OHweather

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.

I don't think anything will stick right now. The airmass gets pretty dry by Friday night and through the weekend, and it's a short fetch. The airmass is also a bit warmer than the October 2013 event. So any showers could have some flakes mixed in Saturday or Saturday night, but the only chance at any accumulation would be in the higher terrain of NW PA if a Lake Huron band can establish itself...but even there I wouldn't expect much.

WITH THE COLD POOL ALOFT...LAKE EFFECT RAIN/SNOW SHOWERS WILL GET GOING FRIDAY INTO SATURDAY BEHIND THE FRONT WITH NORTHWEST FLOW OFF THE LAKE. NOT SURE HOW MUCH THOUGH WITH VERY DRY AIR IN PLACE ON SATURDAY AS HIGH PRESSURE FILLS IN BEHIND THE FRONT. AT THIS POINT...GIVEN THE DRIER AIRMASS...RESTRICTED THE COVERAGE TO THE AREAS IMMEDIATELY DOWNWIND OF THE LAKE.

Apparently those squirrels haven't seen recent runs of the CFS I'm a bit nervous about this winter...hopefully we can get some lake effect events even if we overall have a slow winter.

Some 4-5"+ amounts in Lake and Ashtabula Counties! Very impressive 1100 PM HEAVY RAIN CONNEAUT 41.93N 80.58W 09/12/2015 M5.45 INCH ASHTABULA OH MESONET 1100 PM HEAVY RAIN CONCORD 41.40N 81.85W 09/12/2015 M4.08 INCH LAKE OH MESONET 1100 PM HEAVY RAIN EASTLAKE 41.67N 81.42W 09/12/2015 M3.38 INCH LAKE OH MESONET 1100 PM HEAVY RAIN NORTHEAST OHIO APT. 41.78N 80.70W 09/12/2015 M2.68 INCH ASHTABULA OH ASOS 1100 PM HEAVY RAIN CLEVELAND HOPKINS AIRPO 41.41N 81.85W 09/12/2015 M2.76 INCH CUYAHOGA OH ASOS 1100 PM HEAVY RAIN ERIE AIRPORT 42.08N 80.18W 09/12/2015 M3.74 INCH ERIE PA ASOS It also appears that there were two cheap tornadoes in the Cleveland area this weekend; a brief touchdown near I-90 and Crocker around 5:30PM on Friday...there's video of a condensation on the ground with what appears to be some debris flying up of that tornado...and last night a little after 5:00PM a waterspout made landfall in Vermillion and caused minor roof and door damage to the cities maintenance garage. Hopefully the NWS makes them both official because there's strong evidence for both tornadoes being on the ground...the Vermillion waterspout/tornado even had a small radar signature, which is impressive for a waterspout that far from the radar site.

I saw one circulation just off shore near Bratenahl on radar, but nothing else that made it close to shore in Cuyahoga County.

Cuyahoga county getting a lot of rain now. There have been several small circulations on radar with the showers over the lake, and I have reason to suspect a waterspout may have moved onshore in Vermillion and based on a rumor of debris in the air and a store being damaged in Vermillion (I have no way of verifying the source). Edit: pictures of minor roof and door damage to a building in Vermillion

CLE ended up going with a flood advisory for Ashtabula County with some flooding reported in Conneaut. They said up to 2" fell in that band after 10AM this morning on top of what fell last night. The latest RAP runs are absolutely off the charts for this evening with strong omega, decreasing shear above 10k feet and the aforementioned high RH air and instability. We shall see what happens.

It still looks like we'll get a little trough to drop across the lake in a few hours. The NAM and RAP both have lake induced CAPE increasing to over 2000 J/KG by late this afternoon with humidity up to roughly 15,000 feet and well aligned winds up to about 10k feet. I'd have to think thunder/graupel and possibly waterspouts will accompany any activity later along with heavy rain. There's been a persistent lake effect band in northern Erie County PA into eastern Ashtabula County and the KHZY ASOS (or is it AWOS? not sure) suggests that radar is under-estimating rates beneath the band by at least half if not more. HZY has measured 2.12" of rain as of noon and that lake effect band is probably producing 0.25-0.75" per hour rates beneath it so there's probably a lot of ponding there.