Winter 2013-2014 has seen many records for cold and snow. Many places across the Midwest and the Great Lakes have approached or exceeded seasonal snowfall records; others have been locked in brutal cold for most of the December 2013 – February 2014 period (Fig. 1), expected to continue well into March. Minneapolis, MN and St. Cloud, MN are already in the “top 10” of most below zero low temperature days during the period Oct. 1 – Sept. 30. The Great Lakes are more ice-laden than they have been in 20 years; as of Feb. 28, 2014, the lakes were nearly 86 percent ice-covered (Fig. 2).
Except for a couple of significant storms, California and most of the southwest have been exceptionally warm and dry.
What’s been missing is coast-to-coast storminess. Now, a major West Coast storm (Fig. 3) is poised to march across the U.S. bringing a wide array of wintry precipitation, some heavy, to places from California to the Mid-Atlantic (Fig. 4 – Fig. 6) during the first three days of March 2014.
This should dramatically change the U.S. snow cover map. As of the early morning on Feb. 28, 2014, only 36.9 percent of the U.S. had snow coverage (Fig. 7). This is down substantially from what was observed on Feb. 7, 2014 when U.S. snow coverage was at 67.4 percent (Fig. 8).
Snow is expected, even across higher elevations of Arizona, where snowfall has been sparse to non-existent this winter. Flagstaff, for example, reported only 2.1 inches during February 2014. On average more than 20 inches falls during the month. Since July 2013, 33.5 inches has fallen at Flagstaff; that’s less than half the average amount of 73.2 inches. Last year through Feb. 28, 53.1 inches of snow had been reported.
The big news, however, will center on the interaction between this storm and an advancing arctic air mass east of the Rockies (Fig. 4 – Fig. 6). The arctic air mass is bringing readings well below seasonal averages across parts of Montana and the northern Plains. For example, tonight, the low at Great Falls, MT may be 40 degrees below average. The heart of this arctic air mass will remain along the northern tier, but very cold air will still slide southward into the Central Plains and then points east and south during the weekend and into early next week.
As the storm redevelops across the southern Plains, warm, moist air from the Gulf of Mexico will be drawn northward. Where this air mass rides over the advancing arctic air, wintry precipitation is expected. Deeper into the cold air, snow will fall. To the south of the snow area, where the cold air is not as deep, sleet or ice pellets (rain that freezes on the way to the ground) is anticipated. Where the cold air is the shallowest, rain will fall, but not freeze until it strikes ground-based objects (freezing rain). Precipitation will likely transition among these three categories as the depth of the cold air changes during storm passage. For example, the forecasts for parts of Kentucky indicate mixed frozen precipitation transitioning to all snow as the colder air mass deepens Sunday night into Monday morning.
According to data posted at WTHR-TV (Indianapolis), and updated here, Indianapolis has already had a record-breaking snow season (Dec. – Feb.) and its fourth greatest overall winter snowfall.
Season (Dec – Feb)
Winter (Fall to Spring)
The official forecast for the weekend calls for upwards of 3 to 6 inches for Indianapolis, which will push the winter snowfall numbers toward or above those last seen in the winter of 1981-1982. Expected amounts could easily top those forecasted since the snowfall event will be starting tonight and continuing into early Monday.
Philadelphia has also had near-record breaking snowfall. Back in January, the city reported its tenth snowiest day in the past 130 years. For the winter, the city has reported its third greatest snowfall on record.
Winter (Fall to Spring)
Current winter storm forecasts for Philadelphia are already calling for 5 to 11 inches of snow during the period from late Sunday into late Monday. Look for these forecast numbers to rise as the weekend unfolds. In short, the second snowiest winter ranking is easily within reach.
Although this will be a far-reaching storm event, a classically intense low-pressure system might not be in the cards. Instead, a series of lows are expected to move along the slowly advancing cold front (Fig. 4 – Fig. 6).
Once the cold air overtakes the Nation, it will be slow to relax its wintry grip.
When March comes in like a meteorological lion, it’s supposed to leave like a lamb. Right now, almost anything seems better than the winter of 2013-2014.
© 2014 H. Michael Mogil