Absolute Vorticity

About half a dozen out of 20 18Z GEFS members are pretty good hits for snow next week. My early prelim thoughts based on most guidance is rain Wed then mix / snow for some time Wed night thru Thurs night.

Several overnight models continue the “ice ice baby” theme for next week. Something to watch!

GFS ZR accumulation

Pretty wicked baroclinic zone setting up next week so there is plenty of potential for heavy precipitation. Rain, snow, or ice…or more than likely a combination of all of the above is on the table. This is going to be a fun one to watch. A simple surface map with projected temperatures tells a lot. Check out that extreme temperature difference over a rather small distance! Something is brewing for sure.

The Euro is colder than the GFS and develops a stronger surface low tracking to our south. Rain to heavy freezing rain and snow per the overnight run. Big time ice for Cincinnati, along with some snow. Heaviest snows fall just to our north. I would very much appreciate avoiding the ice storm zone as Les and I discussed yesterday or the day before

The SE trends to a more wintry outcome as Trev noted have continued overnight. Especially EU/EPS. Lexington to Indy corridor is the transition zone atm, and won't be able to narrow that down any time soon.

Bgoney wrote: ↑Sat Jan 29, 2022 7:05 am The SE trends to a more wintry outcome as Trev noted have continued overnight. Especially EU/EPS. Lexington to Indy corridor is the transition zone atm, and won't be able to narrow that down any time soon.

Pretty much. For forecast and public awareness purposes, rain transitioning to an ice/snow mix (with an emphasis on uncertainty) is about all we can say at this point. Having said that, in my opinion, this setup has the most potential we have seen so far this season.

Euro text data looks devastating for CVG in terms of a crippling ice storm. Glad this system is still around Day 5. 0.75 to 1" of the QPF we get is ice. Rain, a ton of ice then a few inches of snow on top is what the Euro has for Cincinnati. We def want this look to change and I'm sure it will. I've had enough of ice and I'd rather have all snow or all rain to be honest. My hood and the trees don't get along very well. See Nov 2018. CMC also looks icy and a lot of the GEFS members do too. This system looks like it is going to be our next forecast focus. Rain Tues night and Wed with the action changing to ice then snow probably sometime on Thurs is a rough guess. As mentioned, we're going to need several more days to pinpoint this one but if the Euro is correct right now, this is not good at all. Power outages with a bunch of cold air coming in behind this system is No Bueno. Let's hope for all snow or all rain. Seriously.

Good Morning and downright cold this morning. Looks like a busy period ahead. ICE is something I never want and give me all rain before the ice. This system looks to be loaded and how does it develop and work its way northeast. Will we have one big system or several waves as the cold works its way southward. A big concern would be heavy rain and snow melt could also cause some flooding though the cold returning may put a hamper on that as well.

The ice threat and quite frankly the wintry threat as a whole would be majorly reduced if this storm comes out in one big piece. We do need one low to come out to start lowering the heights then have the front stall over the Apps for the second low to work along. Yeah, we could see ice from that scenario but we need that scenario for us snow lovers too.

Overnight AFD from the boys. You would expect the uncertain tone this far out.

As the large-scale pattern continues to amplify going into the
middle of the week, a more significant period of active weather is
expected to develop across the eastern half of the CONUS. At this
point, there is general agreement in the large-scale features from
GFS/ECMWF/CMC runs. A deepening trough upstream of the region will
gradually move east, providing broad support for lift in the right
entrance region of an upper jet, as moisture streams into the region
from the south. At the surface, a sharp frontal zone is expected to
develop, between high pressure off the southeast coast and another
high moving south from the Canadian Prairie provinces. The end
result will be a lengthy period of precipitation that will
overspread a large swath of the region, with a surface front
somewhere in the vicinity underneath the upper support. Although
there are some timing differences amongst the models, for the ILN
CWA, right now this appears most likely to occur during the Tuesday
night through Thursday time frame.

At this point in the forecast cycle -- for a system likely to impact
the area next out on Day 4 through Day 6 -- getting into too many
specifics would be difficult. There is high confidence in a lengthy
period of precipitation for the region. There is low confidence in
precipitation type or any particular impacts. What should be noted
is that this overall setup, from a pattern recognition standpoint
(and supported by CIPS Analog guidance) is one that can support a
range of precipitation types. When considering the rather large
potential error in model placement of the surface front, it is
unclear specifically where any of these different precipitation
types may occur. While there is no guarantee the worst of the
weather will occur in the ILN CWA, there does appear to be the
potential for accumulating wintry precipitation somewhere in the
region, and possibly to a significant degree.

6z EU ensembles continue with the Icing trends

I'm late to this party. I have seen mention of this possible icing event on fb last night. I sure hope it doesn't pan out. Guess I better spend the day watching the models.

The energy should be coming on shore the Pacific NW in the next 36 hours. Models by Monday should start to really hone in on this thing. I would continue to expect some good swings this weekend though.

EDIT: I should say low #1 Low #2 the second low in the STJ will be coming into California in about 60-66 hours. Looking like it is coming into Southern Cali on the 12Z GFS run which is a bit south of 6Z.

So far with the gfs the arctic front is further south than earlier runs of the gfs

Yes you can see the front digging further southwest which is exactly what we need and this usually leads to at least a 2 wave system.

GFS came way NW, much stronger with the secondary low and a stronger trough overall. Mainly a rain maker and we avoid the bad icing on this run.

The major item we are seeing is this will most likely be a two wave process. How far apart they are will determine how much cold air gets in here for the second wave.Many more runs to go and again lets get the northeast system out of here plus with that system it is adding more cold to eastern Canada.

Overall the latest run of the gfs is much better if you want winter weather. Sure it may not show it on the maps but minor things point to a more winter like event for us on Thursday into Friday.

GFS remains the farthest NW of the globals. Has the Arctic high still in Canada early on, whereas the EU has the center of high hundreds of miles south on the Dakota's border

The windshield washer rule is in effect here. The GFS swung to the left, or further NW with this run. It will likely swing back the other way with the next run. I'm more interested in what the Euro and CMC say about this than I am the GFS. It seems those models, especially the CMC, have done better this month.

dce wrote: ↑Sat Jan 29, 2022 11:22 am The windshield washer rule is in effect here. The GFS swung to the left, or further NW with this run. It will likely swing back the other way with the next run. I'm more interested in what the Euro and CMC say about this than I am the GFS. It seems those models, especially the CMC, have done better this month.

I agree and the models are trying to figure out which wave will deepen the most. Many questions to be answered to say the least.

Not a fan at all what the cmc is throwing out but it makes more sense than the gfs basic maps though look between the lines of the gfs and the outcome is more towards the cmc than itself

What is wild about how these models get in new data and how it works out new details. Great example is the AO had been showing positive for the period Feb 2-4 for days and days and then boom out of nowhere a strong negative for those days. I believe the current northeast storm is helping in turning the AO negative and this should help in slowing down the systems next week.

As others have noted, the 12z GFS is the furthest NNW with the surface low track. A blessing for us actually as it keeps the ice to the north. Crippling ice storm for C IN and NW OH!