12/5-12/6 Nor'Easter/Snowstorm Potential

[HAltschule]

GFS models have come around and suggest the 1st major snowstorm of the season will affect the Northeastern US Monday into Tuesday...including NYC, PHL, BOS and points north and west. Albany, NY south into the Catskills and Poconos stand to get the bullseye of snow. It appears plenty cold enough in all layers for heavy snow. All areas in the northeast stand a good chance of a 6"+ storm. On Tuesday, vort lobe that enters the base of the storm may actually pull the storm westward or slow it down. This *could* mean a prolonged period of heavier snow if this happens. With gas at $2.29 a gallon here, it's time to fill up the gas cans in preparation.

Happy forecasting.

 

[Saul Trabal]

Originally posted by HAltschule
GFS models have come around and suggest the 1st major snowstorm of the season will affect the Northeastern US Monday into Tuesday...including NYC, PHL, BOS and points north and west. Albany, NY south into the Catskills and Poconos stand to get the bullseye of snow. It

In response, good sir, I say...

;p~~~~~~~~~~~"

:x

Gads, I hope that's not going to happen. I drive a school bus, and I don't want to lose work because of a snowstorm.

:roll:

 

[HAltschule]

Well Saul,

If you wish hard enough you may just miss the storm. There seems to be some serious model disagreement with the track of the storm. The 12z SAT. ETA model brings the storm further south and really misses the northeast completely. The 12z SAT. AVN, however, brings the storm closer to the coast and dumps snowfall across most of the Northeast cities and coastline. Still, the potential of 6"+ is there IF the AVN is right. I am eager to see the 12z MM5 run from this morning and what this model's solution is.

 

[B Ozanne]

Its been a roller coaster ride with this one, not quite ready to get all geared up for a storm yet. NWS is back on track for at least some snowfall, but too early to nail down the totals. In the meantime we are lined up for 2-4 inches tonight/Sunday. I wonder if a few inches of snowpack will change the dynamics of the monday/tuesday sytem at all.

 

[Jeff Snyder]

Originally posted by Benjamin Sipprell

I'm just going to chime in on a few notes: Perfect bombogenesis set up ... the subtropical and polar jets clash to generate 200 knot winds at 300 mb ... massive divergence in the left exit region allows for a low pressure center originating out of the southeastern states to deepen to 964 mb off the coast of Newfoundland! ... even to 960 mb.

A perfect Nor'Easter set-up. The low currently is a little far to the east but the prominent snowy region of the northeastern side of the low seems to hit areas like Cape Cod head on. Should be interesting to see future model runs.

Meanwhile a high pressure digs southward out of the Canadian maritimes and reaches 1044 mb with 504 thicknesses over the central Great Plains! 850 mb temperatures get as low as -21 F.

Could this 4 to 5 day forecast of the GFS really come true?

 

[Sam Sagnella]

The 12z GFS is still coming out, so I may need to edit this post down the road, but anyhow, the 12z runs of both the NGM and the NAM are indicating a significant (6"+) event for the major cities beginning early on Tuesday. FOUS guidance for KLGA indicates a column that is entirely below freezing for the duration of the event with between .4" and .77" of liquid precip falling during an 18hr period beginning around 06z Tuesday. If this does pan out, then here in Fairfield County we are looking probably at Winter Storm Warning criteria being met with a total accumulation of greater than 6".

EDIT: The 12z GFS run is out thru 48hrs and it certainly did not help clear up any of the previous discrepancies with the NAM; the 12z GFS 48hr surface low is ~200 miles farther south and east than the 12z NAM at the same time and 10mb weaker. Such a solution would obviously lower the snow totals significantly along the New England coast, but with such poor model agreement the best thing to do is to use a makeshift blend of the two. For this reason, I will go with a preliminary total of 4-6" for my area, though the potential for higher accumulations is definitely there.

12z NGM FOUS (KLGA):

42020959966 06619 140510 36999594

48020957921 03918 090214 31999493

12s NAM FOUS (KLGA):

42026989125 09616 110318 35999594

48044968306 04612 073619 26989491

54007826209 -1110 113113 18009488

 

[HAltschule]

I just looked at the 12z MM5 which is out to 42 hours now. It definitely brings the storm much closer to the coast just south and east of Delaware. Thus, I am buying into the ETA and MM5 and keeping an all snow event for the northeast cities. Philly should see a 5-10" snowfall and NYC/NJ should see a 5-10" snowfall. Albany, NY and places further inland will likely only see a 1-3" snowfall since we will be on the NW fringes. The MM5 track may actually increase the QPF from what the ETA has...thus I am not ruling out the possibility of raising my snow totals upward.

