Absolute Vorticity

0.16" total here, CVG 0.21"

Good Morning. Good news is rainfall totals for the upcoming system will not be quite as high that the models showed the past few days. Still an inch of rainfall is possible but the higher numbers very unlikely. How far does the warm front go tonight and with a somewhat weaker system imo going to be tough to get it much north of the river. So overnight and early Saturday we can see the big temp difference where it could by 58 in Maysville and 38 in Brookville,In. Locally around the I-275 corridor is even more of a challenge but if the mild air arrives its short-lived and we finally are seeing a more normal pattern for mid-Dec. The models are starting to get colder later next week and that is probably in response to the AO becoming neutral or negative. Would not be surprised at all that by this time next week temps for highs will be in the 30's which is just a hair below normal for this time of year. Still believe snow chances are there for Christmas but I still have a problem with the NWS stats that say you must have 1 inch of snow on the ground at 7am for a white Christmas. So after 7am you could get a foot of snow and it would not go down as a white Christmas.

Good Morning folks and Happy Friday to you all! 20s and 30s this morning behind the front. More rain will be coming in but not until later this afternoon. Another wet drive home is likely and a very wet night is ahead. Temps will rise thru the 40s and into the 50s Sat morning with rain continuing. Once the front passes, the rain is over and temps will fall. I still like 1-2" of additional rainfall depending on where you are. I think more south and less to the north is the way to go. Perhaps a little thunder across the south is possible but no severe wx is expected with this system thank goodness!

We will feel like December Sun thru about Thurs of next week with highs in the 40s and lows in the 20s. Plenty of sunshine and dry weather at this time is expected. Next system still poised to move in around Christmas Eve or so. Euro continues to paint a wet picture while the GFS has a series of smaller systems traversing the area with mostly rain and perhaps some frozen to the north. CMC has a better shot of seeing frozen precip from Cincy north changing to rain. Just not quite seeing the pattern getting cold enough yet for an all out snow event thru New Year's. We will continue to monitor this for you as always.

Good Morning Les and it looks like we differ somewhat on the forecast but we both have reasons that make perfect sense. Many times as we know when this happens it tends to end up somewhere in the middle of our forecasts. The good thing is the wacky pattern we have been on is taking a well deserved break and a pattern that I have never seen last so long in December.

tpweather wrote: ↑Fri Dec 17, 2021 7:23 am Good Morning Les and it looks like we differ somewhat on the forecast but we both have reasons that make perfect sense. Many times as we know when this happens it tends to end up somewhere in the middle of our forecasts. The good thing is the wacky pattern we have been on is taking a well deserved break and a pattern that I have never seen last so long in December.

Yeah, I think you're going a little colder then I am attm but none of us are wrong with our thinking this far out in time. The overnight Ensembles, GEFS and GEPS (Canadian) looked colder then the OP models. EPS isn't and support more of what the OP's are showing. So both of our ideas are absolutely on the table right now. I'm just taking the persistent warmth that we're seeing and some of the head fakes we've seen in the past (cold wise) into consideration. It is coming, I have no doubt, I am probably just a little more delayed with it then you are.

The Euro Monthly MJO forecast was updated yesterday and it's not too shabby! We should have some fun in January if this is correct.

Les like you I look at so many factors in trying to make a forecast and the past few weeks the pattern was one that we have not seen much and I got fooled in having the cold air come in faster. I feel better since that pattern is out of here. I went colder but the main reason is the coldest air in the NH looks to be on this side of the planet and when that happens all you need is a little help to get colder air in our area. I believe that is with the AO starting out and then hopefully the NAO will follow to some extent which then gives us an even better shot of colder air but the most important things is systems will tend to be further south and that increases the chances for snow in the area. Concerning the mjo and yes it looped back into phase 6 the last few days plus once you get into later Dec phase 7 becomes warmer. So does the mjo continue on or does it become very weak and the effects are less and we look at other items on the table that may take over. Weather never takes a break and will thrown curve balls left and right and sometimes models do a great job hitting those curve balls but other times the models go down swinging.

