OHweather

The storm pulling out faster and letting dry air in really killed this one. We have the long fetch and good instability but yeah, dry air is often killer. The winds don't look too strong by late tonight though but we'll see.

Ehh CLE is going to punt this another shift. Leaving the watch as is for Ashtabula and NW PA

Agree. Even with my forecast as is (assuming it doesn't over-perform), I'd still issue advisories for Lake, Geauga and Ashtabula...and at least consider going for one for Cuyahoga too...especially since it's the first accumulating snow of the season. We should find out what CLE's going to do soon.

Wow! Dew points in the 10s must be helping the snow make it to the ground

I'm still not sure on this one. I just can't get over a period of extreme instability with a favorable fetch with winds not moving much for almost 12 hours tonight through early tomorrow afternoon, and then only gradually shifting to the W and eventually SW. Normally a very dry airmass wins out over extreme instability, but there is some moisture and we have a long fetch, and it's not impossible we get a Lake Michigan connection, especially early on in the event. With the winds not moving much, if a band forms late tonight (which I feel decent about) it may not get disrupted as much as I initially thought. Even if it's snowing half an inch to an inch per hour under it (as opposed to something like 2" per hour), several hours of a band will easily push places up to advisory or warning criteria snows. The more I look at the models there really isn't much of a trough moving through...it looks more like ridging trying to build in from the west altering the winds a bit...but we should still hold on to some convergence in the Snowbelt downwind of the lake tomorrow afternoon, with the convergence really intensifying in the evening as temps drop over land. My other big debate is Cuyahoga County. If banding doesn't get disrupted tomorrow, the wind direction supports banding into northern and eastern Cuyahoga County for several hours...which would be long enough for at least advisory criteria to be reached. With somewhat questionable moisture and the models weakening the convergence for a time tomorrow I still think keeping the highest amounts out of Cuyahoga County is probably the right call...but if the convergence and hence any banding is more persistent tomorrow, which is possible (let's get real, the NAM and GFS are way too low resolution to try to resolve that), I don't see why someone in the higher terrain in east-central or northeast Cuyahoga County couldn't also get a 6" amount. Due to some mitigating factors I'm still OK with the map I made this morning, but I'm less confident than I normally am and can see fairly easily how this could overperform some.

I *finally* got around to putting numbers on my map and tweaking things. Unfortunately, I definitely had to lower amounts from my initial thinking. The models all converged on a solution that was weaker with the storm, which allowed drier air to move in quicker. Of course, the Euro showed this solution two days ago, and I wrote it off since seemingly every other model disagreed with it. I've found that when I disagree with the Euro it usually pulls off the coupe, so maybe I should stop doing that. The winds will be WNW late tonight into Sunday morning, and moisture looks pretty good through tonight, so I do think that there's an initial burst late tonight into Sunday morning. Instability will be extreme by this point too. It still looks like things may get disrupted for a few hours Sunday afternoon as a little wind shift moves through, but we should see another increase Sunday evening as ridging over land causes convergence to increase over the Snowbelt. As for amounts, instability is still going to be extreme and although moisture actually looks pretty marginal now, we do still have a long fetch working for us and the potential for some convergence over the Snowbelt to try to help focus things. Winds do look to go to a more true WNW direction which should try to push things into northern Lorain and Cuyahoga Counties, so I kept the idea of light accumulations there. The window for that looks to be a few hours long late tonight into Sunday morning, and with more questionable moisture I decided to only go with 1-2" there. We've seen bands in this area surprise with a WNW flow before, so I suppose it's not impossible someone gets 3 or 4" in northern Cuyahoga County (outside of the far east side where I have it drawn in), but it's not likely. I overall decided not to shift the area of heavier amounts much farther south in the heart of the Snowbelt compared to my first guess. There will be a pretty strong lake-land temp differential, which should create a pretty decent lake aggregate trough and tend to try to keep snow a little closer to the lake. With two potential windows for banding along with extreme instability and a long fetch, I still think a few or several inches could fall, but think amounts should stay under 6". Confined the heaviest accumulations to the higher terrain. Hopefully we get a more legitimate event soon!

