Tutorial on reading forecast models at the end of this thread.

Winter Weather Advisory

URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE NEW YORK NY
406 PM EST THU FEB 4 2016

...COASTAL LOW TO BRING SNOW TO REGION LATE TONIGHT INTO
FRIDAY...

NJZ004-006-103>108-NYZ068>075-176-178-050515-
/O.NEW.KOKX.WW.Y.0003.160205T0600Z-160205T1500Z/
EASTERN PASSAIC-HUDSON-WESTERN BERGEN-EASTERN BERGEN-
WESTERN ESSEX-EASTERN ESSEX-WESTERN UNION-EASTERN UNION-PUTNAM-
ROCKLAND-NORTHERN WESTCHESTER-SOUTHERN WESTCHESTER-
NEW YORK (MANHATTAN)-BRONX-RICHMOND (STATEN ISLAND)-
KINGS (BROOKLYN)-NORTHERN QUEENS-SOUTHERN QUEENS-
406 PM EST THU FEB 4 2016

...WINTER WEATHER ADVISORY IN EFFECT FROM 1 AM TO 10 AM EST
FRIDAY...

THE NATIONAL WEATHER SERVICE IN UPTON HAS ISSUED A WINTER WEATHER
ADVISORY FOR SNOW...WHICH IS IN EFFECT FROM 1 AM TO 10 AM EST
FRIDAY.

* LOCATIONS...NORTHEAST NEW JERSEY...LOWER HUDSON VALLEY...AND NEW
YORK CITY.

* HAZARD TYPES...MODERATE SNOW AND REDUCED VISIBILITIES.

* ACCUMULATIONS...SNOW ACCUMULATION OF 2 TO 4 INCHES...WITH
LOCALIZED HIGHER AMOUNTS.

* WINDS...NORTH 10 TO 20 MPH WITH GUSTS UP TO 30 MPH.

* VISIBILITIES...ONE QUARTER TO ONE HALF MILE AT TIMES.

* TIMING...RAIN WILL MIX WITH SNOW EARLY FRIDAY MORNING...
BECOMING ALL SNOW BY DAYBREAK. THIS WILL IMPACT THE MORNING
RUSH HOUR.

* IMPACTS....HAZARDOUS TRAVEL DUE TO SNOW AND REDUCED
VISIBILITIES.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WINTER WEATHER ADVISORY MEANS THAT PERIODS OF SNOW...SLEET...OR
FREEZING RAIN WILL CAUSE TRAVEL DIFFICULTIES. BE PREPARED FOR
SLIPPERY ROADS AND LIMITED VISIBILITIES...AND USE CAUTION WHILE
DRIVING.

It's not that 2 - 4 inches is or should be a big deal, but the sudden shift in the forecast may take people by surprise.

chance of delayed opening or snow day?

I forecast the weather.  Forecasting the behavior of school administrators is above my pay grade.

So there have been three storms in the forecast for the next few days, and until this afternoon, this one, the first, has been fairly far out to sea.  Over the last few model runs, however, it has been trending west and it looks like now we will get some wetness.  

Overnight it will start as rain.  It is hard to tell when it will transition to snow, but it is likely to be right before or during rush hour.  The earlier the transition, the more snow will accumulate. 

Part of the issue with these storms this year is that there are two anomalous elements.  Anomalies in forecasting are components of the climate that are behaving in unusual ways.  The models are built on averages, and anomalies present problems that the models do not have the resources to solve.  This causes a bias in the model -- it tends to make the same mistake over and over -- which the forecasters can only understand after they have seen it a few times.

In this year's case, the biggest anomaly we have is the warmth of the water in the Atlantic Ocean.  This adds energy and water to systems that come up the coast (apparently) and seems to be pushing the precipitation shield farther west than the models would expect from the same set-up they have seen in previous years.  

The other anomaly is (surprise!) el Nino.  In the case of these systems, it seems to be forcing more energy into the southern stream, so when the storm cuts across the Ohio Valley and the Carolinas it picks up more strength than they would normally expect.  This also sends it north and west.

