December 2023 Weather Discussion

[Trevor]

Yeah all the 00z models came in different than they have for a couple days now which is always fun ugh lol.

Let’s see if they correct back at 12z. No changes to the forecast attm but will keep an eye on it.

[Bgoney]

Ensembles certainly look to be in the weak first wave and a secondary low development to the east camp. Really puts a question mark on QPF amounts, in that they may not be as robust as earlier modeled

[Trevor]

Ensembles certainly look to be in the weak first wave and a secondary low development to the east camp. Really puts a question mark on QPF amounts, in that they may not be as robust as earlier modeled

If that solution plays out, amounts would be lowered for sure. Going to see what 12z does. The models were so consistent for a few days so it’s always nice when they do this

[Bgoney]

Ensembles certainly look to be in the weak first wave and a secondary low development to the east camp. Really puts a question mark on QPF amounts, in that they may not be as robust as earlier modeled

If that solution plays out, amounts would be lowered for sure. Going to see what 12z does. The models were so consistent for a few days so it’s always nice when they do this

Lack of temperature gradient is really limiting the strength of these storms in the mid section of the country. Other reasons for sure but this is a big one imo

[tpweather]

Ensembles certainly look to be in the weak first wave and a secondary low development to the east camp. Really puts a question mark on QPF amounts, in that they may not be as robust as earlier modeled

If that solution plays out, amounts would be lowered for sure. Going to see what 12z does. The models were so consistent for a few days so it’s always nice when they do this

Lack of temperature gradient is really limiting the strength of these storms in the mid section of the country. Other reasons for sure but this is a big one imo

100p/c agree. On the east coast there is enough temp gradient plus warm Atlantic waters aiding stronger systems well east of us. Lack of snow cover in the northern plains is making it easier to warm things up quickly after any cold front plus any cold air we are getting from Canada will moderate for the same reason. Again most on here are still looking at the last 10 days for any changes and again will this be delayed and like most if we do see a pattern change it would probably be one where we return to normal and no big shots of cold. Could that bring any winter weather any yes but nothing great.

[Trevor]

I think it more-so has to due with timing issues between the jet branches. There is still a solid baroclinic zone shown with a temperature difference of +/- 20 degrees. It could be stronger and tighter, sure. But the ingredients are there for a strong storm. Sometimes the timing just doesn’t line up properly.

Not yet sold on the new model output versus what we have seen for a few days now. I’d want to see it for another couple of runs at least before making any major changes to the forecast.

[tron777]

Thoughts from the boys via their overnight AFD.

We continue to monitor the development of the next weather system to
affect the Great Lakes and Ohio Valley for this upcoming weekend.
For Saturday, a long wave trough across the Plains will undergo a
negative tilt as it progresses east across our region into Sunday.
Surface low pressure over the southern Plains is forecast to deepen
as it quickly heads northeast, likely tracking to our west, and into
the western Great Lakes by Saturday night. This process will induce
a low level jet which will transport moisture northeast ahead of an
attendant cold front. WAA showers will increase late Friday night,
followed by categorical PoPs by Saturday night as the front pushes
east through the area. Models are now indicating some surface
instability, so a low chance of thunderstorms are forecast. We will
continue to assess the strength of the low and low level wind fields
to see if a cool season QLCS would be possible with the cold front.
Confidence is still not there yet to mention in the HWO. In any
case, it will be breezy to locally windy Saturday into Saturday
night. After mild lows in the 40s, highs on Saturday will range from
the upper 50s to the lower 60s. CAA will ensue Saturday night with
frontal passage. For Sunday, models are now indicating that a
secondary low may form along the passing cold front just to our
southeast, heading northeast toward New England as it deepens due to
increasing favorable upper level jet energy. Forecast highs in the
40s and 50s will likely be early with CAA likely occurring during
the day. Pcpn will be likely especially east closer to the secondary
low track. By Sunday night, pcpn will taper off to scattered rain
and/or snow showers as temperatures drop into the upper 20s to the
lower 30s by Monday morning.

[tron777]

I think it more-so has to due with timing issues between the jet branches. There is still a solid baroclinic zone shown with a temperature difference of +/- 20 degrees. It could be stronger and tighter, sure. But the ingredients are there for a strong storm. Sometimes the timing just doesn’t line up properly.

Not yet sold on the new model output versus what we have seen for a few days now. I’d want to see it for another couple of runs at least before making any major changes to the forecast.

I agree... it is definitely a timing issue. It usually is. Not sure I am buying the strong low / phased idea anymore since the pattern seems to be progressive. It's been that way for years. We see a nice phased system in the medium to long range end up weakening and being further East when you get into the short term. It has happened time and time again over the years during the cold season. The secondary low idea though does hold some weight. As you said, we have several more model cycles to go before we can get this system nailed down. Either way, the driest time this weekend maybe the first part of Saturday as temps soar into the 60+ degree range ahead of the storm. Then we see rain move in with gusty winds Sat night into Sunday. The front passes on Sunday with more wind and falling temps. TBD on any backside snow Sun night into early Mon morning which will depend on when / where the secondary low pops (assuming we see it).

[Trevor]

I think it more-so has to due with timing issues between the jet branches. There is still a solid baroclinic zone shown with a temperature difference of +/- 20 degrees. It could be stronger and tighter, sure. But the ingredients are there for a strong storm. Sometimes the timing just doesn’t line up properly.

Not yet sold on the new model output versus what we have seen for a few days now. I’d want to see it for another couple of runs at least before making any major changes to the forecast.

