Detailed Forecast

The winter weather advisory continues to be in effect for all counties except Putnam, Rockland and Westchester.  The reason for this advisories, as we’ve discussed in previous posts… is the threat for freezing drizzle prior to sunrise on Monday.  So as of late night… lets look at the current conditions:

3am Temperatures:
– 30° to 33° (Sullivan, Delaware, Greene, W Ulster)
– 32° to 36° (Orange, E Ulster, Dutchess, Columbia, Putnam, Rockland, Westchester)

The radar is quiet, not showing any precipitation over the last 3 hours.  Here is the computer guidance showing the total preciptation through the Monday morning commute:

Total Precipitation through Noon Monday

Notice that there is some light moisture, maybe up to 0.05″… or some spotty drizzle.  Where you see the gray on the map, it’s suggesting enough precipitation to dampen the roads.  So if temperatures are near or below freezing, those damp roadways could freeze and become black ice.  So let’s take a look at the low temperatures between now and noon on Monday…

You can see that most locations hover just a degree or two above freezing.  HOWEVER… there are some colder spots on this map, where you see pinkish coloring, that are at or below freezing… 31° or 32°.  If those colder locations also see the trace amounts of precipitation… we could have some icy conditions on untreated surfaces.  Sidewalks, driveways, and potentially roadways… could be icy in spots.

This will be a potential problem… because it won’t “rain” in any location… but a light mist is possible.  This will make it more difficult for some people to realize that the surfaces may be damp, and potentially icy… increasing the odds someone is caught off guard.  Ultimately, we’ll all have to take extra caution on Monday morning… and see how the situation unfolds.  As you see… it’s VERY Little moisture, and VERY marginal (near freezing) temperatures… but it’s enough that some localized icing could occur.  Be alert Monday morning.

The Monday AM Commute Could be Icy in Spots.  The National Weather Service issued a Winter Weather Advisory for much of the region, due to the threat of ice.

In short… some spotty light precipitation is possible after midnight tonight.  NE winds will hold today’s cold air in place, as a coastal storm stays well off shore.  Temps could be right around freezing with the onset of some patchy light rain showers and drizzle.  You can see the futurecast radar for 4am shows the Hudson Valley (circled), with patchy freezing drizzle in pink.

This could cause some icy spots on untreated surfaces in the morning, and could result in some school delays on Monday morning.  We’ll have to see how the situation develops overnight.  Not all of the data indicates temps will be cold enough for icy spots, but when dealing with the threat for ice, it’s best to err on the side of caution.  We’ll likely have another discussion this evening, and let you know if this event looks more or less likely.

Timing:

-12am to 8am : patchy freezing drizzle possible.  Mainly in traditionally colder valleys.

Impact:

– icy untreated surfaces possible

We are monitoring the potential for some potentially icy weather to impact the region overnight Sunday into Monday AM, a coastal storm will be moving up the coast but far to our SE, but some moisture from its outer fringe may impact the region. Cold air from yesterdays cold front will still be lingering by this time, but warmer air will be overriding the colder airmass, this sets up the potential for a period of sleet and freezing rain. The period of icing may have impacts on the Monday AM commute. The graphic below shows the storm moving to our south but precipitation reach our region, you can see the cold air “damming” in some of the valley locations while warmer air erodes the cold air from the top down, which is easily visible here. You can see in the second image where temps at this time are actually warmer across some of the higher terrain.

At the moment this is a low confidence forecast as we will need to monitor the development of the coastal storm to fully understand its impacts here by tomorrow night, we will have more on this as we headed into tonight and tomorrow, but please keep this potential factored into Monday AM plans and commutes.

A look at the next three days shows some positive news for anyone hating on the current arctic airmass, not only a dry and sunny few days but a slowly moderating airmass will take hold, keep in mind that it will be short lived and no heatwave by any means, more so just temps moderating towards average. In terms of staying power? Colder air arrives again for the weekend and then the roller coaster repeats as we head into early next week.

A frontal passage similar to last week will impact the region tomorrow, like the previous event it will be colder air rushing behind the front and the sooner the cold air rushes in the more wintry precipitation is likely. As the cold air approaches the precipitation with be collapsing southeast, so minimal accumulations of snow and ice are expected. Here is a rough idea of how things may play-out today.

4AM to 7AM- Light wintry mix and scattered light rain spreads from NW to SE, most likely to impact Delaware, Sullivan, Ulster, Greene and Columbia Counties first then spread south.. Light rain more likely south with wintry mix NW, little or no accumulations likely, some slick spots possible in colder locations.

