Absolute Vorticity

tron777 wrote: ↑Wed Sep 25, 2024 12:35 pm

tpweather wrote: ↑Wed Sep 25, 2024 12:32 pm

tron777 wrote: ↑Wed Sep 25, 2024 12:24 pm

tpweather wrote: ↑Wed Sep 25, 2024 12:21 pm Something to look at as well is once it just becomes the upper system around where does it go. Still blocking north and east and this thing could be around the eastern USA into the middle of next week.

Could be Tim, I agree. I am keeping POPS in the forecast thru Monday. Currently Friday and Sat are the highest chances for us locally IMO.

We are on the same page and yes we may be dry by Tuesday but along the east coast and even the mountains may still have some rainfall. Going to need a strong cold front to push move things along and that does have a shot next week and yes could we be talking a early frost and not going to say yes but upper upper 30's and low 40's seem like they may happen late next week and with the vegetation getting some moisture this will make it easier for frost to form. My guess it would be in outlying areas like usual at first so not expecting CVG or urban areas to have frost.

Speaking of a strong cold front, it'll likely pass thru the area dry but that should be on Wed of next week. That frontal passage should give us a taste of Fall for a change as you mentioned. I do not expect it to be cold enough for frost but it'll at least get us thinking about it. I expect another strong front down the road too around the 10th or so of October give or take. Long range GFS on past runs tries to get another hurricane into the Gulf in the fantasy range too. Could we get impacted by another tropical system? Stay tuned... At least we're out of this boring weather pattern now.

Great point Les about another possible tropical system. Again this would help keep in cold air away for awhile longer. Again the number of tropical systems in this part of the world lower than expected but the impact seems to be high for the amount of storms.

tpweather wrote: ↑Wed Sep 25, 2024 12:50 pm

tron777 wrote: ↑Wed Sep 25, 2024 12:35 pm

tpweather wrote: ↑Wed Sep 25, 2024 12:32 pm

tron777 wrote: ↑Wed Sep 25, 2024 12:24 pm

tpweather wrote: ↑Wed Sep 25, 2024 12:21 pm Something to look at as well is once it just becomes the upper system around where does it go. Still blocking north and east and this thing could be around the eastern USA into the middle of next week.

Could be Tim, I agree. I am keeping POPS in the forecast thru Monday. Currently Friday and Sat are the highest chances for us locally IMO.

We are on the same page and yes we may be dry by Tuesday but along the east coast and even the mountains may still have some rainfall. Going to need a strong cold front to push move things along and that does have a shot next week and yes could we be talking a early frost and not going to say yes but upper upper 30's and low 40's seem like they may happen late next week and with the vegetation getting some moisture this will make it easier for frost to form. My guess it would be in outlying areas like usual at first so not expecting CVG or urban areas to have frost.

Speaking of a strong cold front, it'll likely pass thru the area dry but that should be on Wed of next week. That frontal passage should give us a taste of Fall for a change as you mentioned. I do not expect it to be cold enough for frost but it'll at least get us thinking about it. I expect another strong front down the road too around the 10th or so of October give or take. Long range GFS on past runs tries to get another hurricane into the Gulf in the fantasy range too. Could we get impacted by another tropical system? Stay tuned... At least we're out of this boring weather pattern now.

Great point Les about another possible tropical system. Again this would help keep in cold air away for awhile longer. Again the number of tropical systems in this part of the world lower than expected but the impact seems to be high for the amount of storms.

Exactly Tim! 1992 is a great example of that. A quiet season but we all remember Andrew in Aug of 1992. As you've said before, all it takes is 1.

Side note.... there was a tornado yesterday that occurred in Preble Co Ohio.

Quite the stream of moisture well ahead of Hurricane Helene. This could be a drought buster for parts of the southern Appalachians.

dce wrote: ↑Wed Sep 25, 2024 1:09 pm Quite the stream of moisture well ahead of Hurricane Helene. This could be a drought buster for parts of the southern Appalachians.

Too much of a good thing. I think that there will be massive inland flooding with this thing over GA, NC, TN, WVA, VA, and parts of KY.

