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February 2011

Winter Storm Threat: Feb 9-10 (final call)

The precipitation shield did fill in a little bit from DC and points south on the models, but not to the degree I thought they were going to. I made some adjustments to the forecasts because of that, bringing the 1-2″ line and the 2-4″ contour over the Apps. further south. I brought the 1-2″ contour up north in southeastern NC due to the warmer temperatures.

It will be hard to tell how much the DC area gets due to snow sublimation in the lower levels early on, but I could see DC/MoCo getting a dusting to 1/4″ with a small chance of going higher. Areas north of MoCo up towards Frederick and Baltimore could see a dusting at best.

Winter Storm Threat: Feb 9-10 (first call)

Another system with wintry precip. will move through the region late Wednesday through Thursday, and it yet another storm in an endless streak of high-difficulty forecasts. Most of the snow in this one will be isolated to the western Appalachians and to southern VA and NC, with accumulations of half and inch or less possible up to the Mason-Dixon line.

I weighted the NAM heavily again with this latest forecast, and I included some input from the ECMWF. I think the GFS is completely off in shutting down the precipitation once it gets south and east of the Apps, which is mostly due to the weakening of the upper-level vorticity that the GFS portrays. The NAM has been miles better in preserving the upper-level energy compared to the GFS, and it has been verifying noticeably better.

Here’s the first call for the event… a final map will be put up either late tomorrow or around noon on Wednesday.

Temperatures will be a bit of an issue as well, with rain and mixed precipitation in NC and VA to go with the snow.

What to Watch Fore(cast) – Feb 7-14

Snow threat forecast for the Thursday storm coming later!


A shot of snow early in the Apps – A quick round of 2-4″+ will move up the western side of the Appalachians into the Northeast Monday and Tuesday

Lake-effect machine lives again – Wednesday and Thursday will bring a good round of lake-effect snow to the Great Lakes, which could result in another foot or more of snow in places that have already exceeded their yearly normals (especially in Upstate NY).

Messy mid-week system – A winter storm will be putting down snow from the Southern Plains eastwards through the Southeast and into the southern Mid-Atlantic. Totals won’t be too high to the east, but the affected Plains states could see 6″+ accumulations.

Weekend warm up in the East – A nice February thaw period will start this weekend across the South and East, which should continue through most of next week.


Storm #1 is heading up through the eastern U.S. right now as it tracks into eastern Canada. This storm has an inland low and is developing a coastal low, and these two together will produce some snowfall over the Northeast over the next day or so. Widespread areas of 2-4″ of snow accumulation are forecast for the western Appalachians through the Northeast. Along the coastal areas in the Mid-Atlantic and Southeast, it looks like it will be mostly rain or drier.

Storm #2 is diving into the Plains, and will develop and swing into the Southeast by late Wednesday. This storm could be a real winter storm for the Southern/Central Plains as widespread snowfall of 4-8″ and localized amounts of 12″+ are possible in Oklahoma and Kansas starting late Tuesday and going through Wednesday. This storm is forecast to weaken a bit as it moves into the Southeast, but a band of 2-4″ of snow is still possible through Tennessee, Kentucky, the Carolinas and southern Virginia as it pushes off the East Coast on Thursday. The snow could fall as far south as central Alabama and Georgia.

Another round of cold air will take over Wednesday and Thursday in the East, but change is on the way! Our friend the sub-tropical ridge will develop over the Southeast and it will change the pattern up for awhile as the eastern half of the U.S. experiences near normal to above normal temperatures this weekend and through most of next week. This thawing period may not be permanent, however, so enjoy it while it lasts!

Mid-Atlantic – The Week Ahead (Feb 6-13)

Halftime special weekly forecast! (And what a horrible halftime show it was!) I decided not to do a snowfall map for Mon/Tue since it’s not too big of a deal for most of the population. 2-4″ in the western Apps and in western/northern PA, with some light rain for MD and maybe some back-end flakes that don’t do much. Looking into Thursday’s storm I still won’t discount 2-4″ for most of the region, but right now a more southern/out-to-sea solution is favored over a storm working north into Baltimore and southern PA. It’s not out of the question, though, so I’ll keep an eye on it.

Perhaps what could be bigger news for those tired of the cold is that a warm up period is on the way. We’ll start to see the temperatures move to the near normal or above normal category this weekend as temperatures continue to climb into next week. A lot of that snow that we might get on Thursday won’t last too long. We could see some 60s hitting DC next week!

First call for the Thursday storm coming at you tomorrow.

Tracking two storms for next week

Two storms will impact the Mid-Atlantic next week. The first one will be late on Monday and into Tuesday, and is currently progged to be mostly light rain to the east of the Appalachians as some snow falls on the western side. The GFS shows a changeover to snow at the end of the storm, which could bring 0.5-1″ of snow to the northern parts of the region. I’ll make a snowfall map for this storm tomorrow if the storm looks like it could be interesting.

There is a stronger storm moving through the area on Thursday, which looks a lot better in terms of getting the Mid-Atlantic in the snow. A wide variety of solutions, from a miss to the south to a 6-12″+ bulls-eye over the region are still on the table. Right now I’m leaning towards 2-4″ for most, with some higher amounts in the southern half of the region. That storm will have first call and final call forecasts, the first of which will probably be going up Monday.

More on this tomorrow in the Mid-Atlantic Weekly Forecast.

Update for tomorrow (Feb 2)

It looks like the freezing precip. will be pushed even further north than the updated forecast (by 30-40 more miles from the south AND east). It was hard trying to determine which would win between the CAD and the warm air advection in the lower levels. Models are trending warmer, so it appears as though the WAA will win out in VA/MD/Delmarva/NJ and bring mostly plain ol’ rain to these parts.

The concern for freezing rain and sleet at the onset of the precipitation is still there, but the changeover (if there is one for some areas) should happen well before morning rush hour for most of MD/VA and there shouldn’t be too many problems out there as road crews keep the roads treated.