7AM-10AM- Precip overspreads the entire region, light rain likely across SE parts of the region, mixing change over line begins across higher terrain and slowly spreads SE with arriving cold front. Precipitation begins to dry slot across NW regions cutting off potential accumulations, warmer air stubborn to depart valley locations.

10AM-1PM- Frontal passage ends precipitation from NW to SE, precipitation remains rain south and east and ends before change over can occur, crashing temps will result in refreeze and areas of black ice through the evening into the overnight.

Synopsis- In a repeat of the last winter weather threat, it appears to things will work against any widespread and high impact snow or ice across the region, warm air not eroding out of the region in time for the moisture to depart, dry air turning off precipitation as cold air approaches NW regions. Any snow or ice accumulations look to be limited to areas away from the valley floors and our northern more and western most zones with the exception of Ulster and Dutchess and points north  where cold air may settle into the Valley locations.

Areas most likely impacted by snow or ice- The following areas should be prepared for the potential for slick afternoon travel due to light accumulations of snow and ice, less than an inch for most. Sullivan,Delaware, Western Ulster, Western Greene, Eastern Columbia and Eastern Dutchess Counties, Potential exists for snow/ice further south into Eastern Dutchess and Ulster  County as colder air drains down valley, as seen on NAM Model Loop below.

Timing for potential slick travel due to snow and ice in the above locations- 10AM and after

*ALL AREAS WILL HAVE PM BLACK ICE POTENTIAL 

 

Model Discussion-

Both the HRRR and NAM model do a great job highlighting the above points, you can see the valley trapping warmth as noted by areas south of the black line we have added, areas to the north,west and east of this line have the highest probability of a light accumulation of snow or ice while areas along it or just to the south have a lower probability. Models also show the moisture drying up on the backside as the front approaches, which will also be a contributing factor in the little or no accumulations of frozen precipitation. Keep in mind that surfaces aren’t very warm, it won’t take much cooling for some roadway icing although it appears limited to grassy surfaces where it does occur. The post frontal passage freeze up will likely cause additional issues that persist into Wed AM.

Accumulations-

Not much to write home about, you can see how both the HRRR and NAM models highlighted the limited amounts of snowfall and most are confined to the areas described above, even in these locations is a somewhat low probability of accumulations due to loss from initial melting on surfaces.

 

One thing is for sure, since November 1st, the pattern has become much more wintry.  Temperatures are about 5 degrees below average after the first 10 days… and things are about to get more wintry around the region.

Timing:
– sunset – 2am : cloudy skies with patchy drizzle and spot rain showers
– 2am – 5am : rain showers develop from west to east
– 5am – 10am : rain changes to wet snow from NW to SE
– 9am – 12pm : wet snow tapers off from west to east

Impact & Accumulation:
– Valley (I-84 on south): slushy coating on grass… icy spots possible by mid to late AM
– Valley (north of I-84): slushy coating to 1 inch, mostly on grass… slushy & icy spots on roadways around AM commute
– Catskills & areas above 800ft: slushy inch or two possible.  Icy roads likely for much of AM commute

Futurecast Radar : 12am – 1pm Tuesday

You can see on the radar simulation, that all of the action is off to the north and west of the Hudson Valley until after midnight.  That’s because the frontal trough will hold to our west, providing the focal point of heavy snows well to our west.  Areas like Buffalo, Syracuse and the Adirondacks will see their first significant snowfall of the season.  However, in the Hudson Valley… it’s more of a reminder that the transition toward winter continues.  As the morning commute begins near sunrise… many areas may still be a cold rain.

You can see on the closeup shot, that the Catskills and upper HV will be the first to change over as the cold air sinks in at all layers of the atmosphere.  The transition should occur rather quickly, with rain showers becoming a period of steady wet snow.  Temperatures will be in the mid 30s where it rains… and in the low 30s where the transition to wet snow and sleet occurs.  Untreated roads could become slick and icy if a burst of snow occurs, which is likely… especially in the northern half of the HV.

As the commute continues, by 8am and 9am, the rain/snow line continues to push SE into the valley.  Many kiddos will head off to school in the falling wet snow.  Temperatures will initially be above freezing, so roads will start just wet.  But areas well north of I-84 could see the best chance for icy and slush covered roads.  This rain/snow line will push through the region rather quickly… and by 12pm, it’s pretty much over for everyone.  So it’s a quick transition from cold rain… to wet snow… to over.

