Saturday, January 22, 2011

Update On Tuesday/Wednesday Storm

As always, I will start this discussion by saying that this is an early view of the upcoming storm. Things will change from now until Tuesday!

It's looking like things are slowing down with this upcoming system. We probably won't see precip in our area until Tuesday evening. It could initially start as a brief wintry mix, especially for areas west of I-95. Then we will see periods of rain through Tuesday night and into Wednesday. A few wet snow flakes could mix in with the rain as the storm system exits. For now, it appears that the best chances for any accumulations will stay well west of I-95 and into the Blue Ridge.

I'm only trusting one computer with this forecast - the ECMWF (European). It hasn't flip-flopped as much as the GFS, in addition, the operational forecast is closer to the ensemble mean, unlike the CMC.

I've posted some maps below. The first three are ECMWF precip, isobars (lines of constant pressure), and surface temps. Notice how the low (indicated by the isobar circles) tracks over SE VA and into the Atlantic. Also notice how surface temps stay in the upper 30s during most of the event.

This will be key to the forecast. From what I've learned from previous storms like this one, when the boundary layer (low levels of the atmosphere) is saturated, temps need to near or below 35 to get snow in central VA.

I've posted maps from the ECMWF ensemble for all you weather geeks (like myself) so that you can see how it stacks up with the operational forecast.