Monsoon's Forecast: The Groundhog Day Holy Mess
This is a challenging forecast—again—because of the storm’s complexity. Timing (of precipitation arrivals and mixing) will be the key in terms of school scheduling. There is also the wildcard of warmer air aloft, which affects the precipitation type we will see.
But you didn’t come here for hogwash and horsefeathers, now did you? No, you came here for a definitive forecast. And a definitive forecast you shall damned well receive.
Reading/Berks: flurries and light snow showers arrive as early as 8 or 9pm this evening, becoming a steadier snow after midnight. The snow will mix with sleet and freezing rain by early Tuesday afternoon, becoming all ice by late afternoon. Snow accumulations 2 to 4 inches.
Snow arrives late Monday night into Tuesday morning.The temperature will rise only into the upper 20s through this period, so the precipitation that does fall—even if it is rain—will freeze to surfaces.
There will be a bit of a lull in the precipitation later Tuesday evening before the moisture cranks up, delivering us nearly an inch of freezing rain overnight into Wednesday morning. The temperature will finally climb above freezing by late Wednesday morning, so plain rain will fall then. However, expect hazardous driving conditions through the afternoon and evening as the rain will simply coat the thick ice and snow already packed on roadways.
Freezing rain Tuesday into Wednesday will create widespread icing before the precipitation changes to plain rain later Wednesday.Finally, on Wednesday evening, as arctic air floods the region, the precipitation will likely end as snow showers, with steadier bands producing perhaps an inch of additional accumulation. Oh, and it will be quite windy, too.
The aforementioned arctic air will drive temperatures down into the teens by Thursday morning, and highs will only reach the mid 20s on Thursday. Single-digit lows are possible on Thursday night into Friday.
My primary concern with this storm is icing. If we have a prolonged period of sleet and freezing rain—and I think we will—we will see downed power lines, downed tree limbs, and travel difficulties, especially on back roads and untreated surfaces. In addition, the widespread icing will make for poor flying weather (e.g., ice-clad wings and runways), so expect a prolonged period of delayed and cancelled flights from Tuesday morning into Thursday morning. School scheduling percentages...
Probability of at least a delay Tuesday: 90%
Probability of cancellation Tuesday: 80%
Probability of at least a delay Wednesday: 80%
Probability of cancellation Wednesday: 70%
Probability of at least a delay Thursday: 65%
Probability of cancellation Thursday: 40%
Probability of at least a delay Friday: 45%
Probability of cancellation Friday: 25%
And now, by popular demand, here’s the outlook for some other places…
Pittsburgh: snow arrives by 6 or 7pm tonight, then continues overnight, accumulating an inch or two before changing over to freezing rain before dawn. Freezing rain changes over to plain rain by late morning Tuesday. Temperatures will rise well above freezing throughout the day, so this precipitation should not create icing. Rain may freeze on surfaces on Tuesday night, especially at higher elevations, so use caution. Rain will change back over to light snow on Wednesday afternoon and evening, accumulating only a coating to an inch.
Philadelphia, northern Delaware, and South Jersey: snow arrives after midnight and accumulates only a coating to an inch before changing to freezing rain and sleet by mid-morning Tuesday. This mess changes to all rain by late afternoon, so impact on the evening commute should be minimal. Freezing rain overnight and into Wednesday morning will likely compromise the AM commute, but will quickly change over to rain. There may be a few snow showers in the evening, but these will yield little to no accumulation.
Central and northern New Jersey, as well as NYC: snow arrives after midnight and accumulates 4-6 inches before changing to freezing rain and sleet by mid-afternoon Tuesday. There could be a half-inch or more accumulation of sleet and ice by Tuesday night. Icing will be a major problem on Tuesday and will likely cancel schools and make travel treacherous. Freezing rain continues overnight, but plain rain by late morning should wash away a lot of the “ick.” Expect snow showers by late afternoon into the evening, then clearing.
Of course, stay tuned for updates and tweakage on the forecast and throughout the storm…
On a final note, monsoonmartin.squarespace.com has had its best month ever in January, thanks to you guys – well over 5,000 hits. I know that a video of a bulldog humping a stuffed animal can get 5,000 hits in a few hours on YouTube, but still, this is a major milestone for me. So hey…thanks for tuning in, or dialing me up, or whatever. Big ups to the Weather Crew!!