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21

Winter Storm Threat: March 20-21 (Only/Final Call)

Lots of uncertainty with this setup given that 1) surface temperatures are marginal, 2) mixed precipitation could greatly reduce snow/sleet totals depending on how far north+west the mixing line goes, 3) precipitation rates fighting daytime sun both Tuesday and Wednesday, 4) it’s actually two waves creating snow Tuesday night through Wednesday.

There’s going to be a lot of variability, but the corridor of 4-8″+ has the highest confidence based on the factors listed above. Anyone in the less than 4″ contours could see notable local variances based on elevation and where the best snow bands set up both Tuesday and Wednesday. Tuesday will be more elevation dependent than Wednesday, and banding will be the more significant factor Tuesday night into Wednesday.

Winter Storm Threat: February 21-22 (Only/Final Call)

Lots of uncertainty with this system. How much precip. falls as snow before the changeover, timing of the changeover, rates during the daytime hours, etc. The only thing that’s not really in question will be the surface temperatures at the start of the storm. Cold, cold, cold.

20150221-22_MAsnow_final

Models overall show a little more potential to get higher totals than lower totals east of the Appalachians.

My brain is done. k bye.

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: Jan 21 (Final Call)

I strongly believe there will at least be a band (if not continuous then broken) of 8-12″ somewhere from this storm. In this update, I placed it where I think it will be most likely, but would not be surprised if it shifted north or south. It is really hard to pin down the area of best banding, so I won’t be too hard on myself if it doesn’t end up where I have it.

20140121_MAsnowFinal

I tweaked the northern and southern edges as well now that I have higher confidence in the forecast where these gradients are. Basically everyone has the same to higher snowfall compared to my initial map. Add the cold and wind to this event and it’s gonna be a fun day to be outside. Areas around DC northward should stay below freezing through Saturday morning, so this snow pack should have some real staying power!

Winter Storm Threat: Jan 21 (Initial Call)

This storm has really come together on the models in the last 12-18 hours. The vort max has just enough of a dig and neutral/negative tilt to pop a surface low and draw some moisture into the disturbance, which is something these past clippers were missing.

20140121_MAsnowInitial

There should be some nice snowfall ratios around DC and points north… certainly better than 10:1. Cold air will be moving into the region tonight, and most areas from southern VA northward will be below freezing at the onset of snowfall. Further south into North Carolina, surface temps may be above freezing at the onset of precipitation, which could hurt snow totals. There is still a fair amount of disagreement with what area gets hit with the heaviest snow, with some models highlighting just south and east of D.C. as others track the best snow over the northern suburbs. That will be something that I will try to iron out with my final update tonight in addition to the northern and southern cut-offs for the 1″+ area.

Winter Storm Threat: Dec 21-23 (final call)

No major changes to the forecast, though I did decide to go a bit more aggressive with the totals in some areas. The most notable changes were in northern PA and southwestern NY, with an 8-12 inch contour added as lake-effect off of Lake Erie helps drive up totals. The back edge of the main area of precipitation is expected to change over to snow, but how much of that actually accumulates ahead of the later snow is uncertain.

Localized totals of >12 inches are possible within the 8-12 inch contours.

Winter Storm Threat: Dec 21-23 (initial call)

Most if not all of the snow with this disturbance will accumulate well behind the cold front, with lake-effect snow bringing some respectable totals to western PA and WV. Most of the snow will fall Friday morning through Saturday afternoon. Low-level temperatures will limit accumulations across central and eastern PA.

South and east of the 1″ line could see snow in the air Friday, with little to no accumulation expected.