purduewx80

Thanks for posting the anomalies...the original ECMWF image I shared was supposed to loop and show this but it's not animating. Also...well said on the short-term trends tomorrow. Models not handling convection in FL very well this morning so it's likely none of them have it pegged here tomorrow either.

Interestingly, the past few RPM runs are mixing the core of the LLJ down through the inversion Friday morning. It has temps maxing out at 67 for EWR, 65 at NYC and LGA, and 62 at JFK - all records for the 21st. Could see high wind warning criteria met on LI if that verifies, especially where the convective precip ends up.

60ish. Upper 50s near the water, no higher than 65 if low clouds scatter out. Mid-60s look more likely in interior New England.

I created a discussion for Friday.

Aside from the 12km NAM, the latest guidance is suggesting LI and CT have the greatest risk for rainfall amounts over 2 inches. Various pieces of both global and hi-res guidance are painting >4" amounts in CT.

Surprised there hasn't been more chatter on this. Could be an impressive outbreak across Florida tomorrow, spreading into coastal NC/Outer Banks tomorrow night. This product from HREF is indicative of rotating thunderstorms from the Fort Meyers area up to Orlando/Canaveral in the afternoon. These may be more QLCS tornadoes embedded in the squall line, although I wouldn't be surprised to see a supercell or two embedded in it and isolated out ahead of it. The wind fields in place would also support severe gusts w/i the squall. Would think SPC upgrades to enhanced if this remains consistent.

should be a lot of snow melt and river flooding up in northern new england. some of the rivers have ice, so the quick melting and potential for heavy rain may cause more flooding than we'd otherwise expect w/ a quick mover like this.

The pattern change across eastern North America from today to Friday is phenomenal, notably so from the Southeast to the Lakes but especially so over the Canadian Maritimes. 500mb anomalies there shift from ~250m below normal today to something off the charts late Friday. Also note how the western Atlantic ridges flexes once again, as we've seen time and time again in 2018. Positive temperature anomalies will also be impressive, and it is likely that record warmth will occur in parts of New England. NYC's 65F from 2013 may be hard to beat but BOS could easily reach or exceed 1957's 62F reading. As the +EPO-driven Pacific jet currently bringing thunderstorms to the Seattle area dives into the Southern Plains the next couple of days, deep meridional flow will develop in the eastern US. This unusual south-to-north flow at all levels of the atmosphere will draw Caribbean and Gulf of Mexico moisture due north along the East Coast, setting the stage for a heavy rain and wind event in the Northeast. As @bluewave has alluded to, nearly all model guidance forecasts record precipitable water in the region Friday - both for meteorological winter and perhaps the entire cold season. We shall see if OKX and CHH set an impressive record. What is certain is that heavy rain will occur in the Northeast as a result of the anomalous warmth, moisture and 60-80KT+ low level jet. Mesoscale details probably will not be known until Thursday or even early Friday, but the synoptic drivers seem to favor much of the region experiencing a convective squall of sorts in the WAA regime Friday morning. Widespread 1-2" amounts will be common, but any areas that get stuck under the conveyor could see upwards of 4" in short order. Lapse rates favoring convection may allow the shallow inversion to be penetrated in parts of the region. While I don't expect widespread thunderstorms with wind damage, parts of NJ, Long Island and southern New England could see this jet mix down in the heaviest of showers. Anyone flying in or out of the Northeast Friday may want to consider alternate plans. Given this system is occurring on one of the busiest travel days of the year, delays could get out of hand in a hurry.

yep, i'm on board the ~mid-jan thru mid-march train. i doubt the cold will bust, but there is some risk for suppression thru that period. i'd be more concerned if i were a new england snow weenie than a nyc weenie.

By all the models, you mean the end of the operational GFS and the end of the ensemble means? The warming isn't even forecast to occur until the end of December. MJO will rule through early January.

I don't recall. I'm no expert on the stratospheric stuff, but I know it takes time for the warming to result in the PV splitting. Mike Ventrice's outlook issued today suggests the transition occurs in the 2nd week of January and mid-month on is when all hell breaks loose.

Worth noting that despite this being a December thread, none of the (potential) sensible wx impact from any (potential) SSW event will occur until January. Friday's system is highly anomalous, as bluewave has pointed out, and its sensible weather will also not disappoint.

it's you (or the data source/type).

happens all the time in short-term and long-term forecasting.

250mb winds came in at 193KT on the 00Z sounding, 1KT shy of the record. There were some 198KT obs just below 250.

Looks like the heaviest snow from this norlun trough is currently falling to the N and E of ACY. The Brigantine cam shows this nicely. Thermal/lift profiles easily suggest localized 1-2"/hr rates are probable along the coast today.

Bit of a norlun feature showing up over central NJ tomorrow. The ocean will come into play, producing steep low-level lapse rates that tap squarely into the DGZ. The inverted trof feature develops as a result of the incoming upper vort. I doubt that hi-res has nailed the location of this yet, but areas near ACY to as far north as BLM are in play. The probability for the city to see snowfall Wednesday appears to be slim, however. Some guidance indicates the potential for a max of 2-4" should the tail end of this feature set up inland. Most of the guidance w/ available soundings show 200-300 j/kg of CAPE where low-level lapse rates max out around 7.5.

I've seen countless instances where a jet was not initialized properly until it was sampled on the West Coast...specifically while living and forecasting in the Midwest. Because of the way models are initialized, there is rarely going to be an instantaneous change in the modeling given new obs, which is why the trends are important to watch. I am curious to see whether the introduction of higher-res GOES-16 and GOES-17 data changes this.

meteorologists don't look at ensemble average snowfall a week+ in advance to predict whether or not there may be a storm.

12Z Euro a big hit next weekend...double digits.

Owing to narrow fgen forcing, good jet config and steep lapse rates aloft, this could be a very localized overperformer (1-2") this afternoon, probably terrain-favored as NJwx alluded to yesterday. Could be a surprise in/near the city too despite the warm layers in the soundings.

00z EPS next Saturday is about as good a signal for a d10-11 storm as you can get. It also trended more in favor on just about every major 500mb feature in play.

Flights holding for ORD's runway treatments are leaving holding pattern contrails:

pretty much a slam dunk blizzard for chicagoland is incoming. convection feeding into the ccb is always a good sign that gravity waves will easily penetrate down to the surface. same as in ghd2. that's a wall of snow incoming on radar, too.

the source region for the incoming air mass is not emanating from far eastern canada.