The weaker low (Euro beats EVERY other model again) does a couple things: -More WNW winds yes -Cyclonic flow doesn't stick around as long -Moisture diminishes quicker. I didn't get around to making a final map tonight, but am thinking I'll shift the snow a little farther southwest but not going with widespread 6"+ amounts...my thinking is 3-6" should cover it for the "jackpot zone" in NE Ohio...but I'll look again in the morning

With winds trying to turn more WNW early Sunday, that tends to strengthen convergence near the lakeshore…especially when surface pressures over land are trying to rise and push winds more offshore. The 0z hi-res NAM shows convergence starting to develop over the Snowbelt by 4am Sunday, and shows it persisting until the end of the run at 7am Sunday. The 0z GFS also has pretty strong convergence across the Snowbelt Sunday morning, but actually weakens it for a few hours Sunday afternoon. I can’t get a good zoomed in version of the lower res NAM right now, but it appears to do something similar. The GFS and NAM then both flare up convergence late Sunday into Sunday evening as ridging really starts nosing in, before any banding would then shift offshore: I’m not sure what causes this possible brief weakening of the convergence Sunday afternoon. The NAM appears to hint at potentially a very, very subtle trough moving by, possibly disrupting the wind fields? Either way, as we head towards evening, convergence should really increase as temps on land plummet and surface pressure continue to rise from the south. If there is indeed a small trough that passes early Sunday afternoon, which would argue for decent activity Sunday morning, as heavy lake effect often occurs just before a trough passes. With pretty good evidence for decent convergence Sunday morning for several hours, I’d have to imagine a fairly well defined convergence band will form. With winds over the lake fairly strong and out of the WNW, this convergence and any associated band would likely settle inland a little bit into southern Lake, a good portion of Geauga and central and southern Ashtabula Counties. With a WNW wind, there is some risk of any band settling into northern Cuyahoga and perhaps even northeastern Lorain County too. If convergence weakens as shown on the models Sunday afternoon, any band could become disorganized for a few hours…although with well aligned winds, good shear, orographic lift in the higher terrain of the primary Snowbelt and still some frictional convergence, I can’t picture the snow completely stopping. I’d then expect the snow to redevelop Sunday evening as ridging really builds in and convergence increases again, although by this point the band would likely occur farther northeast than Sunday morning and slowly be shifting farther northeast as time went on. As for how steady any banding would be, the NAM doesn’t show winds moving much late Saturday night into Sunday morning. There are some fluctuations, but no large shifts until Sunday afternoon when the winds start backing towards the southwest. With any banding Sunday morning driven by convergence caused largely by the lakeshore, and winds not moving a ton, it’s quite possible that any band late Saturday night into Sunday morning is fairly steady for several hours, before convergence possibly weakens for a time Sunday afternoon. By Sunday evening the winds will be shifting, so any band that redevelops along the eastern lakeshore may only stay over any given spot for a couple of hours. As for potential Lake Michigan moisture, the models are trying to signal a significant band developing over Lake Michigan Saturday night on a NNW wind behind the surface low, with the band possibly swinging east late Saturday night into Sunday morning as the low pulls northeast and the winds go more westerly off of Lake Michigan. The models are trying to hint at pretty good convergence with this band, with colder air trying to work in from the southwest. This could give a few hours of good Lake Michigan pre-seeding late Saturday night into Sunday morning. By Sunday evening the winds may be too southerly to get good Lake Michigan moisture to Lake Erie. So, with all of this said, let’s try to figure out how things will play out and how heavy amounts may be: I think there’s a good chance a good W-E convergence band develops after midnight Saturday night into mainly the primary Snowbelt…initially Lake, northern Geauga and Ashtabula Counties. The band should settle south some early Sunday morning as there seems to be good agreement on the winds going WNW in this timeframe. This should push the band into a good portion of Geauga County and southern Asthabula County, with northern Lake and Ashtabula Counties possibly seeing a lessening of snow at this time. With a WNW flow over the lake, if it actually occurs as currently modelled, convergence would likely increase enough along the central lakeshore for some banding into northern Cuyahoga and perhaps northeastern Lorain County Sunday morning for a few hours…with the best potential for decent snows on the east side, although not impossible for some accumulations on the west side. There seems to be support for convergence weakening for a few hours Sunday afternoon, possibly due to a weak trough moving through and altering the wind fields, which may disrupt the band some. However, there should still be enough support for at least snow showers continuing. Winds do start backing slowly Sunday afternoon so the snow should end during the afternoon in Lorain and much of Cuyahoga County, and shift north some in Geauga County. By Sunday evening, rapidly falling temps overland and high pressure continuing to nose in should cause convergence to increase again…probably across Lake and northern Ashtabula Counties…likely causing any banding to reflare. The banding should slowly shift northeast up the shoreline and be out of Ohio around midnight or so Sunday night. With extreme instability, decent moisture, high inversion heights, fairly low wind shear and the potential for Lake Michigan moisture helping things late Saturday night into Sunday morning, snowfall rates of 1-2” per hour seem possible under any banding. If banding becomes slow moving for several hours as I expect, snowfall totals would quickly approach half a foot in the favored areas and could exceed it. With 850mb temps cooling below -10C by Sunday morning with 925mb temps of -5C through the event, any decent snow band will produce accumulations down to the lakeshore…and in the lower elevations of Cuyahoga and Lorain Counties…although, warmer surface temps near or slightly above freezing near the immediate shoreline could cause lower snow ratios and hence somewhat slower accumulations near the immediate lakeshore under any banding. If banding becomes more disorganized for a period Sunday afternoon as seems possible, snow accumulations would obviously slow considerably. By Sunday evening moisture and inversions do fall some, so snow rates may not exceed 1” per hour consistently in any re-flareup as it looks now. I’m not extremely confident in throwing out hard accumulation numbers yet…although I will certainly do so Friday evening at some point…however, I suspect that locations that get under the good band Sunday morning…assuming it forms…would likely be the jackpot. At this point I think this occurs in far southern Lake, the northern half of Geauga and central Ashtabula Counties. Moderate accumulations could occur in parts of eastern Cuyahoga County and also along the lakeshore where banding may not be as consistent during the heaviest part of the event. I do think there’s opportunity for prolonged enough banding with good rates to see totals of at least 6” wherever the jackpot zone occurs…with a decently large area seeing at least 3”. Potential caveats are the Euro is weaker with the surface low than the GFS/NAM/Canadian/UK and has a shorter window of good lake effect. The Euro did trend some towards the more amped camp this run. The GFS has remained extremely consistent with its solution. This gives me decent confidence the event plays out similar to what the GFS would imply, but it’s not 100% confidence yet. With that said, here’s my general thinking…I’ll put hard numbers on this Friday evening.

