Observations and winter storm chances

[WXBUFFJIM]

Good morning everyone. Observations are alot different today than yesterday at this time. Yesterday if you can recall, the high temperature was 49 at Reagan National in Washington, 43 in Baltimore, and nearly 55 in Norfolk, VA. Right now, it's only 19 at DCA, 18 at BWI, and a cold 28 in Norfolk, VA. A much colder airmass. The low this morning in Baltimore was 15, Washington was 17, and Cumberland, Maryland was 7 above zero and these places have not recovered at all even with sunshine.

The next forecast issue comes later tonight with the presence of an alberta clipper system. With this clipper, snow is likely tonight across the Middle Atlantic states for a brief period of time. This clipper is already producing snow across the southern great lakes and upper midwest. Areas affected include Betton Harbor, Chicago, and near Rockford, Illinois. Minnepolis is even seeing some light fluffy snow out of this clipper. Accumulations should generally be 1-3 inches in these places with locally higher amounts in lake effect favored zones.

As this clipper tracks east tonight, QPF is likely even into the Chesapeake Bay as the following computer model displays show from 12z.

ETA AND GFS 12-24 hours
http://www.nco.ncep.noaa.gov/pmb/nwprod ... p_012s.gif
http://www.nco.ncep.noaa.gov/pmb/nwprod ... p_018s.gif
http://www.nco.ncep.noaa.gov/pmb/nwprod ... p_024s.gif
http://www.nco.ncep.noaa.gov/pmb/nwprod ... p_012s.gif
http://www.nco.ncep.noaa.gov/pmb/nwprod ... p_018s.gif
http://www.nco.ncep.noaa.gov/pmb/nwprod ... p_024s.gif

As indicated, later tonight into early Saturday, snow accumulation of 1 inch or less is expected from Philly down into the DC area. Most areas will see a dusting more than likely. This clipper is moisture starved, but just enough moisture exists combined with the track to produce this light accumulating snow tonight into early Saturday for the mid atlantic.

After tonights snow departs the middle atlantic, colder air will be reinforced into the northeast and middle atlantic states, which will set the stage for a significant southern stream storm across the middle atlantic states through later this weekend. The latest model guidance is still on track for good overrunning and cold air damming east of the appalchians. As a result, a significant winter storm is in the cards from New York City and north central PA southward into western Virginia, western north carolina, and the north central Chesapeake Bay area including the nations capital. The following shows this trend very well.

GFS and ETA 54-72 hours
http://www.nco.ncep.noaa.gov/pmb/nwprod ... p_054s.gif
http://www.nco.ncep.noaa.gov/pmb/nwprod ... p_060s.gif
http://www.nco.ncep.noaa.gov/pmb/nwprod ... p_066s.gif
http://www.nco.ncep.noaa.gov/pmb/nwprod ... p_072s.gif


http://www.nco.ncep.noaa.gov/pmb/nwprod ... p_054s.gif
http://www.nco.ncep.noaa.gov/pmb/nwprod ... p_060s.gif
http://www.nco.ncep.noaa.gov/pmb/nwprod ... p_066s.gif
http://www.nco.ncep.noaa.gov/pmb/nwprod ... p_072s.gif

Looking at the timing of all this brings ice, sleet, and snow into northwest North Carolina and SW Virginia by Sunday morning before quickly becoming a potential icestorm. Ice accumulation of 1/2 inch is posible with this and travel problems are likely. Cold air damming will likely contribute to this potential prolonged icing problem. This icing precip could change over to rain later Sunday. But if the cold air damming stays intactas advertized, then we could just prolong the ice and have a serious problem for western VA into northwestern North Carolina.

Meanwhile significant snow is likely to overspread the cities of Washington DC, Baltimore, and Philadelphia Sunday afternoon through Sunday night. Snow accumulations will likely range from 1-3 inches in southern Maryland including Fredricksburg, Maryland. 3-6 inches is likely from Washington DC to Annapolis. These places could change over to sleet and freezing rain from south to north Sunday night into early Monday.
Meanwhile expect a band of 4-8 inches of snow in Baltimore, MD, York, PA, and Philadelphia, PA. Some places within this band could see over 8 inches of snow, especially in heavier mesoscale snow bands. Some of these mesoscale snow bands could be associated with thunder potential as well. Meanwhile with the system a bit further away from northeast PA, northern NJ and New York City, 2-5 inch snows seem more likely at this point. North of that into New England, little accumulation is expected what so ever.

Note that north of Annapolis and DC, precipitation will prodominantly fall as snow and it could be heavy at times with the potential of thunder in some spots, especially in areas along mason dixon line and extending eastward into southern and central Jersey. It's those convective and mesoscale bands that could enhance snow amounts locally. Stay tuned.

Jim

[southeastva]

What do you think we will get here in Hampton Roads, Virginia. I am in Isle of Wight County (on the west side of the James River).

[WXBUFFJIM]

There could be some icing away from the Chesapeake Bay initially. But I think for the most part, hampton roads will remain wet with liquid precip for the most part on Sunday.

Jim

[JCT777]

Great update, Jim. It should be a wild weather weekend, for sure!

[Chris the Weather Man]

Great update, Jim. It should be a wild weather weekend, for sure!

100% correct, John.... Could we see a big storm Next weekend?

[paradoxsixnine]

What do you see for the central NC area, or is that close enough to what you are calling the NW part of NC?

-Chauncey