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Pattern December, Make analogs relevant again

Well in looking at GFS for me, looks like a busy" first week "of 2018. With borderline ZR/IP event (off by couple of degrees 192 to 228), followed by mid to upper teens (ground freeze) which would lead to a significant "Impact" event (264-288), then #3 as a heavy snow event (324-348) , but then this is the 18Z GFS...
 
gawxnative said:
Well in looking at GFS for me, looks like a busy" first week "of 2018. With borderline ZR/IP event (off by couple of degrees 192 to 228), followed by mid to upper teens (ground freeze) which would lead to a significant "Impact" event (264-288), then #3 as a heavy snow event (324-348) , but then this is the 18Z GFS...
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About the same for me. No shortage of opportunity. You can add one for me next week.
 
Shawn said:
I'm about 20 min from there. Spent a large portion of my childhood at Skate Station and at a friend's house in the Grove.
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I use to go there as a kid myself. Always preferred there rather than 3 fountains. I'm right across from the elementary school. That's pretty cool man.
 
Webberweather53 said:
Not so amazing if you like getting another sleet fest in or around RDU. ;):p
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Sleet can be fun. I'm sure you know since you like hockey. In Feb 2014, CAE was on the transition zone and we picked up nearly 3 inches of sleet. I remember having my skimboard out there and ive never had more fun in a winter storm than with that storm. It was just like skimming the ocean but better haha.
 
Xtreme Weather said:
Ice storm remains on the table...Going to be interesting CAD setup depending on strength of the HP in the NE this very well could extend over into E AL and N GA esp in the higher terrain seen it numerous times. Outside of this possible event not seeing much hope for wintry precip of any consequence for other areas in this pattern setup...

...Carry on
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Agree on both counts. As far as the ice storm, it is bothersome as even being in Coosa county, I'm still in the cold flow valley that leeches down through Randolph and Clay counties. Yall can have it, I just have cut the large oak limbs off the house and I don't need ice taking more down.
 
Gefs through day 8
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SD said:
Lol mystery 850 bubble
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It's certainly unusual but like we saw in the most recent winter storm it's possible. The precipitation was so intense that we created an in-situ CAD dome as melting hydrometeors amidst modest CAA cooled the low levels while deposition of water vapor into snow crystals and condensational heating warmed the mid levels so it created a weak inversion that led to mixed precipitation and a weak CAD dome despite there was just a primary coastal low. Thus, we can do that even in Miller As, eventually you reach a point where latent heating from deposition and condensation overwhelms the melting you'd see in the low levels as aforementioned and observed in the storm earlier this month. It's an extreme case but it does happen from time to time. On the flip side of this, there's actually a way you can still technically get all snow even with a big inversion and well above freezing warm nose associated with CAD. In the beginning of the February 2003 presidents Day storm the inversion over RDU was so intense despite the 5C ish temps aloft, light snow fell at the surface because as the rain drops fell into the cold low level CAD dome, they froze so quickly that they shattered instead of freezing into solid ice pellets. This shattering of new ice nuclei kickstarted the Bergeron process yet again and we got snow instead of ZR or IP as the sounding at the time suggested
 
