Thursday, March 14, 2013

March 18-20 Potential Winter Storm

A lot of uncertainty remains with this storm system. I will try to address it in the discussion below.

Shown above is the forecasted 500mb height anomalies from the latest European model. Medium range model guidance is in solid agreement of a track benefitting the North Plains and Upper Midwest for snowfall. Despite this solid agreement, the typically-rock solid European model has been going back and forth for a while, lowering its consistency. However, I have a feeling that this track that smacks the North US with snow will be the storm's ultimate track.

Part of the reason for my choice of this track is the alignment of the high pressure system in the Southwest US and offshore of that region. The storm system will be sliding off of that high pressure system, and this means the placement of that high pressure is key. Right now, that high pressure system is too slanted and too far offshore for the storm to go further south. In response to the lack of strength the ridge has on the West Coast, the storm no longer wants to move down further south into the central Plains or a similar region. Another reason is just how the storm appears on this forecast chart. The lowest height anomalies are tilting to the southeast, and this makes the storm system want to pull further east as well, moreso than pulling it south.

General feeling is a 6-12'' event across the north Plains and Upper Midwest. Confidence is too low to address the issue any further than that. Also, for those of you who saw me mention the potential major Nor'easter int he next 5-10 days earlier this morning, the potential still remains. Shown below is the latest European snowfall map in the next several days. I am unwilling to address that region any further, as confidence is even lower compared to the Midwest.