January 18th Winter Storm Looms

Good Morning!

A winter storm threatens us this Saturday. We began a mild stretch of weather last week and it will continue this week. However, by a stroke of luck (seriously I think Mother Nature feels bad for winter weather lovers), a clipper-like storm is expected to deepen in New England on Thursday which helps to usher cold air into the northeast late Friday. Behind the clipper system a 1042mb High Pressure follows:



This *fresh* source of arctic air is what sets us up nicely for Saturday. With cold air in a place, and a low pressure approaching from the west, we have ingredients to make a snowstorm. Like the trend has been this winter, this Low Pressure will cut to our west which will try to raise temps along the coast. That same High Pressure will also act as a block, so when the LP does cut, a secondary LP will try to develop off our coast.

A lot can still change with this system since we are very reliant on a singular High Pressure (giving us cold air AND acting as a block for the primary low). My initial thoughts are a widespread 3-6" snowstorm for the region, more N&W, before changing to rain. Let's see what trends models show this week leading up to the event. This would hit us late Friday night and last thru most of Saturday.

Thanks Frank! I just spotted this on the 10 day and came here to see what was being discussed, and you're on top of it. A nice way to start the week.

This is why I tell people/friends to go to this site.When I tell them about a NAO,NPO,AO,they kinda look at me"strange-like"cause I'm into weather,anyway so we have Saturday to watch,plus possible 2 other one's down the road..ok will spread the word,stock up on salt,and see what happens ...

Woah starting with 75% right off the bat! If you read banter you will see my new way of taking any possible storms. Am not getting excited and if it turns to rain which models are showing that just stinks, can't we get a storm like we used too? And Frank liking that your thinking 3-6 area wide, thats high for your initial thoughts, heres to hoping you are right or it even over performs but again as I said in banter I have no expectations until it is snowing.

jmanley32 wrote:Woah starting with 75% right off the bat!  If you read banter you will see my new way of taking any possible storms.  Am not getting excited and if it turns to rain which models are showing that just stinks, can't we get a storm like we used too? And Frank liking that your thinking 3-6 area wide, thats high for your initial thoughts, heres to hoping you are right or it even over performs but again as I said in banter I have no expectations until it is snowing.

Also don't forget Franks confidence index is just for the probability of at least an inch of snow in Central Park. At this stage a 75% confidence for that meager amount seems likely.

WTS I do like his initial thoughts of 3-6 area wide with more N & W. Right now in this setup I'd sign for that.

CPcantmeasuresnow wrote:

jmanley32 wrote:Woah starting with 75% right off the bat!  If you read banter you will see my new way of taking any possible storms.  Am not getting excited and if it turns to rain which models are showing that just stinks, can't we get a storm like we used too? And Frank liking that your thinking 3-6 area wide, thats high for your initial thoughts, heres to hoping you are right or it even over performs but again as I said in banter I have no expectations until it is snowing.

Also don't forget Franks confidence index is just for the probability of at least an inch of snow in Central Park. At this stage a 75% confidence for that meager amount seems likely.

WTS I do like his initial thoughts of 3-6 area wide with more N & W. Right now in this setup I'd sign for that.

Absolutely, 3-6 I won't be upset that you get 6+, I just want to see some snow this year!! AHHHH LOL

12z GFS snow map

And of course it's due to come in for our meetup Saturday- possible drinking game there - a shot for every inch that falls in the city???? Looks like I'm taking the train in!

Dunnzoo wrote:And of course it's due to come in for our meetup Saturday- possible drinking game there - a shot for every inch that falls in the city????      Looks like I'm taking the train in!

Check our back channel thread - may need to reschedule. But let's make a decision on Wednesday.

All major models show a significant front-end thump of snow before changeover to rain. To reiterate, greatest threat for heavy snowfall is N&W of NYC, while Jersey Shore and LI will once again struggle with boundary temps mid-way thru the storm event.

Canadian does a good job showing the changeover process.

Saturday morning - early afternoon we are all snow



Saturday mid/late afternoon into night changeover to rain occurs in the aforementioned areas



How do you avoid a changeover? By a weaker primary low that does not fully cut to our west, but instead transfers energy to a secondary low off the coast. However, our NAO is projected to be POSITIVE not NEGATIVE for this event, so a transfer is unlikely or it will happen too late for our area to benefit (New England would get most).

Frank_Wx wrote:Canadian does a good job showing the changeover process.

