Now that March is here, we have the “typical” late winter/early spring set-up that involves a combination of rain, rain/snow mix, and snow with a 100 mile stretch! Alright, this is not uncommon for this time of year, but it makes for an interesting forecast with little room for error.

The current thinking with the system for Tuesday afternoon through Wednesday morning involves a rainy scenario for the Metro (possibly mixed with wet flakes) during the afternoon and evening. In fact, the precipitation may be moderate at times. The current track of our storm system is just not quite far south enough to drag in enough cold air for an all snow event in Omaha. The snow chances for Omaha will increase Tuesday night and continue into Wednesday AM, but it seems as of Monday AM, 2 to 3 inches would be the worst case scenario! It is a whole different story literally just a set of counties west and north of Omaha. A 35 to 50 mile difference in those directions could lead to double the snow (if not more in a few isolated areas).

As for parts of extreme southeast NE, extreme southwest IA and northwest MO, rain will be the biggest factor with any light snow chance not coming into play until Wednesday AM. Indeed a lot of variation in a small stretch spatially! This is still a very tricky forecast, it will not take much fluctuation in the expected storm track to create a different forecast scenario (on both ends of the rain or snow spectrum). In this case, it just so happens that the two most populated cities in Nebraska happen to be located where any forecast fluctuation can have the biggest impact on what type of precipitation falls from the sky and when.

Amazing how things can go from one extreme to another. It is not uncommon to bring in a taste of mild air briefly into our neck of the woods for February, but looking back to the past week or so, changes have been pretty amazing!

When our warm up began on Friday, February 11th (42 degrees for a high) our snow depth in Omaha started off at 6 inches. Once Tuesday, February 15th arrived, the snow depth in Omaha had been reduced to ZERO as an official observation. That is fast melting and we had yet to hit our 68 degree high for the upcoming Thursday.

Speaking of 68 degrees, that mark fell one degree short of a record high for the Omaha Metro, the previous record was 69 degrees set in 1981! Within the last week, we made it into the 60s for highs two times and the 50s two times as well. Other readings were well into the 40s. Keep in mind that the average high for this time of year is near 38 degrees.

As we approach the upcoming week, the jet stream will trend back farther south dragging colder air with it. That being said, the coldest air will still lock up north of the KETV viewing area bringing bigtime snow amounts to the Dakotas. As for us, we will have moisture to work with, but that precipitation will fall in the form of rain and t’storms come Saturday evening into Sunday AM. Our next minor snow chance may arrive Monday AM with the backside of the system that will pound the Dakotas and Minnesota!

We are lucky! Yes, I said it, we are lucky! The mess that parts of Missouri, eastern Iowa and Illinois are going to go through makes our forecast seem somewhat nice. Even farther south, the Dallas airport was forced to close due to icing, this lead to the cancellation of all sorts of flights. Blizzard warnings line up from northeast Oklahoma and stretch all the way into the Great Lakes region. Columbia, MO may see 14 to 20 inches of snow by Wednesday morning, not to mention the fact that winds will vary in the 25 to 35 mph range.

2 feet of snow is likely in Chicago by Wednesday afternoon. Wind gusts tonight may approach 50 mph there. On the other end of the spectrum, tornado watches were issued earlier today across parts of the southeastern United States and severe weather will continue to be an issue into the Tennessee Valley this afternoon. Travel will become impossible throughout portions of the central plains and upper midwest later today!

So in a way, we are lucky! Thankfully we are not dealing with the mess that a Columbia, MO or Chicago, IL is going to experience. At the same time, our weather is still not very good and I ask that all of you take a little extra time and hold back travels if possible.

This flow can be referred to as a northwest flow which can bring about several difficulties when forecasting. A small change in the forecasted track within this type of flow can also lead to bigger errors when forecasting snow amounts. Several of our snow-making systems this season have had more “clipper-like” characteristics. Typically in a clipper-like scenario, bitterly cold and dry air can dominate a storm system really limiting the amount of moisture within a storm, therefore, reducing the amount of snow a location receives.

We have seen several systems drop southeast with clipper-like features this season, none have really produced tremendous amounts of snow (OK, we did see appx 7″ to 9″ with one system, but that covered an extended period of time and was “weak sauce” compared to numerous events from last year).

Speaking of last year, it’s easy to remember that we had way more snow here, but the whole entire pattern that set up those large snowfall totals for the season was very different. More times than not, it is fairly common for our winter storm systems to develop on the lee side of the Rockies over portions of eastern and southeast Colorado. Once these systems eject eastward, they can tap into more abundant moisture accompanied by milder air tied into the Gulf of Mexico. If the steering winds are favorable, a low pressure system can bring a considerable amount of snow to our area over a shorter duration of time associated with the storm track.

In this more typical scenario, the snow type is also different. Throw out the dry, light and fluffy stuff from northwest flow, a more typical winter storm track for the central plains will have more moisture content to it with bigger flakes! So far this season, we have not seen that “typical” winter storm setup, but this is something that is not that all uncommon in a La Nina period for our area.

