weathermedic

The snow cover is definitely helping keep the temperatures a few degrees colder

Upton's morning AFD Regarding the potential for a coastal storm for this upcoming weekend, if any impacts were to occur it appears that the timing would be late Saturday night and into Sunday, and possibly Sunday evening for some eastern sections. Most of the dynamic modeling continues to show the storm being the nearest of misses, or, with the NYC metro not experiencing any snow impacts. The longwave pattern does amplify, but the mean eastern trough also begins to progress east while amplifying. A good rule of thumb is whether the 500 mb vorticity maximum or the 850 mb low gets north / south of Cape Hatteras. Just about all the dynamic and AI modeling has the vort max / 500 mb low going just south of Cape Hatteras. Climatologically that is a miss with respect to big snow for our area. In some cases far eastern areas get brushed. Therefore, at this point in the modeling / forecast process the most likely scenario is the nearest of misses. However, some impacts cannot be completely ruled out, especially further east as there remains some room for the modeling to wobble slightly further west which would bring eastern portions of the region in play for some minor to moderate impacts. Some coastal impacts remain a possibility in terms of minor coastal flooding. Stay tuned to subsequent forecasts for any changes.

Good read from Upton's morning AFD: Regarding the potential for a coastal storm for this upcoming weekend, if any impacts were to occur it appears that the timing would be late Saturday night and into Sunday, and possibly Sunday evening. Most of the dynamic modeling has the storm being the nearest of misses, or a side swipe / brush for eastern sections east of the NYC metro. The longwave pattern does amplify, but the mean eastern trough also begins to progress east while amplifying. At this point in the modeling / forecast process the most likely scenario is the nearest of misses, or perhaps the region gets bisected with a sharp cut off in moisture / QPF. With an eastern track and arctic air in place beforehand precipitation would in the form of all snow. Most of the modeling on most of the more recent runs has had the main 500 mb vorticity maximum pass just south of Cape Hatteras would typically means a miss for our region with heavy snowfall. However the slightest misrepresentation of the upper levels by NWP would have massive consequences in terms of sensible weather, especially further east across the region. Strong winds remain a distinct possibility, especially further east. Stay tuned because changes in the forecast for the second half of the weekend remain in play.

9.5 inches here with about .5 of that as sleet

Looks like gravity waves on radar

Another 1.8 inches in the past hour for a total of 8.1 inches so far

Meanwhile at the southern end of this huge precipitation shield covering the country, tornado watches up for AL, GA and FL

Co-worker in Medford NJ reporting sleet now

Just measured 2 inches in the last hour. Total up to 6.3 inches now here in Sheepshead Bay Brooklyn

I just measured 4.25 inches at my station in Sheepshead Bay Brooklyn

3 inches at my location in Sheepshead Bay

Also don't forget if cities/towns just use plain salt, it does not have the same melting power when temps get below 20 degrees. I know NYC Sanitation salt trucks have the ability to mix in liquid calcium chloride when they spread so that should help

NYC Sanitation just gave the order for all their trucks to drop their plows and commence plowing operations. Had one just come down my block. That layer of salt they spread last night did nothing as the road is still white after the plow went by.

Latest graphic from Upton

Bernie Rayno with a nice explanation on things https://x.com/AccuRayno/status/2015106637212659787?ref_src=twsrc^tfw|twcamp^tweetembed|twterm^2015106637212659787|twgr^c7b51d61c8a3e5047944a1f086a006052f31bce0|twcon^s1_c10&ref_url=https%3A%2F%2Fpublish.twitter.com%2F%3Furl%3Dhttps%3A%2F%2Ftwitter.com%2FAccuRayno%2Fstatus%2F2015106637212659787

Meanwhile barometer is still rising at 30.64 (approx 1038 mb)

