Browse Tag

2013

Winter Storm Threat: Feb 3 (Final Call)

Brought things northward with this update due to that pesky “warm” layer aloft. This is a considerably tough forecast across the southern areas near the 1″ line as the models generally have isothermal temperatures along the freezing line between about 850mb-750mb. Temperatures at the surface are also around freezing, with sub-freezing temperatures in most of the layer just above the surface to about 850mb. So yeah, a lot of potential for the southern areas to either bust high or low with this event.

20140203_MAsnowFinal

I included the “locally 8-12″ because it’s really hard to pinpoint where the places that get it might be. My best guess for spots of 8-12” would be in the MD/WV panhandles into south-central PA, and if the European model is correct, possibly into central NJ.

Winter Storm Threat: Dec 8-9 (Final Call)

Not much difference from yesterday’s forecast, with the 1-2″ contour extending further south around DC/MD and a bit further north in central PA. Cut back totals in the westernmost areas in WV and OH. Areas west of I-95 remain at risk for a likely amount of 0.1″+ of freezing rain after the snow falls, with some areas (mostly around I-81) getting into the 0.25-0.5″+ range.

Winter Storm Threat: Dec 8-9 (Initial Call)

So I’m going to just ignore tonight’s snow in the northern areas in order to focus on the Sunday event, which is quite challenging with a strong CAD signal from a 1036+ mb High over PA as the precipitation starts to move in from the south and west. I expect most areas to start off as snow or a snow/sleet mix before changing over to sleet/freezing rain and eventually just rain. There is some potential for significant impacts west of I-95 on Sunday if the sleet and freezing rain persist for awhile, but most/all of the region is expected to be just rain by Monday morning rush hour. The highest freezing rain totals are expected to be around I-81, but even areas just west of I-95 could end up with at least a tenth of an inch of freezing rain. There is still some question as to how much cold air gets locked in east of the mountains and how much QPF overruns the cold air before above freezing mid-levels bring in the sleet and freezing rain.

There’s still plenty of uncertainty and room for change, so stay tuned for updates here and on Twitter! My second (final) forecast will be up tomorrow morning.

Winter Storm Threat: Nov 26-27 (Only/Final Call)

We have quite the complicated winter storm on our hands for tonight through tomorrow, with some snow/mixed precipitation expected on the leading edge of the system that will change over to rain in many areas before the back edge transitions over to snow. Accumulations of 1″+ are mostly reserved for the mountains where the back-end snow will last long enough for such accumulations, with the westernmost areas expected to be all snow. Snow and mixed precipitation at the start of the event tomorrow morning is difficult to assess in both the start time and duration before it changes over to rain, and will generally be west of (and maybe a little east of) I-95. Isentropic lift will battle against dry air in the lower levels at the onset early tomorrow morning, with steadier precipitation moving in between mid-morning and mid-afternoon across most of the region.

If temperatures are cooler at the onset of precipitation, snowfall may be able to get to 1″ east of the forecast line before changing over to rain. Widespread rainfall of 1-3″+ is expected along/east of the Appalachians as this system moves through tomorrow afternoon through Wednesday before the back edge switches over to snow. The wet, saturated ground could hurt snow totals on the back edge of this system unless the snowfall rates are good enough to overcome this obstacle.

Winter Storm Threat: Mar 24-25 (Final Call)

Same general theme, with a slight shift south along the southern edges and a more pronounced southern shift towards the upper part of the map. Risks are generally to the higher side on the southern fringe areas if the models are to be believed (especially if the overnight front-end thump is fairly wet).

Winter Storm Threat: Mar 24-25 (Initial Call)

The DC-Baltimore-Philly areas are expected to miss out on the more significant accumulations yet again as bothersome low-level temperatures above freezing and March climo. rear their ugly heads.

One of the saving graces with this event is the onset of snow will be overnight, though this did not really help the I-95 corridor and points east during the last event back in the first week of March. Surface temperatures will generally be above freezing in the lower elevations, so these areas will need good rates to make up for it. A large chunk of the precipitation is expected during the daytime hours, where we will have the March Sun to contend with in addition to the temperatures. Higher elevations that stay at or below freezing will fare much better with accumulation.

Forecast confidence is normal to slightly below normal.

Winter Storm Threat: Mar 5-7 (Final Call)

There were some detail changes due to adjustments in the storm track, which mostly affected central/northern PA, southern VA and the Delmarva Peninsula. Higher confidence in the higher snow totals brought some upscale changes to northern VA.

It’s still a low confidence forecast overall, with both upside and downside risks across most of the impacted region.