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Webberweather53 said:
It's certainly unusual but like we saw in the most recent winter storm, wherein the precipitation was so intense that we created an in-situ CAD dome as melting hydrometeors amidst modest CAA cooled the low levels while deposition of water vapor into snow crystals and condensational heating warmed the mid levels so it created a weak inversion that led to mixed precipitation despite there was just a primary coastal low. Thus, we can do that even in Miller As, eventually you reach a point where latent heating from deposition and condensation overwhelms the melting you'd see in the low levels as aforementioned and observed in the storm earlier this month. It's an extreme case but it does happen from time to time. On the flip side of this, there's actually a way you can still technically get all snow even with a big inversion and well above freezing warm nose associated with CAD. In the beginning of the February 2003 presidents Day storm the inversion over RDU was so intense despite the 5C ish temps aloft, light snow fell at the surface because as the rain drops fell into the cold low level CAD dome, they froze so quickly that they shattered instead of freezing into solid ice pellets. This shattering of new ice nuclei kickstarted the Bergeron process yet again and we got snow instead of ZR or IP as the sounding at the time suggested
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To get shattering of the rain drops as they enter the CAD dome and generate snow at the low levels you want the coldest low level temps in the shallow cad dome to be at least 8-10C (or more) below freezing and the cloud condensation nuclei (CCN) that the water freezes onto needs to have a high freezing temperature when water is contact w/ it. Water in contact with CCN like pollen, dust grains, soot, and salt crystals will freeze at different temperatures. Henceforth, even if you got the temperature profile, moisture, lift, etc exactly right you still could screw up the precipitation type at the surface (esp determining sleet vs freezing rain) because you don't know the distribution of CCN in the cloud that's producing the precipitation. Even with current observational techniques we can't adequately observe CCN, thus it is parameterized in NWP models and most assume models stereotypical marine CCN distributions (which isn't correct for us on the continental landmass). It's just another limitation of NWP modeling for winter storms
 
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This is from Fox 5 Atlanta facebook page:

Snowy start to the New Year ? The Peach Drop might not be the only thing falling to ring in the New Year. Some of the weather models are hinting at snow !
 
Webberweather53 said:
I wouldn't say that at all, Atlanta and points NE should be keeping a close eye on this, because it would take next to nothing verbatim to give the metro area a big ice storm
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Agreed, it doesn't take much of CAD to produce wintry precipitation in Atlanta as long as we have a nice HP parked to the NE bleeding in some cold, stiff NE winds. I'm starting to get January 2005 vibes from this setup. Started off as sleet, changed over to rain/freezing rain, the changed over to all freezing rain (with some light snow changeover periodically). It's the coldest ice storm I have seen to this date with temps staying in the mid to upper 20s most of the event. 24hrs later we were in the mid 40s and ice seemed like a daydream lmao.

Although February 2014 was an overrunning event so it's not the same, I remember most models kept forecasting major ice here (1/2 inch or greater) up to the day of that event and we ended up getting mostly a sleet storm (2 inches) with a light glaze of ice and light snow on the backside. I think the airport got more ice though.
 
FFC is taking notice....

000
FXUS62 KFFC 221946
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
246 PM EST Fri Dec 22 2017

.LONG TERM /Sunday through Friday/...
By Wednesday through the remainder of the week the pattern is a
bit more unsettled but also more uncertain. For several days, run
to run consistency has been a problem so will need to see more
consistency before honing in on a single solution. Will see a
weak shortwave move across the Gulf states in the base of the
large eastern US trof which will draw moisture across most of the
area. Low end pops introduced area wide with higher probs across
the southern half of the area...i.e. south of I20. New 12z ECMWF
is more aggressive with the moisture which spreads further north
meanwhile the GFS is much drier and keeps the deeper moisture
south. An ECM solution could mean a mix of wintry precip across
the northern counties early on Wed with a GFS too dry for precip.
Model blends paint low end pops which we have added and included
a R/S mix given the forecast profiles Wednesday into Wednesday
night. At the same time reinforcing arctic high slides into the
great lakes and begins the process of wedging into NE GA by late
Wed into early Thu setting us up for wedge conditions through
Friday. Will need to watch Thursday into Friday as another wave
moves through the flow with some moisture overrunning the CAD
that could mean some more wintry mix. ECMWF not as bullish on the
moisture arriving over the CAD until after the extended period.
Either way, it makes Day 6 and Day 7 of this forecast a low
confidence forecast. Will need to watch for sure as wedge events
can always be a challenge.

Stellman
http://forecast.weather.gov/product...FC&product=AFD&format=CI&version=1&glossary=1
 
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