Jan 22, 2013 Noon Update

Friday Storm Update

As the last few discussions have mentioned, a storm is expected to affect the area on Friday with snow. Until this point, there has been a general consensus for moderate accumulations, ranging from light on some models to significant on others. Today's model guidance, however, has considerably changed from yesterday, with only the UKMET model holding on to a strong northern low pressure. The GFS model has been consistently suppressed with the low pressure intensifying too far offshore, with only light snow showers, while the CMC has been continuously trending south and weaker. The 12z ECM was also weaker and further south than the 0z run, which had significant snowfall across the area.

This event is still at least 78-96 hours away, roughly 3.5 days, and additional changes are expected with the model guidance. Some, but not all, storms this winter have had moderate to significant changes within the 3-4 day range, including 12/29 when a coastal low developed much closer to the coast than initially thought, 1/16 when a storm originally shown to be significantly suppressed ended up far north enough to keep the heaviest snowfall north of the area, and 1/17 when a storm initially shown to remain only in southern Virginia significantly trended north to affect locations up to central NJ, but with the model guidance overdone on the northern extent. In this case, such significant changes are not too likely, although considering that the shortwave responsible for this event is still over the Pacific with a lack of data sampling, along with different handling of the northern stream and the trough over the region with each model run, additional changes are expected with the model guidance, and the possibility remains that the models trend towards at least a somewhat more amplified storm to result in a moderate snowstorm for parts of the region.

At this time, the 5-day forecast remains the same, highlighting snow developing in the afternoon and ending overnight with the potential for moderate accumulations, although I will continue to monitor the latest trends, and should a weaker solution become more apparent, the forecast may be revised to reflect more light as opposed to moderate accumulations, although there remains high confidence on snow falling with accumulations across the area. Stay tuned for more information with tonight's update.