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OHweather

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OHweather last won the day on September 30 2019

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  1. There's definitely a signal for a deep storm next weekend...is it rain, is it snow...on the coast or inland? Who knows. But that's a lot of energy running around trying to phase, and I'd expect models to be all over until we're much closer in. Even if it's mostly rain for the coast, an intense storm like that would be way more interesting than anything else we've seen lately.
  2. A few quick-ish comments, since I don't have the time to put together a more complete write-up this week. Some of these thoughts on tropical forcing and the GLAAM echo those of @Armando S and @Snowy Hibbo over the last few days. What are the main problems in this pattern? A very strong and coupled stratospheric PV and lingering influence of what was a dominant +IOD event. Several members here successfully predicted those concerns in the fall (I became too optimistic about those issues improving too quickly, admittedly). The strong and coupled stratospheric PV supports a +AO, +NAO, +EPO and western North American troughing, much as we've seen, and much as many model runs have unsuccessfully tried to get rid of. I don't think we permanently shake either of those 3 features until we weaken the stratospheric PV. This shows how strong and coupled the PV has been since early January, with a persistent and strong +NAM (AO) throughout the troposphere and stratosphere...it's impressive: The recent strong MJO propagation and sharp AAM increase are the most significant attempts yet to disrupt the strong PV, though the effects are not as swift and significant as hoped yet. The AAM situation is improving...as has been pointed out here and on Twitter, an initial sink in momentum in the subtropics did not allow the added momentum in the tropics to get deposited into the higher latitudes...with a belt of higher momentum persisting in the sub-polar latitudes, likely a result of the coupled PV (and indicative of a +AO): January 16th AAM by latitude: We have seen some improvement of that, though it's still not optimal: A positive East Asian Mountain Torque will add momentum in the mid-latitudes for the foreseeable future, with a particularly strong push in the short term and potentially again in the day 10-15: Assuming momentum increases in the mid-latitudes as the +EAMT extends the Pacific jet over the next 2-4 weeks, there would be better potential to disperse that into the higher latitudes, create tropospheric blocking, and disrupt the stratospheric PV at least some. As the +IOD's influence continues to slowly diminish, the low frequency forcing in the central Pacific should have a slightly greater influence. There may be a decent uptick in Pacific forcing in early-mid February when the Kelvin Wave that briefly gives us a weak phase 5-6 RMM next week interacts with the low frequency forcing over the Pacific, and both the CFS and EPS have at least modest low-frequency uplift over the central/western Pacific through much of February (EPS shown): Plus, as Armando pointed out the other day, as wavelengths shorten the Indian Ocean forcing itself does become a colder signal. So, tropical forcing doesn't look to favor prolonged warmth over the next few weeks. Basically, in terms of the PV: It's strong and resilient now, but climo says it should start weakening soon, and an increase in momentum in the mid-latitudes due to a generally +EAMT for the next few weeks may help start that process. Any significant upticks in Pacific convection would also help weaken the PV. Is this enough to weaken the PV in time to salvage most of February? In terms of tropical forcing: It doesn't look to favor prolonged warmth in February, though we will need the strat PV to weaken some for the generally neutral to favorable tropical forcing to have a more desirable impact. As the +EAMT extends the Pacific jet starting next week, the PNA should rise. However, until the stratospheric PV weakens more substantially, the EPO, AO, and NAO will all be favored to stay positive. This may change as early as 10-15 days from now, though I suspect we really need to wait until about a week into February for these changes to become more likely, as this is when the op GFS and EPS, which have done well with not trying to weaken this strong PV this winter, attempt to show some warming in the stratosphere. We still average slightly more than half of our snow from here on out, and in the Mid-Atlantic February is the snowiest month on average, edging out January. The road gets narrower as we head through February for deep cold and prolonged snow cover, though there is plenty of time for snow. I'll believe sustained cold when I see it, but if we can weaken the PV quickly enough most of the sub-seasonal forcings lean cold in my view for the eastern U.S., and the CFS and EPS weeklies develop a seasonable to chilly pattern by the second week of February and largely continue it through the month. There's still reason for hope, but I'd be cautious until we see more legitimate signs that the stratospheric PV is in fact going to weaken notably.
  3. The EPS has some warming, especially 10mb and above, starting around day 10. I'm not sure if it would be enough to make a big difference, but it's the most warming the EPS has shown in the stratosphere in at least a few weeks.
  4. We’ll have several delectable STJ shortwaves to work with between the 25th and the first few days of February...will we get enough cold air for one of them to work? Regardless of the exact details at this range, can’t disagree that an active STJ running under a Hudson Bay block is intriguing!
