OT: Minor to Moderate Snow/Mix Likely Sat Evening (2/8) through Sun am

[RU848789]

This event is looking a bit snowier and more impactful than today's event, although we're still ~60 hours from the start of the event relative to the 12Z models coming out now (which had 7 am EST data inputs). Could see snow starting late afternoon/early evening Saturday and at least a few inches of snow are expected for areas N of 276/195 (and maybe down to Philly/SNJ) with several inches possible along/N of 78 before any mixing with or changeover to sleet and maybe freezing rain or plain rain (most likely to see plain rain south of 276/195 and it might be all frozen N of 78). The precip should be over by 7-10 am on Sunday. Note that some models are showing up to 0.2" of freezing rain for even the 95 corridor, especially south of 276/195, where a change to freezing rain or rain is more likely. The chances of a complete miss or an all rain event are about nil this close in.

Will post the 12Z model summary around 1 pm, but we already have a couple of fairly snowy predictions being made by both News12 and TWC, which both have a lot more snow forecast than today's event. Specifically, TWC has a 3" line along 276/195 from about Hatboro to Trenton to Belmar with 3-5" from that line north to close to 78 with 5-8" north of 78 and 1-3" south of 276/195 to about a line from Wilmington to LBI, while News12 has their 3" line from about Titusville to Sandy Hook with 3-6" north of that line through the rest of CNJ and all of NNJ (and adjacent EPA/NYC) and 1-3" south of that line with the 1" line going from about Salem to AC. On the other hand, as per below, the NWS is a bit less bullish with 1-3" from about 276/195 to 78 and 3-5" north of 78, but 1" or less south of 276/195 (including Philly/SNJ). Stay tuned.

https://www.americanwx.com/bb/topic...ng-sunday-nyc-li-s-of-i78-on-the-edge/page/3/

https://forecast.weather.gov/produc...&format=CI&version=1&glossary=1&highlight=off

Area Forecast Discussion
National Weather Service Mount Holly NJ
646 AM EST Thu Feb 6 2025

.SHORT TERM /FRIDAY THROUGH SUNDAY/...
For now, general consensus amongst forecast guidance is that this
system is trending slightly colder, meaning more snow is possible!
As precipitation begins on Saturday afternoon, most locales should
encounter a period of light snow as temperatures will be below or
around the freezing mark heading into Saturday night. However, a
modest ramp-up in warm air advection is anticipated to occur later
Saturday night as a warm nose aloft progresses northward. This will
result in a gradual change over to sleet and/or freezing rain from
south to north. Point forecast soundings suggest that freezing rain
may be favored over sleet so have included this potential in the
forecast. As temperatures warm overnight throughout the atmospheric
column, a changeover to plain rain is expected across the Delmarva
and most of the Coastal Plain. However, frozen precipitation may
hang on for the duration of the event especially up in the higher
elevations of the Lehigh Valley, Poconos and northern New Jersey.
The timings and specifics of the changeover are not yet set in
stone, but the greatest potential for a prolonged period of frozen
precipitation lies over the usual spots of the higher terrain areas.

In terms of amounts, the current forecast calls for 0.40-0.70" of
liquid QPF. Breaking this down into snow/sleet totals, anticipate a
C-1" for the northern Delmarva and much of the I-95 corridor
including the Philadelphia metro. Just north of the I-95 corridor up
to and including the I-78 corridor, expecting 1-3". Once north of
the I-78 corridor and especially north of I-80, amounts upwards of 3-
5" are possible. There will also be freezing rain accretion over
most of the area, but amounts should generally range from a T-0.1"
(locally higher). Considering this, Winter Weather headlines will
likely be needed within the next 24-48 hours.

 

[Section124]

Thanks for creating this thread. Was starting to plan my Sunday before the Super Bowl at Hunter and was curious on snow amounts. 5-8" may be enough to make the trip back home a pain. Need to see how this develops.

 

[bac2therac]

some of the 12z runs dont appear to be that great per the weenie board...some are though

 

[RU848789]

Brief 12Z global model summary (too far out for the meso/short-range models, like the NAM, RGEM, HRRR etc.) is below and the general message for CNJ is a wide range of outcomes are possible from 1-3" like the GFS and NWS say, up to maybe 3-6" as per the UK and TWC/News 12. Less than 1" seems very unlikely as does more than 6-7", but stranger things have happened. I also don't detail which model mixes when, where and how much sleet/freezing rain/rain they might show, because that's too complicated, but, in general, mixing/changeover are much more likely south of 78 and especially south of 276/195, which is why the models show less snow there.

