(Premium) Winter storm threat next week

Forecast models continue to show a classic pattern progression across the Northern Hemisphere over the next several days, with a continuation of a wave progression that favors the development of a Western USA ridge and Eastern USA trough by the beginning of next week. The redevelopment of this large ridge in the Western USA, extending northward into British Columbia, is expected to be the focal point for the potential development of a storm system in the Eastern USA between February 24th and 28th.

Potential Impact Level: Moderate | Confidence: Low | Dates: February 24-28, 2016

The changes in the hemispheric pattern, which currently is quite unfavorable for snow in our area, have begun with a peristent pattern of tropical forcing near the dateline. This is expected to strengthen over the next few weeks, further reinforcing the development of a large trough and upper level low centered near the Aleutian Islands.

Such an anomalous feature often contributes to a large ridge, which builds to the east of that Aleutian trough, over the Western United States. This ridge can often extend northward into British Columbia and even parts of the Arctic, known as an “EPO Ridge”. These ridges are quite important, as they act to dislodge cold air from the Arctic regions southward into Canada.

Of additional importance is the fact that the Pacific remains quite active, with shortwave energy moving eastward through the Pacific and then over the top of this Western USA ridge axis. Fundamentally, this suggests that these disturbances will have the ability to move southeastward, and then amplify near the Mississippi River Valley or Southeast Coast.

Forecast models, not surprisingly, are catching on to this idea over the next 5 to 7 days. Pacific energy surges east/southeastward into the Mississippi Valley, as a ridge axis builds on the West Coast and toward the Rocky mountains. Cold air remains entrenched to our north over Canada as a result of the ridging in the Western Arctic.

The signal has strengthened over the past few days, with individual operational model guidance and ensemble guidance catching on to the idea of a specific storm threat between February 24 and February 28. This storm looks likely to be of Southeast US origin, with an initial low pressure area forming to our south and then amplifying up the East Coast.

The details of any specific storm threat, at this range, remain extremely muted. The track of the storm system is of particular concern — with a lack of high latitude blocking, the potential exists for a storm track closer to the coast and precipitation-type issues near the coastal plain. However, the potential would exist, with a  favorable track, for a widespread Eastern US winter storm.

Over the next several days, these details should begin to come into focus. At this time, however, we are focusing on a general period of time for a storm system and not the particular and intricate details.