Saturday morning - early afternoon we are all snow



Saturday mid/late afternoon into night changeover to rain occurs in the aforementioned areas



How do you avoid a changeover? By a weaker primary low that does not fully cut to our west, but instead transfers energy to a secondary low off the coast. However, our NAO is projected to be POSITIVE not NEGATIVE for this event, so a transfer is unlikely or it will happen too late for our area to benefit (New England would get most).

Can't see any of the maps you posted in your last two post Frank.

Dunnzoo wrote:And of course it's due to come in for our meetup Saturday- possible drinking game there - a shot for every inch that falls in the city????      Looks like I'm taking the train in!

If we get that 3 to 6 and the pattern changes to cold and snowy, I nominate Janet for Queen of NJ Strong for making it all happen scheduling the meet up event for this Saturday!

CPcantmeasuresnow wrote:

Frank_Wx wrote:Canadian does a good job showing the changeover process.

Saturday morning - early afternoon we are all snow



Saturday mid/late afternoon into night changeover to rain occurs in the aforementioned areas



How do you avoid a changeover? By a weaker primary low that does not fully cut to our west, but instead transfers energy to a secondary low off the coast. However, our NAO is projected to be POSITIVE not NEGATIVE for this event, so a transfer is unlikely or it will happen too late for our area to benefit (New England would get most).

Can't see any of the maps you posted in your last two post Frank.

Me either Frank.

No images showing.

It looks like tropicaltidbits is down, if Frank was using that that may be the issue. It is a general 3-6 for most, with a bit more N/W as Frank said.

Frank_Wx wrote:Canadian does a good job showing the changeover process.

Saturday morning - early afternoon we are all snow



Saturday mid/late afternoon into night changeover to rain occurs in the aforementioned areas



How do you avoid a changeover? By a weaker primary low that does not fully cut to our west, but instead transfers energy to a secondary low off the coast. However, our NAO is projected to be POSITIVE not NEGATIVE for this event, so a transfer is unlikely or it will happen too late for our area to benefit (New England would get most).

A few things against, a few things for. The clipper that scoots by and delivers the cold air for Wed into Thursday actually seems to amplify a weakly negative NAO, albiet east based, as it gains latitude into the N Atlantic as our weekend system sets up. We have to watch this for trends.

I really dont like the strongly amplified MJO in Octane 6 while this system makes its way to the EC nor do I like the last week or so the SOI has been in a positive state. That said, anomalously cold air will be in place and is notoriously under appreciated in the modeling at this lead time so a continued wait and see approach is where Im at. I do worry that the amplitude of the MJO will lead to a trend to a stronger primary to the west of us flooding the mid levels but well see.

Coast and LI will see a thump from latest guidance and then switch over.
The air mass isn't early Dec but deep Low level Winter arctic cold.
I like what I am seeing - these fly in here faster and move out faster too.
Lots of meetings and teaching today but things are looking good to kick start us into a 30-45 day winter pattern.

Damian: “CP, is it going to snow?”
CP:”I made a few calls.”

dkodgis wrote:Damian:  “CP, is it going to snow?”
CP:”I made a few calls.”

Oh if I only had connections. If I did winters here would make the Tug Hill Plateaus winters seem tame in comparison.

dkodgis wrote:Damian:  “CP, is it going to snow?”
CP:”I made a few calls.”

LOL, looks like NWS got those CP calls, their latest has us all snow for the upcoming event.ATM, that is!

Not much change to what Frank has written up. General 3-6" seems like a good call ATTM, lesser as you head to the coast line.

But again, we are still 4+ days out so things trend in either direction. Details matter especially where the best rates setup.

The jet stream would be indicative of best rates on I-81.

Here are my Sudden Thoughts and Second Thoughts (RIP Bill Lyon):
A. The temperature profiles on the GFS have trended colder over the past 72 hours for Saturday. A couple days ago I was forecast to approach 40 degrees by Saturday evening. Now I am unlikely to get above 35 degrees (and even that only very briefly at the end of the storm Saturday night). This indicates the strength of the High Pressure and how difficult it will be to scour out the cold air. This bodes well for prolonged front-end thump snows most of the day Saturday.
B. The NAM is still out of range but the 12z has Friday evening temperatures in the low 20s in SNJ and the teens in CNJ/NNJ. If true, temps could be in the teens almost statewide by Saturday morning which would be consistent with what I mentioned in Point A. It will take a long time to warm those temps up.
C. Most of the state is at or below freezing up until almost the end of the storm Saturday evening. The exception is the coast. The 850 freezing line is southeast of most of the state for most of the event. While most areas probably do change to rain before ending -- I think for areas away from the immediate coast that will be "after the damage is done" so to speak in terms of snow accumulations.
D. Frank's 3-6" sounds like a solid guess for most of the state at this point, but with delayed changeover I wouldn't be surprised if areas further North and West hit 7 or 8" out of this.
E. Timing has shifted a bit. Originally looked to start Friday night. Now looks more like snow spreading into the area late morning Saturday and getting heavier during the afternoon and evening before winding down/changing to rain Saturday night. This means Saturday morning may start just cloudy, but most of Saturday afternoon and evening may be very snowy across the area.
Those are my impressions for now.