• The GFS is the least snowy model, showing <1" south of 276/195, 1-3" for 276/195 up to 78 and 2-4" N of 78 to 84
• The CMC shows 1-2" south of 276/195, 2-4" from 276/195 to 78 and 3-5" N of 78 to 84
• The UK is the snowiest model and shows 2-4" from Wilmington to LBI up to 276/195 and shows 4-7" N of 276/195 up to 84
• The Euro shows 1/2-2" south of 276/195, 2-4" from 276/195 to 78 and 4-7" north of 78 to 84

 

[RU848789]

some of the 12z runs dont appear to be that great per the weenie board...some are though

Not sure what they're talking about, as per my comments on the models. And I didn't even add the NAM/RGEM which are 3-6"/2-4" for CNJ respectively. Only the GFS shows 1-2" for parts of CNJ towards 276/195.

 

[rurichdog]

The 540 thickness line is way too far north to support the snowfall amounts some of the models are spitting out for our area.

 

[bac2therac]

Not sure what they're talking about, as per my comments on the models. And I didn't even add the NAM/RGEM which are 3-6"/2-4" for CNJ respectively. Only the GFS shows 1-2" for parts of CNJ towards 276/195.

I think weenie map with another mixed precip event shouldn't be taken verbatim

 

[RU848789]

First NWS snowfall map and it generally follows what the NWS said this morning, i.e., <1" south of 276/195, 1-3" from 276/195 to 78, and 3-5" north of 78. They're not biting yet on the higher snowfall amount being seen in most of the models, which is probably a wise choice, as it's usually easier to ramp up predictions with greater confidence than to have walk back initial forecasts which are too high.

 

[RU848789]

The 540 thickness line is way too far north to support the snowfall amounts some of the models are spitting out for our area.

We've had good snows in the past with the 540 line well north of us - it's just a rule-of-thumb. If it were that good of a guide, the models would simply use it directly to determine the rain/snow line, but they don't. Having said that one often needs something to overcome that impediment to snow, like very good dynamics aloft producing good rates and dynamic cooling. Or maybe those models will just be wrong, like most were on the snow vs. sleet today. No pros I know of were saying the precip would go almost directly to sleet when it started, so something was clearly missed.

 

[RU848789]

NWS-NYC surprisingly issued watches for their whole area. South of the Tappan Zee, which includes Union up to Bergen/Passaic and NYC/LI, the watches are generally for 2-4" of snow with some freezing rain, which is driving the watch, since 6" of snow is the criterion for a watch. For their counties north of the Tappan Zee, the watch is for 4-7" of snow, with no mixing assumed.

https://forecast.weather.gov/wwamap/wwatxtget.php?cwa=OKX&wwa=winter storm watch

 

[RU848789]

I think weenie map with another mixed precip event shouldn't be taken verbatim

Absolutely agree, which is why I think the NWS initial map is pretty good.

 

[RUhasarrived]

Lee Goldberg just mentioned a storm next Thursday as well.
Remember that week in 1994 when we had storms on Monday,Wednesday and Friday?

 

[HeywoodGiant]

The 540 thickness line is way too far north to support the snowfall amounts some of the models are spitting out for our area.

who is that in your icon?

 

[Postman_1]

 

[RU848789]

This event is looking a bit snowier and more impactful than today's event, although we're still ~60 hours from the start of the event relative to the 12Z models coming out now (which had 7 am EST data inputs). Could see snow starting late afternoon/early evening Saturday and at least a few inches of snow are expected for areas N of 276/195 (and maybe down to Philly/SNJ) with several inches possible along/N of 78 before any mixing with or changeover to sleet and maybe freezing rain or plain rain (most likely to see plain rain south of 276/195 and it might be all frozen N of 78). The precip should be over by 7-10 am on Sunday. Note that some models are showing up to 0.2" of freezing rain for even the 95 corridor, especially south of 276/195, where a change to freezing rain or rain is more likely. The chances of a complete miss or an all rain event are about nil this close in.

Will post the 12Z model summary around 1 pm, but we already have a couple of fairly snowy predictions being made by both News12 and TWC, which both have a lot more snow forecast than today's event. Specifically, TWC has a 3" line along 276/195 from about Hatboro to Trenton to Belmar with 3-5" from that line north to close to 78 with 5-8" north of 78 and 1-3" south of 276/195 to about a line from Wilmington to LBI, while News12 has their 3" line from about Titusville to Sandy Hook with 3-6" north of that line through the rest of CNJ and all of NNJ (and adjacent EPA/NYC) and 1-3" south of that line with the 1" line going from about Salem to AC. On the other hand, as per below, the NWS is a bit less bullish with 1-3" from about 276/195 to 78 and 3-5" north of 78, but 1" or less south of 276/195 (including Philly/SNJ). Stay tuned.

