After being in the “Winter doldrums” for a good part of the season, we’ve finally turned to a little more active weather in the past week. It was a very cold week with a couple of light snow events in the west, a significant snow in parts of the east and finally, some sleet ice and snow for everyone overnight and this morning. COLD looks to dominate as we head into this final week of February, but additional winter weather in terms of significant snow.. well..frustrating news continues.. it will be close by but chances look “iffy” at best. We’re talking about a week out so a lot can and will change in the days ahead. In today’s entry we’ll also take a look at the week in review, what’s behind the cold this month and how the cold has really tipped the balance of Winter 2014-2015 temperature wise.
Looking ahead at the next week (which takes us right up to the end of February) there is high confidence that the cold weather pattern will continue. Take a look at the upper air forecast pattern. The ridge of high pressure continues to hold along the PACNW coast and polar lows continue to circulate from Greenland to Hudson’s Bay. This type of pattern features cross polar flow and for us, northwest flow from our cold air source region. The ridge out west and the lows to the northeast will vary somewhat in strength and position, but the overall flow pattern for us looks cold.
One thing to note is the flow of air through the southern states, which is not exactly favorable to lift storms northward, and that will have an impact on snow chances which we’ll discuss below.
Since we don’t live in the upper atmosphere, we’ll take a look at the surface air mass difference from average. These charts are in degrees C and on this chart 1 degree C equals 1.8 degrees F, so where you see temperatures are 1C below average, that means 1.8F below average. Also remember averages are now higher.. its late February..so average highs are in the mid to upper 40s and average lows in the mid to upper 20s. Daily average temperatures are in the mid 30s. These charts compare the difference in daily average temperatures from “normal”, so the coldest of the cold is not what would have been if we were still in mid January. You can track several cold air masses from Canada, one arriving early in the week and another late week.
What about snow? The problem this winter is that we’ve been unable to take advantage of the cold while it’s around to get bigger snows for a widespread part of the region. We’ve spent a lot of time in the “doughnut hole” with storms in the Southwest and the south dropping too far south to really impact us — only to blow up into big storms along the east or northeast coast. Now and then a system will push back against the cold and we’ll wind up with a weak and disorganized light event or (only once) a significant event for a small part of the area. The cold has been just too strong against the moisture or when a potentially more favorable storm is seen, a stronger downstream east coast system has eventually and reliably pushed the incoming forecast system more southward (and weaker) with time. Alternatively, when the pattern becomes more stormy, we’ve just been too warm. It’s been a disappointing winter for snow-lovers for sure.
Looking ahead, not much precipitatable weather this week as we remain under cold and dry air. Next weekend and into Monday of the following week will be the next opportunity for a significant system in or near the area. This far out there can/will be a LOT of changes so the model maps below are just a preliminary first look from the standpoint of a week-10 days out. All of the models continue the same frustrating pattern if you like snow.
The U.S. GFS model forecasts big High Plains and Southern Rockies snows this weekend and Monday tantalizingly close, only to shift slowly south and weaken during the week and pass us by through the Southern Plains, Mid South and into the Southeast U.S. The system then restrengthens and big snows turn up in the Carolinas, Appalachians and the snow-choked New England areas by the end of next weekend and early the next week. (note the stripe of snow over STL is from what it was seeing for this morning, so disregard that and part of the heavy rains over the Mid South are for the system we just had this morning).
The Euro model also shows the big snows in Colorado/the Panhandles, and western Kansas this weekend and early next week. Yesterday at this time it showed a track potentially through the eastern district next weekend. Overnight, it targeted the I-44 corridor and both districts. Today it has again shifted southward with light accumulations possible through next Saturday and then a possibly more significant snow *just* south of the district with big snows from Little Rock through the Ohio Valley to Louisville, and into the mid Atlantic and Northeast.
The Canadian model also shows the area remaining “in the doughnut hole” with bigger snows west and south of our region. It alone tracks more significant snow toward Kansas City late next weekend and into Monday.
Time will tell if these trends continue or if they will change. Our President’s day system went through several south-north-south shifts in the days leading up to the event. On the one hand, the persistence of the pattern we’ve seen this year would argue that the computer model guidance is probably on to something by taking the southern route. The fact that a southern track is favored by 2 of the 3 model guidance products available is significant. On the other hand, patterns do change as evidenced by the snow drought in New England prior to the month’s open. Folks in Boston where season snow totals now stand at 98.7″ (8.2 Feet) can certainly vouch for that.
