purduewx80

a SPECI just came out w/ a peak of 69KT! KDEN 131735Z 33045G64KT 1/4SM R35L/1600V2000FT SN BLSN VV005 M02/M02 A2905 RMK AO2 PK WND 34069/1712 TWR VIS 1 P0000 T10171022 $

Just an incredible storm to watch in real-time. Winds have rapidly increased at DEN over the past hour, with frequent gusts over 50MPH occurring now. Their transition to +SN is under way as convection moving in from the east allows for some dynamic cooling. Could be quite the snowfall gradient today due to the mesoscale nature of the precip there. Lowest sea-level pressure I can find is 971.7mb at La Junta, CO: 60-65 mph winds showing up a few hundred feet above the airport/city on RadarScope: College of DuPage WV - their 96-200 image loops show the double phase, bombogenesis and severe squall line nicely.

Definitely a lot of evidence that by ~4/1 we should be into a consistently much warmer pattern. Looking forward to it.

Thanks! The recent trend for delayed spring warmth has been in the back of my mind since last fall, and I see no reason to stray from that line of thought for now. 2012 does seem like a long time ago. I was in Madison, WI then - warmest March by far there (earliest 80s, etc, etc).

Reference: next week - beware smoothed out ensemble means. The first image is GEPS, EPS + GEFS valid next Tuesday AM, the 2nd the operational ECMWF, GEM, GFS + FV3. A concentrated positive anomaly on the ensemble means can mean a few things, including the potential for a blocking high. In this case, the means are hinting at an omega block across western Canada, w/ an upper low on either equatorward side of the anomalous PNA ridge. Indeed, all of the operational runs are now evolving to such a block. Despite no AO, EPO or NAO blocking, the above to me combined with a potentially more coupled ocean-atmosphere El Nino suggests: 1) our pattern will be slower to evolve back to a mild one than currently modeled, and 2) a slow-moving cutoff near the SE or Mid-Atlantic coast is within the realm of possibility ~a day either side of next week's equinox. Once the chilly air early-mid week moves out, the coldest air masses relative to normal over the CONUS may shift across the southern US. 850mb positive temp anomalies seen in much of the guidance will not necessarily portray what is to occur at the surface, depending on NE/Canada snow cover and surface high placement (i.e. cool onshore flow and/or backdoor cold fronts). Assuming eastern Canada maintains deep snow cover and a NW-flow pattern is established, it could be a bit of a roller coaster for us, with repeated invasions of colder than average air into the Northeast interspersed with 1-to-2-day warm-ups. The 12Z EPS, though often of little use beyond D7-10 this past winter, is holding on to the +PNA longer than the past couple runs. It will be important to watch how the index evolves over the next several days for those hoping for a flip to true, extended spring warmth. Bottom line - enjoy the milder weather Thursday-Saturday. An anomalously warm long-term pattern appears unlikely in NYC anytime soon.

ECMWF vis/cigs are some of the best products out there. The NSSL WRF visibility is great too, but it overproduces fog across snowpack. RAP/HRRR are also useful in the short-term. Climo/pattern recognition is probably the best tool of all though.

Exactly. NAM usually is too aggressive with low ceilings in WAA patterns this time of year, but the GFS boundary layer issues also lead to it underrepresenting the risk for fog/stratus.

Could be looking at some decent thunderstorm activity in the region on Friday. Lapse rates are stellar and there will be a decent wind field associated with the Plains bomb as it shifts into Canada.

About the only part of their post that is accurate. Using the 00z EPS, I'm calculating average temps at NYC are ~1.5F below normal today through the 19th. There are more below normal than above normal days in the forecast.

ZR happened due to a dry slot moving in (check out WV loops) - lost the seeding/ice crystals. Now it's flipping back to PL/SN w/ lift provided by the lower level warm fronts.

14.1" at Central Park since Jan 1. Season to date is 20.5", which is 2.4" below average.

i'm off this week and slept in, so i'm not sure. seems about right, was between 3-4 when i went to bed last night. pellets did not last more than a few min at a time.

you can't just look at its snow maps and say it was abysmal. no model is going to capture the nuances of marginal setups in an urban heat island perfectly. it was an almost entirely snow event here in bed-stuy, save a few minutes of pellets here and there, which i doubt took off more than an inch. i think one lesson from this storm is to not expect urban areas to accumulate in marginal setups during march unless +SN is falling. if this storm had occurred during the day, it would've been no more than a 1-2" storm aside from some shady grassy areas.

Curious to see what the fake BOS final will be; the FAA reported just over a foot on the field on calls this morning.

https://www.spc.noaa.gov/products/md/md0153.html

obs thread

same...some aggregate flakes here and there. should be a good storm for us.

18Z NAM coming in wetter, but also sleets more in southern parts of the city. Lift in the DGZ showing up over LGA at 06Z is more impressive than the 12Z run - this is suggestive of the 1-2"+/hr rates over the city, even if they only last 2-3 hours.

Possibly, but brightness temperature maps aren't an indicator of where stratus will be. The HRRR's ceiling products keep a dense low level stratus deck around past sunrise.

The wet-bulb zero line at the surface is still NW of the city by a good bit, but aircraft soundings out of LGA in the 17Z hour showed that it's only the lowest few hundred feet where that's the case. Everything above that is sufficiently cold for primarily snow as precip works into the area.

12Z HREF will probably continue to support that, looking at the various NSSL 12Z runs so far. Another + for 1-2"/hr rates is the 6-6.5 C/km lapse rates aloft as the 850-700mb circulation shifts by to the S. Convective precip will be likely as a result.

Sneaky warm layer at 850 to start (pellets or freezing rain) but dynamic cooling flips it over eventually. Surface temps should stay below freezing for the entire city given the low track and air mass to our N/NE.

Nearly an inch in northern Queens. Was a big difference between Bed-Stuy and LIC when I got off the G.

Double digits for SE MA.

18Z RGEM also more amped; 994 over the Benchmark at 18Z Saturday. 3mb deeper than the 12Z run, closed 700 low is also deeper. Hard to see for sure on the b&w maps but it looks wetter from NYC up to BOS.