NHC has the track much further west than what the OP models are showing through Georgia and also its track into Tenn and far west KY

Hey Bgoney and I am surprised how many models take it into western Ky and western Tn. For a rather rare system I thought the models may be all over the place. This is a fun storm to watch and again I need to see where its at say around noon on Thursday. Several items in place with of course the Hurricane itself and then a rather strong upper low. Two other factors include the ridging to the north which has been there awhile plus the Atlantic is backed up as well. Have a storm get this strong this quick is one thing but this storm is big in size and covers a ton of area. To me it seems the models are moving it a tad fast but if the flow is strong enough and then you get help from the upper system maybe the timing is correct. So still keeping 1-3 inches locally with lower amounts to the north and higher to the south and that is for the entire weekend. Could this bust and yes on both sides of the totals and my guess a sharp cutoff later Friday but also a few hours of heavy rain can add up quickly as well.

Whats interesting is the Nam is moving the system further east so is this model on to something or again will this just be a blip in the runs.

tpweather wrote: ↑Wed Sep 25, 2024 4:19 pm Hey Bgoney and I am surprised how many models take it into western Ky and western Tn. For a rather rare system I thought the models may be all over the place. This is a fun storm to watch and again I need to see where its at say around noon on Thursday. Several items in place with of course the Hurricane itself and then a rather strong upper low. Two other factors include the ridging to the north which has been there awhile plus the Atlantic is backed up as well. Have a storm get this strong this quick is one thing but this storm is big in size and covers a ton of area. To me it seems the models are moving it a tad fast but if the flow is strong enough and then you get help from the upper system maybe the timing is correct. So still keeping 1-3 inches locally with lower amounts to the north and higher to the south and that is for the entire weekend. Could this bust and yes on both sides of the totals and my guess a sharp cutoff later Friday but also a few hours of heavy rain can add up quickly as well.

That’s about the best you can forecast at this time. Only thing I would put a 50% chance of those totals north of the river . How the two lows interact in the TENN/OVs is still a very big question mark

The latest thinking from the boys for Fri - the weekend:

Friday is shaping up to be a wet and breezy/windy day as the
remnants of Helene move north then northwest across the
Tennessee Valley. The surface pressure gradient will increase as
the low moves northwest. This, along with strong winds aloft,
should bring wind gusts in the 25 to 35 mph range. There could
even be some isolated 40 mph gusts, especially along and south
of the Ohio River. Saturated low levels should prevent winds
from getting stronger (limited mixing). Widespread showers,
isolated thunderstorms, are expected south with decreasing
chances of pcpn as one heads north. Despite the tropical
moisture, the speed of the pcpn shield should limit rainfall
amounts which will actually be beneficial to our drought
stricken region. By Friday night, the mid level energy that once
was Helene will be merging into a synoptic mid level closed low
to our southwest. This process will result in a decrease in
pcpn chances overnight. Winds will also diminish as the surface
low undergoes frictional decay. Rainfall amounts will range from
0.25 to 0.50 inches north to 1.50-1.75 inches along and south
of the Ohio River.

For the upcoming weekend, more opportunities for rainfall will
be possible as the center of the mid level closed low slowly
rotates east/northeast across Kentucky and Tennessee, weakening
and shearing as it goes along. Will continue with clouds and
chances of showers, with some isolated thunder possible during
the peak diurnal cycle.

The mid level closed low is forecast to weaken, shear, and open
up as upstream energy digs east/southeast into the Great Lakes
Monday into Wednesday. This process will also be associated with
a cold front, expected to pass through during the
Tuesday/Wednesday time frame. Lingering pcpn chances should end
after frontal passage.

As for temperatures, they will be held down on Friday with
clouds, rain, and wind. The weekend will feature highs 75 to 80
and lows in the 60s. A cooling trend is then expected by
Wednesday behind the cold front, along with a much drier
airmass.

This will be my final posting today as I need to catch up on some streaming shows lol. I guess over the past 24 hours the models have no doubt got stronger on this system and even the Euro has caught up to the stronger storm. Still need until at least noon to see if the forecast bodes well. The storm itself should get quite strong overnight and I do expect the heavier rains to start falling on the northern and eastern side of the storm instead of the southwest side like today. That is another reason I believe we can get a decent amount of rain because we should be in the area that has some decent rainfall amounts. Make my final call by noon or so on Thursday and it may be the same as I have mentioned all week. Would love to see those 1-3 inch amounts and no won't erase the drought but puts a nice dent in the drought plus this time of year moisture can soak in quite nicely and we are not going to have any heat to just erase it after a few days. Mother Nature is starting her balancing act and from what I am seeing so far for the upcoming later fall and winter we will have plenty of moisture around but will it be in the form of rain or snow and that is way to early to even guess.

