Absolute Vorticity

tpweather wrote: ↑Mon Jan 30, 2023 8:09 am So how does the week look and the only part of the forecast I disagree with from the NWS is later Wednesday into Thursday. This should be the strongest of the waves this week and we have another cold front heading this way. Models are usually horrible at this set up until about 24-36 hours in advance. They usually keep the precip to far south in these situations. Models have the original High Pressure over Indiana later tonight through Wednesday morning and this at first will keep precip at bay later Tuesday into the day on Wednesday. That high moves eastward and then the strongest wave heads northeast out of Texas. So I expect somebody in the Ohio Valley to get hit with a winter storm watch mid-week. At this point most likely spot is in central Kentucky as we could see a decent ice storm for them. North of there including the local area would most likely be snow or a mix.

Frz/drz is something we need to be aware of all week as temps near or slightly below 32 at times and road temps should come down several degrees from this weekend.

So really I am going out on that lonely island which I have not done much this winter season but finally I jumped ship and decided that the island looks halfway decent. So will other folks join me on that island later this week or do I end up like Gilligan and unable to get off the island and nobody comes to my rescue.

Tim... I like the spot of the incoming high over MN, but the problem I am seeing is the timing of the cold front in the northern stream. It's too fast so it's keeping the southern wave suppressed. I think the only way it would work is if the cold front slows down. I see no model showing that at this time. I'd love to see that change to join you on the island but currently, I'm still anchored off shore.

I haven't given up on that wave for later on tonight into Tues morning. I still believe that one needs to be watched for us down here and into Matt's hood. Otherwise, Northern posters will have a little fun today.

tron777 wrote: ↑Mon Jan 30, 2023 8:34 am I haven't given up on that wave for later on tonight into Tues morning. I still believe that one needs to be watched for us down here and into Matt's hood. Otherwise, Northern posters will have a little fun today.

Hey Les we are on the same page for later tonight and Tuesday morning so yes I expect an advisory to be issued later today. I understand exactly where you are coming from with the high pressure and sure it could overtake the entire Ohio Valley and you end up dry and cold mid-week. Again I make my forecast first and then look at the models which is probably bad at times but I have done this my whole life and sometimes old habits are hard to change

Just looking at the nam and 24 hours ago showed no precip Oklahoma or southern Missouri and so far through the early hours of the run it shows a decent amount of precip for those areas. No doubt since yesterday afternoon models are painting more precip to fall and further north and west. Does the High Pressure win out is the question and the Nam shows that high a tad stronger as well in the northern/central plains area.

tpweather wrote: ↑Mon Jan 30, 2023 8:48 am

tron777 wrote: ↑Mon Jan 30, 2023 8:34 am I haven't given up on that wave for later on tonight into Tues morning. I still believe that one needs to be watched for us down here and into Matt's hood. Otherwise, Northern posters will have a little fun today.

Hey Les we are on the same page for later tonight and Tuesday morning so yes I expect an advisory to be issued later today. I understand exactly where you are coming from with the high pressure and sure it could overtake the entire Ohio Valley and you end up dry and cold mid-week. Again I make my forecast first and then look at the models which is probably bad at times but I have done this my whole life and sometimes old habits are hard to change

It's all good Tim! It's okay for us to disagree at times because it truly is rare that we do so. It helps us both to learn more I think.

tpweather wrote: ↑Mon Jan 30, 2023 8:52 am Just looking at the nam and 24 hours ago showed no precip Oklahoma or southern Missouri and so far through the early hours of the run it shows a decent amount of precip for those areas. No doubt since yesterday afternoon models are painting more precip to fall and further north and west. Does the High Pressure win out is the question and the Nam shows that high a tad stronger as well in the northern/central plains area.

Did you see the ice storm warnings for Memphis? The weather map this morning shows advisories and warnings all over the place to the SW. Even the advisory for our northern posters today and the advisory to the south for tonight's wave. We are in no man's land attm. So Cincinnati...

