Absolute Vorticity

airwolf76 wrote: ↑Fri Jan 05, 2024 12:00 pm

tron777 wrote: ↑Fri Jan 05, 2024 11:35 am

Trevor wrote: ↑Fri Jan 05, 2024 11:30 am

airwolf76 wrote: ↑Fri Jan 05, 2024 11:29 am

tron777 wrote: ↑Fri Jan 05, 2024 11:25 am

I agree Doug. I am going with 2-4" now instead of 1-2" that I mentioned yesterday, For I-70 folks... I think 1-2" looks good.

just curious what are you thinking for my area?

I meant to answer that yesterday Charles but I forget where exactly you are in PA!

I think it's Monroe Co, right Charles??? The more inland you are and NW of I-95, the better. I think it's mainly a rain event for the I-95 corridor. NWS Mt Holly has 6-10" for Monroe Co per their latest AFD.

Yes. southern Monroe. you remembered. thanks

I think 6" is doable for your area. It's going to depend on how strong the surface low gets and how much warm air is involved. That is the only concern that I have for SE PA. If we see a stronger low then the bust potential is there. You know how your area works with these set up's much better then I do so just offering up my 2 cents and what I would be on the look out for.

tpweather wrote: ↑Fri Jan 05, 2024 12:04 pm Good Afternoon and I see Les and Trevor are saying go big or go home lol. Locally I am still going 1-2 with 1.8 at CVG so I am on the higher end. I can see where we get the higher totals but have not convinced myself that is the way to go. Biggest issues is dry air at the start of the storm and do we have a 3hour period or 6hour period of snow that comes down hard enough to accumulate. Temp though looks decent around the 30-33 mark locally and that is a plus.

I do believe an advisory will be issued and my guess is they will go 1-3. Trev this has been your storm so time to bring to the finish line lol.

2" and we all 3 win lol But seriously Tim.... I had to side with Trev on this one as the majority of the data is suggesting better QPF and heavy precip rates for a 4-6 hour period which should get underway prior to sunrise so that should also help with morning accumulations. I think by noon it'll be a wrap so a quick hitting system.

12Z UKIE looks pretty juicy from what I can tell from the freebie maps from the Meteocentre site. Can't see Pivotal Weather on the customer side so if I am converting MM to IN correctly, the UKIE gives us something in the 0.30 to 0.40" range for QPF? If someone could check Pivotal for me to confirm that my math does not suck that would be appreciated. Thanks all!

tron777 wrote: ↑Fri Jan 05, 2024 12:28 pm 12Z UKIE looks pretty juicy from what I can tell from the freebie maps from the Meteocentre site. Can't see Pivotal Weather on the customer side so if I am converting MM to IN correctly, the UKIE gives us something in the 0.30 to 0.40" range for QPF? If someone could check Pivotal for me to confirm that my math does not suck that would be appreciated. Thanks all!

Ukie 0.40 with the heaviest snow band right across the metro.

Trevor wrote: ↑Fri Jan 05, 2024 12:30 pm

tron777 wrote: ↑Fri Jan 05, 2024 12:28 pm 12Z UKIE looks pretty juicy from what I can tell from the freebie maps from the Meteocentre site. Can't see Pivotal Weather on the customer side so if I am converting MM to IN correctly, the UKIE gives us something in the 0.30 to 0.40" range for QPF? If someone could check Pivotal for me to confirm that my math does not suck that would be appreciated. Thanks all!

Ukie 0.40 with the heaviest snow band right across the metro.

Beautiful! Thank you Sir! This old brain still has a few cells firing!

How long do we expect for dry air to delay the precip are models currently still showing that in the .40qpf or does it not pick that up?

tron777 wrote: ↑Fri Jan 05, 2024 12:32 pm

Trevor wrote: ↑Fri Jan 05, 2024 12:30 pm

tron777 wrote: ↑Fri Jan 05, 2024 12:28 pm 12Z UKIE looks pretty juicy from what I can tell from the freebie maps from the Meteocentre site. Can't see Pivotal Weather on the customer side so if I am converting MM to IN correctly, the UKIE gives us something in the 0.30 to 0.40" range for QPF? If someone could check Pivotal for me to confirm that my math does not suck that would be appreciated. Thanks all!