billg315 wrote:Here are my Sudden Thoughts and Second Thoughts (RIP Bill Lyon):
A. The temperature profiles on the GFS have trended colder over the past 72 hours for Saturday. A couple days ago I was forecast to approach 40 degrees by Saturday evening. Now I am unlikely to get above 35 degrees (and even that only very briefly at the end of the storm Saturday night). This indicates the strength of the High Pressure and how difficult it will be to scour out the cold air. This bodes well for prolonged front-end thump snows most of the day Saturday.
B. The NAM is still out of range but the 12z has Friday evening temperatures in the low 20s in SNJ and the teens in CNJ/NNJ. If true, temps could be in the teens almost statewide by Saturday morning which would be consistent with what I mentioned in Point A. It will take a long time to warm those temps up.
C. Most of the state is at or below freezing up until almost the end of the storm Saturday evening. The exception is the coast. The 850 freezing line is southeast of most of the state for most of the event. While most areas probably do change to rain before ending -- I think for areas away from the immediate coast that will be "after the damage is done" so to speak in terms of snow accumulations.
D. Frank's 3-6" sounds like a solid guess for most of the state at this point, but with delayed changeover I wouldn't be surprised if areas further North and West hit 7 or 8" out of this.
E. Timing has shifted a bit. Originally looked to start Friday night. Now looks more like snow spreading into the area late morning Saturday and getting heavier during the afternoon and evening before winding down/changing to rain Saturday night. This means Saturday morning may start just cloudy, but most of Saturday afternoon and evening may be very snowy across the area.
Those are my impressions for now.

Nice write up. I think though just as important as temps will be where the best forcing occurs. The H7 strong jet stream winds (70 knots+) will cause lift and where that sets up determines who gets 6". If that sets up further west then we will struggle to get 3 inches even NW of 95. That is a rather fine detail that we just don't know yet. All IMHO of course.

heehaw453 wrote:

billg315 wrote:Here are my Sudden Thoughts and Second Thoughts (RIP Bill Lyon):
A. The temperature profiles on the GFS have trended colder over the past 72 hours for Saturday. A couple days ago I was forecast to approach 40 degrees by Saturday evening. Now I am unlikely to get above 35 degrees (and even that only very briefly at the end of the storm Saturday night). This indicates the strength of the High Pressure and how difficult it will be to scour out the cold air. This bodes well for prolonged front-end thump snows most of the day Saturday.
B. The NAM is still out of range but the 12z has Friday evening temperatures in the low 20s in SNJ and the teens in CNJ/NNJ. If true, temps could be in the teens almost statewide by Saturday morning which would be consistent with what I mentioned in Point A. It will take a long time to warm those temps up.
C. Most of the state is at or below freezing up until almost the end of the storm Saturday evening. The exception is the coast. The 850 freezing line is southeast of most of the state for most of the event. While most areas probably do change to rain before ending -- I think for areas away from the immediate coast that will be "after the damage is done" so to speak in terms of snow accumulations.
D. Frank's 3-6" sounds like a solid guess for most of the state at this point, but with delayed changeover I wouldn't be surprised if areas further North and West hit 7 or 8" out of this.
E. Timing has shifted a bit. Originally looked to start Friday night. Now looks more like snow spreading into the area late morning Saturday and getting heavier during the afternoon and evening before winding down/changing to rain Saturday night. This means Saturday morning may start just cloudy, but most of Saturday afternoon and evening may be very snowy across the area.
Those are my impressions for now.

Nice write up.  I think though just as important as temps will be where the best forcing occurs.  The H7 strong jet stream winds (70 knots+) will cause lift and where that sets up determines who gets 6".  If that sets up further west then we will struggle to get 3 inches even NW of 95.  That is a rather fine detail that we just don't know yet.  All IMHO of course.

And the surface low seems to drift further and further north on each GFS run. Fankly I'm puzzled it stays as cold as it does with the low that far to our north.