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Wintry December 28-29th Possible Winter Storm

Would not be surprised if this is the globals tendency kicking in. Losing systems in the day 3 to day 5 timeframe, only to reel them back in, is very common.
 
6z GEFS looks much better than 0z to me. Someone else can give us the individual member panels and the total accumulations later.
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Don't forget the rgem it looks pretty good on Wednesday, seen the losing storm before on globals pretty discouraging to see them all do it but need the NS to show more depression today
 
Yep, I think the trends are clear here that this one is a dud. It was never going to be a huge precipitation maker but has been taken over by the northern stream and been squashed like a bug. Unfortunately with the extreme cold press coming down like shown on the EURO, we may lose all precipitation until it warms up. Always a chance it could change back but odds are getting longer
 
Here’s the latest AFD from FFC:
LONG TERM /Tuesday Night through Sunday/...
A complex extended forecast period is in store for the local area.
As we begin on Tuesday night...Deep mid and upper level troughing
will be in place across the majority of the CONUS as Hudson Bay
vortex remains relentless. Such a pattern typically indicates
greater potential for cold air intrusions across the Southeast...and
this looks certainly likely as sfc pattern shows shows a strong
1040+mb arctic high already diving into the northern Plains.

With the above pattern in mind...as we look closer to home there is
indication of decent sfc convergence by Tuesday night across the
TX/LA coast as a vort ribbon helps enhance lift along the leading
edge of the aforementioned arctic airmass. As the arctic sfc high
continues to build south...moisture is expected to become elongated
across the Southeast. Deepest moisture looks confined to central
Georgia ahead of the front throughout most of the day Wednesday.
Will have to keep a close eye on exact timing vs how far north
precip shield moves in given Wednesday morning temps as well as temp
trends during the day.

The real challenge begins Wednesday night into Thursday. It first
seemed as though model guidance discrepancies were decreasing...and
then the 00z Euro arrived...completely dry. This throws a wrench in
what was some increasing confidence in a winter weather
scenario...but will not completely discount potential quite yet.
Early Thursday the parent arctic high will have migrated into the
Great Lakes region and is expected to continue east. This would set
up a strong...classical CAD event on the lee side of the
Appalachians into Georgia. In addition...moisture advection above
the sfc in the form of isentropic upglide/WAA is expected to aid in
the development of a warm layer of air above a shallow layer of cold
air at the sfc. Assuming the event unfolds...current sounding data
would suggest frozen precip /snow and maybe sleet/ potential
increasing Thursday morning into the afternoon across the northeast
mountains with the remainder of areas in the wedge seeing freezing
rain/sleet potential: areas deeper in the wedge outside of the NE
mtns will likely see more sleet and areas near the leading edge of
the wedge boundary will see more freezing rain. WAA will continue to
increase through the afternoon and evening which will eventually
promote a transition to more freezing rain and perhaps sleet across
the entire wedged area.

Main questions with this event still include: 1.Moisture
availability likely supplied by Baja Pacific trough unless
persistent polar trough cuts off feed 2.Timing and strength of
WAA along with progression thru the day/night 3.How cold sfc temps
and dewpoints get within the wedge

Many times model solutions erode CAD events too soon so beginning
Friday will side more with the Euro. In addition...Operational Euro
agrees better with ensemble data than GFS. This would argue for a
rather strong arctic front to push thru Saturday. Although this
would erode the CAD...very cold air would move in behind the
boundary...potentially allowing for some of the coldest temps seen
in a while. Meanwhile...the GFS brings a bullish slug of moisture
thru the area by Sunday...which would cause concern for rain and
snow across portions of the area. For now...blended model guidance
for the POP forecast which indicates slight chance rain and snow for
north Georgia. Regardless of which model verifies...winter does
not plan to leave anytime soon.
 
It's not impossible we see some trend back toward moisture. Shawn was gfs colder this run?
 
FV3 model (GFS replacement) has more precip with 0Z run than the 0Z GFS fwiw right now of course. It had some dryer runs yesterday 0Z Dec 24 and 6Z. I think 12Z had issues and it didn't load past 9 hours. 18Z was back being wetter than like this past 0Z. It'll be interesting to see how this model does going forward.
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Here is 24 hour total precip from 18z last night FV3 vs GFS. Again fwiw
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It's pretty obvious why the models have trended towards suppression w/ this storm, notice the trough off New England and south of Atlantic Canada, even out to 60 hours on this Euro run, is deeper. The deeper this trough gets the more confluence we see off the east coast & ultimately the more our wave gets sheared apart, & thus the more suppressed it becomes
ecmwf_z500_dt_noram_11.png


Last 3 0z Euro runs also showcase this trend, notice the trough over New England sags south w/ each successive run as our storm became more suppressed & sheared. This trend has been ongoing for several days in the NWP models across most suites...
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It's actually funny that the GFS is the most progressive model on the planet and yet it still has a decent amount of moisture. It's the warmest solution too. Lol
 
deltadog03 said:
It's actually funny that the GFS is the most progressive model on the planet and yet it still has a decent amount of moisture. It's the warmest solution too. Lol
Click to expand...

What’s funny is that a few days ago it kept showing nothing while the other models were all in...Now it’s the opposite...


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deltadog03 said:
It's actually funny that the GFS is the most progressive model on the planet and yet it still has a decent amount of moisture. It's the warmest solution too. Lol
Click to expand...

The reason the GFS is further NW of the Euro has to do w/ its handling of a shortwave trough currently over Manitoba, Saskatchewan, and northern Alberta. This system will determine how much suppression we observe w/ our storm on the 28-29th, the more it digs around the base of the low pressure gyre over the Hudson Bay and the slower it moves (as shown by the Euro) the more suppression we get and vis versa. The GFS is faster/more progressive w/ the shortwave in the northern stream and already has it off New England by day 3, whereas the Euro keeps it centered over the eastern seaboard, which imparts more confluence & shearing on our s/w that ultimately rips it to shreds.

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Blue_Ridge_Escarpment said:
My question is, how in the world has the GEFS stayed so high with qpf. Heck look at the 6Z run, one of the better runs I’ve seen.
Click to expand...
The weird thing about the run is that the precip did go down a bit from 0z, but the snow map increased. Something seems fishy. I was hoping someone would post the ones from Weatherbell.
 
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