Possible Snowstorm December 8th-9th

sroc4 wrote:

skinsfan1177 wrote:Hi res man looks great a lot of laten heat release. I mentioned that yesterday

Skins Im not sure what you mean by latent heat release?  

Memory serves me correctly you can see it on the high-resolution nam model it has to do with the convection down to the South releasing Heat which pushes storms more North I remember reading this at one point somewhere on here

12z GFS continues the creep west.......

You guys may see some flakes south and east but I'm going to be sucking virga up here in hudson valley. Where's CP?

nutleyblizzard wrote:UKIE is west of 0z run.

Yes it's five to ten  inches. From the city on East even slightly west of the city is in on this I would say we're now starting to get a consensus that this will be our first snowfall of the year my best guess right now would be one to three inches for the city and nearby burbs and 3 to 6 South and East obviously the later in the day it fell on Saturday the better if it fell Saturday night

nutleyblizzard wrote:GEFS just came in west. Very good trends with the 12z suite.

If we do get snow this would be a big fail by the Euro and GFS and the big win for the CMC and ukie. you can also add in the Navy and the JMA which have been all over this event

nutleyblizzard wrote:GEFS just came in west. Very good trends with the 12z suite.

Yes .4lqe into the City and .5 at the Queens Nassau border they are wetter than the operational.

Far enough west to get me some snow?

skinsfan1177 wrote:

sroc4 wrote:

skinsfan1177 wrote:Hi res man looks great a lot of laten heat release. I mentioned that yesterday

Skins Im not sure what you mean by latent heat release?  

Memory serves me correctly you can see it on the high-resolution nam model it has to do with the convection down to the South releasing Heat which pushes storms more North I remember reading this at one point somewhere on here

I dont recall that partcular convo, and Im not exactly sure how that would work in this particular set up.  If you can find the discussion or if someone else can explain I would appreciate it.  As far as I know the main determining factors are first at 500mb:

positioning of the N energy with respect to the Southern energy, and how focused or strung out is the S energy.  Take a look at the differences between GFS vs CMC today at 12z.
Looking at the CMC first.  If you go and look at the surface/precip maps youll notice there is zero precip that makes it into the area.  The reason is this.  N energy for the most part is steering the storm.  That is its main role in this set up.  On the CMC the timing of the S energy is such that it is actually slightly behind the N energy in the race to the coast.  As a result the N energy actually deflects the energy OTS and  keeps the trough orientation way too positive.  

The GFS on the other hand you can clearly see the S energy is out ahead of the N energy.  Keep in mind its the S energy that is creating the system, and the northern energy that is steering it.  By being out ahead of the N energy the trough can go closer to neutral or only slightly positive as it reaches the coast which changes the steering flow more NE instead of ENE like the CMC shows.  The N energy is actually very close to digging into the back side of the S energy on the GFS which would only further aid in tilting the trough neutral faster.  

By changing the steering flow from ENE to a more NE direction you change the stregth and area of best Potential vorticity advection(PVA).  PVA is the area out ahead of the main vort max in the 500mb maps that has the best veritical motion potential often the NW side of the developing LP.  I wont go into any more detail on this for now.

 



The second key factor in how far N&W the precip shield can expand is the position of the upper level jet streak.  I dont have time for a detail explanaition but simply stated the Right rear quadrant of a jet streak is a favorable position for enhanced vertical motion from the lower levels.  The reason is because the jet streak creates an upper level area of divergence created by the air racing away from slower moving air behind the jet streak.  The air in the upper levels is replaced by air in the lower levels creating enhanced lift in the R rear quadrant of the jet streak. Vertical motion leads to condensation, and precipitation.  More simply stated if the jet streak is too far S and E then our area falls out of the favorable R Rear quadrant and falls in an are of subsidence or sinking air.  If its further N&W then we may fall in a more favorable area of convergence and the precip shield will expand further N&W accordingly.  Here are the differences between the CMC and GFS.  




These differences are subtle but are the reason for the difference in precip into the area of GFS vs no precip on CMC

UKIE looks nice too regarding position of the S and N energy with respect to each other.

EURO is caving and attempting the partial phase NAM shows

EURO 10am Saturday

1pm Saturday

Have a feeling EURO still trying to correct west. It does look on the warm side and precip is falling during the day. But again, I think this model is still catching on. Long Island seems to be in line for a nice burst of snow. Accumulations mainly on grassy areas.

NAVGEM also came back west. Is this looking like an all snow event right now? Could the storm come back 'too close' to the coast and cause p-type issues?

Bernie Rayno says "sound the alarms!" for the NW trends

https://www.accuweather.com/en/videos/snow-threat-increasing-for-mid-atlantic-and-northeast/9rnwjszde6cnohbua9msckvashyfoajo?SearchForm-input=snow%20threat%20increasing%20for%20mid-Atlantic%20and%20northeast

SENJsnowman wrote:NAVGEM also came back west. Is this looking like an all snow event right now? Could the storm come back 'too close' to the coast and cause p-type issues?

I'm thinking it will be mainly snow. May have to create a snowfall map :O

SENJsnowman wrote:NAVGEM also came back west. Is this looking like an all snow event right now? Could the storm come back 'too close' to the coast and cause p-type issues?

Closer to coast means I get more snow...

Temps dropping on Saturday I had a feeling it would come back

Wow, well call me calling it too early, this looks great for my area, hopefully it comes a bit forther west so NW folks can get into this. Are we looking at possible mothrazilla? GFS is close to 6 plus especially eastern LI and east.

Frank_Wx wrote:

SENJsnowman wrote:NAVGEM also came back west. Is this looking like an all snow event right now? Could the storm come back 'too close' to the coast and cause p-type issues?

I'm thinking it will be mainly snow. May have to create a snowfall map :O

Waiting for those madonnes Frank lol, prolly won't get with this one but glad to see you back around, would love to see a snow map.

Euro:

Yep looks like 1-4+ for most of area, possible room to be higher amounts too, just goes to show how much we cant rely on models but a day or two out, well some of the time anyways.

We will have to account for melting as this looks like a mainly daytime event hopefully it can slow down a few hours so we can get some nighttime snowfall so why all the Euro and other models is showing 3 to 6 inches it will most likely be 1 to 3 of a wet slushy snow. still nice to get on the board early in the season for a change