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Wintry December 28-29th Possible Winter Storm

1300m said:
GFS showed similar improvements at H5 as the NAM. CMC looked anemic at H5 and very dry. 12z German ICON remains consistent.

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Verbatim that's a major ice storm for areas like Fayetteville, & Columbia, SC
 
Combined precipitation for the 27th & 28-29th events from the CMC... Lol I swear this happens every time, and now it's likely occurring with our first wave inside 24-36 hours.
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If these models come even close to verifying, Eric will reach legendary status in the weather world for bringing them up first. Lol
 
1300m said:
Not to diminish Webber's contributions, but many meteorologists I know, including myself, have been looking at the German model at least since January of this past year. It was the most amplified with that storm (with higher QPF and more mid-level WAA) and ended up verifying.
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My bad!! You all will be legends!! Lol
 
1300m said:
Not to diminish Webber's contributions, but many meteorologists I know, including myself, have been looking at the German model at least since January of this past year. It was the most amplified with that storm (with higher QPF and more mid-level WAA) and ended up verifying.
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Sorry about that bud, I hope it verifies cause i'll be the first one to come on here and say you guys said it first.
 
1300m said:
Not to diminish Webber's contributions, but many meteorologists I know, including myself, have been looking at the German model at least since January of this past year. It was the most amplified with that storm (with higher QPF and more mid-level WAA) and ended up verifying.
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Agreed, you were also all over this from the get go. We also know that NWP can't resolve broad, gentle lift & WAA over top a shallow low-level cold air dome, and corrections of 100-150 miles northwestward (even if the synoptic pattern doesn't really change a lot) are commonplace w/ overrunning even inside 36 hours...
 
Webberweather53 said:
Agreed, you were also all over this from the get go. We also know that NWP can't resolve broad, gentle lift & WAA over top a shallow low-level cold air dome, and corrections of 100-150 miles northwestward (even if the synoptic pattern doesn't really change a lot) are commonplace w/ overrunning even inside 36 hours...
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Hopefully CAE gets into some action. I'll take anything afforded.
 
Webberweather53 said:
Agreed, you were also all over this from the get go. We also know that NWP can't resolve broad, gentle lift & WAA over top a shallow low-level cold air dome, and corrections of 100-150 miles northwestward (even if the synoptic pattern doesn't really change a lot) are commonplace w/ overrunning even inside 36 hours...
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If the infamous NW trend is commonplace why don't models factor it in?
 
GaWx said:
IF this (near 0.50" ZR) were to be close to verifying, I want to check one other event to make sure but I do believe this would be the worst widespread ZR for upper coastal counties of GA to far S SC since Jan of 1922. It almost certainly would be worst for right in the city of SAV since then and by what I think would be some margin. So, a truly historic (96 years) hit is a real possibility there. It is crucial that ZR amounts don't rise above here because that's when the damage and outages would rapidly increase. The JMA and ICON qpf's would cause massive damage. Hopefully they're both overdoing their 1.25" (which would be near the severe hit of 1922) as often is the case with the JMA. As it is at this near 1/2" level, it would already cause quite a number of problems for sure, including many outages and slippery driving/walking in certain areas, especially if it gets down to 30. We've got numerous very large oaks in and near the city that would be a big concern with just the 0.50" of ZR.

The comparison to the surface wx maps of the massive Jan 1922 ZR is eerily similar.

Keeping in mind the Irma hit, there have been other instances of a big tropical hit in the area followed by a sig wintry hit somewhere within the CHS-SAV corridor the following winter: 1894/1895, 1898/1899, 1989, 1979/1980 come to mind.
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Let's hope that doesn't happen, Larry, but if it does, to mitigate it, make sure the wind doesn't blow, lol. Use you new Xmas magic abacus if you have to, but stop the wind!!! A half inch is bad enough, a half inch in wind is like an inch with mostly still. Things will break badly, and those trees have been waiting since 22 to get thinned out, and that ain't good! Best of luck!!
 
1300m said:
Exactly. With a steep isentropic surface from a very strong CAD dome we just need a little nudge to get overrunning going. It's one reason I think these super high resolution models may be on to something, because they may be picking up on the magnitude of the overrunning where guidance like the GFS and CMC don't stand a chance until the precipitation is already developing.
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Are these model available for the public anywhere?
 
Last 3 GEFS runs have been trending drier though the SE coast is still hanging onto to ~0.25" qpf.

Edit: my numbers are for only the 12/28-9 (2nd) wave.
 
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1300m said:
GFS showed similar improvements at H5 as the NAM. CMC looked anemic at H5 and very dry. 12z German ICON remains consistent.