Total snowfall amounts will generally be a trace coating on grassy surfaces, up to a half inch or so in some colder spots.  The higher elevations could see an inch or two, and also the best chance of icy roadways.  But even in the valley, temps will tumble by mid to late morning, with most locations being in the low 30s.  That could result in some icy travel conditions for the late morning commute.  But as things dry out… the PM commute looks much better.  With a few breaks of sun, temps in the low to mid 30s, should dry any road surfaces, and give us a safe but cold afternoon commute on Tuesday.

We’ll have another discussion Monday night… but the chances of a major change in the forecast are quite low.  This is a high confidence forecast.  We really want to exercise caution with the Tuesday AM commute, as rapidly falling temps into the low 30s and a burst of snow, just as kids are getting on the bus and travelling to school… could cause a few extra headaches.  Have a good Monday, and we’ll have more updates tonight.

Could Tuesday bring the first snowfall of the season to the lower elevations of the region? A look at the NAM model shows a very similar set up to the one we had earlier in the week, bug different is the amount of cold air and its ability to catch up to the moisture faster. The result is the potential for a brief onset of rain or wintry mix that transitions to snow from NW to SE. Below are a few graphics showing snowfall accumulations which are generally pretty light but enough to make for some headaches, temperatures which are cold enough for accumulations and an animated simulated radar showing the evolution of the event.

Concerns are the afternoon and evening commute which could be impacted by slick roads, the time frame between 3-7PM would be where slick conditions may persist, the combination of setting sun, temps below freezing and light snowfall coupled with school departures and commutes could present a hazard. We all know that sometimes the lightest of accumulation on semi warm roadways, combined with the first widespread snowfall of the season and occurring near peak commute has been a recipe for horrendous travel in the past.

We will continue to monitor and keep you all ahead of any changes. Stay Tuned.

 

 

Compared to what some of the computer guidance suggested last weekend… the Hudson Valley will dodge a bullet on Thursday.  But even though we won’t see our first widespread accumulating snowfall… we will still likely see a widespread reminder that if winter is not here… then it surely is not far away.

Timing:
– 10am – 2pm : Rain showers develop from west to east
– 4pm – 8pm : Rain showers mix with wet snow north of I-84 [Changes to Wet snow in Catskills]
– 6pm – 10pm : Rain mixes with wet snow south of I-84 [Mostly wet snow north of I-84]
– 8pm – 12am : Rain & wet snow tapers from west to east

Impact/Accumulation:
– Valley south of I-84 : little or no accumulation (maybe slushy coating on grass in spots)
– Valley north of I-84 : slushy coating to half inch possible, mainly on grassy surfaces
– Elevations over 800ft : coating to an inch or two possible, slick roads possible after dark

Futurecast Radar: 11am Thu – 1am Fri

The arctic boundary is approaching the Hudson Valley as the precipitation moves in from the west.  The timing is close… but not quite where it needs to be for an early November snowstorm in the Hudson Valley.  The light rain showers will fall during the afternoon… becoming a steady rain.  The cold air will cut into the valley, causing temps to tumble through the 40s in the afternoon, and into the 30s by early evening.  You can see the high elevations are the first to transition to wet snow.  Sullivan County and the Catskills should be wet snow by dark… with the wet snow flakes gradually making their way down to the valley (especially in the upper half of the Hudson Valley).

Since timing is absolutely critical… we can’t completely rule out the possibility that a burst of wet snow doesn’t reach the mid and lower Hudson Valley before ending.  So even near the I-84 corridor we could see a slushy coating of wet snow on the grass in spots.  But it’s likely to produce no accumulation in most of the valley areas.

You can see the warmth of early November really prevents any wet snow accumulation in the valleys… and really even away from the valley floor, the wet snow has a problem sticking.  Without a purely wintry air mass in place… it’s extremely challenging to get snow to fall this early in the season.

And so, that’s what we’ll likely see on Thursday afternoon and evening… the battle of the seasons, between an autumn air mass and our first purely wintry airmass of the season.  The wintry air mass will win out… but it should be too little too late for snow lovers.  But fear not… more opportunities are on the way as November continues.

Another frosty start around the region, as changing the calendar really seems to have changed the weather pattern.  Colder Canadian air has pushed into the northeast, and through the coming week… we expect reinforcing cool shots to keep us near to just below average for early November.

We’ll track a weak disturbance passing by to our NW on Tuesday, that will bring us clouds and the slight chance at a shower or two… otherwise we look dry through the first half of the week.  Afternoon temps should be in the upper 40s to low 50s most days… which is a degree or two below average.

Tomorrow we’ll have a detailed look at the first 2 weeks of November.  Will the pattern warm back up, will the cold stick around?  Check back with us Monday morning.  Have a great Sunday!