Absolute Vorticity

I’d be happy with the nam!

I think about 5” of the snow total for Cincy is sleet, so still a 5.7” snowfall. If the dry slot fills in, it would be way more.

I tried my best to watch this video from Bam weather and okay no longer need to watch. Moving forward and I still have no reason to believe this system is going to have its energy jump to the east coast. Imo it makes no sense and I have mentioned for many many days. If I am wrong then I take my lumps and move on but my biggest concern has always been the middle part of the storm and do we see a period of sleet or even a period of frz/rain. Yes there is a northeast wind that I thought would hurt the folks to the northeast and when you get a system that gets itself together and mainly moves west to east precip types and precip rates plus even a northeast wind that eats at the precip can go on for many hours and yes you will get a few bumps when the storm gets stronger at times and weaker at times but this is not one where we the storm explodes. Yes a good amount of moisture from the western GOM and yes do the storms rob us of this and I don't believe so but again that part is a nowcast when they develop.

Great read from Louisville talking about everything brought up here and then some



For the past week or so, the global models have been in remarkable
agreement with a major winter storm poised to affect the region.
We`ve seen the usual track spread and run to run continuity issues,
but the spread and continuity issues continue to decrease as we draw
closer to the event. The 03/12Z data suite exhibited a notable
shift to the south due to models recognizing the strength of the
Greenland blocking downstream which will likely limit this system`s
ability to gain latitude as it comes through the Plains and into the
Ohio Valley. The pre-existing cold airmass in place is not all that
deep and is not expected to become increasingly deep through the
weekend.

Model guidance has continued to tighten up a bit and a more
southerly storm track has emerged in the data. Given the downstream
blocking, it doesn`t appear that this system will gain latitude and
some further shifts may occur in the next 24-36 hours. Overall, the
global model solutions are in general harmony here with the
Euro/Canadian leading the way and the GFS coming into line with this
cycle. The Canadian remains the coldest of the models, but recent
verification shows this cold is likely too bullish. The mesoscale
models have similar agreement though they do not go all the way out
through the event.

There remains a bit of uncertainty regarding QPF amounts, placement,
precipitation type, and precipitation duration during the event.
Timing of precipitation onset remains quite good. The most
interesting trend that we`ve seen is that the dry advective NE
surface flow coming out of western PA/Ohio has been trending
stronger in the datasets. We believe that this drier/cooler airmass
will likely be stronger in nature and help offset the latent heat
release of convection within the warm advective scheme. This
results in slightly cooler profiles which increases snow production
across our northern areas and shifts the more significant icing
further south into KY and perhaps all the way down to the KY/TN
border. Not only will that NE flow help result in efficient wet-
bulbing, it will lead to a rather impressive temperature gradient
across the region. This strong thermal gradient will result in a
stronger area of low-level frontogenetical forcing. Additionally,
the global models show that we`ll be in the right entrance region of
the upper level jet extending from northern IL eastward into the
northern Mid-Atlantic. Based on this dynamical setup, banded heavy
precipitation is likely across southern IN and portions of north-
central and east-central KY.

In general, the forecast is closely modeled to the Euro/Canadian/WPC
blend. This results in higher snow/ice amounts than in the
traditional NBM. While an initial prediction of snow/ice amounts
will be forthcoming with this forecast package, additional revisions
are likely all the way up to the start of the event.

======================================
Sensible Weather for the Event
======================================

In terms of sensible weather, we expect snow to break out early
Sunday morning, probably just before sunrise across western KY and
then rapidly spreading eastward. A gradual change to a wintry mix
of snow/sleet/freezing rain will likely occur over southern KY
during the mid-late morning hours as the low-level warm advection
scheme grows stronger. Further north/east, the low-level dry air
coming out of OH will likely offset the latent heat release and
result in a continued wet-bulbing of precipitation resulting in
generally snow across southern IN with a gradual mix of
sleet/freezing rain working in from the Parkways northward by late
afternoon/evening. Based on this scenario, some decent snowfall and
sleet accumulations are likely across southern IN, portions of north-
central and east-central KY. As stronger forcing arrives in the
afternoon, there is a bit of elevated instability that develops. So
it stands to reason that thundersnow, thundersleet, and even thunder
freezing rain may be observed across the region. So locally heavier
precipitation may occur in spots.

