Jan 24-26 Weekend Snow and Sleetfest Model Thread Part Tres

[stormtracker]

7 minutes ago, yoda said:

Yes I know its the 18z HRRR at the end of its run, but note 700-800mb.  Doesn't go positive aka above 0c.  This is the sounding at DCA.  Yes, its probably rimed snow... but i don't think this shows a pure sleet profile 

 

Hope the HRRR is right, all these low balling ass predictions for us in DC can go up in smoke.   Come on HRRRRRRRRRrrrrr

[Eskimo Joe]

Amazing AFD from LWX. Absolutely worth the read.

Quote

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
234 PM EST Fri Jan 23 2026

.WHAT HAS CHANGED...
Some subtle tweaks were made to snow and ice amounts in the latest forecast updates. Main change was to reduce overall totals a bit to account for more sleet. Also nudged down some of the freezing rain totals, as model sounding profiles support mostly sleet for many areas. Winter Storm Warnings remain in effect for all areas starting Saturday evening and continuing through early Monday morning.

&&

.KEY MESSAGES...
- 1) Major winter storm will impact the region late Saturday
  through Sunday evening.

- 2) Frigid temperatures this weekend and into much of next week.
 
- 3) Light accumulating snow possible on Thursday. 

&&

.DISCUSSION...
KEY MESSAGE 1...Major winter storm will impact the region late Saturday through Sunday evening.

Some small tweaks were made to the forecast today, as mentioned in the "what has changed" section above. The overall forecast and associated impacts hasn't substantially changed anywhere at this time however. Winter Storm Warnings were issued earlier today for all zones, but the exact snow/sleet/ice totals will vary substantially from SE to NW, which we'll dive into below. 

Starting with tonight, very cold temperatures move in this evening following a potent arctic cold front that just pushed through earlier today. Cold Weather Advisories remain in effect for the entire region starting this evening and continuing  through Saturday morning. This is really setting the stage for the impending winter storm, set to arrive Saturday evening/night. 

No major adjustments to the QPF forecast this afternoon, as things are pretty much the same in that department as we saw with last night's model guidance. A broad 1.5-2.5" of QPF is expected across the region (more in the SE, less in the NW). 

Now, the hard part is getting the precipitation type right, and that is where the biggest question will be with this system. No matter what precipitation type you see, this will be a high-impact winter storm for all. At the surface, this seems like a perfect setup for snow, with a strong (1050 mb) high pressure to our north funneling in arctic air into the region. Temperatures will be in the 20s for the entire event at the surface, but the problems start aloft. The area of low pressure tracking to our south will bring in strong warm advection in the mid-levels. While this event will start as a period of heavy snow (potentially 1-2"/hr at times) overnight Saturday into early Sunday morning, a potent warm nose aloft will quickly transition most locales to sleet by mid-morning. Now, this will be very heavy sleet at times, especially before the afternoon, so even the sleet accumulations could amount to a few inches. Hence, the storm total snow forecast you will see on weather.gov/lwx/winter will be showing the combination of snow and sleet. These sleet totals could harshly cut into snow totals, even from what is currently in the forecast, so it is essential to look at all probabilities (10th and 90th percentile forecasts) on the webpage as well for your planning purposes. The further south you look during this storm, the more likelihood of encountering freezing rain. Right now, the highest likelihood would be east of I-95, and especially later in the afternoon when the warm nose strengthens significantly (7-8 deg C) aloft. Given how cold the air mass is below the warm nose however, some question as to how much freezing rain there is, versus those droplets refreezing in the cold layer back into sleet. But for now those details were just a bit too specific, and I'd like to see a bitmore consistency in the guidance before lowering totals from I-95 westward. I say this just to bring up the entire range of possibilities, as there is still some uncertainty with precipitation types. 

Snow to liquid ratios look to start around 15-18:1 with this system for the entirety of the area, while then trending down toward 7-10:1 Sunday morning into the afternoon (lower where some mixing occurs). A pending dry slot could also play into amounts as well. Snow should be fluffy in nature, particularly within the initial warm advection conveyor belt Saturday night. Expect some crustiness of this snowpack given any mixing that may occur as the system kicks out heading into Sunday night.

Upslope snow will linger along and west of the Allegheny Front into Monday morning, as will the potential for some light snow or freezing drizzle near and east of I-95.

When all is said and done, the most likely area for the highest snowfall totals is across northern MD and over VA near and west of the Blue Ridge. Chances for a foot of snow remain quite high along/west of the Blue Ridge up to northern MD. Further south and east, mixing may ultimately put a lid on just how high snowfall totals get, though lift through the DGZ and therefore snowfall rates prior to any mixing look impressive. 

The combination of heavy snow and ice alongside prolonged very cold temperatures presents a unique and significant risk to life and property across virtually the entire region.

Monitor the latest forecasts at weather.gov/lwx/winter for updates on this situation. Now is the time to make preparations for the storm. This includes getting any necessary groceries or medicines that you may not be able to access this weekend into early next week due to any potential closure. Have an emergency kit in the car including extra batteries, a flashlight, and blanket just in case you get stranded. Make sure to refuel or charge your car before the storm hits. Check on elderly friends, family, and neighbors and don't forget about pets or livestock during this prolonged cold period.

 

[psuhoffman]

This is what I am thinking 

[clskinsfan]

Radar out west starting to blossom nicely. 

