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Western PA/Pittsburgh Winter 2021/22 Discussion


meatwad
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Just now, Rd9108 said:

I think tonight will get a little dicey. it doesn't take much accretion to cause problems. Hopefully we get atleast an inch of snow to freshen things up.

Agreed. Glad the snow largely survived the warm part of this week but what’s left looks like hell.

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31 minutes ago, TimB84 said:

Well 1” of zr qpf doesn’t mean 1” accretion, correct? I don’t subscribe to Pivotal premium but I know there are maps for more realistic accretion. What % of zr qpf usually “sticks”?

Right, some models just show basically (If Surface Temperature is <=32) and precipitation is liquid based on higher levels of the atmosphere being above 32. Then show as ice. It's literally just a total of how much qpf falls as rain while surface is at or below 32.

Pivotal does have ice maps that utilize the FRAM method which is much more accurate at depicting actual accretion but they are for pay only.

It's not a simple this % will accrete type deal, you need to take into account surface and air temperature, solar radiation, albedo of the object, winds, latent heat release and that effect on already accreted ice, how thick the warm layer is (is the droplet super cooled or above freezing) even the kinetic energy of the droplet when it hits the object. Needless to say it's a lot of complicated interdependent factors lol

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met from another forum

 

Surface temps appear to be a bit colder than forecast, KPIT is down to 31/29 in west Pittsburgh, and KAGC is now down to 33/32 in the southeast part of the Burgh. Front has cleared all parts of the Burgh, which is seen with both airports now reporting a north wind. Only a matter of time before we begin to ice up as temps continue to drop. 

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13 minutes ago, RitualOfTheTrout said:

Right, some models just show basically (If Surface Temperature is <=32) and precipitation is liquid based on higher levels of the atmosphere being above 32. Then show as ice. It's literally just a total of how much qpf falls as rain while surface is at or below 32.

Pivotal does have ice maps that utilize the FRAM method which is much more accurate at depicting actual accretion but they are for pay only.

It's not a simple this % will accrete type deal, you need to take into account surface and air temperature, solar radiation, albedo of the object, winds, latent heat release and that effect on already accreted ice, how thick the warm layer is (is the droplet super cooled or above freezing) even the kinetic energy of the droplet when it hits the object. Needless to say it's a lot of complicated interdependent factors lol

Would think that most of those factors work against efficient ice accretion during the day today even in areas that are below 32.

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11 minutes ago, Rd9108 said:

met from another forum

 

Surface temps appear to be a bit colder than forecast, KPIT is down to 31/29 in west Pittsburgh, and KAGC is now down to 33/32 in the southeast part of the Burgh. Front has cleared all parts of the Burgh, which is seen with both airports now reporting a north wind. Only a matter of time before we begin to ice up as temps continue to drop. 

Looks like that wind shift occurred at around 3:00 this morning at PIT and between 4:00 and 5:00 at AGC.

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27 minutes ago, Rd9108 said:

met from another forum

 

Surface temps appear to be a bit colder than forecast, KPIT is down to 31/29 in west Pittsburgh, and KAGC is now down to 33/32 in the southeast part of the Burgh. Front has cleared all parts of the Burgh, which is seen with both airports now reporting a north wind. Only a matter of time before we begin to ice up as temps continue to drop. 

Wouldn't the front already being through help cool the upper levels at some point?  I mean even if it gets stuck just past the county, wouldn't the cold air up above catch up to the front?  This is a weird one, so I'm not sure I understand all the dynamics.

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2 minutes ago, Ahoff said:

Wouldn't the front already being through help cool the upper levels at some point?  I mean even if it gets stuck just past the county, wouldn't the cold air up above catch up to the front?  This is a weird one, so I'm not sure I understand all the dynamics.

HRRR and the like even have modest warming (a degree or two) before it starts to cool back down. It’s these kinds of storms that make me realize how much I don’t know about weather.

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1 minute ago, Ahoff said:

Looking at the national radar...This thing is a monster.  Mexico to Maine and  Missouri to the coast.

For being a weak low pressure there is a ton of moisture transport with this thing. Pretty cool to see on the radar. 

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Not in our area, but the NWS in Charleston has upgraded some of its southeast Ohio counties to an Ice Storm Warning. Now talking about potential for widespread power outages and up to 3/4" of ice accumulation.

URGENT - WINTER WEATHER MESSAGE
National Weather Service Charleston WV
1102 AM EST Thu Feb 3 2022

KYZ101-102-OHZ067-075-083-084-040015-
/O.UPG.KRLX.WS.W.0004.000000T0000Z-220204T1200Z/
/O.NEW.KRLX.IS.W.0001.220203T1602Z-220204T1200Z/
Greenup-Carter-Morgan-Athens-Jackson OH-Vinton-
Including the cities of Flatwoods, Raceland, Russell, Grayson,
Olive Hill, Carter Caves State Park, Grayson Lake State Park,
McConnelsville, Stockport, Athens, Jackson, Wellston, Oak Hill,
McArthur, and Hamden
1102 AM EST Thu Feb 3 2022

...ICE STORM WARNING IN EFFECT UNTIL 7 AM EST FRIDAY...

* WHAT...Significant icing. Snow accumulations of up to 3 inches
  and ice accumulations of three tenths to three quarters of an
  inch.

* WHERE...Portions of southeast Ohio and northeast Kentucky.

* WHEN...Until 7 AM EST Friday.

* IMPACTS...Expect widespread power outages and tree damage due
  to the ice. Travel could be impossible. The hazardous conditions
  could impact the morning or evening commute.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

Travel is strongly discouraged. If you must travel, keep an extra
flashlight, food and water in your vehicle in case of an
emergency. Prepare for possible power outages.

Additional information can be found at
https://www.weather.gov/rlx as well as on our Facebook and
Twitter pages.

&&

$$
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Just came home from out running errands. My temp is still holding at 33.4. Driving on Mcknight road and about is was 36 in my car. Rain has picked up to moderate. 

According to everyone here posting most of us from central Allegheny county and east won't be changing until evening. I guess that's good to keep the ice down but I think we will still see the worst ice tonight. The Canadian doesn't have us switching to snow until after 1:00 am and then we get a couple inches tomorrow morning. Blustery and cold tomorrow with snow showers. 

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1 minute ago, north pgh said:

Just came home from out running errands. My temp is still holding at 33.4. Driving on Mcknight road and about is was 36 in my car. Rain has picked up to moderate. 

According to everyone here posting most of us from central Allegheny county and east won't be changing until evening. I guess that's good to keep the ice down but I think we will still see the worst ice tonight. The Canadian doesn't have us switching to snow until after 1:00 am and then we get a couple inches tomorrow morning. Blustery and cold tomorrow with snow showers. 

The Canadian is always warmer than every other guidance it seems. I'm guessing we switch over around dinner time. 

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50 minutes ago, Ahoff said:

Wouldn't the front already being through help cool the upper levels at some point?  I mean even if it gets stuck just past the county, wouldn't the cold air up above catch up to the front?  This is a weird one, so I'm not sure I understand all the dynamics.

With the air being less dense up there, you would think so. 
Still much to learn I guess.

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