  5. 2.0" of sand here in Hackettstown. I think I've pushed 8" of lake effect off my car that's been lighter than the 2" that was on my car this evening! There wasn't even that much sleet, but the flakes were of poor growth and rimed at times for much of the event. Mixed with freezing drizzle at 23 degrees as the precip let up around 6 PM too. Taken on its own and not in the larger context of this winter, this wasn't a bad little event IMBY.
  6. Serious doubt has certainly crept into my mind the last several days... The MJO getting into Phase 7 should attempt to give us a +PNA and opportunity for a snow event around the end of January / beginning of February, but the strong MJO propagation, +East Asian Mountain Torque and AAM spike are likely not going to have the response I thought they would...especially if the MJO gets into 7 and then dies and re-emerges in phase 5 like the EPS and GEFS show. Aside from a brief window of plus or minus a week around the turn of the month, we will remain in a generally unfavorable pattern through early February if the EPS and GEFS are right with their MJO progression. It's interesting, the analogs for the EPS forcing on StormVista's corporate page are generally cold with plenty of blocking through and through over the next month, but I believe the strong and coupled stratospheric PV and general hostility to sustained Pacific forcing we've seen all season (despite the modest El Nino in the SSTs and lower frequency forcing over the central Pacific) are prohibiting a better response to the current MJO pulse, still. Perhaps the CFS is right with its MJO forecast or perhaps the medium range models are missing the influence of the +EAMT and phase 7 MJO...and heck even the CFS and EPS are both seasonable to chilly in the northeast for much of February...but I have to think the MJO dying before getting into phase 8 and then emerging in phase 5 would allow the utter dominance of the base state since fall, with only a few interruptions, to win out again. If the base state wins out again, the EPS progression would maybe give us another shot in mid-late February which isn't too late for snow, but it is too late to salvage the essence of winter outlooks such as what I put out if we don't see much if any snow until then. I'll try to gather some more coherent long range thoughts later this week after the hectic few days at work surrounding this weekend's largely light event (that isn't bailing out places that need snow) are behind me, and perhaps things look better by the time I do that. But oof I have a horrible feeling hanging over my head WRT the fate of this winter.
  7. Updating these thoughts...obviously, the Midwest is in progress or starting shortly... Boston: 2-4" Worcester: 4-7" Albany: 3-6" NYC: 1.5-3" NW NJ: 3-5" Allentown: 2-4" Philly: 0.5-1.5" Atlantic City: T-1" Lancaster, PA: 1-3" Baltimore: 0.5-1.5" DC: T-1" Roanoke: Near 0 snow, some ice Richmond: 0 Bonus: Cleveland 3-5", Columbus near 0 snow, some ice, Detroit 4-8", Indianpolis near 0 snow, some ice, and Chicago 3-5" and some ice I'm just happy to be getting a half decent snow at this rate!
  8. They all have question marks, but they all can go big if the cards fall right. We just need one!
  9. With all of the waves I laid out starting around the 25th, they all can do anything from significant snowstorm to inland threat (or next to no threat/all rain) to slide off to the south. So we may see some pretty amusing runs, with a few runs occasionally hitting a grand slam (like yesterday's 18z GFS) while others find a way to whiff with every wave. It's not a perfect pattern, but there's no shortage of opportunities with this active STJ and there is just enough of a polar injection the last 8 or so days of January to make it work with any wave that doesn't cut too early.
