Winter Weather Overview

Welcome back to Jump Seat. As the North Atlantic hurricane season comes to a close, it likely won’t be long until meteorologists begin mentioning the possibility of wintry precipitation in their forecasts. In years past, we reviewed winter weather aviation forecasting products (METARs, TAFs and FICONs) and filing best practices with the usual uptick in holiday travel. This week’s Jump Seat article highlights this winter’s seasonal outlook, as well as a primary focus on winter weather in the Northeastern U.S. and useful sites for forecasting accumulating snowfall across the country.  

Seasonal Forecasting 

Seasonal climate outlooks issued by the National Oceanic and Atmospheric Administration (NOAA) and the Climate Prediction Center (CPC) predict the probability of above, near, or well-below seasonal average temperature and precipitation across the United States. Data is based off a three-decade dataset, spanning from 1991 to 2020. Image 1 below displays a three-month temperature outlook (January through March of 2026). Much of the CONUS can anticipate equal chances of either a warmer, colder, or average winter through the first quarter of next year, with the desert-Southwest, Eastern Maine, and much of Florida likely to see the greatest chance of warmer-than-average temperatures. Image 2 paints the likelihood of a generally drier-than-normal winter across the southern-most areas of the country, with the Ohio River Valley and Mountain West regions anticipated to see a wetter-than-average January, February, and March. Regions elsewhere have equal odds of the precipitation outcomes, whether that be a drier, wetter, or average season.  

Images 1 & 2: January through March 2026 seasonal precipitation and temperature outlooks across the United States. Forecasts provided by the National Weather Service (NWS)’s Climate Prediction Center (CPC).  

A Focus on the Northeast: Nor’easters and the I-95 Corridor  



The Northeastern U.S. presents itself as a primary location for significant weather impacts from Nor'easters, largely in part due to a stark temperature gradient caused by the jetstream pushing cold and dry Arctic air towards the warmer ocean waters of the Atlantic gulf stream (the ocean current, not the jet). Nor’easter storms are most frequent between the late-fall and early-spring months (September through April) and have coined the nickname from the strong northeasterly winds that the storms can generate. Dependent on the exact storm track and air temperature, these storms can produce heavy precipitation, powerful winds, and even coastal flooding and erosion for coastline communities - all of which can significantly hinder travel plans and flights across the densely populated Washington, D.C., Philadelphia, NY-Metro and New England areas.  

The precise track of the center of the low-pressure can play a significant role in precipitation type and totals across the Eastern Seaboard. A nor’easter whose center is located just 30nmi offshore can present far greater impacts for coastlines and deliver lesser effects northwards. An offshore track storm keeps colder Arctic air inland and moist air right along the coastline, creating an ideal atmospheric profile for snowfall. Nor’easters that track inland are often weaker and usher milder ocean air inland, allowing for mixed (rain-snow) precipitation along the coast.  

To determine a storm’s rain vs. snow line, meteorologists often initially use the “540 line”, an isobar (line of constant pressure) that represents the vertical distance (5,400m atmospheric thickness) between 1000mb and 500mb aloft. If the thickness is less than 5400m, it suggests that the atmosphere is cold enough to support snowfall, as colder air is denser. Thickness greater than 540 can indicate warmer, less dense air, and the likelihood of rain if precipitation were to fall. Locations north of the 540 line, on average, receive snow, whereas locations south of the 540 line receive rain. It is important to note that forecasters reference the 540 line in conjunction with other factors (especially elevation) from the meteorology toolbox. 

How Much Snow Will I Get?  

With talk of a winter-storm in the forecast, one question on everyone’s mind is, “how much snow will I get”? While an answer to this question can be challenging to pinpoint even the day of a winter storm, probabilistic snowfall forecasts within a 36-to-48-hour timeframe of an event are often published by 116 out of the 122 National Weather Service (NWS) Weather Forecasting Office (WFO)’s. Using a blend of computer models and meteorologist-input, these graphics display the range of potential accumulations from the beginning to end of an anticipated snow-event. The forecasts are often issued in a low-end, high-end, and most likely snowfall total. Users also have the option to toggle between a point (ex. 3”) and range (ex. 2-4”) output forecast. 

Take, for example, the New York, NY forecast area, as seen below. Prior to an expected snowstorm one weekend this past January, the OKX WFO issued their expected snowfall amount forecast, painting a general idea of 3-5” for the KEWR, KJFK, and KHPN terminals, with locally heavier amounts upstate.  

Image 3: Experimental and previous forecast output from a snow event. Issued by the National Weather Service (NWS) Weather Forecasting Office (WFO) in New York, NY (January 2025).  

To find your intended National Weather Service office’s winter weather forecast page, please reference the following website, which includes the extensive list of the offices that issue these forecasts: https://www.weather.gov/prob-snow. Many additional forecasting tools and references can be found there, as well, including text-based probability tables, and onset and end-timing graphics - just to name a few.  

As always, the team of ARINCDirect meteorologists are here to answer all of your winter weather related questions and concerns. Please don’t hesitate to reach out to us should you need to discuss your game-plan with the threat of any impending winter weather. 

Did You Know?

• Much like tornadoes (Enhanced Fujita, or EF) and hurricanes (Saffir-Simpson), significant winter storms in the Northeastern United States also have a metric to classify their impacts. Known as the Northeast Snowfall Impact Scale, the NESIS takes into account an area’s population per square-mile and total snowfall. This scale was created largely due to the vast economic and transportation development across the Northeast, and the significant impacts that accumulating snow can have on their operations.  For more information, and for a rank of historic winter storms, reference: https://www.ncei.noaa.gov/access/monitoring/rsi/nesis  
• Nor’easter storms can be split amongst two main classifications – Miller Type A and B, dependent on the location of their development and storm track. Miller Type A storms are considered the “classic nor’easter” for their rapid intensification and track up along the Eastern Seaboard. Miller Type A’s feed off of the gulf stream’s warm ocean waters, delivering intense precipitation and hurricane-force winds along the coastal Mid-Atlantic and New England. Miller Type-B storms are less common and often form in the Midwest, strengthening as they approach the Appalachian Mountains, bringing significant snowfall across the Ohio Valley and higher elevations of the Northeastern U.S.  

Image 4: The two primary classifications of nor’easters – Miller Type A and Miller Type B – and the regions most impacted by their storm track.