32 officially this morning at CVG. I got down to 30 with a decent frost.

tpweather wrote: ↑Fri Dec 17, 2021 7:35 am Les like you I look at so many factors in trying to make a forecast and the past few weeks the pattern was one that we have not seen much and I got fooled in having the cold air come in faster. I feel better since that pattern is out of here. I went colder but the main reason is the coldest air in the NH looks to be on this side of the planet and when that happens all you need is a little help to get colder air in our area. I believe that is with the AO starting out and then hopefully the NAO will follow to some extent which then gives us an even better shot of colder air but the most important things is systems will tend to be further south and that increases the chances for snow in the area. Concerning the mjo and yes it looped back into phase 6 the last few days plus once you get into later Dec phase 7 becomes warmer. So does the mjo continue on or does it become very weak and the effects are less and we look at other items on the table that may take over. Weather never takes a break and will thrown curve balls left and right and sometimes models do a great job hitting those curve balls but other times the models go down swinging.

Tim... Models can sometimes take a little while to adjust to the new pattern. They can and do struggle with blocking as well. Overnight Ensembles were generally colder (minus EPS) then the operationals as I posted moments ago. I am watching the Ensemble guidance closely for any trends that may develop in the next week. If last night's runs hold or continue to improve, then I would expect to see the storm track suppressed even further to the south which would help us out and make your call golden. I think the NAO block is going to be fine. It's the Pacific side that concerns me. EPS still has it too far to the West but as we approach the New Year, GEFS and GEPS were both showing the ridge moving more eastward into more of Alaska. That makes a big difference in where the cold air goes so that really needs to be watched closely.

Les you make a great point about the pacific. We need the more eastward movement of the ridge into Alaska. If it stays put just west of there we get just your normal kind of cold which is what we really are looking at over the next 2 weeks. Getting that ridge further east though would help in bringing down the really cold temps in eastern Alaska and western and central Canada. I believe you are correct we are seeing the same pattern and just a little bit off next week but we are probably in the same ballpark and at the end sure we will probably go into extra innings.

BTW the La Nina is helping us because normally the cold we are seeing especially in western and central Canada would not be as cold so tapping that would lead to less cold being able to enter the lower 48.

One correction I want to make from yesterday and that is how the coldest air is on this side of the planet. I should have made it clear that is in relation to normal. Siberia is always frigid but its the cold on this side of the planet compared to normal that I should have stated more clearly. Sometimes the fingers work faster than the brain which in my world it does not take much these days.

tpweather wrote: ↑Fri Dec 17, 2021 7:49 am Les you make a great point about the pacific. We need the more eastward movement of the ridge into Alaska. If it stays put just west of there we get just your normal kind of cold which is what we really are looking at over the next 2 weeks. Getting that ridge further east though would help in bringing down the really cold temps in eastern Alaska and western and central Canada. I believe you are correct we are seeing the same pattern and just a little bit off next week but we are probably in the same ballpark and at the end sure we will probably go into extra innings.

BTW the La Nina is helping us because normally the cold we are seeing especially in western and central Canada would not be as cold so tapping that would lead to less cold being able to enter the lower 48.

One correction I want to make from yesterday and that is how the coldest air is on this side of the planet. I should have made it clear that is in relation to normal. Siberia is always frigid but its the cold on this side of the planet compared to normal that I should have stated more clearly. Sometimes the fingers work faster than the brain which in my world it does not take much these days.

We really need to see the -PNA back off some too. It is very deeply negative so we're going to be fighting the SE ridge at times. We also have a fast Pacific Jet too so going to be tough to get a big storm without some kind of jet stream amplification.

What has been wild about the current pattern and of course the Tornado's that hit but also the December derecho that hit Wednesday in the midwest. I have never seen one in December and usually they happen in June and July when you get the big surge of heat in the Central Plains. Well we got that surge but this derecho headed from southwest to northeast while most of the ones I have seen go northwest to southeast. We may not see this kind of pattern in years.