https://www.americanwx.com/bb/topic...ng-sunday-nyc-li-s-of-i78-on-the-edge/page/3/

https://forecast.weather.gov/produc...&format=CI&version=1&glossary=1&highlight=off

Area Forecast Discussion
National Weather Service Mount Holly NJ
646 AM EST Thu Feb 6 2025

.SHORT TERM /FRIDAY THROUGH SUNDAY/...
For now, general consensus amongst forecast guidance is that this
system is trending slightly colder, meaning more snow is possible!
As precipitation begins on Saturday afternoon, most locales should
encounter a period of light snow as temperatures will be below or
around the freezing mark heading into Saturday night. However, a
modest ramp-up in warm air advection is anticipated to occur later
Saturday night as a warm nose aloft progresses northward. This will
result in a gradual change over to sleet and/or freezing rain from
south to north. Point forecast soundings suggest that freezing rain
may be favored over sleet so have included this potential in the
forecast. As temperatures warm overnight throughout the atmospheric
column, a changeover to plain rain is expected across the Delmarva
and most of the Coastal Plain. However, frozen precipitation may
hang on for the duration of the event especially up in the higher
elevations of the Lehigh Valley, Poconos and northern New Jersey.
The timings and specifics of the changeover are not yet set in
stone, but the greatest potential for a prolonged period of frozen
precipitation lies over the usual spots of the higher terrain areas.

In terms of amounts, the current forecast calls for 0.40-0.70" of
liquid QPF. Breaking this down into snow/sleet totals, anticipate a
C-1" for the northern Delmarva and much of the I-95 corridor
including the Philadelphia metro. Just north of the I-95 corridor up
to and including the I-78 corridor, expecting 1-3". Once north of
the I-78 corridor and especially north of I-80, amounts upwards of 3-
5" are possible. There will also be freezing rain accretion over
most of the area, but amounts should generally range from a T-0.1"
(locally higher). Considering this, Winter Weather headlines will
likely be needed within the next 24-48 hours.

Added in the updated NWS snowfall and ice accumulation maps and Lee Goldberg's snowfall map. The NWS and Lee are fairly well aligned with less bullish snowfall amounts than either TWC or News12 (which are unchanged from those above) and it seems to me that the NWS/Lee are likely taking the conservative low end ~48 hours from the start of the event on Saturday late afternoon/early evening, while TWC/News12 are taking the aggressive high end. Will be interesting to see where we end up, but it at least seems likely that CNJ is going to get a couple of inches of snow with more possible.

As speculated above, the ice map from the NWS shows 0.1-0,25" of possible ice accretion from freezing rain for large swaths along and NW of 95 all the way up to 84 (and part of SNJ), as well as swaths of 0.01-0.10" for the rest of the region. As per another post, the NWS-NYC issued watches for their whole area (for 2-4" and some ice for NENJ/NYC/LI and for 4-7" north of the Tappan Zee) and I'm confdient we'll see similar watches (including ice potential) posted from the NWS-Philly by 4 am at the latest (or they might skip that and go directly to warnings along/N of 78 and advisories south of there).

 

[BIGRUBIGDBIGredmachine]

Let's push the model to dropping 8"+ snow in College Park MD , like to keep the Terp attendance down for Sunday's noon tip-off.

 

[rurichdog]

who is that in your icon?

Mad Dog Madison (real name Connie Madigan) from the movie Slap Shot.

 

[HeywoodGiant]

Mad Dog Madison (real name Connie Madigan) from the movie Slap Shot.

I thought it was ed van impe

 

[rurichdog]

We've had good snows in the past with the 540 line well north of us - it's just a rule-of-thumb. If it were that good of a guide, the models would simply use it directly to determine the rain/snow line, but they don't. Having said that one often needs something to overcome that impediment to snow, like very good dynamics aloft producing good rates and dynamic cooling. Or maybe those models will just be wrong, like most were on the snow vs. sleet today. No pros I know of were saying the precip would go almost directly to sleet when it started, so something was clearly missed.

I'm just going by what I learned in class. When the 540 line is progged to be north of the Connecticut coast, don't be shocked at how far north the rain/snow line races in. Again, I take a more holistic approach to looking at model output and what it might do. Sometimes I'm right, sometimes I'm wrong. I did win the New Brunswick Forecasting Game in 98 and the RU Met Club Snow Pool in 99(?) so at one time I did know a thing or two. But if I was great I'd have won a few more. If I didn't have to work Sunday early I'd enjoy watching out the window with a glass of Four Roses. I don't get too wrapped up in all the model shifts and analyses.