Week in review:
The first significant winter storm system of the season finally arrived for a part of the eastern forecast district on Monday, February 16th. Here’s a look at several radar shots as the storm moved through the region. Moderate to heavy snow was common for the eastern district with the western district on the fringe.
These maps show the total accumulation of snow for the region as prepared by the National Weather Service office responsible for the area:
Kansas City MO:
The western district including Kansas City and parts of the eastern district including the STL metro have STILL not seen a major storm this year.
Very cold air followed the storm and that allowed record cold temperatures in some areas, especially for those areas near or with significant snow on the ground. The eastern forecast district was colder with more snowfall on the ground. Here are the temperatures near sunrise on the morning of Thursday, February 19th.
Temperatures are the coldest of the winter with near zero to below zero over the eastern district, aided by deep snowcover and the high being directly overhead at the coldest part of the night:
The lack of deep snowcover and the timing of the center of the Arctic high’s passage overhead meant the western district (it was east and southerly winds were already developing) was “warmer” with lows cold, but not the coldest of the winter.
Cold was widespread and deep that morning.
Another system brought a mixed bag of rain/sleet/snow and ice Friday night and Saturday morning. This caused the issuance of the second winter storm warning of the week for the eastern forecast district. Ice accumulations were significant over SEMO/S IL, while STL/KC again sat out the storm with minor totals.
Behind the cold this month:
The sea surface temperatures continue to govern our pattern this month. Warmer (than average) water off the west coast and in the central Pacific has taken control and is helping to maintain a ridge of high pressure over the western continent and the eastern Pacific with a downstream trough over the eastern continent. Early in the month and in late January the pattern was slightly shifted east from this current pattern, allowing the core of the cold to focus most on the Northeast and the central U.S. to be more susceptible to milder down-slope flow off the Rockies. Now, the westward shift has brought the cold into the central U.S. and allowed frequent storms along the east coast.
Another interesting note is that these big east coast snows and cold and the central U.S. cold have occurred despite a positive to strongly positive Arctic Oscillation. That’s normally the hallmark of a milder winter pattern. This index remains positive into the foreseeable future, despite the cold forecast to continue.
The Pacific is in control, with a negative East Pacific Oscillation in progress and expected to continue, a colder signal.
February has been very cold…with a sharp and short transition to warmth in the west:
Update on Winter 2014-2015:
The very cold weather this February has changed the meteorological winter stats in a big way. Remember at the end of January the mild December and mild January left us with a very warm winter to date. At the time we stated it would be hard to verify a below average winter temperature-wise without some extremely cold (relative to average) weather in February. We’ve had just that– and with 7 days to go in the month (and meteorological winter) here’s where North America stacks up (the chart is in degrees C and remember 1 degree C is roughly equal to 1.8 degrees F).
Although the far western part of the western district (Topeka) is still very near the palest yellow (a quarter of a degree C above average) the remainder of the western and all but the far eastern portion of the eastern forecast district is now portrayed as within + or – 0.25 degrees of average. The far southeast is actually within the palest blue (a quarter of a degree C below average). That’s a big change from three weeks ago.
Take a look at the three months of meteorological winter stacked up against each other. (December was warm.. January was warm..but not so much and February to the 20th is much colder).
The stat sheet (and remember this is in degrees F) bears this out with STL/KC now about 1/2 of degree below average for the winter and Topeka barely hanging on to just over 1/4 degree above average.
Snow has done better this month and it’s been the “snowiest” month of the 2014-2015 season (remember a snowfall season runs from July 1 to June 30 so it’s “first flake to last flake”) at all three stations. Still– we are anywhere from 5-9″ below average for a snowfall season. Parts of SEMO/SW IL where seasonal snowfall averages are lower are actually in better shape due to the storm last week, they are now near seasonal averages. It’s been the winter with numerous small snow events for the major official reporting stations in the forecast districts. St. Louis has had 14 measurable snowfalls with the greatest calendar day total of 2.9″. Kansas City has had 16 measurable snows this season so far with the greatest calendar day total of 2.6″. Topeka has had 14 measurable snow events with the greatest calender day snow of 1.8″. Once again, the SEMO Ozarks, SE MO and SW IL have fared better (thanks to the President’s day storm) with one big event (Farmington with 7″ of snow).
With the cold pattern we have in place, apparently to the end of February, we’ll certainly be in a favorable temperature setup for more snow. We’ll just have to see if we can get the moisture to sync with the cold. That’s been a real problem this winter so far with storms either sliding by west..south and then east of the region or getting their act together after passing by. The cold pattern looks to continue into early March, but signs point to a flip toward Spring by mid month.. right on cue.