Winter storm watch issued
Early December snow, once a rarity, has come down on the Lehigh Valley in small amounts in four of the last five years. This Wednesday, forecasters say, will be a lot different.
The National Weather Service has issued a winter storm watch in effect from Wednesday morning through Thursday morning for snow accumulation sin excess of 12 inches, the “most impactful winter weather” in several years.
Forecasters expect the nor’easter to creep into the area around noon or slightly after, making travel “difficult to impossible” and affecting both the Wednesday evening and Thursday morning commutes.
It will follow the area’s first measurable snowfall of the season, which came last Wednesday.
It was more than a dusting, but certainly less than a storm, depositing a few inches in the higher elevations and small amounts elsewhere.
On Monday morning, precipitation began as rain before changing to snow, amounting to less than half an inch measured at Lehigh Valley International Airport by 1 p.m., according to the National Weather Service.
Already, the forecasters are focused on this week’s main event.
Amounts: Empire Weather, which provides localized forecasts for The Morning Call, said if Wednesday’s storm reaches its potential, the Lehigh Valley will see more than a foot of snow by the time it ends early Thursday.
The weather service also is forecasting over a foot of snowin the region, and said in its morning forecast discussion a slightly
more inland track could result in snow amounts in excess of 18 inches for areas north of Interstate 78.
Bust potential: The main bust potential for areas north of I-78 is a southern storm track that would shunt the precipitation shield farther south and cut snow amounts considerably.
Areas northwest of I-95 and south of I-78 — including the Lehigh Valley — are in the “sweet spot” for heavy snow, the weather service said. The area has a thermal profile cold enough to support mostly snow, with a widespread 12-18 inches expected, and some potential for isolated higher amounts.
The main bust potential for most of the Lehigh Valley is a warmer solution for the storm, which would cause a change to sleet or freezing rain. This would cut accumulation considerably, and the weather service said this potential “warm nose aloft” bears watching.
For the I-95 corridor and points south, the snowfall forecast remains highly uncertain. It’s possible Philadelphia and its suburbs will see a transition to mixed precipitation and/or rain, with a change back to snow near the end of the storm. Forecast snow amounts range from 4-12 inches in this area, and will be highly dependent on the storm track and other factors.
A slow melt, initially
The weather service rule of thumb for Wednesday’s storm looks like this: in general, the farther north and west, the better the chances of seeing more snow and vice-versa. That means you better know where your snow shovels and winter boots are.
December snowstorms totaling more than 6 inches have been rare occurrences in the Lehigh Valley in recent decades, records show.
The one-day December snowfall record for the Allentown area is 13.1 inches Dec. 24, 1966, followed by 12 inches Dec. 14, 1917, and 9.1 inches Dec. 9, 2005.
Looking past the storm, the Valley is in for a slow melt. Highs will likely struggle to reach freezing Friday, with widespread lows in the teens Saturday morning.
Temperatures Sunday could push near 40 degrees, finally kickstarting the melting process.