THE TIME HAS COME! For the first time this fall, we are looking at the potential for a decent lake effect snow event in Northeastern Ohio late Saturday night through Sunday night. A fairly potent low pressure will track northeast across Lake Erie Saturday evening and push a strong cold front across Lake Erie. Behind this front, the coldest airmass of the season thus far will move into Northeastern Ohio on a west to at times west-northwest wind. This system will drop moderate to heavy snow across Iowa, southern Wisconsin, northern Illinois, Michigan, far northern Indiana and perhaps extreme northwestern Ohio. Very little synoptic snow from this system will fall in Ohio outside of far NW Ohio, where perhaps a few inches may fall Saturday into Saturday evening. 925mb temperatures will fall below freezing quickly by mid to late Saturday evening across N OH, signaling any remaining precipitation changing to snow. The deformation zone will miss NE OH well to the northwest Saturday night due to the low track being to our northwest, so any synoptic snow showers will not add up to much. The attention will then turn to Lake Erie later Saturday night as instability increases off the lake and winds become better aligned out of the west. The GFS and NAM (NAM shown above) both bring the winds around to westerly with moderate lake induced instability, moisture to about 8k feet and high inversion heights by 6z Sunday. This should allow some lake response to begin late Saturday night. With a mainly west wind, you’d expect the best snow to occur over Lake, Geauga and Ashtabula Counties in NE Ohio into NW PA, with northern Cuyahoga County (especially northeastern) possibly getting grazed. The question at this point is how strong is convergence over the Snowbelt, and is any upstream lake moisture involved? The NAM and GFS both briefly get winds to a little more WNW for a few hours Sunday morning, before ridging starts building in and the winds starts slowly turning more W and then eventually SW. The GFS has a similar, brief backing of the winds to a slightly more WNW direction early Saturday, so this is actually pretty good agreement among the two American models at least. Both models have extreme lake induced instability (lake to 850mb temp differentials of 20-22C, lake to 700mb temp differentials of 30-32C, lake to 500mb differentials of near 40C, and 750-1000 J/KG of lake induced CAPE, to go with inversions remaining near 10-15k feet), moisture to at least 7-8k feet, and fairly negligible low level wind shear. This would seemingly support any bands producing heavy snows. As winds start backing Sunday afternoon thanks to ridging building in, convergence should remain strong/possibly strengthen across the northern primary Snowbelt, but banding will also start slowly shifting up the lakeshore. Inversion heights and moisture depth really start diminishing Sunday evening after remaining decent to favorable through Sunday afternoon, and by midnight Sunday night any lake effect should be light to moderate and confined to perhaps northern Ashtabula County and Erie County PA as winds continue to back as ridging pushes in. The NAM maintains decent lake effect conditions at Erie until midnight Sunday night, before ridging pushes the winds completely offshore, inversions crash and moisture goes away. This should cause an end to the lake effect in NE Ohio by midnight Sunday night. In general, the ingredients appear to be there for heavy lake effect snow: -Instability is moderate to extreme late Saturday evening through Sunday evening -Moisture depth is between 7-10k feet through Sunday afternoon -Wind shear is fairly weak -Steep lapse rates and high RH through the snow growth zone much of the event -Long fetch The big questions are when does convergence flare up and help support a strong, single band, exactly where does the band setup, does the band move much, and how will Lake Michigan moisture possibly influence lake effect off of Lake Erie?

