Pre-Christmas Winter Storm Possible Next Weekend
Holiday Travel Contingencies Should Be Considered
Warm ENSO Flavor to Month of December Continues
Despite both the Relative Ocean Nino Index (-.80 SON) and the Multivariate ENSO Index (ON) both being indicative of a meager La Niña event, the month of December has featured a notable departure from the type of pattern normally associated with cold ENSO. Although inconsistencies of this nature are much more common in weaker ENSO events, the deviation during this month of December has been much more prominent than one would expect.
Here is the prototypical La Niña pattern:
Note the prevalent ridge south of the Aleutians, which tele connects to the downstream trough over the west in what is known as the RNA (-PNA) pattern. However, the mean pattern this month has been essentially the opposite, with an Aleutian low that is very redolent of the baseline El Nino pattern.
This type of pattern is much more conductive to east coast winter storms during the winter season, and with winter set to begin this weekend, the atmosphere looks as though it just may oblige during the peak of pre-Christmas roadway roadway congestion.
High Volume of Holiday Road Traffic Potentially Impacted by Weather
The combination of the MJO entering phase 6 and the continuation of a surplus of Angular Atmospheric Momentum will ensure that the aforementioned El Niño like deviation to the pattern will continue throughout the upcoming week and into the weekend.
There is now strong cross-ensemble suite support that this will lead to the amplification of a northern stream shortwave courtesy of a deep eastern northeastern trough, at the precise time that pre-holiday roadway congestion is anticipated to peak this weekend.
While significant snowfall, or even a storm, is far from a certainty, what is a certainty is that area roadways are going to begin to look a lot more like Christmas this weekend. Thus it is advised that travelers have contingencies in place in the event that the weather follows suite.
More to come this week-