Mild/Wet Rest of the Week. Watching Monday.

Jonathan Carr
By December 28, 2021 15:16

Mild/Wet Rest of the Week. Watching Monday.

Discussion: Conditions should remain mundane (for December) through this weekend. Above-average temperatures and wet at times. 250mb jet analysis indicates a very zonal patten across the US meaning flat and lateral. This allows some weak surface lows to track W to E generating precipitation. But with no cold allowed to lock-in, we’re most likely dealing with rain or possibly mixed precipitation for NW areas with little-to-no accumulation. The weekend looks the mildest and most unsettled (Jan 1-2). But then temperatures are modeled to get knocked back into the 30s for January 3-4.

January 3 is a synoptic storm signal with a marginal temperature setup. In other words, it won’t be cold ahead of it and a snow rain line will likely impact at least some part of NJ throughout the event. But I am gaining confidence in the signal. Teleconnections indicate the NAO (blocking) and AO (rigidness of polar jet) transitioning from negative to positive. The PNA (ridge or trough in W US) is transitioning from ridiculously negative to near neutral and the EPO (Eastern Pacific ridge or trough) is correlating with the PNA transition. All of these teleconnection observations typically (not always) indicate a synoptic winter storm for either the Mid-Atlantic or NorthEast US. So for these reasons, I’ll be monitoring the Jan 3 period on model guidance for the next few days and will report accordingly if the chances increase.

Otherwise, it’s uncertain as to weather Jan 3 will start a prolonged or transient period of cold. If the current N Hemispheric jet pattern were to hold, then the SE US ridge, currently over above-avg Sea Surface Temperature Anomalies (SSTA) for much of the W Atlantic, would continue to dominate the Mid-Atlantic and SE US regions with warmer temps. It could just be a transient trough that swings through. We’ll see.

In English: Thursday and the weekend looks like the best chances for rain. Temperatures should continue to stay “not that cold for December” through Thursday and then likely very mild for the weekend. Monday then presents a chance for rain and/or snow with a sharp temp drop for next week. I’ll check back in on Thursday to see how the Monday (Jan 3) storm signal is looking. Be safe! JC

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Jonathan Carr
By December 28, 2021 15:16