That's sort of what I'm thinking for a preliminary jackpot zone..:and id agree that a storm moving more E as opposed to cutting would allow the winds to have a more northerly component. I'm going to try to have a more substantial post tonight but it will probably be pretty late.

Although I do share your concerns that you and dta may be too far south by a little bit, it should get into Lake and northern Geauga at the least...it does look like every model gets wind around to at least west (at least to me lol)It looks like they put the mention in their HWO as far west as Cuyahoga

The GFS remains consistent in its idea of about an 18 hour window for very good lake effect with a W to WNW wind...the 12z Canadian looks similar to the GFS in terms of lake effect. The Euro has the low that tracks to our north winding up more to our northwest on Saturday which delays the cold some and results in a shorter window. At this point I'm pretty confident in accumulating lake effect, but not confident on amounts. Something like the GFS or Canadian would be a significant event, likely featuring a single convergence band into the primary Snowbelt with heavy snows for a good 18 hours...the GFS has about an 18 hour window from late Saturday evening through much of Sunday afternoon with extreme instability (near or above 1000 J/KG of lake induced CAPE) and good moisture, with well aligned winds at west or WNW...I'd be shocked not to see totals pushing a foot in such a scenario. On the other-hand, the Euro would be much more pedestrian (but still likely accumulating LES). With a W or WNW wind this looks like a primary Snowbelt event...Lake, northern Geauga and Ashtabula Counties east into NW PA. The areas that could also do well depending on exactly how much of a northerly component the winds have would be NE Cuyahoga and the rest of Geauga. Still lots of details to work out (and lots of time for change)...so I'm trying to temper my expectations (especially since the Euro hasn't been consistent on a good event)...but a GFS and Canadian scenario would be fun.

Going for a repeat this year, just 10 days later

The models seem to be continuing to come into agreement on a cold enough airmass for the first decent LES of the season this weekend. There's still some time to change, but if the general idea holds for another day I'd become pretty confident in the cold happening. Just for kicks, since this is the first GFS run that really agreed with the Euro on the amount of cold for this weekend, the 12z run looked decent in BUFKIT. Not great, but decent. Plenty of instability and enough moisture with W to WNW winds. The window for this possible weekend event wouldn't be tremendous, possibly not even more than 24 hours, but there could be enough to work with to get a warning criteria event in the primary Snowbelt especially given a W to WNW event favoring a single band. Later on during the week of Thanksgiving there's still a lot of uncertainty. The ensembles have been consistently hinting at a second shot of cold possibly around Thanksgiving or Black Friday and then perhaps a third shot later that weekend...but aren't agreeing on where each shot of cold dumps in the US which has large implications for us. It's possible one or both of those shots dumps in well to our west, which would quite possibly limit how much LES we'd get once that cold eventually sloshed east. But, we could have something to track in the fairly near future...I'm personally more curious in what happens Thanksgiving week just because I'll be up there, but this weekend could bring something half decent.

