Potential for a sneaky severe weather threat on Sunday (12/29)

Models are getting into slightly better agreement in terms of a possible severe weather risk this coming Sunday. There are a lot of similarities to this event with the one we had on December 11th where several tornadic circulations produced damage in portions of the area. As of now, the area with the highest potential for severe weather appears to be along and east of the US Rt.15 corridor including the Baltimore and Washington metro areas. The main hazards would be embedded areas of 50-60mph wind gusts, but a brief tornado cannot be ruled out if this comes to fruition. 

The image above is a sounding over central MD as depicted by the EURO model. Similarly to the event earlier this month, there is extreme low level wind shear, and very favorable curved AND stretched hodograph. This is thanks to a strong 50-60kt LLJ above our heads. This will allow any surface based storms to exhibit rotation. Temperatures are well above normal, at least in the mid 50s, but possibly as high as around 60 degrees especially if the storm timing is a bit earlier. This will lead to low but not 0 instability, and with the amount of shear present, it wont take much to produce severe weather. 

One thing that is not as favorable a the one earlier this month is the LCL levels. They are higher with this event, and that leads to a slightly lower severe weather risk. Still, with the aforementioned extreme shear, there certainly is a risk of severe weather. Its likely that a line of low topped downpours and embedded thunderstorms will form along the cold front sometime Sunday afternoon or evening. The earlier this occurs, the higher the risk of severe weather will be. 

Other models (the GFS and GEM) are less aggressive, especially the GEM. But the GFS looks to be trending towards the more reliable EURO model which increases confidence. If this continues, then SPC may issue a level 1/5 marginal risk of severe weather. With still 4 days of time ahead of this, there is time for change. But there is fairly high confidence in at least a low end severe weather risk. Heavy rain will also be a concern, with 1-3" not out of the question. 

We will have a better idea on what to expect on Friday, as we will start to be in range of the higher resolution short range models.