Wintry February 19-21, 2020 Winter Storm

[Ollie Williams]

Verbatim, more than likely rates will overcome.
Frame 1



Frame 2

 

[John1122]

850s/925s look good for all of Tennessee and the western 3/4ths of NC. 2m aren't super and the rates aren't quite heavy enough in the North Carolina rain areas to overcome bl temp issues that run.

 

[ajr]

I wouldn't worry too much about what p-types are showing up on the surface... the euro isn't going to accurately paint a RS line (especially not at this range)

 

[John1122]

I won't be surprised if the moisture field isn't done moving North and West. More precip in this case doesn't mean more warmth at upper levels like it does with a Miller A. Would mean better top down cooling.

 

[ajr]

I wouldn't be surprised if the EPS has a few more juiced members with this trend

 

[NickyBGuarantee]

View attachment 34829View attachment 34831

This is quite literally screaming a more enhanced precip Shield as we get closer to verification

I can visually see the gifs we’re going to make of the trend of more qpf

 

[Myfrotho704_]

NC/parts of SC is sitting quite pretty right now, those “BL” issues could very easily be squashed, those warm layers I’m seeing on the euro are so small (15-25mbs) it would only take moderate precip to make that a solid snow event, those big dog members we’ve been seeing on some of those ensembles are probably showing heavy precip thrown into those cold 850s/925s,

 

[Ollie Williams]

Here’s a comparison between the CMC and Euro. Just a little more separation between the N/S and SW on the Euro, then things would be identical.
Euro.

CMC

 

[ajr]

Just for fun, this is where the GEFS had us a week ago for later this week:

 

[Myfrotho704_]

 

[Myfrotho704_]

Control

 

[Ollie Williams]

Probabilities went up with @metwannabe in the sweet spot.

 

[Myfrotho704_]

Kinda suprised it didn’t show more snow then that especially around the piedmont of NC (CLT) but precip was probably still a bit to light

 

[Webberweather53]

Remember that in an overrunning setup like this, precipitation, and especially precipitation rates, are going to be almost entirely driven by processes that global NWP models traditionally don't handle terribly well:

1) Low mid-level warm air advection

2) Frontogenesis

3) Isentropic upglide

For those in the western Carolinas and perhaps even NE GA, some element of cold air damming will be present which essentially acts as effective topography, creating the impression of orographic lift. This process to is often misrepresented time & time again in most NWP models, especially global models.

 

[Myfrotho704_]

 

[Myfrotho704_]

NAM however was a tad bit worse at H5, but ofc it’s gonna change since it’s not at its best range

 

[LovingGulfLows]

NAM looks like it could be good for a decent portion of N GA if the temp profiles are right. 850s crashing just as the precip is really getting going. 2m temps around 35-38. Future runs will be interesting.

 

[John1122]

NAM looks pretty good there for Tennessee. Said it already but still not sure this is done moving North and West with the precip field. Several years ago it kept showing my area with 1-2 inches and heavier totals south. I ended up with 9.5 inches and snow was about two counties north into Kentucky at verification time.

In North Georgia just to the south of the frozen line the surface is low to mid 30s but there's a nasty 850 warm nose causing rain to fall. Same in northern Alabama. Looks like 850s are several degrees above surface temps in those areas. Further east in the upstate and all of North Carolina the 850s are pretty chilly.

 

[Forevertothee]

GSP discussion

Not impressed at all....

.LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 335 AM EST Monday: While model guidance overall agrees on the
dry weather pattern for the weekend as sfc high pressure builds in,
disagreement continues for Thursday and Thursday night. Models have
already flip flopped a handful of times for this time frame, and it
seems to continue. With nearly zonal flow aloft and sfc high
pressure expanding across much of the northern CONUS, latest 00Z
ECMWF highlights plenty of moisture spread across the Gulf states
and Southeast, as a system moves near the area and eventually
offshore the Carolina coast. As colder air infiltrates into the
area, uncertainty unfolds in regard to precip type with this system
- rain, rain/snow, snow. Meanwhile, the GFS is somewhat similar,
though shows a much drier and slightly warmer trend for the FA.
Thus, given the discrepancy, have collaborated with neighbors, and
kept with light precipitation tapering off throughout the day on
Thursday. Mainly as all rain across the area, with rain/snow mix
becoming light snow showers across the NC mountains Thursday into
Thursday evening. For now, have kept QPF near zero.

With colder air expected for the end of the week, expect a warming
trend for the weekend, with normal to just above normal temperatures
on Saturday and Sunday.


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[NCCWOP9077]

Large increase in members for measurable snow at RDU on the 00z EPS, roughly 31/50

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