After some much needed rainfall last weekend and a quick shot at light accumulating snow in the north this week dry weather has returned and with it mild temperatures this weekend. This dry pattern looks to continue this coming work week with little if any chance for measurable precipitation. There are signs of a colder pattern attempting to work south and west from it’s semi-permanent location over the Great Lakes and New England, but it will fight persistent and stubborn Pacific downslope warmth trying to flow off the high plains all week long. The resulting battle will give us changeable weather with temperatures up this weekend then down early this week — only to resurge, back off and advance again. Overall, the eastern district will average a little cooler while the west will be a little warmer. Stronger and more sustained cold won’t materialize until next week (if it develops–and as of right now). For snow-lovers it’s been a miserable winter — we’ve had no major winter storms – and there’s really no good news to share in that regard for the next 7 to 10 days with no major winter storms in sight.
This past week featured very cold weather to start with early week lows falling as low as +1 to +2 out west and in the single digits and teens east. Warmer air followed and then a clipper tracking south and west of their typical path brought some light accumulating snows to the KC area midweek. Here’s a shot of downtown KC as the snow fell.. not much accumulation in the city but more to the north.
By the weekend that snow was gone with warm weather returning. Saturday temperatures were downright springlike in many areas.
Snow depth meanwhile is confined to areas along and north of 40 degrees North. Last weekend’s I-80 snowstorm left more snow in Chicago than they had to date for the year before that. New England meanwhile dealt with another major storm. Some areas have 30″ to 50″ of snow on the ground.
Yet another major winter storm is ongoing this weekend with an additional 12-24″ expected through Tuesday.
40 degrees North is a good dividing line for seasonal snow totals. North of there snow has been much more common. Locally, our season totals range from 5-10″ for the western district and 1-5″ for the eastern district. STL has seen a bit more as has the lower Ohio Valley — but not much.
That means most of us have seen only 25 to 50% of our average snowfall this winter so far.
Looking ahead at this week.. we mentioned this will be a battle between colder air trying to back in from the east and northeast fighting mild Pacific downslope air off the Rockies. We’ll take a look at the model ensemble forecast of temperatures at 6PM each day. Remember an ensemble forecast is one based upon many different “versions” of the same model averaged together. It gives us a more accurate feel of expected weather rather than just one model run. This chart is in degrees “C” so keep that in mind when looking at the scale. Click each image to make it larger and more readable. This gives you a sense of the flow of the air masses and the back and forth we’ll experience this work week through next weekend.
It’s easy to see the flow of the cold air is directed east of our area through the Lakes and into the east.
Looking further ahead, you can see the colder pattern appears to successfully fight off the warmth the week of Monday Feb 16th.
Here, the angle of the cold is still mainly east of us, but now far enough west to suppress the mild Pacific flow.
Overall, lets take a look at the atmospheric oscillations which can be a guide to how long term trends are shaping up. These don’t determine the weather, but are a result of pressure patterns in place and serve as a guide or a “signal” for warmth or coolness. Shown are the Arctic Oscillation (AO), the East Pacific Oscillation (EPO), the North Atlantic Oscillation (NAO) and the Pacific North American Pattern (PNA). Each has a positive, neutral or negative phase. The more extreme the phase is, the more significant the signal. The AO has been positive and is generally forecast to remain positive for the next 10 days, a milder signal. The EPO is strongly positive now, but is expected to be nearly neutral or slightly negative over the next two weeks, a mild signal to start but not all that significant later. The NAO is expected to remain weakly to moderately positive (a mild signal), while the PNA becomes moderately negative (a cooler signal). These all suggest we’re not looking at “lock in” cold even as it turns colder next week, so this might not be a sustained cold outbreak (lasting 2-3 weeks). Caution is advised though as these have not been as reliable as usual this winter, especially the AO and NAO.
Looking at the stratospheric polar vortex, it’s been strong and locked over the Siberian coast and the Barents/Kara Sea. Over the next 10 days it weakens and moves more toward the pole.
We’re still not seeing a pattern like this (from early January) though, which was a brutally cold signal:
Remember a weaker and more split vortex allows cold more free reign to slosh southward.
As was mentioned earlier: not much in the way of precipitation opportunities for the next week:
The clipper track is evident along the edge of the true cold from the upper Midwest to the Northeast.
Snowfall: if you love snow, this is painful to look at. Areas which have been getting snow will see it continue to pile up.. areas which have missed out will continue to miss. The Canadian model is alone in bringing in some snows by mid month, but that is suspect.
It has been mild to date for this first week of the month around here and that pretty well seals the deal in terms of winter (Dec-Jan-Feb) temperatures. It will go down as an above average winter temperature wise. There’s almost no way we could get cold enough long enough to erase the mild temperatures of the majority of the winter.
That will do it for this week, we’ll have another post next weekend (or before if something changes) with our next weekly update.