFS model Wednesday 7pm

The models differ on whether snow accumulations will occur or not. The GFS is light on precipitation totals and the NAM has at least moderate amounts of precipitation. Slushy accumulations on the grassy surfaces can not be ruled out. With that said, one factor that will play to motorists advantage is that the temperature is expected to stay just above the freezing mark through most of the event. This along with already warm ground temperatures will inhibit snow accumulations on the roadways. However, as the temperature plunges overnight Wednesday into Thursday morning any remaining area of moisture could freeze and cause slick spots on the bridges and overpasses. The image below is the 850 mb temperatures overnight Thursday which drop to -10 to -12 degrees C.

Ross Ellet

SUNDAY RAINFALL TOTALS…
November 29, 2009

It Is All About The Track And Cold Air
November 28, 2009

The computer models are still having a tough time with this weeks storm system. It all comes down to two things: the storm system’s track and the timing of the cold air. Unfortunately, the computer models are still struggling with both.

The storm system is currently over the southwest providing mountain snows. The storm system will continue on its southerly track moving across Texas and Louisiana before taking a turn to the north and moving into the midwest and northeast. At the same time a second weather system will drop out of Canada providing a blast of cold air.

Depending on the track and timing of each weather system we could see rain on Wednesday changing over to some snow. Yesterday the GFS had the storm system developing south and east of our viewing area and leaving us untouched. Today’s 12z GFS model run suggested a much different scenario.

This model run shows heavy rain across the viewing area with the cold air lagging behind until Wednesday evening. It then has rain changing over to some light snow. The models should come into better agreement over the next day or two along with additional model guidance assisting the forecast process. Regardless of the storm’s track, the cold air will arrive for Thursday. Take a look at the 850mb temps for Thursday.

It is down to -8 to -10 degrees C which is cold enough with a partly cloudy sky to keep highs below the 40 degree mark in northwest Arkansas and in the low 40s for the river valley.

Ross Ellet

 

Snow Possible Next Week
November 27, 2009

A big pattern change is on the way for later next week, that much is certain. The culprit will be a cold front along with a developing low pressure center that will move through the area on Wednesday. After this point, the forecast gets very complicated with all the details.

The Super Doppler Storm Team relies on several computer models to help with forecasting the weather several days out. At this point there are three computer models we are keeping our eye on, and they don’t agree at this point. Here is the latest data and the different possibilities that could take hold on Wednesday and Thursday.

Model #1 GFS:

The GFS keeps us dry at this point with temperatures in the mid to upper 40s on Wednesday and highs in the mid 40s on Thursday. It is forecasting the arctic air moving in very slowly and mostly to our northeast. It then develops a low pressure center and tracks it up the east coast. If this solution is correct we will most likely stay dry while the east coast braces for its first major Nor’ Easter of the year. One thing to note is that the GFS has a bias predicting winter storms tracking to far to the south about 7 times out of 10 looking 3 to 6 days out.

Model #2 European:

The European develops the low much further west and north, it also has more cold air on the backside of the storm system. If this solution is correct we could see a mix of rain and snow across the area with a very cold day on Thursday.

Model #3 Canadian:

The Canadian develops the low pressure further north and west, it also brings in the cold air very quickly on the storms northwest side. If this solution is correct it could provide rain late Tuesday night switching over to some snow in northwest Arkansas on Wednesday. The model is indicating approximately 0.60″ of precipitation near the Arkansas/Missouri border. However, the model is even more bold on Thursday with the arctic blast.

If the model is correct it could keep some areas of the viewing at or below freezing for the entire day on Thursday with morning lows possibly in the upper teens.

At this time it appears that the most likely scenario would be something in the middle and close to the European computer model’s output with temperatures dropping through the day on Wednesday with rain mixing with some snow in northwest Arkansas and rain for the river valley. Thursday will likely be cold with highs in the upper 30s to mid 40s. However, as you can see above there is still quite a bit of uncertainty in exactly how much cold air arrives mid to  late week and how much if any rain and snow falls.

Ross Ellet

 

Quick 3 Hour Warm Up Today
November 27, 2009

Ross Ellet

NEXT CHANCE FOR RAIN…
November 27, 2009

The dry weather pattern will continue today and Saturday, but an approaching cold front for the weekend should change that.  We are not expecting any severe weather or any winter weather.  Rainfall totals could be close to 1.00 inch, especially in SE OK and SW AR.   The rain will then clear out of the area by Monday afternoon.

PRECIPITATION FORECAST (MONDAY MORNING)

PRECIPITATION FORECAST (MONDAY MORNING)

BLOG ENTRY BY: PATRICK CRAWFORD (11-27  5:30 AM)

Great ISS Sighting Visible Friday
November 26, 2009

Space Shuttle Atlantis has undocked from the ISS and is expected to return to earth Friday morning. However, the International Space Station will be left behind and it will put on its own bright show on Friday evening streaking across the sky. You can see the ISS by looking to the West/Northwest at 6:02 pm. The space station will fly nearly overhead and move out of view around 6:07 pm.

Ross Ellet

BIG WARM UP ON THE WAY!
November 26, 2009

Temperatures will be below average for your Thanksgiving afternoon, but expect a substantial warm up by Friday.  Strong winds out of the Southwest and plenty of sunshine will warm temperatures well above our late November normals.  Here is a look at the difference in afternoon temperatures for Thursday and Friday:

BLOG ENTRY BY: PATRICK CRAWFORD (11-26  8:00AM)

Updated Tornado Statistics…
November 25, 2009

Many thanks to my producer Jennifer Dreisbach for passing along this information.  Even though it’s not severe weather season, it’s always interesting to talk about tornadoes.

VorTek has just completed its annual compilation of the most tornado-prone cities in the United States with populations in excess of 100,000 (based on 2000 US Census data). Each of the following six states contain two of these cities (Oklahoma, Alabama, Kansas, Texas, Iowa, and Minnesota). Oklahoma City, Oklahoma remains the most tornado-prone city in the United States followed by Little Rock, Arkansas.

By means of the Site Assessment of Tornado Threat (SATT) software, VorTek has just completed its annual compilation of the top twenty tornado-prone states based on the latest National Weather Service data for tornadic activity from 1950 through 2008. Arkansas replaces Mississippi as the most tornado-prone state. “

Drew Michaels