By mid-late evening, snow looks to be in progress in areas along and
north of I-64, with a band of sleet/freezing rain covering much of
central/southern KY. Some plain rain and even some thunderstorms
may be possible down along the KY/TN border. Here, we have quite a
bit of uncertainty in regards to precipitation type. We`ll likely
be just watching observations as the battle between the low-level
dry/cold air rages against the warm nose aloft. As the system
translates eastward we may get into a dry slot with some loss of
moisture in the DGZ. A period of light freezing rain/drizzle may
encompass much of the region. However, colder air will pull into
the region late Sunday night resulting in a rapid changeover to all
snow from NW to SE by Monday morning. Precipitation will likely
continue into Monday late morning before diminishing in the
afternoon hours. Gusty winds late Sunday night and Monday may pose
issues in areas that receive significant ice, resulting in scattered
to numerous power outages.

Regarding accumulations, there is still quite a bit of uncertainty
as outlined above with QPF placement, transitions, and durations of
particular P-types. However, there appears to be enough confidence
to go with some broad accumulation predictions. I want to stress
that these are a work in progress and may change upward/downward in
future forecast updates. For now, we`re going to go with
snowfall/sleet accumulations of 6-10+" across our far northern CWA,
roughly from Jasper, IN to near Madison, IN. South of there, along
the I-64 corridor south to the WK/BG Parkways a band of 3-6+" of
snow/sleet. Between the WK/BG Parkways down to roughly the
Cumberland Parkway, a band of 1-3" of snow/sleet are expected, with
a coating to 1, perhaps 2" south of the Cumberland Parkways.

With regards to icing, a significant and highly impactful ice storm
is possible across much of central KY. A corridor of heavy icing
appears likely roughly along the WK Parkway from Hartford northeast
through E-town up toward the southern side of Lexington proper. Here
ice accumulations of a quarter to three quarters of an inch are
possible. It isn`t out of the question that some locations could
see up to one inch of ice. Lesser icing is forecast to the north
and south of this corridor. Again, we want to stress that these
amounts are the first cut of the forecast and changes to the
atmospheric temperature structure could increase/decrease these
amounts as well as shift them north or south.

Given the continued uncertainty here, the Winter Storm Watch will
remain in effect for this forecast cycle. Given the southward trend
in the datasets today, we extended the watch to the south to cover
the rest of our CWA. As our forecast confidence increases, upgrades
to warnings and advisories are likely on the next forecast issuance.

======================================

Thanks Bgoney for posting the Louisville NWS. Almost to a tee what we have been talking about and that makes me feel somewhat more confident of how we see this playing out

tpweather wrote: ↑Fri Jan 03, 2025 3:59 pm Thanks Bgoney for posting the Louisville NWS. Almost to a tee what we have been talking about and that makes me feel somewhat more confident of how we see this playing out

Probably not what our I70 crew would like to hear

Grandpa Wooly went out early this afternoon with a Grand Wooly #1 to do a little squirrel hunting. The signs are starting to come into the picture for the event Sunday. The squirrels were moving faster than we've ever seen em. They, along with the little tweety birds, were on the move gathering and feeding up. Seems to happen when a low is building. The flurries were flying and the sky was slate gray. Grandma Wooly has been busy tidying up the woodpile and getting the wood stove ready! Grandpa Wooly and #1 did mess up Grandma's kitchen . . . if you know what I mean. Fried up nicely.

The ol gadgets though have been quite finicky today. Not getting a good read. Need a bit more time. I think I'll travel across the yard and talk with Cousin Jed in his woodpile. He has some different gadgets and see what he is getting.

18z ICON just ran again. Looks similar to the NAM, but keeps the frozen precip South of Cincy, so this would probably be mostly snow.

ICON has been fairly consistent until now. This morning it had Dayton at 16 inches, now 2.

Bgoney wrote: ↑Fri Jan 03, 2025 4:04 pm

tpweather wrote: ↑Fri Jan 03, 2025 3:59 pm Thanks Bgoney for posting the Louisville NWS. Almost to a tee what we have been talking about and that makes me feel somewhat more confident of how we see this playing out

Probably not what our I70 crew would like to hear

Kind of funny how they are ignoring the American models. They mentioned a further shift south is possible

mainevilleweather wrote: ↑Fri Jan 03, 2025 4:15 pm ICON has been fairly consistent until now. This morning it had Dayton at 16 inches, now 2.

If GFS goes South, writing may be on the wall for the I-70 crew.

Lucky for me I can never blame the models. I look at them as a tool but at the end of the day I need to forecast what I see. If I am wrong hopefully smart enough to learn something but with this old man you never know.

CINCINNATI01 wrote: ↑Fri Jan 03, 2025 3:26 pm How long has this forum been around? I remember being on this when I was a teenager and now I'm 30

August of 2008. We are coming up on 17 years. Wow!

