December 22-23, 2022: Warm Rain to Arctic Chill

[IceCAPS]

15 hours ago, Ji said:

15 hours ago, Terpeast said:

Not sure when NAM gets into its range, but it seems to be trending colder at precip onset. Only checked 850 temps, not ptype

Frustrated that 850 is below 0 but still rain. So Frustrating. Worst winter ever

You're too funny Ji!  "Worst Winter ever" on the first day of said Winter.... Let's just delay our collective call on THIS being the worst of all time just yet.  Although, you may be proven correct, I'm going to hold out hope for a middle of the road Winter myself with three months of it to go. Heck March around these parts can be interesting! 

[MN Transplant]

9 minutes ago, high risk said:

         Here is how it works.     Inside the GFS, there is a bucket for snow accumulation.   Anything from the direct model integration of the microphysics scheme that reaches the ground as snow or sleet goes into the snow accumulation bucket as a liquid equivalent.   This liquid equivalent is output as a snowfall product.

          The snow (+ sleet) is also passed into the land-surface part of the model where an SLR is applied.   This determines how much snow is on the ground in the model.

           The disconnect has 2 sources:      1)  users apply their own ratios.  Most use 10:1, but some use the generous Kuchera.   Kuchera for this case will love the crashing temps and put some weenie ratios and end up with big accumulations     2)  the snow depth is instantaneous, and some melting (not in the Friday example) or compacting may occur by the time shown

            The model is absolutely "handling the fast-moving front".   Right or wrong, it has snow falling on the cold side of the front.   The products showing "snowfall" do have an element of post-processing artifacts, especially the Kuchera.

Yes, I didn’t mean to imply that the model was handling it incorrectly, only that the accumulation maps were not showing the entire picture due to processing choices. There is no physical/meteorological reason why there is a hole in the accumulation product NW of Philly, for example.

[Terpeast]

Looked at the models and trends today. I’m not buying into the anafront, but it wouldn’t surprise me to see a brief snow shower or two (no accumulation) just as precip shuts off on fropa. I’ll take that. 

[WxUSAF]

Euro wants nothing to do with post frontal snow unfortunately. About a 20F temp drop in 6 hours per euro, and 30F in 12 hours.

[Eskimo Joe]

12z Euro/NAM/GFS seems insistent on some little 925/850 wind maximum hitting Baltimore some time between 12z and 18z Friday. Even GFS BUKFIT has some decent winds mixing down to the surface.

[Eskimo Joe]

Oh, nice

 

[usedtobe]

49 minutes ago, WxUSAF said:

Euro wants nothing to do with post frontal snow unfortunately. About a 20F temp drop in 6 hours per euro, and 30F in 12 hours.

It's what you'd expect with most fronts east of the mountains. 

[WEATHER53]

Often our Arctic  fronts have big dry high pressure pushing them but this is strong low wrapping around Lakes area.  Not as dry.

The results of these rare  blast throughs are hard to predict and wild to watch 

 

 

[nw baltimore wx]

In true weenie-style, even a pessimistic @usedtobe sighting has me thinking snow.  Especially because he said, "most fronts," and not, "this front."

[WEATHER53]

3 hours ago, H2O said:

VDOT already beet juice spraying. WTF

Beetlejuice ???

[Ravens94]

18z HRRR for tomorrow 

[NorthArlington101]

Just now, Ravens94 said:

18z HRRR for tomorrow 

It's willing to play ball with the anafrontal too -- massive grain of salt, given its the long-range HRRR, but seems to want to flip most to snow. Around B'More it even manages to spit out an inch on the ol' 10:1.

[Ravens94]

Just now, NorthArlington101 said:

It's willing to play ball with the anafrontal too -- massive grain of salt, given its the long-range HRRR, but seems to want to flip most to snow. Around B'More it even manages to spit out an inch on the ol' 10:1.

Yep

[ravensrule]

1 hour ago, usedtobe said:

It's what you'd expect with most fronts east of the mountains. 

Great to have you post Wes. Hope all is well with you and your family. Don’t be a stranger. Every time you post i get a little tingle thinking it’s going to snow. 

[WesternFringe]

2 hours ago, NorthArlington101 said:

Unfortunately for our I-81 comrades the 12z EURO is putting out a icier solution than earlier runs. Cut back snow totals a decent bit.

That is consistent with what LWX has been forecasting for out here in Augusta County.  An inch or two of snow/sleet with .1 to .25 freezing rain.