I agree... it is definitely a timing issue. It usually is. Not sure I am buying the strong low / phased idea anymore since the pattern seems to be progressive. It's been that way for years. We see a nice phased system in the medium to long range end up weakening and being further East when you get into the short term. It has happened time and time again over the years during the cold season. The secondary low idea though does hold some weight. As you said, we have several more model cycles to go before we can get this system nailed down. Either way, the driest time this weekend maybe the first part of Saturday as temps soar into the 60+ degree range ahead of the storm. Then we see rain move in with gusty winds Sat night into Sunday. The front passes on Sunday with more wind and falling temps. TBD on any backside snow Sun night into early Mon morning which will depend on when / where the secondary low pops (assuming we see it).

Timing is key. We have heard and said that many times over the years. We should get a tat of it

Will know in a couple frames, but I’m wondering if the secondary low will pop closer to us given the location of best energy at 500mb?

[Trevor]

The secondary low indeed does track closer to us. But there is more to it than that.

First low tracks through Wisconsin, second low tracks from the Deep South through SE Ohio, then a third low develops over New England.

Messy setup, but it doesn’t change much to the forecast for us. Strong storms late Sat, flurries and snow showers on Sunday.

This run gives Cincy 1.50” of rain. There is a sharp cutoff in Indiana.

[Trevor]

Little index finger of CAPE late Sat. It isn’t much but we don’t need a whole lot this time of year.

Our risk is definitely a bit lower though with the primary low tracking so far away from us and having less wind energy aloft.

Even gradient winds on Saturday will be of the 25-35mph variety versus 35-45mph.

Again all of that is if the new model runs are the way we go.

If future runs return to a stronger and further south primary low our strong storm chances increase.

I think the 00z runs tonight will be very telling on if this is a trend or we correct back.

[House of Cards]

Here's to hoping for the new model runs panning out. I really hate the nasty wind makers, my house sits at the bottom of a hill, it's a bloody wind tunnel. If the winds get too nasty, it'll play havoc with my icicle lights, and I'm too much of a chicken to get up there to fix them, I have to get my friend/former neighbor to come do that.

[dce]

The Euro also says that we will stay all rain. Looks like a decent snowstorm for Pennsylvania on up into interior New England. Just not enough arctic air around for the Midwest to get much snow from this.

[Bgoney]

Secondary low looks like it is also trending weaker. Folks north/west of 71 might be looking at lesser amounts of qpf

[Trevor]

GFS and Euro precip totals from 12z

[Trevor]

GFS is heavier locally and Euro is lighter with a larger aerial coverage.

[Trevor]

18z NAM is essentially a complete miss...

[fyrfyter]

18z NAM is essentially a complete miss...

It is the NAM after all. Next one will show storms and then a thumping of snow…

[tron777]

Good afternoon all! Well good evening by now I guess. Anyway... 18Z GFS is back to showing a strong primary low in Wisc / Western Mich with a nice secondary low that is moderately strong with a nice track for snow lovers too! However, with no cold air to work with it is a cold rain unfortunately. We need the trough to go negative tilt to have a more dynamic storm system with a stronger / deepening low so you get dynamic cooling in the deformation zone to get the thumping of snow on the backside. At this point, that doesn't look to occur and if it does it would be east of the OV. I like Doug's post from earlier and he's right. Without any cold air to work with, the storm has to make its own cold air basically and we can score from these situations but it's very rare that we do. So right now, my best guess is rain Sat afternoon and evening with falling temps on Sunday with the front passage and I would not be a bit surprised that we get no back end snow whatsoever. If we do manage to see any flakes, it would be of the flurry or snow shower variety and it would not be a big deal anyway.

The other possibility is that the progressive idea is right and we just see a glorified frontal passage and that's a wrap. I cannot rule out that possibility but I think it is less likely. The two low idea (or three if you count New England) IMO is the most likely scenario at this time. As others have stated, this would cut down on the severe threat and heavy rain threat. It'll be windy either way but probably falling short of wind advisory criteria which is good for folks that have Christmas lights / decorations up.

[Bgoney]

For the long term (2 weeks) minor changes in 500mb pattern but nothing to change our outlook. Canada still struggles to get proper arctic air to fill in. Lower 48 for the most part in a NW flow , but more of a PAC NW flow. Coldest anomalies remain on the other side of globe

IMG_0965.gif

[tron777]

As we have talked about before, the EPO is still positive. We need it to be negative and get a nice blocking ridge over Alaska to send the Arctic air south from Siberia to fill Canada up with cold.

[Trevor]

Last three runs of the Euro for reference (oldest to newest)

[Bgoney]

The trend continues.. BGFC has just issued a screw-zone watch for areas N/W of 71 for QPF totals , with a possible expansion to areas S/E of 71 in later updates

[tron777]

The trend continues.. BGFC has just issued a screw-zone watch for areas N/W of 71 for QPF totals , with a possible expansion to areas S/E of 71 in later updates

Agreed. Even the wintry side is about dead for our area as the best chance for that now looks to occur well to our East.

[tron777]

Today and Friday though are nice days to get anything done outside that you need to with sunshine and highs in the 50s. Still looking at 60 on Sat but rain (whatever we do see) looks to move in earlier in the day as models are speeding up the arrival of the cold front. The front should now pass thru Sat night so temps will fall then and remain nearly steady (perhaps rise a few degrees) on Sunday with cool and blustery conditions.