The GFS and Euro have really trended cooler for this upcoming weekend and have a WNWish wind...so I'd have to think if the idea holds that the first plowable LES could be on the table in about a week. As for Thanksgiving week when I'll be in town, the idea seems to be for a second, possibly larger surge of cold somewhere later in the week. Whether or not this second dump of cold comes in far enough east to give us another shot of LES later in the week is debatable, but that's a long ways off.

BUF just went with an advisory for SW NY and CLE probably should do the same for NW PA. Probably too warm for much more than heavy snow or graupel showers in NE OH that maybe drop a quick coating but not more. Edit: although let's see how cool eastern Cuyahoga and Geauga can get over the next hour with all that moisture still over the lake.

So far it looks like NW PA and SW NY have struggled to change over to snow in the higher terrain, although I think it's very close. In SW NY, most stations under the band are in the 30s, with several at 35 or cooler, which given heavy precip rates is probably resulting in snow falling. In Erie County most stations are in the upper 30s/lower 40s, however a couple of stations under a heavier band in the NE corner of the county are down to 34-35. The band is really starting to crank now with some 40-50dBZ echoes out over the lake and some lightning showing up south of Buffalo, near Erie and also in the squalls over the western part of the lake. Some deeper synoptic moisture is starting to rotate south over the lake and 850mb temps should cool a tad more over the next few hours, so if the band is going to dynamically cool the column in NW PA and SW NY enough for a change to snow it will do it reasonably soon. BUF has added some accums to the higher terrain downwind of the lake this afternoon, but CLE still ( ) has all rain for everyone till this evening. Given over 1000 J/KG of lake induced CAPE, deep ambient moisture and strong convergence, I'd have to imagine this band will be capable of producing precip rates of a quarter inch per hour or more...so if a change to snow does occur, I still think my idea of a "surprise" advisory or warning event in the higher terrain in NW PA and SW NY is on the table. For NE Ohio, the trough swings through around rush hour and brings the winds around. Instability and moisture are still plenty favorable for decent precip rates at this point, although the temps around 700mb may warm just enough to prevent much if any lightning from occurring with any lake effect precip this evening. Surface temps have warmed into the mid 40s, but temps aloft are plenty cold enough and dew points are near 30, so any half decent squalls should still produce wind swept graupel or wet snow. In fact a station along the lake in NE Ashtabula County just dropped into the 30s under the heavier band.

The lake effect potential today into tonight is interesting. I don't really have time to do a write-up because it's 3AM and I have a dynamic met exam at 10AM...however, deep ambient moisture to 10-15k feet, inversions of 10-15k feet and strong WSW winds should cause a strong convergence band to develop along the eastern lakeshore by later this morning. This band should hug the Lake/Ashtabula shoreline and move into NW PA and SW NY and could produce thunder and lightning. The winds gradually go more WNW and eventually NW later this afternoon into this evening as a trough moves through, which should push a decent band into the Cleveland metro before a more disorganized multi-banded setup develops by mid-evening. Lowering inversions should cause a weakening of lake effect tonight. 850mb temps will be right around -5 to -6C this afternoon and evening, possibly warming a bit tonight, with 925mb temps near 0C...both of these values are pretty marginal. I'm pretty hot on the idea of the convergence band along the eastern lakeshore into NW PA and SW NY kicking butt this afternoon with probably some thunder and lightning...so I think there's a better than 50/50 shot that dynamical cooling does the dirty work and allows for mainly snow by this afternoon in inland NW PA and SW NY under the band. With the possibility of heavy precip for several hours over similar areas, an advisory or even warning criteria snowfall amount in the higher terrain here wouldn't shock me...Lake and Ashtabula don't have the benifit of higher terrain, but some sloppy accums would be possible if the heavy band can in fact hug the lakeshore. In Cleveland proper and Geauga/Trumbull Counties the short duration nature of the heavier snows will also make accums more questionable...but heavier bursts could cause a quick, slushy accum late this afternoon into early this evening, especially in areas that have the benefit of a little more terrain. The bigger story may be an unanticipated impact on the evening rush. Most forecast outlets appear to be expecting all or mainly rain this afternoon, but with cold air aloft, any heavier showers should easily fall as snow or graupel. With winds possibly gusting to 35-45MPH, any heavier snow showers could cause quite a wintry scene for brief times, even if they don't accumulate. We shall see. Perhaps trying to understand cyclostrophic balance at 2AM has made me insane.

