Rain possible this week followed by renewed cold. Southern storm track remains active, but longer term a pattern flip may bring back mild weather

This was a winter weather patterns certainly repeated; there were persistent clouds in December, warmth in January, cold in February and snowfall has been missing (or hitting) consistently in the same areas.  Kansas City had nuisance snow (3″ or less) #17 while St. Louis, SE Missouri, the SE Missouri Ozarks and SW Illinois had the second significant snow of the season. In fact,  SE Missouri, the SE Missouri Ozarks and SW Illinois are now above average in snowfall for the snow season (July 1 to June 30) while the major metro areas including KC and Topeka are continuing to run below average without a lot of hope of catching up before time runs out on snowfall potential.  We’ll recap meteorological winter, which ended February 28, in a separate post.

The week ahead

Average highs in early March are near 50 and we’re still going to be dealing with some cold shots over the coming week, though as the seasons change we are going to start seeing more warmer and Springlike weather.  We’ve got a springtime type system on the way early in the workweek.

This system will take shape in the Rockies and track northeast into the Lakes. This is a typical Springtime track and, one in which later in the season, would usually provide some strong thunderstorm chances.  Not so this time due to the cold air in place and dense snowpack.  If anything the warm air and cold ground may combine to produce dense fog and perhaps some icing issues as temperatures approach freezing. Any ice would be brief, occur in the middle of the night and change to rain by Tuesday morning.  This will be one of those nights where temperatures slowly rise beginning tomorrow evening.

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This does not appear to be a big weather maker.  Although rain will be likely, total rainfall amounts will be light.. a quarter inch or less in most areas, as it appears right now.  Here is the NAM and GFS model’s take on rains through Tuesday evening. These models have been trending drier in the west; so it’s possible KC will sit out this event (what else is new for them?) or wind up with scattered spot showers instead of likely light rain. In the east, there may even be a rumble of thunder or two.

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This system is on the leading edge of the next Arctic blast so those warming temperatures Monday night and Tuesday will crash back down to frigid levels (by March standards) Tuesday night through Thursday morning.  Lows back into the single digits and low teens return by this timeframe.  There could be some issues in the east with lingering rain changing to snow Tuesday night, but this would not be a major event and a bigger threat may come from standing water from rain (and melted snow) flash freezing on roadways.

Southern Storm Track may become an issue late week

At mid and upper levels, the weather pattern begins a transition this week.  We’re beginning with the major ridge into Alaska and a trough and cross-polar flow into mid-continent.  That continues the trend of directing Arctic air south at low levels with southwesterly flow aloft bringing waves of spin over us.  The “L” off of southern California (Monday) bears watching as it is the next upper level storm system.  It will move inland midweek and be absorbed into the large upper level circulation over Hudson’s Bay.  This is a very similar pattern to last week and means another moist system runs into cold arctic air.

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This is the recipe for another possible snow/ice event from the southern Plains through the Mid South and to the Mid Atlantic.  That’s right, the southern storm track. This will bear close watching for SEMO/SW IL as they remain sensitive to any northwestward shift in the track of this upper level system.  One model, the NAM is the lone model bringing this snow into SEMO/SW IL late this week the others keep the snow south..though some just barely.  It will certainly be worth keeping an eye on.  KC will be too far north to worry about any impact regardless.

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Beyond that, the upper ridge breaks down and shifts eastward to the inland west.  That eventually redirects the cold shots to the northeastern U.S. and brings back mild cross-Rockies downslope flow back to the Plains. That means it will be back to the generally warmer pattern like we had in late January.  That would also be a dry pattern with no moisture source for us.  This pattern opens up the door to glancing cool (not cold) shots as the cold heads across the Lakes into New England.  Unfortunately for them it may open the door to more snow opportunities for Boston.

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Winter Storm #2

Let’s take a look at the snow just ended. Here’s a series of regional radar maps as the system entered and moved through the region this past weekend. (Click for a closeup view)

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It was mostly a snow event, but look at the pinks in southern MO and southeast IL showing a little mixing of the snow with freezing rain and sleet as temperatures warmed late Saturday night.  You can also see a second band of light snow forming over the KC area.

Here’s a simplified storm total snow map.  The heaviest snows fell from central MO to north and east of STL and on into central IL.  A second band of heavier snows joined this band in central IL from southwest Illinois.

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When compared to the last issued forecast map, you can see pretty good agreement in the western district with little snow NW of KC and heavier amounts SE.

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In the east, not too bad although as was hinted at in the Facebook post, there was a very sharp cutoff from heavier snows to almost no snow.  In reality the heavier snows extended further south and east and the little to no snow was further north and west..so the gradient was even tighter.

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The storm was well behaved and there is always an uncertainty as to where the heavier bands of snow set up once the event begins.  The big change was that compared to the way it was looking this point last weekend, there was a lot more cold air hanging on for a lot longer than the models were showing, so we didn’t have the ice issues. After wobbling several hundred miles north/south the southern track again prevailed, much like the mid February storm, but this one was more of a classic “I-44″ snow track compared to the Ohio Valley track of the mid month system.   Kansas City missed the boat again and will likely emerge out of the snow season WITHOUT a major snow event, the most snow falling in a calender day this snow season there has only been 2.6”. Frustrating for snow-lovers there with heavier (5″) snows only a county or two south of the city.  The midweek clipper low discussed last week also wound up tracking east and denying KC much snow as well.

Cold:

It was another very cold week.  Overnight lows tanked to near zero again the morning of February 27th after the area endured double-digit below wind chills the previous Monday morning.

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The last week of February was bitterly cold from the Rockies to the eastern seaboard and from the Canadian Prairies to the Mexican side of the Rio Grande.

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We’ll update the blog midweek should it appear a more significant threat may arise for the late week system and otherwise we’ll have our next weekly update out next weekend.  An upcoming post will also look at the winter season just ended.

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