[SnowenOutThere]

8 minutes ago, bncho said:

What a prolific THUMP on the HRRR

6 minutes ago, MN Transplant said:

Lord help us all for looking at the HRRR at range, but it is a good 0.70" QPF before the flip in DC.  Nice run.

Man it would be true QDF bomb. Just tons of moisture left to go even after we sleet. Probably near an inch of QPF so another 3 inches of sleet or some amount of freezing rain. Please just once let it be right, though I'd love another tick southeast to get Cvill off the gradient. Still need to decide if I travel up north to NOVA. 

[SnowenOutThere]

Just now, psuhoffman said:

This is what I am thinking 

Is this including or excluding sleet? Not as big of a deal up your way but I'm probably adding 1-3inches of pure ice with the sleet part of this storm.

[stormtracker]

So on the NAM so far, doing comparison it is actually colder...might not lasts through the run, but it's there

[psuhoffman]

Finishes looking at the HRRR

[clskinsfan]

NAM noticeably colder in central VA. By like 3 degrees at the surface. 

[Solution Man]

1 minute ago, stormtracker said:

So on the NAM so far, doing comparison it is actually colder...might not lasts through the run, but it's there

Definitely a change in snow footprint through 21

[SnowenOutThere]

NAM has the intense southern 850 winds remaining further south and west so far in its run. Should buy us some time in regards to ptype.

[stormtracker]

Not wanting to read too much into any of this, it's probably just slower..but its noticeable colder out to our sw and south of us

[Ji]

Hope the HRRR is right, all these low balling ass predictions for us in DC can go up in smoke.   Come on HRRRRRRRRRrrrrr

How is Dr u?

[Yeoman]

5 minutes ago, bncho said:

Do any Mets have any possible implications for this?

 

Bye bye snow, hello sleet

[psuhoffman]

5 minutes ago, SnowenOutThere said:

Is this including or excluding sleet? Not as big of a deal up your way but I'm probably adding 1-3inches of pure ice with the sleet part of this storm.

includes sleet 

[clskinsfan]

2 minutes ago, stormtracker said:

Not wanting to read too much into any of this, it's probably just slower..but its noticeable colder out to our sw and south of us

Look a the southern border of KY. The snow/sleet line moved considerably south from the 12Z run. 

[Solution Man]

2 minutes ago, clskinsfan said:

Look a the southern border of KY. The snow/sleet line moved considerably south from the 12Z run. 

Yep mentioned that earlier and the snow sleet line is nc va border now. Looks like we snow 7pm ish

[jgentworth]

6 minutes ago, stormtracker said:

Not wanting to read too much into any of this, it's probably just slower..but its noticeable colder out to our sw and south of us

Comparing hr21z frames between 18z and 12z NAM, the snow line was about 4 counties further South in Tennessee and the 700mb was colder and flatter across. It seemed to lose the more drastic difference though as we moved into hr00z. Snow line is still further south in TN and 700mb is better in places but not drastically.

Through 33, 18z seems colder with snow line and 700mb further south, but over all precip shield seems dryer

[SnowenOutThere]

850mb wind map on 18z NAM is far more favorable than its 12z run. As precip overspreads we still have a good westerly component compared to pure south. 

[stormtracker]

1 minute ago, jgentworth said:

Comparing hr21z frames between 18z and 12z NAM, the snow line was about 4 counties further South in Tennessee and the 700mb was colder and flatter across. It seemed to lose the more drastic difference though as we moved into hr00z. Snow line is still further south in TN and 700mb is better in places but not drastically.

Still noticeable at 36 vs 42...precip field is different as well.  

[Solution Man]

Crush job coming at 39

[stormtracker]

Just now, Solution Man said:

Crush job coming at 39

Im not quite there yet.  If we keep trending little by little like this..buy 0z tomm night we may have an extra hour of snow!

[adelphi_sky]

12 minutes ago, WEATHER53 said:

I don’t see gaps or weakness in the highs from Chicago to Long  Island

Wall to wall 1035+.  It will be a new and learning experience if a modest low can dislodge that 

I was thinking that yesterday. It's like a Chihuahua trying to push around a bull dog? 

[bncho]

NAM noticeably colder in the upper levels

[stormtracker]

Still colder vs 12z...CAD dug in a little deeper as well..precip not super heavy on this panel tho

[SnowenOutThere]

1 minute ago, stormtracker said:

Im not quite there yet.  If we keep trending little by little like this..buy 0z tomm night we may have an extra hour of snow!

[clskinsfan]

Dumps 3.2 inches out here from 36 to 39. We get hammered. 

[stormtracker]

Thermal changes level off at 42, but some good snows 12z

[stormtracker]

2 minutes ago, SnowenOutThere said:

Yeah, it came in right after I sent...I'm about to get 45 now

[Yeoman]

19 minutes ago, WEATHER53 said:

I don’t see gaps or weakness in the highs from Chicago to Long  Island

Wall to wall 1035+.  It will be a new and learning experience if a modest low can dislodge that 

That’s the classic CAD/overrunning trap: the cold air is stubborn near the ground, but 850–700 mb winds can crank WAA over it. So you don’t dislodge the high, you just ride precipitation over it and introduce a warm nose. The surface map looks invincible, and meanwhile sleet is doing victory laps.