Rain, Wind, Cool Air, and a Possible Winter Storm: What We Know So Far
It's a busy and potentially messy weather forecast for New Jersey, as we prepare to transition from winter to spring this weekend.
The Short-Term Forecast
Thursday is starting with patchy dense fog and low clouds, which will give way to sunshine by late morning. High temperatures will be in the mid to upper 60s for most of New Jersey for one more day. As a cold front approaches Thursday afternoon and evening, winds will increase and we'll likely see a round of scattered showers and thunderstorms. Just like Wednesday, localized downpours, frequent thunder and lightning, gusty winds, and small hail will be possible if these storms really get going.
Friday will be noticeably cooler, although high temperatures will likely end up just above normal, in the mid 50s or so. A gusty wind will make the day feel blustery. Skies will average partly sunny, and we will probably stay dry. However, an isolated shower can't be ruled out as another reinforcing cold front traverses the state late in the day.
Saturday will feature a definite chill in the air, as high temperatures will be limited to the mid 40s, at best. At least the first half of the weekend will feature plentiful sunshine amidst the coolness.
Sunday Storm - What We Know, and What We Don't
Spring begins early Sunday morning, at 12:30 a.m. Eastern Daylight Time. And New Jersey's weather for the first day of Spring is looking interesting, as a potential coastal storm system (a.k.a. "nor'easter") steers toward the Garden State. A combination of heavy rain, accumulating snow, and coastal flooding will be possible. However, it is still too early to nail down precise timing, snow totals, and/or weather impacts just yet.
Even so, here's what we know so far:
--How's the forecast confidence? If you asked me Wednesday evening how I thought this forecast was shaping up, I would have told you that we'd probably see mostly rain and maybe a little bit of snow. However, there's no denying Thursday morning's forecast models show a colder, snowier solution for New Jersey. The potential is certainly there for significant snow totals. So, the bottom line is that confidence of a Sunday storm is rising. But, because forecast model solutions are literally all over the place, confidence is very low regarding specific details including storm timing and potential accumulations.
--When will the precipitation start, peak, and end? Again, models are showing a variety of answers to this question. First drops/flakes should fall sometime between about 8 p.m. Saturday and 8 a.m. Sunday. The heaviest precipitation is expected between around Sunday evening and early Monday morning - as temperatures drop during this overnight, the chance for winter weather (rather than snow) will increase as well. The bulk of the storm system will be moving away from the coast by mid-morning Monday. However, lingering showers may persist for a time throughout the day Monday, so it's hard to pinpoint an exact time for the final snowflakes and/or raindrops.
--Will the upper atmosphere be cold enough for snow? Almost definitely. The pair of cold fronts moving through on Thursday and Friday will chill the snow growth region of the atmosphere to well below freezing.
--Will the surface be cold enough for snow? Possibly, at least for part of the day. Sunday's high temperatures are forecast to be in the mid 30s in North Jersey, and around 40 degrees for Central and South Jersey. If temperatures are just a little bit cooler than forecast, it could lead to an all-snow solution. If the precipitation falls hard enough, that can cool the air and would lend to a snowier outcome. Temperatures will likely fall below freezing Sunday night through Monday morning, providing an extended period of potential snow accumulation. On the other hand, the ground is pretty warm right now, given our recent streak of warm air temperatures, so it might be difficult for the snow to begin accumulating (as snowflakes may melt as soon as they hit the ground). So again, a wintry day is not a definite - but this forecast is trending markedly cooler, and therefore the chance for snow is increasing.
--How much precipitation is expected to fall? QPF stands for Quantitative Precipitation Forecast, and refers to the amount of liquid/melted precipitation that is expected to accumulate over a specific area over a designated time period. Across the board, QPF forecasts for New Jersey for this storm system are between about 0.2" and 1.2". Again, that's liquid equivalent and not a snow forecast.
--How much snow might accumulate? This mornings raw model output for snow accumulation literally ranged from 0 to 14 inches. That's pretty funny. But also pretty ominous - over a foot of heavy snow would be significant at any time of the year. More specifically, the raw GFS shows 0 to 7 inches, the European model forecasts 7 to 14 inches, and the Canadian model shows 0 to 4 inches across New Jersey. Calculation off the aforementioned liquid QPF would equate to anywhere between about 2 and 13 inches of snowfall (depending on snow ratio). The rain vs. snow issue will be critical into this forecast. So I am not prepared to favor one side of this range over the other at this time. It's going to be an extremely challenging situation to forecast accurately, and it's way too early to publicize definitive snow numbers. Anyone who says otherwise is wrong.
--Any other significant storm impacts? Coastal storm systems (nor'easters) are notorious for causing significant coastal flooding and beach erosion in New Jersey. (Refer to January's blizzard for an example. Grab a mop.) It's too early to talk about how big the waves and/or surge might be for Sunday's storm. Residents along the Jersey Shore should remain extra vigilant as this storm approaches - even if the forecast shifts eastward (out to sea).
--Is there are chance this storm will miss NJ? Sure. The GFS in particular favored a "completely out to sea" forecast for most of the week, and may trend back in that direction at any time. However, it is notable that all forecast models are now showing rain and/or snow falling from the sky in New Jersey on Sunday. Additionally, the coastal impacts are almost a definite at this point. Hold your breath and cross your fingers all you want - as I said, confidence is rapidly increasing that a storm is on the way Sunday.
--When will we know more? With each successive run of the forecast models, meteorologists get more information and data to make an even more confident forecast. While we'll certainly know more by Thursday afternoon and Friday morning, I suspect it will be difficult to get a fix on the finer details until Friday afternoon at the earliest.