Interesting. I will say that STRONG Ninos tend to still have a diminishing effect on NE Ohio snowfall, as with a dearth of synoptic storms and generally more mild air in general (which limits LES) would still dampen snowfall somewhat. However, having LES to fall back on makes an all out disaster much less likely as it only takes a couple of good cold shots to rack up snow quickly in the Snowbelt. I'm starting to think some modest accums on the order of an inch may be possible Friday night into Saturday in the Snowbelt...with a WNW flow and 850mb temps on the GFS and NAM of -6C to -8C, it should get cold enough inland under any bands for accumulations. The big inhibiting factor will be lowering inversions and gradual drying Friday night which will limit how much precip falls, but it could still be enough for some light accumulations in the Snowbelt.

MAYBE some graupel or wet snow flakes mixing in Friday into Saturday? If I don't see any snow when I'm in NE Ohio over Thanksgiving I suspect I may be waiting till Christmas

I don't think the lake freezing in January will be an issue this year unless December goes against essentially every forecast out there. Even if we end up with somewhat below normal snow, one or two nice southern stream systems combined with a couple good LES events (by good I mean foot plus in the Snowbelt) would still make it fun...especially if it's backloaded and we get a nice busy period in maybe February.

A pretty good band has been over NEOH and dta for a while, I suspect they'll wake up to an inch or so of snow on the ground. CLE put out a special weather statement...parts of NW PA did alright it seems: SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE CLEVELAND OH 236 AM EDT SUN OCT 18 2015 OHZ012>014-022-023-089-PAZ001>003-180845- LAKE-GEAUGA-ASHTABULA INLAND-PORTAGE-TRUMBULL-ASHTABULA LAKESHORE- NORTHERN ERIE-SOUTHERN ERIE-CRAWFORD PA- INCLUDING THE CITIES OF...MENTOR...CHARDON...JEFFERSON... RAVENNA...WARREN...ASHTABULA...ERIE...EDINBORO...MEADVILLE 236 AM EDT SUN OCT 18 2015 SOME OF THE MORE PERSISTENT AREAS OF LAKE EFFECT SNOW HAVE STARTED TO PRODUCE ACCUMULATION. LOCALLY SOME OF THE HIGHER TERRAIN OF ERIE COUNTY PENNSYLVANIA HAS SEEN UP TO 2 INCHES. THE REST OF THE SNOWBELT HAS SEEN ONLY SPOTTY ACCUMULATION OF LESS THAN AN INCH. THE BANDS OF LAKE EFFECT SNOW SHOWERS WILL CONTINUE INTO LATE MORNING THEN START TO DECREASE. SOME HIGHER TERRAIN AREAS COULD SEE ANOTHER INCH OR TWO OF ACCUMULATION. EVEN THOUGH ROADWAY TEMPERATURES ARE STILL ABOVE FREEZING...THE HEAVIER BURSTS OF SNOW WILL STILL COVER THE ROADS AS THE RATE OF ACCUMULATION EXCEEDS THE RATE OF MELT. AREAS OF SLIPPERY ROADS WILL BE PRESENT THIS MORNING SO MOTORISTS ARE URGED TO USE CAUTION AND PLAN ACCORDINGLY.

Looks like showers of graupel/snow have been fairly numerous over the last few hours. You're on the board for 2015-16 at least!

I'm sort of interested in Saturday night wherever the Huron connection sets up. Looks like a little shortwave moves through with a period of good moisture and extreme instability. 850mb temps of roughly -6C in a NW flow are sort of meh, but if the band can setup in the higher terrain of Geauga or (more likely) NW PA a 1-3" type accumulation wouldn't shock me by Sunday morning.

The recent NAM and GFS are looking better for a possible burst of lake effect precip Saturday night...but with 850mb temps of around -5C by that time and a northwest flow blowing lake modified inland and preventing a consolidated band from setting up, I still don't think there's any accums.