Notice the last piece of energy over southern California and this run of the Nam is already showing an area of low pressure that has developed. This was not the case 24 hours ago and this tells me this piece of energy is stronger than models saw 24 hours ago and why you see a more widespread area of precip in the southern plains. for later Tuesday and Wednesday.

tron777 wrote: ↑Mon Jan 30, 2023 8:58 am

tpweather wrote: ↑Mon Jan 30, 2023 8:52 am Just looking at the nam and 24 hours ago showed no precip Oklahoma or southern Missouri and so far through the early hours of the run it shows a decent amount of precip for those areas. No doubt since yesterday afternoon models are painting more precip to fall and further north and west. Does the High Pressure win out is the question and the Nam shows that high a tad stronger as well in the northern/central plains area.

Did you see the ice storm warnings for Memphis? The weather map this morning shows advisories and warnings all over the place to the SW. Even the advisory for our northern posters today and the advisory to the south for tonight's wave. We are in no man's land attm. So Cincinnati...

Les I did see that and believe we will see and advisory for at least parts of the local area issued this afternoon. Just a small amount of ice can cause problems.

Will be back later and time to get the body twisted and turned which I try and do 4 times a year. Fun getting old lol.

tpweather wrote: ↑Mon Jan 30, 2023 9:01 am

tron777 wrote: ↑Mon Jan 30, 2023 8:58 am

tpweather wrote: ↑Mon Jan 30, 2023 8:52 am Just looking at the nam and 24 hours ago showed no precip Oklahoma or southern Missouri and so far through the early hours of the run it shows a decent amount of precip for those areas. No doubt since yesterday afternoon models are painting more precip to fall and further north and west. Does the High Pressure win out is the question and the Nam shows that high a tad stronger as well in the northern/central plains area.

Did you see the ice storm warnings for Memphis? The weather map this morning shows advisories and warnings all over the place to the SW. Even the advisory for our northern posters today and the advisory to the south for tonight's wave. We are in no man's land attm. So Cincinnati...

Les I did see that and believe we will see and advisory for at least parts of the local area issued this afternoon. Just a small amount of ice can cause problems.

I think we'll see one for our southern counties at the very least. I'm not confident on Boone, Kenton, and Campbell being included though.

If the 12Z HRRR is right, we should see an advisory for tonight into tomorrow morning issued for Boone, Kenton, Campbell on south and perhaps even southern Hamilton, Clermont, Brown, and Adams co's. We'll see what ILN decides to do this afternoon as well as watching today's guidance. 12Z RAP agrees as does the 12Z NAM.

Is the wave tonight going to be too far south to affect Warren County?

Closet Meteorologist wrote: ↑Mon Jan 30, 2023 10:05 am Is the wave tonight going to be too far south to affect Warren County?

Yes. Your "action" will be with the current wave moving though the area today.

12Z RGEM is pretty aggressive with the wave for tonight so we'll see if it scores a coup or is just sniffing glue.

12Z GFS is finally joining the party for tonight's wave. In addition, yes it is still a swing and a miss for Tues night into Wed, but it did jump north with precip over Central KY. With the GHD system, it's also more north with rain over Central Ky. We are still dry. However, the trend on the 12Z GFS was definitely a step towards Tim's thoughts. We'll see what happens as we go forward in time.

EDIT: Whoops. I guess I jumped the gun on GHD. I was incorrect on my post here. The GFS is actually trying to change the northern edge of the rain shield over to snow over the Metro and SE counties especially. Granted dry air may win out since it'll try eating away at the northern edge of the precip shield (same issue with all of these waves honestly) so who knows if anything can actually make it to the ground or not, but it's an interesting development nonetheless. Also it's only a small window too, so you'd need another northward bump in the precip shield as well.

Made it back and the body still in working shape lol. Have not looked at anything except the post from here and one thing for is the fog was rather dense this morning but seems to be lifting somewhat. Even though moisture output is not great this week the moisture is available. How much dry air moves in behind each wave is key to the forecast. So a wave later tonight and early Tuesday and this is mainly for folks in the I-275 loop and south. Tuesday we get a push of colder air and also drier air which is a key part to the forecast. We wait for the next wave later Tuesday into Wednesday. This one may be a little further south and will watch to see on Tuesday how big of push for the colder and drier air we see. Then later Wednesday and mainly Thursday is the final wave. That one I believe will be the strongest and have more precip. The question is how much dry air has worked into the area and will this final wave be strong enough to send deeper moisture further north.

