Friday Briefing: Wet Weather for the Weekend, Early March Nor’easter?

Happy Friday! Today will continue to feature more cloudiness, chilly temperatures, and raw weather, as a frontal boundary continues to remain to the south. Periods of rain are likely with a weak frontal system moving through the Northeast. Most of this rain will be on the light to moderate side. In some of the higher elevations over the Northwest Hudson Valley and New England, surface temperature may support some spotty areas of freezing rain, which could make for some slippery spots on roads. But otherwise no significant weather hazards are anticipated today.

Warm-air advection will be increasing. But with cloudiness, temperatures will be slow to rise into the lower to middle 40s, for a good of chuck of the local region. Some areas further north may struggle reach 40, while Southern parts of Pennsylvania and New Jersey may get into the upper 40s. Rain will taper off to showers this evening, then skies will become partly cloudy overnight. Temperatures will continue to remain steady or even slowly rise through the 40s.

3km NAM this afternoon, showing rain. Some pockets of freezing over the higher elevations

3km NAM late this afternoon and evening, showing rain for much of the Northeast, with some pockets of sleet and freezing over the higher elevations in the Interior.

Considerable cloudiness will be around the during the day on Saturday. The best chance for any sunshine will be during the morning hours. Then some showers will begin arriving Saturday afternoon and evening ahead of the next storm system. Temperatures will be moderating into the 50s, despite cloud cover. Then later Saturday into Sunday, more periods of rain are likely as a warm front begins to lift northward and a cold front approaches from the west. A strengthening low-level southwesterly low-level jet and high precipitable values will result in some moderate to heavy rain at times. Rainfall totals could be higher than 1” in some spots leading to some minor flooding in poor-drainage and low-lying areas, especially in locations where the warm front and the cold front combine forces.

GFS model showing moderate to heavy rain over parts of the Northeast with storm system Sunday morning

GFS model showing moderate to heavy rain over parts of the Northeast with a storm system on Sunday morning

High pressure builds for early next week with more tranquil weather and sunshine for Monday and Tuesday. Strong upper-level ridging builds into the Northeast again, and thus temperatures will likely remain above normal for the end of February, with daytime highs in the 50s. Then more unsettled weather returns later next week, as high-latitude blocking strengthens near Greenland (otherwise known as a -NAO). This may eventually lead to a larger coastal storm or Nor’easter developing along the Mid-Atlantic coast for late next week. But details remain uncertain with models showing various solutions, with different handling of the disturbances coming underneath this block.

ECMWF EPS showing the very strong block near Greenland late next week. But also a trough still over the Western US.

ECMWF EPS showing the very strong block retrograding south of Greenland late next week and a trough still over the Western US.

At this time, deep troughiness over the Western United States may make it difficult for more northern and southern stream shortwave phasing too occur. The airmass ahead of this system, will also continue to be not very cold. So any significant snowfall will be depending on the storm rapidly intensifying and with mostly dynamic cooling occurring  There will also be full moon around this time period, when tides will be astronomically higher than normal. So if this Nor’easter develops, serious coastal flooding will also be concern, as a tightening pressure gradient will lead to some strong onshore winds. But this is just speculation, at this time.

The way to turn this storm into a snowier one is if the disturbance coming out of the Western US trough takes longer to eject eastward. This is because if it ejects slower, the blocking will have more time to establish itself, shunting the storm southward while it potentially waits for a phase with more dynamic energy, allowing more cold air to get drawn in while the system is still deepening. This is what the European model suite is advertising — although it still has a warm airmass out ahead of the Western US trough, and it ultimately just misses phasing the main pieces of energy — so it’s certainly not one that is “inevitable” for a turn to a snowier solution, but it is on the table.

Stay tuned for more briefing and other updates on the weekend forecast and this potential Nor’easter late next week.