Good write up (as usual) with the morning AFD out of Upton: A major winter storm will impact the region Sunday into at least early Monday. A Winter Storm Warning Remains in effect for the entire area. Arctic air has settled over the area courtesy of a sprawling 1048 mb high pressure over the northern plains. This high pressure will settle over New England tonight as a winter storm materializes over the southeastern US. Low pressure will develop over the south and be forced to track around the deep cold air damming signature east of the Appalachians tonight, with secondary low development taking place along the Middle Atlantic coast on Sunday. This low pressure will then deepen as it tracks towards the Long Island coast late Sunday into Sunday night before shifting offshore on Monday. The main uncertainty with the system continues to revolve around the timing of potential mixing with sleet for the southern/coastal portion of the region Sunday evening. The model guidance is in overall agreement on the key pieces with the winter storm, but differ slightly on the northward extent and timing of a warm nose around 750 mb. Generally took a blend of partial thicknesses from the GFS, ECMWF, NAM, and RGEM Sunday evening. Most of the guidance has settled on any potential wintry mix occurring around or just after 00z Monday. The NAM is the most aggressive and quickest with the warm nose (sometime mid to late afternoon) and wanted to at least blend its thicknesses in case the warm nose comes in a bit faster than currently expected, which has happened in past events. Snow will quickly develop from south to north across the area Sunday morning as the region lies underneath an intense polar jet streak lifting into southeast Canada. The snow will fall into arctic air with surface temperatures only in the low to mid teens. This is a bit unusual for the area as most snow events over the Tri-State occur with temperatures in the 20s or low 30s. The snow will quickly accumulate as the intensity picks up through the morning. Mid level thermal forcing will increase over the area, especially heading into the afternoon. The 850-700 mb frontogenesis is impressive and the overall deep layer of vertical velocities over the area strongly support heavy snow over the region in the afternoon. Only a slight increase in temperatures is expected in the afternoon, except the southern half of the area where temperatures rise into the mid 20s. As the warming in the middle levels continues, the chance for a mix with sleet near the coast increase sometime late in the afternoon or evening. It needs to be emphasized that the overall impacts will not change and significant snow will occur before any wintry mix. There is a possibility the heavy snowfall rates will be able to hold back the warm nose just enough or create an isothermal layer on the 0C isotherm to prolong heavy snow for even just an hour two. The 00z HREF indicated several hours of over a 60 percent chance of greater than 1 inch per hour rates, and even has a few hours over 80 percent. The probability for greater than 2 inches per hour on the HREF in the afternoon/early evening ranges from 20 to 40 percent. The guidance also offers impressive QPF values between 18z Sunday and 00z Monday with potential of at least a half inch liquid, giving more confidence there will be heavy snowfall over the area. A few lightning strikes cannot be ruled out in the heaviest bands with the impressive dynamics aloft and deep moisture being lifted over the low level arctic air. The strong mid level frontogenesis lifts northeast between 00-06z Monday and this should serve to gradually reduce precip rates. There may also be drying aloft, which will start to reduce snowfall rates where it remains all snow. The southern half of the area should see a wintry mix of sleet, potentially mixed with snow if the warm nose is not as deep. There is also a chance for some light freezing rain and a light glaze of ice as the drying aloft occurs, cutting off snow growth along with the thinning of the depth of the low level cold air. This may also be dependent on how close the low pressure ends up to Long Island. The consensus of the modeling keeps the low just south and east of Long Island, but if it were to end up closer to the shore, some parts of eastern Long Island could briefly rise above freezing with light plain rain briefly possible. The system starts pulling away from the area late Sunday night into Monday morning. Some bands of light snow may return as the trailing upper trough approaches and the thermal profiles become colder heading into Monday. Probabilities for precip decrease significantly Monday afternoon and there is potential anything that falls may just be flurries. Snowfall totals are largely consistent with the previous forecast ranging from around 10 inches near the coast and around 16 inches well inland. The potential of sleet is included in these totals for areas that may see a mix or a full changeover. SLRs are tricky with this event as the arctic air mass supports a higher ratio (around or just above 15:1), especially early in the event. The increasing moisture aloft and warmer air in the middle levels will likely lower ratios to 12-14:1 and will drop further with any mixing in the evening towards the coast. As noted above, snowfall rates of 1-2 inches per hour are expected in the afternoon and early evening. Winds will pick up in the afternoon and evening, especially near the coast and could create near white-out conditions/near blizzard conditions with winds gusting 30 to 40 mph at times. A mix or change to sleet will reduce this potential as visibilities would not be as low.

