wthrmn654 Posted January 24 Share Posted January 24 Upton 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 mid levels continues, the chance for a mix with sleet near the coast increase sometime in the afternoon. Latest model trends this morning have a stronger warm layer with the coastal low development being a bit closer to the coast. This may allow for the mix of sleet to be a bit earlier than previously expected, beginning first as mainly snow mixed with sleet as early as 1-3 PM but becoming more of a primary period of sleet thereafter along the coast into Sunday 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. Given the expected heavy snowfall rates of 1- 2" per hour (or possibly higher), even just an hour or two of mainly snow rather than sleet can result in a 2-5" difference in snow accumulation prior to the transition to sleet. Additionally, 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, mainly for Long Island and the NYC metro 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. Overall, snowfall totals were adjusted slightly downward, mainly for the coast with increasing potential for sleet and an earlier timing of the mixing cutting down a bit on total accumulations. Long Island, the NYC Metro, and NE NJ are expected to see 8-12" total, but this may be in the form of 6-9" of snow and 1-2" of sleet. For more inland areas, total accumulations of 12-15" are expected consisting of primarily snow with less than an inch of sleet. 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, especially for coastal Long Island and coastal Connecticut. A mix or change to sleet will reduce this potential as visibilities would not be as low. 2 Link to comment Share on other sites More sharing options...
NJwx85 Posted January 24 Share Posted January 24 1 minute ago, NorthShoreWx said: I'm not sure everything melts in that melt layer. 50mb is enough, but it looks like no more than 1⁰C. OTOH, I'm not sure how much is even falling into that layer. I'm thinking that's a mix, including some fairy crappy snowflakes from below 775mb. I think the bigger issue is that the mid level warning will hurt rates quite a bit. Some areas might start off at 12 or 15 to 1 and go down to half that by sunset. Link to comment Share on other sites More sharing options...
SACRUS Posted January 24 Share Posted January 24 RAP has mixing around 3pm Link to comment Share on other sites More sharing options...
Roger Smith Posted January 24 Share Posted January 24 Would you expect a zone of enhanced amounts extending west from Long Island Sound across Bronx and Yonkers into n NJ? Looking at the synoptics model and real time I would expect that enhanced zone to be oriented almost E-W, possibly 260 deg? Also that can generate thunder-snow within squall cells. 1 Link to comment Share on other sites More sharing options...
nycsnow Posted January 24 Share Posted January 24 2 minutes ago, SACRUS said: RAP has mixing around 3pm Pretty similar keeps it just below Long Island for a while Link to comment Share on other sites More sharing options...
Picard Posted January 24 Share Posted January 24 How fast does everything overcome dry air? Surface dews are still well below 0 over much of the storms path. Link to comment Share on other sites More sharing options...
EastonSN+ Posted January 24 Share Posted January 24 Link to comment Share on other sites More sharing options...
CPcantmeasuresnow Posted January 24 Share Posted January 24 7 minutes ago, Prue11 said: NOAA has me getting up to 32 degrees tomorrow for a high. How long have you lived on the Delmarva? 2 Link to comment Share on other sites More sharing options...
NJwx85 Posted January 24 Share Posted January 24 3 minutes ago, SACRUS said: RAP has mixing around 3pm To be fair that only shows mixing in the Southern third of the forum and barely at that. Link to comment Share on other sites More sharing options...
nycsnow Posted January 24 Share Posted January 24 Regardless what happens. Gotta give the RAP credit. Hasn’t wavered Lol you’d think they put same maps out just change times Link to comment Share on other sites More sharing options...
Jt17 Posted January 24 Share Posted January 24 RAP has mixing around 3pm Hmm I think it doesn't make it to nyc here - in fact stays south for 8 more hours. . Link to comment Share on other sites More sharing options...
NJwx85 Posted January 24 Share Posted January 24 1 minute ago, Picard said: How fast does everything overcome dry air? Surface dews are still well below 0 over much of the storms path. Everyone should be ripping by 9am. Link to comment Share on other sites More sharing options...
nycsnow Posted January 24 Share Posted January 24 Link to comment Share on other sites More sharing options...
nycsnow Posted January 24 Share Posted January 24 10:1 still a foot plus as well on RAP Link to comment Share on other sites More sharing options...
mikeysed Posted January 24 Share Posted January 24 The RAP is cold bias. Link to comment Share on other sites More sharing options...
EastonSN+ Posted January 24 Share Posted January 24 GFS was snowier West and east. Just a small punch of sleet lol. Link to comment Share on other sites More sharing options...
Snowlover11 Posted January 24 Share Posted January 24 Gfs ticked ever so slightly south, not much but a tickle of a nickel smudge. Snow axis is a little weird though. 1 Link to comment Share on other sites More sharing options...
nycsnow Posted January 24 Share Posted January 24 1 minute ago, mikeysed said: The RAP is cold bias. Also a dry bias… so warm it up a bit give us more precip we still do good lol Link to comment Share on other sites More sharing options...
nycsnow Posted January 24 Share Posted January 24 2 Link to comment Share on other sites More sharing options...
Jt17 Posted January 24 Share Posted January 24 Ukie a little better. . Link to comment Share on other sites More sharing options...
wxman Posted January 24 Share Posted January 24 Just now, Jt17 said: Ukie a little better. . Essentially all snow like it was at 12z. 1 Link to comment Share on other sites More sharing options...
EastonSN+ Posted January 24 Share Posted January 24 1 minute ago, Snowlover11 said: Gfs ticked ever so slightly south, not much but a tickle of a nickel smudge. Snow axis is a little weird though. Yeah I just did the comparison the GFS was about 20 miles south and colder. Just that SMALL warm punch lol. 2 Link to comment Share on other sites More sharing options...
SACRUS Posted January 24 Share Posted January 24 UKIE 2 Link to comment Share on other sites More sharing options...
nycsnow Posted January 24 Share Posted January 24 Ukie great and locked in for days Link to comment Share on other sites More sharing options...
SnoSki14 Posted January 24 Share Posted January 24 I suspect we'll be fighting off sleet for a while as long as precip comes down heavily. Link to comment Share on other sites More sharing options...
NorthShoreWx Posted January 24 Share Posted January 24 1 hour ago, ILoveWinter said: Most people don't follow the models as closely as us weenies and probably don't know that CPK tends to under measure snow! Seems like a nice arbitrage opportunity here lol. Seems like a lawsuit generator if there is a ridiculous measurement reported by the conservancy. Link to comment Share on other sites More sharing options...
nycsnow Posted January 24 Share Posted January 24 1 minute ago, SnoSki14 said: I suspect we'll be fighting off sleet for a while as long as precip comes down heavily. Do you think it can be one of those instances where despite what models show it goes back and forth depending on rates ? Link to comment Share on other sites More sharing options...
JBG Posted January 24 Share Posted January 24 2 hours ago, Winterweatherlover said: It is but it mainly only helps places between 84 and 287 this run, would need another 30 mile tick to mean much for NYC metro. There's warm and there's warm. IP is better than ZR. 2 Link to comment Share on other sites More sharing options...
wthrmn654 Posted January 24 Share Posted January 24 Sister in Tennessee says about 1 inch of snow and now is sleeting, forecast hasn't really changed much at all for her temperature is 23 down there right now 1 Link to comment Share on other sites More sharing options...
nycsnow Posted January 24 Share Posted January 24 2 Link to comment Share on other sites More sharing options...
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