BLOG: Wintry Mix Ahead

A few changes this morning as it looks increasingly likely that we'll see plain rain for a significant period of time for only the third time in the past 50+ days. It's been an amazing stretch of wintry weather and even though rain is in the forecast, so is snow... and unfortunately ice. We'll just completely ignore any significant details about today... cold with clouds breaking for sunshine around midmorning, and as stated yesterday with a light winds and temperatures in the upper 30s it won't feel too bad outside. Rather pleasant relative to many other days we've experienced this
month actually. Monday will be several degrees cooler with increasing clouds, but again, it could be worse.
 
Now that we've taken care of the "boring" stuff, we actually have two separate, but related weather makers for Tuesday and Wednesday. Heights across the East will rise Monday night into Tuesday while they fall dramatically in the Plains as an upper-level trough ejects eastward from the Southwest while a second shortwave trough dives southward through the Rockies. A strong arctic high will press southward out of Canada and into the Dakotas, and an extension of this high will set up across New England where a confluent flow aloft will be found. This will all act to sharpen the temperature gradient through the middle of the country, and with the previously mentioned upper-level features in place low pressure is expected to develop over eastern Texas during the day Tuesday. Well ahead of this low a strong southerly flow will develop and send Gulf moisture surging northward beginning Monday night, and it is actually this southerly flow of air that will overspread the cold dome over the Mid-Atlantic as we head into Tuesday. The warm
advection will be significant enough to produce a little snow and sleet early with some light accumulation possible (an inch or so) in far northern areas, and then a bit of rain for the afternoon.  The warm advection band will move through by Tuesday evening with a brief lull before precipitation picks up again early Wednesday morning as the surface low previously in Texas moves along the baroclinic zone and into the Ohio Valley. Clearly with this surface track you can
expect warmer air to flood northward, and that's what we expect to happen... BUT with a residual cold wedge at the surface we will face a period of sleet and freezing rain Tuesday night in northern and western portions of the viewing area at the least, and perhaps some freezing rain in Baltimore itself late overnight and very early Wednesday. Right now it doesn't appear to be a major icing event for most, but some protected valleys well to the north/west may see as much as two-tenths of an inch of ice. Temperatures will soar into the upper 40s at BWI with low 50s to the south and near 40 north and west. With the amount of snow on the ground street flooding is certainly possible... needless to say it will be a mess.