[MN Transplant]

Cheyenne, WY 43 degrees at 1:05pm local.  11 degrees nine minutes later.

[LongRanger]

what about San Diego?

[TSSN+]

Heh single digits at 1pm. 

[yoda]

Um, travel may become impossible after the flash freeze? Huh?

 

From the afternoon LWX AFD:

 

 

 

The cold air behind this front is going to be some of the

coldest air we have seen in quite some time, and will be quite

deep. This means that it should move in swiftly into Friday

morning. This brings about the chance for some of the

precipitation with the frontal passage to end as some snow. But

there remains a great deal of uncertainty there as far as if

that happens and how much snow might fall. Greatest potential is

along the Allegheny Front and Mason Dixon line. Regardless of

whether snow occurs, there still appears to be some potential

for refreeze of leftover moisture, given the expected rapid drop

in temperatures. Temperatures should drop from the 50s near the

metros in the early morning hours, to the teens by evening.

We`ll continue to evaluate the potential for both anafrontal

snow and a flash freeze as we move closer to the event. Travel

could be nearly impossible should a flash freeze occur.

 

[North Balti Zen]

That's nothing to mess with. I saw the devastating effects of a flash freeze in the documentary film "The Day After Tomorrow". Jake Gyllenhall barely got to safety. 

[TSSN+]

11 minutes ago, yoda said:

Um, travel may become impossible after the flash freeze? Huh?

 

From the afternoon LWX AFD:

 

 

 

The cold air behind this front is going to be some of the

coldest air we have seen in quite some time, and will be quite

deep. This means that it should move in swiftly into Friday

morning. This brings about the chance for some of the

precipitation with the frontal passage to end as some snow. But

there remains a great deal of uncertainty there as far as if

that happens and how much snow might fall. Greatest potential is

along the Allegheny Front and Mason Dixon line. Regardless of

whether snow occurs, there still appears to be some potential

for refreeze of leftover moisture, given the expected rapid drop

in temperatures. Temperatures should drop from the 50s near the

metros in the early morning hours, to the teens by evening.

We`ll continue to evaluate the potential for both anafrontal

snow and a flash freeze as we move closer to the event. Travel

could be nearly impossible should a flash freeze occur.

 

Isn’t it usually nearly impossible on sunny days around the Beltway anyway? 

[jayyy]

Euro wants nothing to do with post frontal snow unfortunately. About a 20F temp drop in 6 hours per euro, and 30F in 12 hours.

Probably the model I’m looking at least at this range when trying to analyze something as specific as timing of a cold front / changeover. Can’t discount it entirely of course, but this is where high res models *should* have a better grasp on details versus the euro.
.

[WinterWxLuvr]

4 minutes ago, North Balti Zen said:

That's nothing to mess with. I saw the devastating effects of a flash freeze in the documentary film "The Day After Tomorrow" . Jake Gyllenhall barely got to safety. 

He was never in danger. He could have built a rocket to get him out if he had to.

[jayyy]

That's nothing to mess with. I saw the devastating effects of a flash freeze in the documentary film "The Day After Tomorrow" . Jake Gyllenhall barely got to safety. 

Ahh, yes, the day after tomorrow analog. Never fails


.

[toolsheds]

1 hour ago, WEATHER53 said:

Beetlejuice ???

Say it 3x really fast and it will snow!

[Lucketts Life]

5 hours ago, H2O said:

VDOT already beet juice spraying. WTF

White dust clouds everywhere today. 

[IUsedToHateCold]

8 minutes ago, Lucketts Life said:

White dust clouds everywhere today. 

Dumb. The rain is just going to wash it away (unless it's for the mountains in the far west that are going to get snow)

[yoda]

Lulz

 

Flood Watch

National Weather Service Baltimore MD/Washington DC

322 PM EST Wed Dec 21 2022

 

DCZ001-MDZ008-011-013-014-504-506-508-VAZ052>054-220430-

/O.NEW.KLWX.FA.A.0024.221222T1600Z-221223T0600Z/

/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

District of Columbia-Cecil-Southern Baltimore-Prince Georges-Anne

Arundel-Central and Southeast Montgomery-Central and Southeast

Howard-Southeast Harford-Prince William/Manassas/Manassas Park-

Fairfax-Arlington/Falls Church/Alexandria-

Including the cities of Aberdeen, Franconia, Centreville, Laurel,

Silver Spring, Reston, Arlington, Severna Park, Herndon, Ellicott

City, Montclair, Odenton, Bowie, South Gate, Rockville, College

Park, Annapolis, Greenbelt, Alexandria, Lake Ridge, Severn, Camp

Springs, Manassas, Glen Burnie, Woodbridge, Bethesda, Annandale,

Columbia, Washington, Arnold, Suitland-Silver Hill, Falls Church,

Baltimore, Elkton, Clinton, Dale City, McLean, Gaithersburg, and

Chantilly

322 PM EST Wed Dec 21 2022

 

...FLOOD WATCH IN EFFECT FROM THURSDAY MORNING THROUGH LATE THURSDAY

NIGHT...