Tons of working parts and my guess the NWS will be busy with different advisories at different times and can very local in nature as well. Still believe Thursday is the most likely period to see some heavier precip that can give us a winter storm watch somewhere in the Ohio Valley. Even before then depending on precip type you may see and smaller area even overnight Monday that can cause a watch or even a warning for a certain period.

Will grab some lunch and look over some reports to the southwest and see how things are developing.

Almost lunch time for me too. There is a small band of snow I am watching over NE OK, SW MO and NW AR and that is tonight's wave that we need to watch develop. The actual cold front, i.e. baroclinic boundary is located over Eastern Ohio back to the SW thru Central KY and Middle TN. Nice temp contrast too. As of 11am, Paducah is at 31, CVG, 32 but go to SE KY and you'll see upper 40s to around 50 degrees in Somerset, KY.

NWS LOU has expanded their WWA for tonight's wave a row of counties north to now include LOU.

I had freezing rain this morning here in Somerville. Cars coated and doors stuck shut.

Seeing some light drizzle here but temps are right at 32 so no issues as of yet. If we can drop another couple of degrees then it may become a different story. So far temps are steady. ILN has ramped up POPS for my hood to 80% for tonight. Tim... I smell a possible advisory being issued with this afternoon's forecast package for possibly River on South.

Bumped me up to 90%

12Z Euro came north too for tonight but not far enough north as the rest of the guidance so I'll ignore it to be honest. I think the CMC, RGEM are leading the way with the NAM also contributing. HRRR and RAP are also in the ballpark. Let's continue to monitor trends folks for the rest of the afternoon and into this evening.

I am looking at the SPC Meso page here and I am watching to see where the boundary stalls as we await the wave for tonight. The center of the SE Ridge is located just off the NC coast near Cape Hatteras so I think the front is already slowing down as we speak and may not move too much more for tonight's wave. If my thoughts here are correct, those of us who live near and south of the River should be in a good spot for some wintry weather overnight and into early Tues morning definitely impacting the morning rush where precip occurs. We are in nowcast mode for sure right now.

tron777 wrote: ↑Mon Jan 30, 2023 1:01 pm Seeing some light drizzle here but temps are right at 32 so no issues as of yet. If we can drop another couple of degrees then it may become a different story. So far temps are steady. ILN has ramped up POPS for my hood to 80% for tonight. Tim... I smell a possible advisory being issued with this afternoon's forecast package for possibly River on South.

Good Afternoon Les. I agree Les and it seems each run of the models is inching northward with precip. Again we are not talking a lot of precip but get the light frz/rain or drizzle in the mix and you can get an advisory. Normally once precip drops you see the temperature drop but with this set up maybe only a few degrees but for the roads 31 and frz/rain compared to just 28 and frz/rain can make a difference. The good thing is we are coming out of a milder period so roads are not too cold and that may help but it will be at night so that is a factor also.

tpweather wrote: ↑Mon Jan 30, 2023 1:23 pm

tron777 wrote: ↑Mon Jan 30, 2023 1:01 pm Seeing some light drizzle here but temps are right at 32 so no issues as of yet. If we can drop another couple of degrees then it may become a different story. So far temps are steady. ILN has ramped up POPS for my hood to 80% for tonight. Tim... I smell a possible advisory being issued with this afternoon's forecast package for possibly River on South.

Good Afternoon Les. I agree Les and it seems each run of the models is inching northward with precip. Again we are not talking a lot of precip but get the light frz/rain or drizzle in the mix and you can get an advisory. Normally once precip drops you see the temperature drop but with this set up maybe only a few degrees but for the roads 31 and frz/rain compared to just 28 and frz/rain can make a difference. The good thing is we are coming out of a milder period so roads are not too cold and that may help but it will be at night so that is a factor also.

I'm thinking we should see mainly snow out of the overnight wave, maybe some sleet. Once the better precip rates arrive, I am thinking that the frz rain stays south of us. It's going to be interesting to watch this unfold regardless. Like you said, not a lot of precip to work with but enough to cause some problems if we get cold enough with even a tenth of an inch of QPF to work with.