Didn't mention the MJO for a.couple days , I wanted to see some consistency, and I like what I see. Using the 850 wind anomalies, we see the easterlies (blues) shutting down closer to the dateline(180) early next week and then beyond the dateline going forward.!!!!!! Westerlies(yellowred) may not look strong but if the easterlies shut down as modeled the MJO will respond accordingly with a cranking back up through 7. I'm pretty pumped up to see this for future gains!!!!!!!

Bgoney wrote: ↑Fri Dec 17, 2021 8:21 am Didn't mention the MJO for a.couple days , I wanted to see some consistency, and I like what I see. Using the 850 wind anomalies, we see the easterlies (blues) shutting down closer to the dateline(180) early next week and then beyond the dateline going forward.!!!!!! Westerlies(yellowred) may not look strong but if the easterlies shut down as modeled the MJO will respond accordingly with a cranking back up through 7. I'm pretty pumped up to see this for future gains!!!!!!!



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Nice to see you excited about it! Now that the typhoon is out of the way, the MJO should recover and continue moving along again. I was worried that it might weaken the wave too much but based on what you posted, that should not be the case. As of 12/15, the Aussies show it still in 6 but the looping is done. It is making a move towards 7 again.

Going to check out the short term models over the next few hours. The warm front is so key in where the heaviest rains will fall over the next 30 hours or so. If the warm front makes a bigger push then folks to the north and west will see some of the heavier rains. If the warm front makes it to the river then we get a nice dose and if the front is further south then heavier rains to the south. Saw some nice rain falling in northern Tn this morning and starting to break out in southwest Kentucky where they really do not need to see any rain during the massive clean up going on there. Again this is not the biggest storm in terms of strength but it does have plenty of moisture available as the recent system on Wednesday was well to the northwest and for the most part did not tap the deep GOM moisture. So that moisture is there to tap and that is why you can get a decent amount of rainfall. I am still going with an inch locally but the bust potential is there and that will be determine by the warm front to the south.

Rain is gathering moving NE over S ILL, West KY and TN. It'll be until later on this afternoon before it gets here so if you need to run any errands today, do so now or around lunch time.

Tellies have updated from the GEFS on the CPC website and I have some positive changes to report. For the PNA, ensemble members are split from keeping it negative to actually rising more towards neutral. This is a big change. Only 2 members have the AO positive. Everyone else is negative and some very negative. For the NAO, about 2 maybe 3 are neutral with the rest of the members all negative. Def seeing some improvements and I think the Ensemble models that I posted about earlier are beginning to slowly respond. I would expect them to respond before the Operational models anyway. Hopefully we continue to see these positive trends (MJO included) over the next week.

Temp dropped to 28 here with a nice frost.

12z NAM has 0.92" at CVG and 0.88" at DAY for the upcoming event later today into tomorrow.

CMH is around 0.70"

tron777 wrote: ↑Fri Dec 17, 2021 9:04 am Rain is gathering moving NE over S ILL, West KY and TN. It'll be until later on this afternoon before it gets here so if you need to run any errands today, do so now or around lunch time.

Les going to be a nice cold rain for several hours.

tpweather wrote: ↑Fri Dec 17, 2021 9:24 am

tron777 wrote: ↑Fri Dec 17, 2021 9:04 am Rain is gathering moving NE over S ILL, West KY and TN. It'll be until later on this afternoon before it gets here so if you need to run any errands today, do so now or around lunch time.

Les going to be a nice cold rain for several hours.

I know it... I hope the cold can become a little more prevalent near Christmas because a cold rain then is utterly depressing lol Even though that is very typical for us anyway.

I did some digging and I think the last time CVG had an official White Christmas was back in 2017. The official definition (which I think Tim posted before) is 1" or more on the ground at 7am on Christmas Day. We had one in 2010 as well. In 2013 and last year 2020 we only had a T of snow so it didn't count. Our odds are only about 17% so not very high, but we are due statistically speaking that is for sure.

Seeing that sunshine here on the eastside

Bgoney wrote: ↑Fri Dec 17, 2021 10:31 am Seeing that sunshine here on the eastside

Seeing some here as well with some clouds mixed in. Temp in the L40s.

Temps should make it to the mid 40's today but once the rain start expect a few degree drop so probably several hours of rain and temp in the 40-42 degree range.