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Webberweather53 said:
The combined precipitation totals of both the Wed and Thu-Fri event have shifted NW vs the 6z run... Let the NW trend begin.
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1300m said:
It's also representing the CAD correctly. Like I've been saying is possible for days, it has it snowing in the teens at RDU (around 17F).
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1300m said:
Not to diminish Webber's contributions, but many meteorologists I know, including myself, have been looking at the German model at least since January of this past year. It was the most amplified with that storm (with higher QPF and more mid-level WAA) and ended up verifying.
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Man, the German model looks sweet. Hope the other models like GFS continue with the NW trend, but if the German is right, then who cares what the others show. Just wonder why we can't have an American model with better resolution like the German. Maybe the GFS replacement one will be better.
 
Brick Tamland said:
Man, the German model looks sweet. Hope the other models like GFS continue with the NW trend, but if the German is right, then who cares what the others show. Just wonder why we can't have an American model with better resolution like the German. Maybe the GFS replacement one will be better.
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The GFS's replacement model (FV3) is suppressed atm, but not as much as the GFS. It seems NCEP has made some adjustments to the FV3 that have partially corrected the GFS's southeasterly bias esp in the short-medium range.

6z GFS
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6z FV3
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http://www.emc.ncep.noaa.gov/mmb/cguastini/fv3/fv3images.html
 
But this one reminds me of the 2014 event where it started pouring down snow and the radar blew up just from a little bit of overrunning.


Sent from my iPhone using Tapatalk
 
1300m said:
Exactly. With a steep isentropic surface from a very strong CAD dome we just need a little nudge to get overrunning going. It's one reason I think these super high resolution models may be on to something, because they may be picking up on the magnitude of the overrunning where guidance like the GFS and CMC don't stand a chance until the precipitation is already developing.
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The one thing that does worry me is that we're probably going to be hard pressed to get southwesterly flow over this low-level CAD dome & thus our mid-level winds will be more oblique relative to the nose of the CAD, which ultimately changes the response w/ this overrunning event... However, even if we get winds that are just a tick south of due west, we'll immediately start tapping into moisture left behind by the most recent CCKW over the tropical eastern Pacific instead of mostly out of the Gulf of Mexico, as we're often more accustomed to seeing. There's certainly a very large contribution of low-mid level moisture from both the tropical eastern Pacific and Gulf in this case...
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metwannabe said:
It is an improvement, precip map only goes out to 72 that is much improved from the 0z run I believe.

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No net change vs the 0z run, but yes for a while there around 60-66 hours there was some improvement. I guess the big takeaway is the suppression trend is coming to a halt in most NWP (besides the low resolution GEFS)
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Webberweather53 said:
No net change vs the 0z run, but yes for a while there around 60-66 hours there was some improvement. I guess the big takeaway is the suppression trend is coming to a halt in most NWP (besides the low resolution GEFS)
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I forget Ryan's site has Ukmet also... lol thanks
 
Well figured NAM would be the wettest. But as y'all have noted, models are definitely a bit wetter for the 1st system
 
1300m said:
Euro at H5 also looked a little better. We need just a little bit more of this trend. As Webber posted earlier, if we can just get winds aloft to tap that moist air to our south it will set off significant overrunning and precipitation will blossom nicely. As bad as it looks with precipitation, it could go from zero to something much bigger with only another tick or two in the same direction at H5.

00Z:
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12z:
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For whatever reason, I can't open these photos. So what is the most notable difference you saw between the two?
 
1300m said:
The disturbance was a little stronger, a little more separate from the northern stream vortex and it was able to veer the flow nearly westerly compared to 00z. You could even see in the precipitation shield that it was closer to the coast (still offshore) than 00z. There was also a little more energy in the vorticity streamers feeding into the shortwave from the south.
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Any good trend works even if it's small for now.
 
1300m said:
Euro at H5 also looked a little better. We need just a little bit more of this trend. As Webber posted earlier, if we can just get winds aloft to tap that moist air to our south it will set off significant overrunning and precipitation will blossom nicely. As bad as it looks with precipitation, it could go from zero to something much bigger with only another tick or two in the same direction at H5.

00Z:
ecmwf_z500_vort_conus2_12.png


12z:
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Yeah, A few years ago I researched the H5 maps for many SE sig qpf winter events that weren't clippers. The one thing that the vast majority of them had: WSW (at least a little S of W) or SW winds at H5 over one's location. VERY few had straight W winds and almost none had WNW winds at the locations of the sig winter event. Again, I'm not talking about light precip events or clippers.
 
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