EDIT: WHEW...MM5 brings this storm along the "prefect track" for a major Northeast Snow storm. MM5 boms out a major storm just south of Long Island. If this pans out, we're talking a minimum of 6-12" of snow for much of the northeast and Southern New England. Tonight's runs should VERY interesting.

 

[B Ozanne]

The 12z MM5 looks really nice. I'm wondering why the Upton, NY NWS hasn't really embraced this yet. They are still trending down with this storm as of 4pm. I guess I wont read too much into that, they are consistently slow on issuing watches and other special products...and they haven't quite grasped evaporational cooling yet.

 

[HAltschule]

Sometimes the NWS is sleeping with these events and doesn't want to "cry wolf" too much. Plus...various in-office rules prevent them from issuing watches too far in advance. Like the 4th or 5th forecast period.

Regardless, I am pretty confident on a moderate event if not a heavy one. So watches and warnings or advisories will fly soon. The MM5 is almost always my favorite pick...esp. when it comes to winter storms. I am waiting for the ETA and/or AVN to come around and verify with the MM5.

This should easily be an all snow situation for NYC, Long Island, CT, PA, etc... 18z ETA for LGA is up to 0.80" or so already. So, it looks like a big snowstorm is on the way. Confidence has gone up a lot more. (Sorry Saul)

 

[Saul Trabal]

Originally posted by HAltschule
I just looked at the 12z MM5 which is out to 42 hours now. It definitely brings the storm much closer to the coast just south and east of Delaware. Thus, I am buying into the ETA and MM5 and keeping an all snow event for the northeast cities. Philly should see a 5-10\" snowfall and NYC/NJ should see a 5-10\" snowfall. Albany, NY and places further inland will likely only see a 1-3\" snowfall since we will be on the NW fringes. The MM5 track may actually increase the QPF from what the ETA has...thus I am not ruling out the possibility of raising my snow totals upward.

EDIT: WHEW...MM5 brings this storm along the \"prefect track\" for a major Northeast Snow storm. MM5 boms out a major storm just south of Long Island. If this pans out, we're talking a minimum of 6-12\" of snow for much of the northeast and Southern New England. Tonight's runs should VERY interesting.

[Maxwell Smart]I asked you not to tell me that!![/Maxwell Smart]

 

[HAltschule]

I can't believe how much the suite of models is flip-flopping right now. Trend is for a more Southern route.....AGAIN.

Low confidence forecast.

 

[David Dildine]

I'll try to leave out all the technical NWS lexicon and acronyms that exist to make ppl look like they know what they're talking about. From a climatological standpoint alone, I think the 06Z NAM is about on point. Beginnings of a comma are starting to appear on infrared.

[BS warning ahead] I think statistically with confluent-flow cyclogenesis, does the heaviest precip not fall closer to the 850 center than a diffluent-flow evolution? True or False (circle one if you have a digital pencil). Lower MD outta do just fine storm-total-wise this time.

This one reminds me of a more progressive Dec. 2000 nor'easter. Or maybe I'm just full of shoot I gtg. The midnight shift wears... as it grows.

- David

 

[HAltschule]

And...unfortunately the 850 mb low track will be nowhere near Albany, NY or Long Island with this storm. Models have sure trended back to the further south and east mode...and now they seem to be in agreement. Looks like the big 6-12" storm that could be, won't be....at least in the NYC and ALB areas.

 

[Dan Robinson]

I'm in Wytheville, Virginia now and have had several heavy bands pass over for the past couple of hours. The temps are hovering around 32-33F so despite the intense snowfall, nothing is accumulating.

I might move up to Roanoke or Bluefield where things should be a tad cooler.

 

[Mike Johnston]

Observations around central Virginia indicate storm track is probably 60 or 70 miles to the S and E than earlier forecast. Steady rate of snowfall at my location in western Henrico County (just W of Richmond) since about 9:00am. Despite warm ground temps, accumulation on grass is approaching 2" and just over the past hour, began sticking on paved surfaces. AFD out of Wakefield has raised possibility of heavy bands over central Virginia later this afternoon, and Winter Storm Warnings moved 2-3 counties to the south and east. Early school closings just now posted and traffic accident reports on the increase. Interesting that most commercial radar presentations showing "mixed precip" over the area, but it is definitely moderate to heavy snowfall.