This isn't really part of the current weather discussion, but I wanted to put it out here as opposed to the weather education thread. I found a website called open-meteo.com. It is an open source API with a great deal of weather info. There are free and pay options. I hope if you have not seen it before that you will find it useful.

tron777 wrote: ↑Wed Sep 25, 2024 1:16 pm

dce wrote: ↑Wed Sep 25, 2024 1:09 pm Quite the stream of moisture well ahead of Hurricane Helene. This could be a drought buster for parts of the southern Appalachians.

Too much of a good thing. I think that there will be massive inland flooding with this thing over GA, NC, TN, WVA, VA, and parts of KY.

I heard on TWC this evening that some areas could get up to 18 inches down that way!!

CVG got to 75, DAY 77 and CMH 78 today.

j.r. wrote: ↑Wed Sep 25, 2024 9:16 pm This isn't really part of the current weather discussion, but I wanted to put it out here as opposed to the weather education thread. I found a website called open-meteo.com. It is an open source API with a great deal of weather info. There are free and pay options. I hope if you have not seen it before that you will find it useful.

Awesome find!

Good morning all! Helene and her leftovers along with an interaction with the upper low to our West are still the main weather topics for this week, weekend and even into early next week. A cold front on Wed will clear everything out and cool us down to more September like levels. Before we get there, rain from Helene will move in later on tonight. Tomorrow looks very rainy and windy esp in the afternoon and evening (for the best winds) Gusts to 50 mph are still possible along with scattered power outages. I have seen some models going with 60 mph+ but I am not ready to commit to gusts that high. It will depend on how strong Helene is at landfall and how fast she moves our way. I like Tim's call of 1-3" for the area. I-70 Crew will be much less of course and south of our CWA much more. The rainfall gradient has not changed any. The steadier rains should taper off Fri night with the dry slot. Then on Sat, more showers are expected, esp in the afternoon as the upper low and Helene will have merged by then and everything stalls south / SW of us so we're on the N side of the circulation. Shower chances continue Sunday becoming more scattered on Monday with a lingering shower even possible on Tues as this thing finally moves off to the East to the Mid ATL states. We will talk about the modeling more later (have to leave for work) but these are my overall thoughts at this time. Nothing much has really changed IMO. Modeling hasn't been too bad.

Looks good Les, a noticeable shift east overnight from the NHC with the track at landfall and its trek northward while being absorbed into the cutoff low. Hopefully that can get much more of West Virginia and Ohio into the higher amounts

Rainfall amounts at CVG:

6Z NAM - 2.59" ending at 2pm Sunday
0Z GFS - 3.31" thru Monday of next week
0Z Euro - 3.10" thru Monday of next week

The wind also concerns me for Fri and Fri night. The GFS has a 979 MB low over Central KY Fri afternoon. The NAM is not quite as bad with a 989 MB low over SE KY. The CMC is 987 MB near Nashville and the Euro is 983 MB over the KY / TN border. 40-50 mph gusts looks good, but if the GFS is right then 60 mph gusts would be in play.

Good Morning and we saw the shift somewhat eastward late yesterday and that seems correct. Going to keep the 1-3 inch total though I believe as usual some area nearby may get a tad more but hard to go with 4 inches because its probably isolated in our area. The winds and that has increased so expect some power outages. Speaking of power outages this storm may cause one of the most widespread outages from a Hurricane in history. The storm is wide plus when you have the storm still a strong tropical storm when it reaches a metro like Atlanta there is going to be problems. Normally you get the outages withing 30-50 miles of landfall but this time not so much. The amount of flooding is another concern as the past few days the front as just stalled east of here and the moisture from the GOM has been steady and this is before Helene. I know in many situations power companies will send crews to the expected hardest hit areas but this time many locations need to keep their crews at home because of how widespread this storm has become. The surge into western Florida is wide and the further north you go we could see 15-20 feet which that is going to cause more damage. Saw a report last night the property insurance cost is so expensive that many folks just don't buy it and wish for the best.

