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February 2013

Winter Storm Threat: Feb 13 (Only/Final Call)

Boundary temperatures and snowfall rates will be the two main things to watch tomorrow as a nice looking vort. max passes over the region. Precipitation will start off as rain for most/all of the region tomorrow, with the back end of the system changing over to a heavy, wet snow. The strong vort. max will help dynamically cool the air as decent rates form up along the back part of the storm, but with the boundary layer temperatures remaining at or above freezing, it will be hard to get a lot of that snow to stick.

Then there is the disagreement between the models. The Euro continues to run drier and further south compared to a host of other models, which is somewhat concerning considering it has never really been on board with the snow totals that I have forecast. Given the non-consensus of the models along with the temperature issues, risks to the forecast are more to the down side throughout the region, though some of the models do still show some upward potential with this storm. All in all, it will just be something that needs to be nowcasted as the bands of snow develop and try to overcome above freezing surface temperatures.

Winter Storm Threat: Feb 7-8 (Final Call)

Much more aggressive with the totals this time around, but there is still more upside risk than downside to the forecast.

I went with a rough 50/50 blend of the GFS and Euro, with some personal touches here and there. NAM’s still out to lunch with it’s QPF and snow totals, so I didn’t even bother with it. There’s going to be some winners and losers in the low-end/mix areas as the details work themselves out. The bulk of the snow across northern MD, southern PA and southern NJ will be during the back part of the storm. The front-end could start off as snow/mix/rain in these same areas and could/should flip to rain at some point before transitioning to snow to end the storm.

Winter Storm Threat: Feb 7-8 (Initial Call)

Just going to start off by saying that forecast confidence is lower than normal. Miller B type storm will form up late tomorrow into Friday and will initially cause mixing/temp issues across the more southern areas. As the coastal intensifies, banding on the back edge of the system could bring locally higher totals from central PA to NJ, NY and maybe even down into northeast MD and northern DE. There’s plenty of risk in either direction, especially across central PA into NJ and NYC/LI.

I didn’t try too hard to figure out contouring based on strict temperature and boundary layer issue areas since there is not enough certainty to really go into that much detail yet. That’s a job that is best saved for tomorrow’s update.