The above is just a theory being batted around the internet, but it would explain why, in the last three systems (I am including the rain yesterday, which would have been a foot or more of snow if it had been seasonably cold), the models have started out showing the heaviest precipitation out to sea and then suddenly shifted inland when the data from the middle of the country started to hit the computers.

Let's see if this works:

Nope.  Too bad, it was a great radar gif from the HRRR model.

Ugh. Like, we'll have to shovel before work?

@max_weisenfeld You are so good at explaining complex systems in laymen's terms! I've been waiting for your take on tomorrow ever since I got an alert on my phone a few hours ago -- thank you for the forecast as well as the cool (and slightly unnerving) explanation of "anomalies." 

so this could include freezing rain right at rush hour?  Love snow.  DON'T do freezing rain! (Like I have a choice).  My son has asked for a ride to school tomorrow.  He may just get his wish.

Any clues about the storm for early next week?  I know it's too early to predict much, but any of the weenies getting excited?  Thanks!

Oy! Thanks for the update!

yuck!

beppolina said:

@max_weisenfeld You are so good at explaining complex systems in laymen's terms! I've been waiting for your take on tomorrow ever since I got an alert on my phone a few hours ago -- thank you for the forecast as well as the cool (and slightly unnerving) explanation of "anomalies." 

I concur. I almost feel like I actually understand complex weathe phenomenon after Max posts!

Thanks, Max! A surprise storm of a few inches is not welcome but a hell of a lot better than a predicted storm of 28+ inches...   

Thanks Max, you are always appreciated, even if sometimes the news is not good!

carolanne said:

so this could include freezing rain right at rush hour?  Love snow.  DON'T do freezing rain! (Like I have a choice).  My son has asked for a ride to school tomorrow.  He may just get his wish.

Any clues about the storm for early next week?  I know it's too early to predict much, but any of the weenies getting excited?  Thanks!

Sleet, maybe.  I don't think it will be cold enough for freezing rain.

This is a mostly slush event.

As for next week, Monday night into Tuesday has some interesting possibilities.

hmmm...when Max uses the word interesting....

That's it, i'm getting milk and bread!

joy said:

hmmm...when Max uses the word interesting....

"surprise"  No time to get to Trader Joe for cauliflower rice, milk, bread....lol

While the heaviest precipitation remains offshore and to the east and north this morning, a wet snow is falling and will continue to fall for several hours.  The nws advisory continues through noon, but snow here should start to taper off after 10 or so.

Thanks Max!  How do projected totals look now?  What I'm really asking is: am I going to have to shovel later, or will it melt before school pick up?

2-4"  Probably will have to shovel.

Driving is messy but not bad. People moving slowly, didn't see any spin outs. Saw a salt truck in Mapkewood.

A salt truck came up our street in South Orange.

The snow is pretty wet and heavy. I'm not looking forward to this shovel-out.

I wish this was a weekend. Shoveling is on me today, during nap time, or it doesn't happen. Starting some preliminary stretching now.

I think this happened because we got our newly repaired snowblower back from P&P yesterday.  I guess they knew ...

Max - I'm hearing murmurs about a bigger storm next week.  Any intel on that??

afa said:

I wish this was a weekend. Shoveling is on me today, during nap time, or it doesn't happen. Starting some preliminary stretching now.

Same. I've got to get the kids to school and myself to work...ugh. I think we're all going to be late today!! 

Are jitneys making out ok? I still remember the morning like this a few years back where it got stuck in the snow.  

I'm really p*ssed.  Brought home new (replacement) snowblower last night.  I was SURE  that would mean no snow!! ;-)

Here in West Orange the plows have been through twice and a truck came through spreAding salt or sand   Seen a few cars driving, neighbor got out ok.

Stil p*ssed.  Not enough snow, looking out, to REALLY use the new snowblower toy     

Be safe