NJwx85

The 12z runs of the 3k NAM and 12k NAM are both similar.

I love how one run of the long range NAM somehow tops the rest of the guidance. You would think everyone on here was either born yesterday or has a very short memory. The NAM is erratic and unreliable until inside of 36hrs and even then it's susceptible to major run to run shifts.

Watches/Advisories coming potentially The GEFS probability of freezing rain has been increasing with each successive model run for this event, with a 50%-60% chance of freezing rain for KLGA and just over 50% for KISP. The 21Z SREF also had between a 20% to 40% chance of freezing rain for the city and Long Island, which are high probabilities for this model, although the most recent run has backed off on these chances. Finally, the deterministic models generally came in colder with the 00Z runs. If this colder solution continues, more in the way of ice is possible, especially because that could mean the colder air filters in during a period of more moderate precipitation. For now, went with ice accretion of between a tenth and a quarter of an inch for western Long Island, New York City, northeast New Jersey, the Lower Hudson Valley, and southwest Connecticut. Elsewhere a few hundredths of an inch to a tenth of an inch is expected. Higher elevations in the Lower Hudson Valley would likely see the highest ice accretion amounts. Additionally, any standing water from rain and snow melt will refreeze during this time frame. While these values do not prompt Winter Storm Watches to be issued (0.50" of ice would be needed), will have to monitor for this potential if it looks like a significant impact to either or both commutes on Friday, as there still remains uncertainty with the exact timing of the transition to the wintry mix. Otherwise, given these ice accretion amounts, Winter Weather Advisories would need to be issued with this afternoon`s forecast package or Thursday morning`s package.

1”+ ZR in the Hudson Valley this run. 0.50” for NYC.

Really all the other models have been slowly trending towards it. Even if it ends up a tad too warm aloft and we get more sleet than it shows, even a quarter inch of ice is no joke.

A glaze is pretty. A half inch will do major damage.

The NAM is way over amped, exactly where you’d expect it to be.

Very unreliable.

Trending towards GFS again. Not good.

That’s the same as 12z was.

GFS still had a major event.

You're correct about it being the wrong run. I wouldn't necessarily say warmer.

18z NAM starting to pick up on the ice threat.

I don't think of areas North of 84 as part of this subforum but yes you're correct.

Not until after 18z when most of the precip is over.

A compromise between the GFS and EURO would be close to a worse case scenario for us.

Big trend towards the GFS this run. Colder surface but mid-levels remain warm. Just an FYI, you need the warm air aloft to get the precip in the first place. If the mid levels trend colder there will be much less precip. Bottom line, virtually no chance of this ending up as a snow event for us.

The 12z NAM was still well out of range but it's at the point where you would expect it to be, over amped and warm. But it's actually not that warm. Look at those surface temps. 32 degrees where it's showing plain rain and temperatures only go down from here.

Hopefully the NWS doesn't down play this and gets the warnings out early so that most people stay home and the roadways can be properly treated.

If the GFS is correct, the surface is already down to the lower 20's by 06z Saturday for the Hudson Valley and interior NNJ. 32 degrees in NYC and drops from there. The heaviest precip falls after 06z.

The coast actually has a potential to see more ZR than the far interior because the colder air is filtering in and that will eventually change over to more sleet the farther NW you get.

The 12z Saturday morning panel is even worse. The far interior flips to sleet with the mid levels cooling but the city flips to ice.

The soundings for the 12z GFS support mostly freezing rain North of I-78 in NJ and the Hudson Valley beginning between 00z and 06z Friday. Just look at 850mb temps compared to the surface and it's easy to see why the GFS is painting such a horrid picture.

This isn't your typical SWFE setup with retreating cold.

It’s too early for the NAM. Need to wait till tomorrow night.