1-25-2011 Technical Discussion

Technical Discussion

Synopsis

A weak disturbance will pass over the region Monday night, giving as a chance of snow showers. Tuesday will feature partly to mostly cloudy skies and warmer temperatures ahead of an approaching storm from the Gulf of Mexico. Clouds will build throughout Wednesday and some snow might be breaking out later in the day. Snow should peak around midnight hours Wednesday night and gradually end on Thursday. Some breaks in clouds are possible Thursday afternoon, however, the skies will remain mostly cloudy. Friday will see cooler temperatures as colder air funnels in from Canada behind the storm system.

Short-term (Tuesday – Wednesday)

A weak cold frontal passage Monday night will not cool the temperature too much as warmer air starts to advect northward on Tuesday as high pressure slides offshore. The skies will likely to be cloudy as some moisture lingers in the atmosphere. The temperature is not going to be as cold Tuesday night as warmer air continuous to flow in from the south ahead of a developing storm in the Gulf Mexico. Wednesday should be an interesting day to forecast as the storm system travels northeastward toward the Mid-Atlantic. In general, Wednesday will feature increasing cloudiness with possible snow showers later in the day.

Mid-term (Wednesday night – Thursday)

The latest models have come into a better agreement on where to put the surface low along the east coast. The earlier runs of WRF seemed invalid as they put the surface low a few hundred miles east of the 500-mb low. However, the WRF has trended westward with this system throughout the day and is now closer to the other model outputs such as the GFS and Euro. In contrast with the original forecast, this system now looks to be more of a Miller-Type B storm instead of Miller-Type A. As the models suggest, the primary low is going to form in the Gulf of Mexico and travel northeastward. However, as it does so, it is going to encounter a wedge of cold air sitting over the Appalachians and might weaken a bit because of that. If this scenario is true, a secondary low is likely to develop somewhere along the South Carolina coast and move northeastward. Whether or not this happens will be the deciding factor on how much snow the Northeast will see Wednesday night. If a secondary low develops, the bulk of precipitation will likely to be confined near the immediate coastline with a sharp precipitation cutoff along the Harrisburg – Scranton line. Another possible scenario is that the primary low stays strong as it moves directly over the Appalachians and New Tri-state area. If this happens, the axis of heaviest snow will be over Central – Western Pennsylvania with the I-95 corridor seeing mostly rain. Which solution is going to pan out is still hard to predict as of now, but leaning toward the former scenario described above.

Long-term (Friday – Saturday)

The skies will remain mostly cloudy in the wake of the storm. Colder air will funnel in behind the storm on Friday. However, the temperatures will be on the rise again on Saturday as a clipper system swings across Southwestern Canada. Some snow showers are also possible during the weekend.

 

David Wang