Ukie 0.40 with the heaviest snow band right across the metro.

Beautiful! Thank you Sir! This old brain still has a few cells firing!

LOL!

All systems go I would say. My alarm for work is 8:30PM this evening so I will probably take a nap in a while then check back in.

CINCINNATI01 wrote: ↑Fri Jan 05, 2024 12:38 pm How long do we expect for dry air to delay the precip are models currently still showing that in the .40qpf or does it not pick that up?

The NAM and other higher res models have us saturating rather quickly.

Trevor wrote: ↑Fri Jan 05, 2024 12:40 pm

CINCINNATI01 wrote: ↑Fri Jan 05, 2024 12:38 pm How long do we expect for dry air to delay the precip are models currently still showing that in the .40qpf or does it not pick that up?

The NAM and other higher res models have us saturating rather quickly.

I agree provided that the heavier rates get in here as the data shows. That I what we are expecting. I like that 4am to 12pm window still.

tron777 wrote: ↑Fri Jan 05, 2024 12:41 pm

Trevor wrote: ↑Fri Jan 05, 2024 12:40 pm

CINCINNATI01 wrote: ↑Fri Jan 05, 2024 12:38 pm How long do we expect for dry air to delay the precip are models currently still showing that in the .40qpf or does it not pick that up?

The NAM and other higher res models have us saturating rather quickly.

I agree provided that the heavier rates get in here as the data shows. That I what we are expecting. I like that 4am to 12pm window still.

Thats about what I'm going with as well.

12z Euro has initialized...

12Z Euro QPF.

CVG - 0.24"
HAO - 0.20"
MGY - 0.19"
DAY - 0.13"
CMH - 0.15"
FGX - 0.56" --- rain / snow mix

Updated discussion from the boys as of 1pm:

.NEAR TERM /THROUGH TONIGHT/...

Updated due to increase in snowfall amounts. Full AFD will be
issued at normal time.

Surface high pressure continues to shift east through the rest
of the afternoon and into the evening. Winds remain light and
out of the east and upper level clouds stream in from the
southwest. These clouds are advecting into the region from a
potent shortwave ejecting out of the Southern Plains. Dry air
ahead of this system likely prevents precipitation onset until
after midnight.

Onset: As precipitation moves into the area, it will be entering
a very dry air mass with above freezing temperatures above the
surface. Some above freezing temperatures are forecast along and
south of the Ohio River. With the dry air in place, evaporative
cooling will take place as precipitation falls. As this process
occurs, some mixed precipitation is possible (partially melted
snowflakes or ice pellets) during the transition to saturation.
Some rain is also possible across the south. Eventually,
precipitation rates and favorable timing will help to allow for
a mostly full transition to snow by the end near term period.
More details on the snow accumulation in the short term period.


&&

.SHORT TERM /SATURDAY THROUGH 6PM Saturday/...

Adjustments were made to the previous forecast given the trends
in the 06/12Z guidance. Complex scenario results in a lower
than desired confidence for this event, but confidence had
increased enough to ramp totals up across the area for this
early afternoon update. The new snowfall amounts are sensitive
to several factors lining up, and there is a possibility for
values to trend lower/higher as confidence increases.

Snow amounts: Snow total forecast was made using the assumption
of higher snowfall rates and higher QPF, leading to a few hours
of accumulating snow. These higher snowfall rates will help to
increase snow ratios as wet flakes fall and quickly stack up.
Given this event will unfold in around 6-10 hours, any
transition to rain will greatly diminish snowfall amounts along
the Ohio River and into southern Ohio. Snowfall rates will also
help to decrease the potential for warm air advection to
disrupt the below freezing temperatures in the lower
troposphere. The highest amounts (2" with locally higher amounts)
are currently stretched across portions of northern Kentucky
into the middle Scioto Valley (Ross County).