I did watch the Weather Channel last night and though very seldom they do have some great reporting on Hurricanes. One thing they had to bring in some extra help and my guess some folks are retired or just behind the scenes are on camera as they had to send out so many folks to give us live coverage. Of course everyone knows Jim Cantore and I believe this is his 112th time reporting on Hurricanes but this is the first time he seemed really concern about the safety of folks reporting plus most the mets reporting have homes and family in the Atlanta area and they are worried about them as well. I truly believe you could see the worry on his face.

Sort of wild and many times we talk about storms and tend to overplay what actually happens. This storm has a chance to be in the top five of all storms ever in terms of low barometric pressure. I believe the blizzard of 1978 is tops so this shows you how strong this will be even once it reaches our area.

tpweather wrote: ↑Thu Sep 26, 2024 6:23 am Sort of wild and many times we talk about storms and tend to overplay what actually happens. This storm has a chance to be in the top five of all storms ever in terms of low barometric pressure. I believe the blizzard of 1978 is tops so this shows you how strong this will be even once it reaches our area.

The wind storm of March 2023, March Super Storm of 1993, and the Blizz of 1978 are tops around here. I don't think Helene will be to that level for us but definitely a top ten 100%, Just glad that we are not looking at an Ike re-do.

Les no doubt a rare system. Some additional thoughts which will probably be many over the next 48 hours. I believe the storm is a tad slower than what it showed for days. We are talking a few hours and a slight shift eastward. The somewhat slower time and eastward track is also letting the upper low west of here drift slightly more eastward and this also gives us a better shot of getting some of the higher totals. After the storm and really talking after the weekend their will be busts both high an low on rain totals but we can say that with most systems. Saw channel 5 this morning and they are still going .5-1.5 and I believe they will finally send totals higher later today. These are tropical rains and you can get a inch or two in just a few hours alone.

I am wondering too Tim if the models are underdoing the QPF for the reasons you mentioned. QPF amounts have gone up though in recent runs. I posted some of that earlier this morning. Second... how strong the low gets will also tell us how much of a wind maker this is going to be for us. Definitely an interesting set up for us to keep our eyes on.

Les Ike was a completely different situation as we know and that happened in September as well. Something to watch on Friday is during the afternoon and if the rain stops for a brief period and you see the sun this can ramp up winds even stronger and yes gusts could reach 50mph to 60mph. I had over 40 possible but will raise that to over 50 from what I am seeing. I have spent more time on this tropical system than I have ever spent on one and being a weather nerd this gets the forecasting juices flowing. Hope we see no deaths with this system but that is unlikely with such a wide area. One thing that is strange is a system like this can save lives. No I am not smoking anything but if you think about how many folks are killed in traffic accidents in a normal 2 day period compared to what we see with a storm like this you probably save lives because the amount of folks on the road are decreased big time.

tpweather wrote: ↑Thu Sep 26, 2024 6:47 am Les Ike was a completely different situation as we know and that happened in September as well. Something to watch on Friday is during the afternoon and if the rain stops for a brief period and you see the sun this can ramp up winds even stronger and yes gusts could reach 50mph to 60mph. I had over 40 possible but will raise that to over 50 from what I am seeing. I have spent more time on this tropical system than I have ever spent on one and being a weather nerd this gets the forecasting juices flowing. Hope we see no deaths with this system but that is unlikely with such a wide area. One thing that is strange is a system like this can save lives. No I am not smoking anything but if you think about how many folks are killed in traffic accidents in a normal 2 day period compared to what we see with a storm like this you probably save lives because the amount of folks on the road are decreased big time.

A storm like this is worth spending a lot of time on Tim since it is a very rare set up for our local area. I expect hurricane force winds to extend all the way into the S apps along with 10-15" of rain. The wind and rain is going to cause a lot of tree damage and power outages with the heavy rains causing a lot of flooding issues. For us, we will see some of those same issues here but on a much much more isolated scale thankfully. It'll be interesting to see how strong it gets before making landfall this evening.