 

* WHAT...Flooding caused by excessive rainfall is possible.

 

* WHERE...DC and portions of Maryland and northern Virginia,

  including the following areas: District of Columbia. In Maryland,

  Anne Arundel, Cecil, Central and Southeast Howard, Central and

  Southeast Montgomery, Prince Georges, Southeast Harford and

  Southern Baltimore. In northern Virginia, Arlington/Falls

  Church/Alexandria, Fairfax and Prince William/Manassas/Manassas

  Park.

 

* WHEN...From Thursday morning through late Thursday night.

 

* IMPACTS...Excessive runoff may result in flooding of rivers,

  creeks, streams, and other low-lying and flood-prone locations.

  Flooding may occur in poor drainage and urban areas.

 

* ADDITIONAL DETAILS...

  - Moderate rainfall is expected Thursday into Thursday evening,

    with rainfall totals of one to two inches. This may lead to

    isolated instances of flooding, especially in urban and poor

    drainage areas.

  - http://www.weather.gov/safety/flood

 

[jayyy]

Lulz
 
Flood Watch
National Weather Service Baltimore MD/Washington DC
322 PM EST Wed Dec 21 2022
 
DCZ001-MDZ008-011-013-014-504-506-508-VAZ052>054-220430-
/O.NEW.KLWX.FA.A.0024.221222T1600Z-221223T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
District of Columbia-Cecil-Southern Baltimore-Prince Georges-Anne
Arundel-Central and Southeast Montgomery-Central and Southeast
Howard-Southeast Harford-Prince William/Manassas/Manassas Park-
Fairfax-Arlington/Falls Church/Alexandria-
Including the cities of Aberdeen, Franconia, Centreville, Laurel,
Silver Spring, Reston, Arlington, Severna Park, Herndon, Ellicott
City, Montclair, Odenton, Bowie, South Gate, Rockville, College
Park, Annapolis, Greenbelt, Alexandria, Lake Ridge, Severn, Camp
Springs, Manassas, Glen Burnie, Woodbridge, Bethesda, Annandale,
Columbia, Washington, Arnold, Suitland-Silver Hill, Falls Church,
Baltimore, Elkton, Clinton, Dale City, McLean, Gaithersburg, and
Chantilly
322 PM EST Wed Dec 21 2022
 
...FLOOD WATCH IN EFFECT FROM THURSDAY MORNING THROUGH LATE THURSDAY
NIGHT...
 
* WHAT...Flooding caused by excessive rainfall is possible.
 
* WHERE...DC and portions of Maryland and northern Virginia,
  including the following areas: District of Columbia. In Maryland,
  Anne Arundel, Cecil, Central and Southeast Howard, Central and
  Southeast Montgomery, Prince Georges, Southeast Harford and
  Southern Baltimore. In northern Virginia, Arlington/Falls
  Church/Alexandria, Fairfax and Prince William/Manassas/Manassas
  Park.
 
* WHEN...From Thursday morning through late Thursday night.
 
* IMPACTS...Excessive runoff may result in flooding of rivers,
  creeks, streams, and other low-lying and flood-prone locations.
  Flooding may occur in poor drainage and urban areas.
 
* ADDITIONAL DETAILS...
  - Moderate rainfall is expected Thursday into Thursday evening,
    with rainfall totals of one to two inches. This may lead to
    isolated instances of flooding, especially in urban and poor
    drainage areas.
  - http://www.weather.gov/safety/flood
 

Wouldn’t be the mid Atlantic without having a flood watch hoisted as the rest of the country is under a winter weather alert of some kind.

Hoping to squeeze out an inch or two up this way before we head into the freezer for 36 hours. Sucks that that is “best case” scenario, but it is December in the mid Atlantic. Snow is allergic to the Delmarva in December.


.

[WinterWxLuvr]

HRRR got a lot snowier here with its latest run