Timing: While some snow is possible during the early morning
hours across the tri-state and northern Kentucky, the best
snowfall rates are expected between 6 am and noon, stretching
from northern Kentucky toward the Scioto Valley. This is the
corridor of highest snowfall amounts (2" with locally higher
amounts). Precipitation rates quickly decrease through the early
afternoon and thermal profiles become less supportive of
efficient accumulating snow.

Could be our classic OV Overachiever

BookNerdCarp wrote: ↑Fri Jan 05, 2024 2:03 pm Could be our classic OV Overachiever

Certainly possible Matt should the heavier precip rates get in here. That is going to be the biggest key to our success as we've talked about in this thread. Once I get home and get a few things done, I will have more tools at my disposal so we can really get into dissecting this thing this evening.

15Z SREF is in and it is very similar to what I posted on with regards to this mornings 9Z run.

18Z HRRR is rolling in now and to be honest, not a huge change from the 12Z run. I think we're pretty much locked and loaded folks and it's still ok to look at additional data coming in but by and large when you get this close to game time, it's pretty much a now cast. I like the timing as well that I have previously mentioned.

Good Afternoon and a bit chilly out there today. Many items go into a forecast and then you try to find the correct mix to put out an accurate forecast. You watch the radar and ground reports and how the models have done so far with the system and then still not easy.

Reason for higher totals is time of day in that 4a-12p tends to be the coldest part of the day. Cold air is a tad stronger than models have shown. Storm not getting to strong so warm air into the system is less.

Reason for lower totals and dry air is one area. Rate of precip falling and can it fall for rather heavy for an extended period and that is not easy.

Looking over everything this afternoon I have went ahead and move totals up and 1-3 inches seems reasonable. Still going 1.8 at CVG but that is a tad higher than my mid-point.

Can we go higher and if so where and that would most likely be east of the area and the bust would be just south of here if precip remains a very cold rain for a longer period.

Will be back later for more fun and games

Finally caught up on the reading here as I was at the dentist most of the morning getting x-rays for this bad tooth ache, will have two teeth pulled next Wednesday! Ugh!! So, we're at 11 pages already with this 1st Winter Storm, wow! I'll be working from home tomorrow morning as the snow will be falling outside my window.

I'll also be watching the temps and the radar tonight drinking some coldies. Currently at 36 degrees here with a filtered sun with a halo in the cirrus clouds...always a good sign of moisture increasing over colder air!

Looks like ILN issued a WWA for southeast counties only.

kywthrluvr wrote: ↑Fri Jan 05, 2024 3:45 pm Looks like ILN issued a WWA for southeast counties only.

I saw that Leslie. My guess they are trying to decide how far west to throw the advisory.

Not sure if this has been mentioned or not. It's colder than it was supposed to be today. Been out most of the day taking Christmas decorations down and loading calcium products. Been in the house for 30 minutes and I'm still chilling. Doesn't help that I have been sick the past few days.

tpweather wrote: ↑Fri Jan 05, 2024 4:11 pm

kywthrluvr wrote: ↑Fri Jan 05, 2024 3:45 pm Looks like ILN issued a WWA for southeast counties only.

I saw that Leslie. My guess they are trying to decide how far west to throw the advisory.

Just getting caught up here. Took down the outside Christmas Lights to keep everything dry. I am a bit perplexed by this. I agree with the advisory but I thought one would have been issued for the Cincy Metro also. Oh well... what do I know.

18Z NAM has 0.35" of QPF at CVG and the 18Z GFS is coming in with 0.40"

Checking in here from the woodpile is Grandpa Wooly. The old lady and I are getting awfully excited for this first blow of the year. It sure feels like that cold you get before a snow storm. Went and checked duck ponds for the morning and they are all frozen. Can't wait for it to start. I better wiggle on into the woodpile. I'll be watchin.