February 19-20 Major Winter Storm Threat

[HKY_WX]

Euro here in southern Franklin County is prob 4-6 snow/sleet and then a 1/2" of ice... 

[HKY_WX]

It's possible the models are starting to realize the strength of the cold dome at the sfc. This is pretty unreal low level cold air. Trying to remember the last time we've had a legit STJ impulse override a cold dome such as this. It's likely you have to go back to the early 2000's or 90's.

Unless we see a trend NW with the SLP over the next few days I think Sleet/Snow is more of a threat than ZR. It's early, but with a Miller A that skirts the coastline, there will only be a thin ZR transition zone. It will mostly be Snow/Sleet given the cold dome and lack of a deep warm nose aloft. My concern is if we get a SLP trend where it gets a bit more NW towards the coastal plain, that could result in a legit changeover to ZR. Time will tell on that. I'm not sold on either at this point in time as it's about 4ish days out.

[Crackle32]

2 minutes ago, HKY_WX said:

It's possible the models are starting to realize the strength of the cold dome at the sfc. This is pretty unreal low level cold air. Trying to remember the last time we've had a legit STJ impulse override a cold dome such as this. It's likely you have to go back to the early 2000's or 90's.

 

 

That's crazy. 60s in Savannah and 20s in Charlotte ?

[Tullioz]

If the Euro is correct, the cold temperatures during and immediately after the storm could rival what we saw in January in the western piedmont. 

[olafminesaw]

[BornAgain13]

UK ensembles shifted south to.

[olafminesaw]

[WinstonSalemArlington]

[Pilotwx]

14 minutes ago, olafminesaw said:

Just your random 37-38 inch snow fall

[WinstonSalemArlington]

it’s great to trend in the right direction 

[Silas Lang]

4 minutes ago, Pilotwx said:

Just your random 37-38 inch snow fall

LOL that's just probability for an inch, FYI. 

[GaWx]

44 minutes ago, HKY_WX said:

Euro here in southern Franklin County is prob 4-6 snow/sleet and then a 1/2" of ice... 

I see the 1/2” of ZR on WB Euro. However, I recently posted that the WB Euro algos for ZR vs IP appear to be off in that it has too much ZR at the expense of IP. In S Franklin Cty in case you didn’t see this, the 925s never get above -3C and the 850s never rise above +2C. That imo would mean little ZR RDU/Franklin Cty and 1.5-2” more IP than what’s on the Euro output.

[HKY_WX]

21 minutes ago, GaWx said:

I see the 1/2” of ZR on WB Euro. However, I recently posted that the WB Euro algos for ZR vs IP appear to be off in that it has too much ZR at the expense of IP. In S Franklin Cty in case you didn’t see this, the 925s never get above -3C and the 850s never rise above +2C. That imo would mean little ZR RDU/Franklin Cty and 1.5-2” more IP than what’s on the Euro output.

Interesting. Not directly related, but I've only ever seen 1 system in NC that ive experienced personally where we received significant sn/ip and also a significant accumulation of ZR. Dec 2002 in Hickory. Received roughly 6 inches of sn/ip followed by .3 or so zr. Extremely rare. Usually it's one or the other due to the nature of storm tracks and limited moisture supply. 

[Pilotwx]

22 minutes ago, Silas Lang said:

LOL that's just probability for an inch, FYI. 

yea , jumped on the old Cm to inches calc. with out reading it fully

[HKY_WX]

57 minutes ago, Crackle32 said:

That's crazy. 60s in Savannah and 20s in Charlotte ?

Taken verbatim that thermal boundary where the cold/warm meet is likely to be the SLP track. Roughly Valdosta GA to Wilmington NC. That really does favor snow in western NC. Areas in the N Foothills and Mtnd would likely get slammed in that situation as it would not changeover

[NorthHillsWx]

If it’s 24 degrees and raining here I give up. 

[tarheelwx]

When I was a kid in the 70’s/early 80’s, we had many storms that started as snow and we probably got a 1/4” or more of ZR.  
TW

[Upstate Tiger]

For you young ones, this kind of storm occurred often in the 70s and 80s except we didn’t have models or American Wx.  Only Charlie Gertz on WYFF or Dr Joe on the radio to give us a 2 day heads up.  
 

LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
As of 100 PM Sat: Upper low will cut off over the northern Plains by
Wednesday morning, with a low amplitude shortwave trough accelerating
ahead of it and crossing the Mid-South Wednesday. This latter feature
will advance to the NC/VA coast by early Thursday. Global models
continue to depict Miller A-type sfc low near the central Gulf Coast
at 12z Wed, which tracks generally to our south through Wednesday
evening. Models appear to be in decent agreement on this general
evolution. 12z cycle ECMWF, along with both EC and GFS Ensemble
means, have trended toward a slightly faster deepening of the low
although the track has not changed much. The closed upper low will be
associated with a 1050+ mb high over eastern Montana and vicinity;
ridging will extend to the Mid-Atlantic Coast and confluence
downstream of the trough may lead to a small closed high to our north
supporting CAD on Wed and a very dry sfc layer.

The Miller-A is likely to bring precip shield over the area on Wed.
The critical difference among models appears to be how well the
precip overcomes what may be exceptionally dry air at onset, and how
temps respond.  There are slight differences in timing that limit
confidence, but these temperature discrepancies are the main factor
in a low-confidence forecast, at least in the sense of precip type
trends or overall impact. The presence of ice nuclei does not appear
to be an issue at the onset of precip, which most likely will not
occur until after daybreak Wednesday; PoPs are mainly in the 10-30%
range Tuesday night, reflecting possibility of earlier onset. The
most plausible middle-ground scenario, taking this into account, is
for rain or snow early in the event, even after PoPs ramp up into the
likely to categorical range (from SW to NE) during the day Wed. With
low confidence on temperature, have tried to minimize the expanse of
subfreezing temps early in the event, leaving mention as a rain/snow
mix in much of the CWA where temps hover just above freezing. A warm
nose may also come into play and some sleet could mix in at this
time. As the low passes the area Wed evening and drying occurs aloft,
p-type changes to FZRA in portions of the Piedmont where temps fall
below freezing; wraparound moisture keeps snow going over the
mountains. Most precip will end Wednesday night, but NW flow snow
could continue Thu along the TN border.

The remainder of the forecast will be dry and cold as the Arctic air
remains over the Southern US. Min/max temps will be 15-20 below
normal Thu-Fri.

[WXNewton]

I find this pretty interesting between the Euro and GFS, here are the 48 hr trends for both models. The Euro has been most consistent with the placement of the gulf low and overall orientation of the moisture. You can clearly see the GFS is trending to show a very similar look to what the Euro has shown for days. Both models are also expanding the precip shield more and more each run while also depicting a colder and more expansive side to the wintry precip. I think these two models will be showing very similar solutions with in the next three cycles. Right now the GFS is going towards the EURO.

 

[olafminesaw]

6 minutes ago, WXNewton said:

I find this pretty interesting between the Euro and GFS, here are the 48 hr trends for both models. The Euro has been most consistent with the placement of the gulf low and overall orientation of the moisture. You can clearly see the GFS is trending to show a very similar look to what the Euro has shown for days. Both models are also expanding the precip shield more and more each run while also depicting a colder and more expansive side to the wintry precip. I think these two models will be showing very similar solutions with in the next three cycles. Right now the GFS is going towards the EURO.

 

Yeah and I think that temperature gradient from the wedge is just going to enhance precip rates, especially wherever that sleet/snow line is

[NorthHillsWx]

ICON coming in colder than last run

[WXNewton]

ICON with subtle shift south with the snow/sleet.

[NorthHillsWx]

1 minute ago, NorthHillsWx said:

ICON coming in colder than last run

NM about the same

[wncsnow]

Just now, WXNewton said:

ICON with subtle shift south with the snow/sleet.

Yep was about to post. Let's see if the GFS does 

[wncsnow]

Just now, NorthHillsWx said:

NM about the same

It's a little colder and SE baby steps 

[NorthHillsWx]

2 minutes ago, WXNewton said:

ICON with subtle shift south with the snow/sleet.

Surface about the same but mid levels a tad bit better for I-85

[NorthHillsWx]

ICON explodes into a MA special and buries DC-East in 20+ inches

[BooneWX]

Fwiw, Eric Webb is in the camp that it won’t have much room to come NW like many storms we’re so accustomed to. He believes the block is keeping this thing pressed and we may be starting to see models correct to that solution. 

[jburns]

All these maps and wordy forecasts I feel I need to jump in with my own. After living here for decades I have honed my winter weather forecasts to be as concise as possible.

I-85

[BooneWX]

Just now, jburns said:

All these maps and wordy forecasts I feel I need to jump in with my own. After living here for decades I have honed my winter weather forecasts to be as concise as possible.

I-85

I’ll take it a step further:

 

North of 85 = eating 

North of 40 = thanksgiving dinner with dessert