Synopsis
A major winter storm will shape up on Tuesday over 1/3 of the nation. A low pressure system coming out of the Rockies will rapidly intensify as it moves across the Midwest. Ahead of the storm system several rounds of wintry precipitation will affect the area starting Monday night into Wednesday afternoon. The first round of precipitation will spread mainly snow across the northern half of the state with some sleet over the southern half. The second round that comes in Tuesday night will produce a wide swath of freezing rain for central Pennsylvania and snow to the north. The storm will gradually wind down Wednesday afternoon. Some sun may peek out later in the day on Thursday and Friday should be another calm day. The weekend features another chance of snow as a low pressure develops off the east coast.
Short-term (Tuesday – Wednesday)
What a mess! A strong upper-level energy ejecting out of the Southern Rockies will spun a strong low pressure system Monday evening. This low pressure system is forecast to intensify rather rapidly as it moves northeastward toward western Great Lakes. To the north of the storm system, a strong high pressure will build southward from west-central Canada and usher in unseasonably cold artic air all the way into the Deep South. This fresh surge of cold air north of the strengthening storm system will cause widespread winter weather across much of the Midwest into the Northeast. Chicago is expected to see more than a foot or two of snow by Wednesday.
However, here in the Northeast, an inverted trough ahead of the storm will push a warm front northward into the Mid-Atlantic. An elongated ridge of high pressure will also build in from upper-Midwest into Southeastern Canada ahead of the approaching storm. With this kind of synoptic setup, some overrunning snow is expected to develop Monday night and continue throughout much of the morning hours on Tuesday. Snow showers will stop a bit Tuesday afternoon and might end as periods of freezing drizzle for southern Pennsylvania. But do not let your guard down. The main bulk of moisture associated with the Midwest storm system will move into the region Tuesday night. This time expect a significant swath of sleet and freezing rain for the southern and central part of the state. The extreme northern areas may stay all snow throughout the whole event and the snow could be heavy at times. The models have fluctuated between cooler and warmer solutions on Monday with the WRF on the colder side. However at this point, the best thing to do is to be prepared for this potentially dangerous storm no matter what happens. Even though there might be a sufficient amount of warm air melting the snow into rain around 850mb, the below freezing surface temperature will allow any liquid precipitation to freeze, especially over the valley regions of Pennsylvania where cold air damming is favored. The timing of the precipitation will also be crucial to how much ice will accumulate. Though given the latest data, things look very serious across much of Pennsylvania as freezing rain is expected to fall during overnight hours on Tuesday when solar radiation is essentially none. The total ice accumulation could be anywhere from 0.3" to 0.75" ending by Wednesday afternoon. With that much of ice accumulation, expect hazardous travel conditions Tuesday night and into Wednesday. Widespread power outages are also possible if ice accumulation exceeds 1" in some areas; breezy conditions on Thursday will also increase the threat for power outages.
The storm will gradually wind down Wednesday afternoon. A dry slot is forecast to move in Wednesday afternoon and may finally put an end to this nasty winter storm. Only expect a few scattered snow showers Wednesday night.
Mid-term (Thursday – Friday night)
Things will be a lot quieter on Thursday as the storm system moves away into Canadian seaboard. Some sunshine may even peak out later on Thursday and that would be a great news for the people who will be digging out from a major ice storm. Though, the temperatures will be significantly colder on Thursday as colder air funnels in behind the storm system. Friday should be another calm day with more clouds building in during the evening hours.
Long-term (Saturday-Saturday night)
See the light at the end of the tunnel? Well, not quiet. Some computer models are suggesting another snowstorm to affect the Northeast on Saturday. This storm will likely be the result of a short-wave diving down from central Canada and catching up with the leftover upper-level energies over the Rockies. However, it is too early for the details so please stay tuned for more updates as the week progresses!
David Wang
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