Absolute Vorticity

NAM 18Z

WAVE3 in Louisville being gutsy on trying to pinpoint where the dry shaft will be this early:

18Z NAM is wonderful! 0.31" for CVG. Would love to see that much QPF. 18Z RGEM has 2-3" for most folks with a few 4" spots down towards LOU.

The boys are sounding more positive today:

Interesting setup with the system moving into the area Friday
into Friday night. There are some concerning signals starting to
develop that there will be some Fgen forcing and banding of
snow across portions of the region. Increased snowfall values
quite a bit with this forecast package, however did not go as
high as they could be and did not go with an advisory do to a
few factors. There is definitely the potential that an advisory
or perhaps more in isolated locations will be needed if these
current trends continue.

Confidence factors include the banded set up with very good
forcing that is expected. Also leading to confidence is general
model agreement.

Less confidence factors include time of day with warm ground,
signal for drier air south of the best banding meaning there
will likely be a decent gradient, warmer air across southern
portions of the region, and recent shift in model solutions
towards this higher snowfall solution.

As mentioned, increased values and trended towards higher
snowfall values and will increase messaging with this package
to allow for greater awareness of accumulating snowfall
potential that is expected. Also increased wording moreso in
the HWO.

18Z ICON looks good too. 3-4" from Cincy on north. 2" for NKY then another 3-4" band in our SE.

The drier GFS is the outlier model. All other models have us in that 0.20 to 0.30" range for QPF. We'll see what the 18Z run does shortly.

tron777 wrote: ↑Thu Feb 15, 2024 4:35 pm The drier GFS is the outlier model. All other models have us in that 0.20 to 0.30" range for QPF. We'll see what the 18Z run does shortly.

Les enjoy the evening and hope everyone gets a decent amount. Made my forecast changes earlier and sticking with them. I will try and catch up later on Friday but it may be Saturday before I post once again. Hopefully by Saturday I have a little time in the morning to post my thoughts on the longer term.

tpweather wrote: ↑Thu Feb 15, 2024 4:38 pm

tron777 wrote: ↑Thu Feb 15, 2024 4:35 pm The drier GFS is the outlier model. All other models have us in that 0.20 to 0.30" range for QPF. We'll see what the 18Z run does shortly.

Les enjoy the evening and hope everyone gets a decent amount. Made my forecast changes earlier and sticking with them. I will try and catch up later on Friday but it may be Saturday before I post once again. Hopefully by Saturday I have a little time in the morning to post my thoughts on the longer term.

Thanks Tim! Safe travels! Hopefully we can do something with this one for a change.

18Z GFS is finally starting to get into the game now. 1-3" for the region. The 3" bands on this run are showing up from I-70, another in NKY and a third in Central KY. QPF is in that 0.20 to 0.30" range depending on if you get into a heavier band or not.

No changes for me . Still feel qpf totals will range. .10-.25” , so snow accumulations of Half inch -2” to be a majority of accumulations for the tri-cities. Given the variables at the start , imo it would take at least a qpf of .35” or higher just to get to 3” totals . I haven’t seen that kind of qpf totals consistently . An isolated 3 perhaps.

tron777 wrote: ↑Thu Feb 15, 2024 4:48 pm 18Z GFS is finally starting to get into the game now. 1-3" for the region. The 3" bands on this run are showing up from I-70, another in NKY and a third in Central KY. QPF is in that 0.20 to 0.30" range depending on if you get into a heavier band or not.

It looks like I am in the game.

Here is the 0z Hrrr. Big shift from the 12z

young pup wrote: ↑Thu Feb 15, 2024 8:48 pm Here is the 0z Hrrr. Big shift from the 12z

hrrr 0z.png

I like that run. Position of the heaviest band will waffle around a bit but you get the general idea. I mostly like it as it shows less on the southern side which matches my map. Too much mixing down there so I’m not buying some of the models pitting down several inches in Central KY.

00z NAM very similar to the HRRR.

Trevor wrote: ↑Thu Feb 15, 2024 9:01 pm

young pup wrote: ↑Thu Feb 15, 2024 8:48 pm Here is the 0z Hrrr. Big shift from the 12z

hrrr 0z.png

I like that run. Position of the heaviest band will waffle around a bit but you get the general idea. I mostly like it as it shows less on the southern side which matches my map. Too much mixing down there so I’m not buying some of the models pitting down several inches in Central KY.

I believe some of you have said this could be a nowcast forecast. Just because of the banding. It will be interesting to see how this all plays out. I hope it doesn't trend to far north.

I hope something happens here at the woodpile with this system. We haven't even had an ice storm that rattles the trees. Grandma Wooly is getting a wee bit ornery.

00z GFS finally looking good. About .25”

0Z Euro looks good for 2-3" across most of the area. 0.22" QPF at CVG.

This is for the entire forum coverage area.


...WINTER WEATHER ADVISORY IN EFFECT FROM NOON TODAY TO 1 AM EST
SATURDAY...

* WHAT...Snow expected. Total snow accumulations of up to two
inches.

* WHERE...Portions of southeast Indiana, northeast and northern
Kentucky and central, south central and southwest Ohio.

* WHEN...From noon today to 1 AM EST Saturday.

* IMPACTS...Plan on slippery road conditions. The hazardous
conditions could impact the evening commute.

SPC Meso page shows a 1010 MB low in Texas and I expect that low to track ENE into OK, and then NW AR, then eventually along the KY / TN state line. Most of the guidance has the low doing so and it also slowly deepens as it moves by to our south.

6Z GFS continues to bump north to match the rest of the models. 0.27" QPF now at CVG. 6Z ICON has a sharper southern cut off (one of Trev's last posts) with the I-70 crew getting the heavier banding. 6Z RGEM has the heaviest snows from the Metro and points south. 6Z HRRR has 3-4" from the Cincy Metro and points north. 9Z RAP has 2" for most of us.... 3-4" I-70 Crew. 3Z SREF plume has 2" at CVG. 2,5 to 3" for folks to the north.

So all in all... all models have the same general idea. Everyone will see snow. Everyone will get 1-2" easy... it just depends on where the heaviest banding sets up for those isolated 3"+ totals. That my friends will be a nowcast.

HRRR continues to be really juicy. Some of these snow bands are going to be no joke. I am starting to think we may have higher road impacts than I originally thought...

Looking at surface temps.... you can see where the front has stalled and the low will be riding along said front. Low 30s in Central KY. 32 in Lexington. But go down to Nashville and it's 41. U40s to the low 50s in MS and ARK this morning. So you can already see the temp gradient / boundary that we have talked about.

Trevor wrote: ↑Fri Feb 16, 2024 6:22 am HRRR continues to be really juicy. Some of these snow bands are going to be no joke. I am starting to think we may have higher road impacts than I originally thought...

Two things come to my mind on roads (and I'm sure you are probably thinking the same thing lol). First... the time of day when the snow starts and second... where do those weenie bands fall? Time of day won't matter if you can get under a couple of them. That is my concern. We just won't know until this afternoon unfortunately. I hope most of it holds off until after 4pm so I can get home from work without too many issues.

Hey Trev... even the off hour HRRR runs look good! The latest one, 9Z, has 3" for almost everyone and isolated 4" amounts where the weenie bands occur. IMO this should be a fun system and the highlight for February.