In a “typical” or “textbook” scenario, snow/liquid ratios can be defined as 10:1 or 12:1 in some cases. In other words, 10 inches of snow would equate to 1 inch of liquid precipitation. However, when a very dry and cold air mass is in place, this ratio can increase quite a bit.

Cold air will hold less moisture than mild air (or air that is “less cold” in the winter months). When dealing with a drier variety or type of snow, it is not uncommon to see a snow/liquid ratio in the 15:1 range or possibly 20:1 in some cases. In situations like these, .25″ of liquid precipitation would lead to higher snow amounts (maybe 4-5″ of snow in the 20:1 case), whereas as a 10:1 ratio may only equate to appx. 2.5″ of new snow. Of course this is just an example, the values mentioned here can vary depending on the individual characteristics of each passing system.

For Wednesday, liquid precipitation amounts may average out at approximately .20″ – .25″ across the Metro. Based on the air mass in place, this could equate to 3″-4″ of new snow for Omaha provided the current going forecast stays on track!

Anyway, bringing this whole thing back into perspective and comparing it to last year, you will find that the story is completely different. Easy enough to say, who can forget the winter we had last year? I found it a little amazing that we have recorded 15.1 inches of snow so far this cold season for Omaha (I must admit I did not think it was that much until I looked at the official number). With that said: 15.1 inches of snow through January 1oth is still above average. Typically through this date, the average is 11.2 iches of snow (since July 1), meaning we are approximately 3.9 inches above normal.

Now if we compare this to the same time period last year, the differences amount significantly! 36.2 inches of snow is the magic number through January 10 last season (2009/2010). The difference in inches: 21.1!  In other words, this time last year we had already seen approximately 2 more feet of snow compared to the 2010/2011 season. That is pretty amazing!

But… with tomorrow being Thanksgiving… it’s only appropriate that I take time to thank those of you who have taken your time through the years to make KETV Newswatch 7 and the Super Doppler Storm Team your number one source for weather information. From the kind words, notes, and comments through the years, it’s very humbling to me to have had the opportunity to give your weather forecasts over the past 14 years.

Finally… from my co-workers at KETV Channel 7 to the many well-wishers throughout our community… I can never be thankful enough for the support and prayers that I and my Nebraska Army National Guard unit received during our deployment to Iraq in 2006-2007. In this era of (seemingly) widespread cynacism… it was refreshing to see that patriotism and kindness remain the norm in our society.

Once again… thank you very much and please don’t hesitate to stop and say hello if you ever see me around town.

Chuck McWilliams

Tyson Pearsall here giving you an update on when we may see our first snowflakes fall in the Metro. Rain chances (first of all) really increase approaching early Friday AM, then continue throughout the day Friday, into Friday night. The moisture gradient seems to really tighten up as we go north of the Metro (smaller rain accumulations), models tend to agree that the bullseye for bigger rain amounts will line up over SE NE, SW IA, NW MO and NE KS. With that said, rain amounts in the Metro seem to be averaging out in the .75″ to 1.00″ range (this may vary a bit literally from northern portions of Douglas county to southern portions of Sarpy county).

We need the rain, I think precipitation will be appreciated. As for snow, yes, a few wet flakes may fall overnight Friday into Saturday early on. As for accumulating snow, it doesn’t seem real likely in Omaha. A combination of a late event “switch over” and warm ground temperatures are not helping the accumulating snow cause. Some minor accumulations may set up over northeast NE, western IA and northern IA through Saturday afternoon.

Cooler conditions stick around through the first part of next week.

1. Partly to mostly sunny skies.
2. Light winds (less than 10 mph).
3. Dry weather (no rain) with low humidity (dew points < 60).
4. High temperatures in the 70s.

Right now… it looks like we could see all of those ingredients on more than one day this work-week… as our Fall starts off rather nicely.  In fact… the weather looks terrific across most of the Midwest and Plains as we close out September and head into October.

Look for cooler temps over the upcoming weekend… but not by alot.   Highs will be in the 60s on Saturday and Sunday… but I expect dry conditions (and relatively light winds) to persist.  Here’s a look at some of the events scheduled around the metro later this week:

• The Fall Home and Garden Expo runs from Friday through Sunday at Qwest Center Omaha.  Hours of the event are 5pm-10pm Friday, 11am-8pm Saturday, and 11am-5pm Sunday.
• Gifford Farm Fall Festival will be held Saturday and Sunday down in Bellevue.  This family-friendly nature and outdoor event goes from 10am-4pm on Saturday and 11am-4pm on Sunday.
• The UNO Mavericks look to make it two wins in a row on Saturday as they take on the Emporia State University Hornets at Al Caniglia Field.  Kickoff for the Mavs’ Homecoming Game is scheduled for 1pm.
• Speaking of football… the Omaha Nighthawks kickoff (literally) their second game of the season at 7:30pm Saturday against the Sacramento Mountain Lions.  Fans planning on tailgating down at Rosenblatt Stadium can expect partly cloudy skies and temperatures in the mid-60s (pre-game) that will drop into the mid-50s by late in the 4th Quarter.

Chuck McWilliams