Wintry mix in the interior, heavy rain and wind this weekend

The coldest airmass of the young winter season is on its way out of the area today, as  temperatures moderate above average into middle and upper 40s for today and Friday. A large high pressure area centered over Quebec will remain in control of our weather for now. Things will start to trend downhill by Friday Night and Saturday with the threat of light wintry precipitation across the interior and higher elevations. Thereafter, a much larger and more intense storm system will impact the area from late Saturday night into Sunday.

Before that storm, a 500mb shortwave and a weak warm front from area of low pressure over Great Lakes will approach southwest on Friday night and Saturday. Significant precipitation is not likely in this region with this system — but there could be enough lift and moisture with these features to produce some light and intermittent precipitation.  At the same time, the high pressure will be slow to lose control and could cause some cold air damming near the surface. Another low will also begin organizing over the Central Plains.

The GFS showing the high over Quebec CAD daming signifcnat

The GFS Friday night showing the high over Quebec, causing some low-level cold air damming ahead of a weak system extending from the Great Lakes  Another low-pressure system getting more organized over the Central Plains.

Over the higher elevations of Northwest New Jersey and Lower Hudson Valley, the GFS model soundings show enough cold air for a light wintry of snow, sleet, and rain on Friday night and early Saturday morning. Very minor accumulations, if any, are expected at this point. For the rest of region, the soundings are warm and any precipitation is expected to be in form of just light rain.  Temperatures over the Interior will likely drop into lower to middle 30s and upper 30 to lower 40s near the coast overnight Friday, and then rise into middle to upper 40s everywhere by Saturday afternoon with mostly cloudy skies remaining.

GFS Bufkit Sounding showing light snow for early Saturday morning

GFS Bufkit sounding showing light snowflakes for early Saturday morning for Newburgh,NY. With moderate omega (lift) and mositure in snow growth zone near 600mb and near or below freezing temperatures below.

Then the subtropical jet stream disturbance that we mentioned in previous premium article will be phasing with a polar jetsteam disturbance over Central United States this weekend. This will result in a low pressure system consolidating over the Central Plains on Saturday. This low will then track into the Great Lakes and deepen rapidly on Sunday. Meanwhile, the high pressure departing northeast from Quebec will cause a tight pressure gradient ahead of the storm, enhancing southerly winds.

This storm will push a warm front and cold front through the region on late Saturday night and Sunday, with enhanced lift for precipitation. This rain could become heavy at times on late Saturday night and Sunday morning. Lift and moisture increase with a southerly low-level jet at over 50kts and precipitable water values over 1.00″.  Models show little instability, but an isolated thunderstorm with very heavy downpours can’t be ruled out. Rainfall totals between 1″ – 2″ are possible for parts of the region. This could cause some localized flooding in low-lying or poor drainage areas.

6z GFS shoing 925mb winds over 50kts Sunday morning over NYC metro region

The GFS showing 925mb winds over 50kt-70kts Sunday morning over NYC metro region. Surface wind gusts to 40mph mostly likely near the shore. Some of these wind could be brought down to surface with any thunderstorms

Some gusty winds and coastal flooding will also be a concern. Models are showing 850mb and 950mb level winds between around 50kt to 70kt on Sunday morning and early afternoon. At this point, sounding show very little instability for much of these winds to frequently mix down. But wind gusts up near 40mph are still possible, especially near the shore. Any isolated thunderstorm could bring down stronger wind gusts. Also, with new moon this weekend, some coastal flooding or beach erosion will be possible during high tides Sunday morning.

The GFS showing heavy rain and strong winds in the region Sunday morning

The GFS showing heavy rain and strong winds in the region early Sunday morning

With the storm tracking well to our north and west, this will allow more warm air to surge into the region. Increasing mid-level heights and strong, deep southerly flow will cause temperatures to rise into at least the middle to upper 50s overnight Saturday and Sunday morning. These temperatures are 10 to 15 degrees above average for this time of year. The 0z/06 ECMWF model shows 850mb temperatures as high as 9°C during Sunday — so this could support temperatures to reach the lower to middle 60s. This would again bring us near record highs for the region on Sunday.

However, this big warm surge will brief. On Sunday afternoon, rain and winds will begin diminish, as the cold front passes through the area. Cold air advection will also cause temperatures to begin to fall. By Sunday evening, temperatures will be falling through into 40s and 30s. An artic boundary will move across region during the morning and early afternoon, causing temperatures remain or steady or slowly falling in the 30s on Monday.

This will lead us into a colder and more wintry pattern for the weeks ahead.