Punxsutawney Phil is probably snoozing peacefully, having gone back to hibernating after all the silly human saps staged this annual folklore ritual before the spring sap even runs. How does a groundhog NOT see his shadow with all the TV lights, anyway? But it’s alleged he saw no shadow. Ergo, winter exits early.
Some may feel Phil gets the win when we head into the upper 40s on Saturday and near 50 on Sunday:
Heck, we already hit 59 and 60 just a few days after our minus 3 and blizzard on Jan. 30. The warmth this coming weekend, too, shall pass. By the very next day, Monday, we are back to below-average temperatures:
It’s not the deep freeze, but there is growing evidence the first part of March, maybe out to mid-month, still has plenty of winter left in it. For the last 10 to 15 days, there has been a tendency for the cold trough in the upper level pattern to settle over the western U.S., with some warmer high pressure ridging closer to the southeast U.S. A strengthened polar vortex has retreated to the far north, where you see the darker purple shading. That keeps the coldest air closer to the polar region:
As we head toward the tail end of this month and the beginning of March, this National Weather Service ensemble mean shows a lobe of the polar vortex dropping back farther south again:
That depicted pattern won’t bring the kind of extremely harsh cold we had at the end of January, but will still feel more like mid-winter. The European/ECMWF ensemble mean, courtesy of Dr. Michael Ventrice and IBM’s The Weather Company, now shows the cold air out west will be pushing east in the 11-15 day period,. This graphic shows the temperature departure from normal, and depicts virtual coast-to-coast below-average temperatures, from Seattle to Boston. The coldest departure shifts from the west to the north central U.S.
If this ECMWF verifies, the return of a more persistent cold pattern does not necessarily mean lots of snow. The main storm track for deeper areas of low pressure in such a pattern would be suppressed well to our south and southeast. As for lake effect, Lake Erie is well iced-over again in the eastern two-thirds of the lake as of this writing. It would take more than a two-day thaw this weekend to change that by itself. However, there are growing signs of a strong to high wind event shaping up for our region by Sunday afternoon, as seen here. It is conceivable winds of that magnitude, in addition to a chance of damaging gusts, could again destabilize some of the ice in the eastern third of the lake:
This wind potential will definitely bear close monitoring.
The NWS Climate Prediction Center seems to be going along with the ECMWF ensemble mean in the 8 to 14 day period. The coldest air is over the north central U.S. and the only part of the lower 48 with above-average temps is Florida:
However, there is still considerable uncertainty about what happens as March goes along. The atmosphere is not responding to the weak El Nino and the Madden Julian Oscillation phrase as it has so often in the past.
It seems as though a more predictable response to the MJO’s “cold phase” for the eastern U.S. has been failing forecasters to some extent, at least in this winter. There may be the handprint of a warming arctic in this. The latter is linked with a more frequently weakened polar jet stream, which is directly tied to the arctic warming, and a weakened polar vortex. This weakened polar jet may be overwhelming the typical atmospheric response to the MJO. In any case, when the polar vortex weakens, there is typically a blocking of west-to-east movement of weather systems in the mid-latitudes, and a lobe of the polar vortex can buckle downward, as in the earlier graphic. If the ECMWF is correct, this will be a second episode of a weakened vortex dropping south in the last month.
Normal climatology, with rising daily high and low average temperatures, will eventually point the thermometer toward a more springlike stance. How much warming occurs after mid-month in March is still beyond our scientific reach. At least one American extended range model, the Climate Forecast System, shows above average temperatures getting back to our region around the middle of next month, with somewhat more persistence.