18Z NAM for CVG - Tons of QPF in typical NAM fashion. If the thermals would be a tad colder, it would be double digits easy! But we still mix as you can see below.

tron777 wrote: ↑Fri Jan 03, 2025 4:26 pm

CINCINNATI01 wrote: ↑Fri Jan 03, 2025 3:26 pm How long has this forum been around? I remember being on this when I was a teenager and now I'm 30

August of 2008. We are coming up on 17 years. Wow!

Yea that sounds right I remember the weather forum on local 12 and when that went down I came across this. Crazy to think I was into weather at the age of 15 lol

tron777 wrote: ↑Fri Jan 03, 2025 4:29 pm 18Z NAM for CVG - Tons of QPF in typical NAM fashion. If the thermals would be a tad colder, it would be double digits easy! But we still mix as you can see below.

Code: Select all

SUN  1P 05-JAN  -4.3    -3.6    1024      86      95    0.06     559     540    
SUN  7P 05-JAN  -4.3    -1.2    1018      92      98    0.41     558     544    
MON  1A 06-JAN  -4.0    -0.5    1012      91      97    0.97     555     545    
MON  7A 06-JAN  -4.6     0.3    1008      88      55    0.29     545     539    
MON  1P 06-JAN  -3.7    -5.4    1005      89      97    0.05     537     533    
MON  7P 06-JAN  -3.8   -10.2    1013      85      34    0.16     538     528    

lol you called it

tron777 wrote: ↑Fri Jan 03, 2025 4:26 pm

CINCINNATI01 wrote: ↑Fri Jan 03, 2025 3:26 pm How long has this forum been around? I remember being on this when I was a teenager and now I'm 30

August of 2008. We are coming up on 17 years. Wow!

Oh my gosh! I think I remember talking about a ice storm and how we knew it was ice because our puppy (who we got in October 2008) was walking on top of it. That puppy left us this summer at almost 16 years old. Crazy .

tpweather wrote: ↑Fri Jan 03, 2025 4:23 pm Lucky for me I can never blame the models. I look at them as a tool but at the end of the day I need to forecast what I see. If I am wrong hopefully smart enough to learn something but with this old man you never know.

Hey Tim, I thought I learned something a few years ago when we saw quite a bit of wintry weather, but I forgot a lot of the lessons from then! Lol

Anyway, we've come a long way with forecasting since we were kids when winter storms were tracked with satellites and local observations across the country (there were no computer models). And we had Tony Sands and a couple other good Mets back then. I remember a lot of bust (in either direction) with winter storm predictions as a kid based on satellite imaginary.

winterstormjoe wrote: ↑Fri Jan 03, 2025 4:39 pm

tpweather wrote: ↑Fri Jan 03, 2025 4:23 pm Lucky for me I can never blame the models. I look at them as a tool but at the end of the day I need to forecast what I see. If I am wrong hopefully smart enough to learn something but with this old man you never know.

Hey Tim, I thought I learned something a few years ago when we saw quite a bit of wintry weather, but I forgot a lot of the lessons from then! Lol

Anyway, we've come a long way with forecasting since we were kids when winter storms were tracked with satellites and local observations across the country (there were no computer models). And we had Tony Sands and a couple other good Mets back then. I remember a lot of bust (in either direction) with winter storm predictions as a kid based on satellite imaginary.

Joe you are correct but I thought it was a great learning area for us as kids. Models are a tool but folks sometimes look at them like they do analytics in baseball. Yes they can help you make a decision but there is more to baseball and weather than analytics. I made up my own weather maps and with the Sunday paper I would get the weather from around the world like Moscow or at the time Peking. That is probably one reason I still search the globe and see what is happening.

18z RDPS a little more north fwiw

Phr0z3n wrote: ↑Fri Jan 03, 2025 4:48 pm 18z RDPS a little more north fwiw
IMG_1240.png

It held the upper level low structure longer with the transfer happening in WV

18z came slightly north with precip shield also.

18z GFS looks decent so far. A little further South with the low and then it jumps way North. Prolonged period of ice as well.

18z gfs

I still not calling this a true transfer in the sense that it is developing a coastal low. Yes we have transfers over mountains all the time and when a stronger system that happens many times on the southeast coast we say yes it transfer the energy from the low on the west side of the mountains. This imo is just the system moving west to east and sure once it gets to the mountains it will lose some staying power unless we have that coastal low but in this case I believe the system just goes out to sea.