CENTRAL AND EASTERN US SEVERE AND WINTER WEATHER THREAT
A powerful storm is currently that is currently soaking the West Coast will also have a significant impact in the Great Plains eastward to the East Coast. The timing and placement of this storm is pretty consistent between the GFS, ECMWF and CMC model forecasts, which gives me fairly good confidence in this forecast. If the current forecast verifies, we could see severe weather as far north as eastern PA and NJ. This will be dependent upon when the storm occludes, which will be the big determining factor to the northern extent of severe weather.
A strong LL southerly jet will force warm, moist air to migrate northward ahead of a long area of concentrated ML vorticity, which will run north-south over almost the entire N-S length of the US. The UL jet will orient itself SW-NE and provide a great area of lift and will also act to strengthen the center of low pressure as it makes its way from the Central US up through the Great Lakes.
Given the current setup, we could see Slight risks for severe weather extending from the southern US in eastern TX and eastward through most of FL, going north up through parts of MO and extending NE through KY west of the Appalachians. The precip. will redevelop east of the Appalachians and affect most of the east coast up through most of NJ. There will likely be a Slight risk issued for areas east of the Appalachians extending from Central FL up to the DC area, with a See Text from DC up through eastern PA and most of NJ.
Eastern PA and NJ may be in for a strong wind event, should this storm have a favorable development. Most of the ingredients are in place for a severe wind outbreak across this region, which will be created by a well-organized line of storms forming along the cold front near the triple-point where the occluded, cold and warm fronts meet. These events are mostly dynamically-driven, and can be a surprise to many people in this region given the unexpectedness of severe weather during the winter months. Warming at the surface will be the main thing to watch in PA and NJ as this storm develops, as it's temp. relative to the ML and UL temps. will make or break the severe threat in this region.
Now, with all of this exciting severe stuff going on, we cannot discount the winter weather that will be associated with this system. The storm will sit in the Central US for a bit before heading east, which will give it ample time to wrap moisture around the northern and western parts of the center of low pressure. This will cause a wintry mix and a good amount of snow over the northern Great Plains and the western Great Lakes region. The possibility of widespread mixed-precip. over these areas could be disastrous, depending on how far south the rain/snow line reaches during this event. The same areas getting hit by winter weather from the current storm could see additional accumulations of frozen precip. However, areas affected ahead of the center of low pressure may be spared the worst, as rain and wet snow will be prevalent, making travel and cleanup considerably easier.
Here's a map for you all to enjoy:
The 5% (i.e. "See Text") and Slight risks are made using SPC risk standards.
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