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winter

Winter Storm Threat: February 16-17 (Final Call)

Cut back on totals in central and eastern Pennsylvania a little bit, and tweaked 8-12″ contour ever so slightly. On the south end of things, I lowered the snow+sleet totals in North Carolina east of the Appalachians and into far southeastern Virginia. Still a solid 5-10″ event around the greater D.C. region.

20150216-17_MAsnow_final

Would have been interesting if people didn’t have Monday off… onset around D.C. is during the afternoon rush hour. At least we get to avoid that fiasco this time around. Should end near or slightly before daybreak for most. Enjoy your fresh pow pow.

Winter Storm Threat: February 16-17 (Initial Call)

Holy crap, a decent storm around D.C. where the rain/snow/mix line won’t be a concern! It’s a miracle.

So the biggest question at this point is QPF. There are some really juiced-up forecast models, and some not so much. Either way, snow ratios start getting good around D.C. and points north… talking 15:1 or better (20:1 along/north of the Mason-Dixon?).

20150216-17_MAsnow_initial

Other questions include how far north the 1+” totals get, and how much snow/sleet occurs in North Carolina and southeastern Virginia before they change over to rain/freezing rain (yes, sleet is included in the snow totals in that region).

The 8-12″ band is a little ambitious, but I feel like the more aggressive play is the correct one at this point. I think a 50/50 blend between the wetter models and drier models results in something close to this, with ratios taken into consideration.

I’ll issue a quick final update tomorrow morning.

Winter Storm Threat: January 25-27 (Only/Final Call)

Not going to go into details because I have spent way too much time looking at this storm between work and home. Also, I’m prepping for a snow chase in New Jersey, so that has taken up much of my afternoon.

20150125-27_MAsnow_final

A bit more conservative than the Euro and NWS overall. The lack of support of big totals from some of the other models in the Mid-Atlantic gave me pause. There’s a lot of moving parts to this system, so it’s really anyone’s game still. I just hope I’m not terribly wrong.

Winter Storm Threat: January 23-24 (Final Call)

Not much change from the initial forecast, save for higher totals across Pennsylvania and slight adjustments to the southern edges of the 1-2″ and 2-4″ contours. The front-end thump will bring most of the snow into the region, with the mountains getting some additional accumulation along the back edge. I don’t anticipate much, if any, additional snow accumulation from the back edge east of the mountains tomorrow afternoon.

20150123-24_MAsnow_final

The event is already underway across western North Carolina and southwestern Virginia, which is unfolding just about as expected (though I’d rather see more snow reports and less sleet reports).

Now I get to start looking at that late Sunday into Monday snow storm…

Winter Storm Threat: January 23-24 (Initial Call)

Lots of things to keep tabs on as this next system moves up through the region tomorrow night into Saturday. Temperatures from the surface all the way up to around 750-800 mb will be cutting it close, but the strengthening low and good rates on the front end of the system will help things along.

20150123-24_MAsnow_initial

Most spots from near the MD/PA border south and near the coast will change over to rain after the snow has fallen (and while most of you south of the Mason-Dixon are tucked away in bed). The back edge of the precipitation Saturday afternoon will likely switch back over to snow, but time of day, surface temperatures and weaker rates means it shouldn’t amount to much for most spots.

Winter Storm Threat: January 21 (Only/Final Call)

More clipper fun for the Mid-Atlantic, only surface temperatures won’t be so wonderfully cold this time around. Marginal temperatures at the surface and around 900-925 mb as far north as I-70 (maybe even further north?) along with mostly light precipitation hurting snow chances. Most or all of the snow will also fall during daylight hours. One plus is it looks like areas from around D.C. northward will get below freezing tonight before the snow moves in, so the ground should still be nice and cold. Definitely more opportunity to end up lower than my forecast as opposed to higher. The Delmarva Peninsula and southern New Jersey could see heavier banding late in the event, which is kind of alluded to on my map with the 2-4″ stripe in southern New Jersey.

20150121_MAsnow_final

I wish I could wait until the 00z models came out for better forecast confidence, but this will have to do.

Winter Storm Threat: November 26 (Final Call)

Well, the model trends over the last 24 hours were not in the direction I though they were going to go, so I had to cut back the forecast along I-95 and make some smaller adjustments on the western edges of the contours. Overall, things have shifted slightly warmer across much of northern VA, DC, MD, NJ and southeastern PA in areas near and west of I-95. With such marginal temperatures of 33-36F at the surface, snowfall rates will be the big thing to watch tomorrow to see who will cash in and who will get stuck with little or nothing. Sloppy, wet snow for the major population centers along and near I-95.

20141126_MAsnow_final

The difference between 4 inches and 8 inches within that contour range will be elevation. Lower elevations can expect totals closer to 4-6 inches, with the higher elevations getting more into the 6-8 inch range. Along the Blue Ridge and Central Appalachians, a few of the higher peaks could hit 8+ inches. I didn’t include it on the map, but I wouldn’t be that surprised if there was one or two reports of 8+ inches in the highest elevations of north-central MD.

Some of the models even show some sleet mixing in, mostly from far northeastern MD into southeastern PA and NJ. That may actually be a blessing in disguise, as sleet can accumulate more easily than snow in marginal temperature situations, and a base of sleet would make it easier for any snow afterward to stick.

Forecast confidence remains on the low side, mostly with the eastern edge of the contours where the rain/snow/mix is the most problematic. A one or two degree change to the surface temperature could mean a big difference for some areas, both to the high side and the low side. There’s also still the question of where the best banding will set up, which will produce the heavier rates and increase the chance for higher accumulations for a select few. My best guess for that is just inside the eastern edge of the 4-8 inch contour up into the 8-12 inch contour.

Perhaps if we can get some big, fat dendrites cascading down along I-95, then that area could actually get a decent accumulation. However, looking at the temperature profiles, that seems pretty unlikely.