Good AM discussion out of OKX The overall synoptic picture into early next week continues to sharpen. At the surface, arctic high pressure slides east from the Great Lakes into the Northeast this weekend. Meanwhile, low pressure develops and tracks through the South before redeveloping off Cape Hatteras, passing near or just inside the 40N/70W benchmark into Monday. Aiding the potential for snowfall, an arctic air mass settles in ahead of the storm. 925 mb temps look to fall toward -20C or below on Saturday, with surface temperatures progged in the teens during the afternoon, setting up one of the coldest days in several years. This will allow snow to fall everywhere at the onset, which looks to develop rather quickly either very late Saturday night, or more likely Sunday morning around or after daybreak. Periods of heavy snow then appear likely late Sunday morning through the afternoon via the strong frontogenetic and thermal forcing aided by an anticyclonic upper jet to the north. Snowfall rates in this period likely eclipse 1 in/hr at times, perhaps closer to 2 in/hr. Given the cold air mass in place initially, SLRs start out on the higher side (15-18:1) at onset, gradually falling back toward 10:1 or lower along the coast by late afternoon as the mid levels warm. With guidance having adjusted to a closer to the coast surface low, the proximity introduces the possibility of enough warm air intrusion around 800 mb for the snow to mix with or change to sleet Sunday evening. Best chances for this are along the coast, including Long Island and NYC metro. Lower confidence in this occurring going north, with all snow still the most likely solution into the Lower Hudson Valley and Southern Connecticut. Freezing rain or drizzle also cannot be ruled out, though significant icing appears unlikely. As the coastal system deepens and lifts north and east into Monday, the boundary cools once again, and any wintry mix likely tapers as snow showers or flurries into late Monday morning or afternoon. Any additional accumulation is likely light. Forecast snowfall totals have decreased slightly along the coast. This is due to the increased potential for mixing as the warmer air aloft works in. It should be emphasized though the heaviest and steadiest precipitation is expected Sunday morning into early evening, with the bulk of snow accumulation occurring prior to any potential changeover. With QPF progged over an inch, areas that remain all snow should be able to yield double digit snowfall. The question becomes how much warm air is able to work in and force a changeover to sleet, cutting down snow totals. All said, still expecting a widespread 8 to 14 inches across the region, with localized amounts perhaps approaching a foot and a half where best banding sets up and ptype remains all snow. Greatest likelihood for this is across the interior. We remain just over 48 hours from event onset, so opted for no headline changes with this update. It appears likely warnings will be warranted for all areas later today or tonight, dependent on no significant deviations in forecast thought. Continue to monitor the forecast on what is increasingly likely to be a major winter storm with significant disruption to travel and daily life early next week.

That is only through 7pm Sunday

I remember in 1994 there was moderate to heavy rain for a good part of the day with temps in the low 20s

Also looks like the wind picks up towards the end of the precip as the low deepens

25 dropsondes reportedly dropped into the low off of Southern California for ingestion into the 0Z models

From Ryan Maue on X: We can partition the model output by how much "snow" will fall -- and then apply a "snow to liquid" ratio (SLR) which is typically 10:1 at temperatures around freezing. But this snow will be falling in frigid air 8°F to 18°F so SLR > 15:1 or 18:1 Do the math: 1.4" QPF x 18:1

Here is the Mt Holly AFD from this morning: KEY MESSAGE 3...There is an increasing potential for the area to be affected by an impactful winter storm late Saturday through Sunday, however quite a bit of uncertainty in the forecast details still remains. Signals in the upper level pattern by late week and the weekend becomes quite active between the northern and southern stream jets. The key elements embedded in these features are currently located over the Arctic and the Pacific Ocean, so it`ll likely take at least a couple more days for guidance to have a good handle on this system. However, almost all available guidance depicts an area of low pressure developing near Texas Friday before tracking eastward along the Gulf coast into Saturday. Beyond Saturday there still remains forecast uncertainty regarding the details of how this system will play out for the east coast. However, at this time most forecast guidance tracks the low north and east towards the North Carolina coast and then off to the north and east from here by the Sunday into Monday time frame. This track puts the mid Atlantic region on the northern side of the system with the main question then becoming just how close to us does the low track. There will be a very strong and broad arctic high to our north and some of our prior guidance had suggested this may be strong enough to suppress the system just south of the area. But over the past 12 to 24 hours there`s been a general trend northward in guidance suggesting the precipitation shield will make it into our area. In fact, snow probabilities of the NBM now show a 60-70% chance of 2+ inches of snow and a 40-60% chance of 6+ inches of snow for areas roughly along and south of the I-95 corridor with decreasing probabilities farther north. These probabilities are higher than with the prior forecast cycle. So while this system still is about 5 days out, the signal for a winter storm to impact at least parts of the area is higher than usual. The timing of this would be as early as very late day Saturday continuing through Sunday and potentially even lingering into Monday depending on the system`s speed. We will stress though that even with this trend in the guidance, most east coast snowstorms typically drop their heaviest snows in swaths 50 to 100 miles wide or less. And considering that the pieces of energy that will drive this storm are still thousands of miles away, that means it`s much too early to have much confidence on how much snow will fall at any given location. Users should keep a close eye on the forecast over the coming days.

Got a total of 1 inch here in Sheepshead Bay Brooklyn today. Had .8 yesterday and .26 of rain today