  10. For the weens...an STJ on steroids and just enough of a polar connection certainly makes the last 8 or so days of January quite interesting... The pattern may not be record cold with a KU threat every 4 days, but there’s some interesting potential over the next two weeks, with 4 things to keep an eye on after this weekend’s sloppy system. Threat 1: Tuesday/Wednesday of next week I ultimately don’t think this one amounts to anything except for maybe the Carolinas/southeastern VA. A fairly potent sub-tropical jet shortwave slides off the Southeast Coast while a lobe of the PV gets displaced into southeastern Canada. I don’t think the two can phase and as is, the trough axis looks too far east for anything to come up the coast without a phase. But, it’s not horribly far off and if this was farther out I’d say to watch it closer. As is there have been some hints that the southern piece may bring some snow to the Southeast near the coast, and that the northern piece may bring snow showers or squalls to parts of the Northeast, even without any sort of phase. Threat 2: Somewhere around the 25th-26th This one is fairly complex, but does have a low probability yet fairly high ceiling. A robust sub-tropical jet shortwave will eject out of the southwest around the 23rd-24th, with what can be called bootleg (but persistent) blocking centered near Hudson Bay. This is a robust piece of energy and some risk for an initial cutter does exist. With the blocking and surface ridging over the top, there would likely be an eventual transfer to the coast after any cutter. If there isn’t an initial cutter, the shortwave looks poised to go negatively tilted as it approaches the East Coast, which could favor a robust low developing offshore and moving up the coast. There would be some needle threading involved for the coastal plain, but the lack of a SE ridge with a trough sitting off the coast ahead of this shortwave and blocking over Hudson Bay does increase the odds of this occurring…again, if there isn’t a cutter. An initial cutter would warm our mid-levels quite a bit along the East Coast as the hour 240 QPF/850mb temp mean image shows…though, if there isn’t a cutter, or if there is a cutter but the Miller B takes over quickly enough, it is a plenty workable airmass. How exactly this storm plays out will depend on the pattern in front of it over the Atlantic, the location/intensity of the Hudson Bay block, and what state the shortwave ejects into the Plains in. Anything from a strong cutter with little snow or just some front end snow in the east, to a cutter with useful Miller B development, to no cutter and a much higher risk of a coastal, to perhaps a southern slider across the Mid-Atlantic seem to be in play based on the pattern and individual ensemble members. Given how moisture-laden this system appears to be, if there is a coastal storm the potential exists for a significant snowfall somewhere. Given the cutter risk and somewhat marginal airmass, at first glance I think this narrowly favors the interior Northeast for snow over the coast, but this is by no means impossible to pull off along the coast either. If there is an initial low that comes out of the Plains and tracks towards the Ohio Valley or Great Lakes, some snow would certainly be possible in the Midwest and Great Lakes. I am curious to see how quickly ridging may try amplifying over western Canada between the 24th and 26th…that has the look of something that may amp more than the ensemble mean suggests at this distance…if that occurred there could be more robust northern stream influence with this system which would increase snow potential. Threats 3 & 4: January 28 – February 1 The ensembles suggest two more waves ejecting out of the southwest the last few days of January, with the polar vortex drifting towards the Davis Strait and allowing colder air to funnel into the central and eastern U.S. With wave after wave moving off the East Coast through this period and potentially developing into a robust storm, the ensemble mean has a persistent 50/50 low feature. With signs of more of a polar connection, a continued active sub-tropical jet, and a combination of an EPO cold press and 50/50 low ahead of any possible system keeping the baroclinic zone to the south, this period is very interesting for the East Coast. However, it is way too early to determine which waves may amp, cut, be suppressed, etc, and it will take quite a while to sort out these wave spacing issues. The EPO and NAO will be worth watching over the next week or two…I definitely can see a brief EPO tank during week 2, as there will likely be cyclonic wave breaks over the northern Pacific starting in about a week. The NAO may dip if any of these storms deepens enough to get a cyclonic wave break over the NW Atlantic, though right now only a small number of ensemble members do that at some point. Either occurring would make things more interesting and I do think we see the EPO try to go more negative than the ensemble means suggest right now during week 2. Overall, the sub-tropical jet will give us plenty of opportunities over the coming weeks for snow across parts of the Midwest, Great Lakes, Ohio Valley, Northeast, Mid-Atlantic, and maybe even Southeast. With still some uncertainty in the pattern and wave spacing issues that will take a lot of time to work out, along with some marginality to the amount of cold especially initially, it’s way too early to guess which wave may develop into a storm and produce snow as there’s a wide envelope of possible solution with every wave ejecting out starting around January 25th. But, there’s definitely potential.
  11. Yeahh that was a low that came up the coast, not a low that came screaming out of the Great Lakes. If this system came in fast enough there'd be some similarities in that you'd have a lot of WAA and moisture running into a robust cold air mass ahead of it, but the slower this trends the less it looks like that. November 15, 2018 has been invoked by many every time we get a WAA snow event since then, and we've yet to have anything else reasonably close to it since then...for a reason. With the continued slower trend since yesterday I'm less optimistic about big snow totals in the Mid Atlantic, especially near the coast...though I still think most start as snow at this point.
  12. As long as we don't trend weaker with the high in front of this, I think most areas, even to the coast in NJ and south of the Mason Dixon line across the interior, start as snow. However, the slower arrival may reduce how long the snow lasts near the coast as others have been mentioning. It's a legit cold/dry airmass ahead of this thing, as long as we don't shred the storm someone likely gets a thump of snow. The high position and low track/strength as progged don't favor prolonged cold air damming...there will be some in-situ damming across the interior that leads to a brief period of sleet or ice up against the eastern slopes of the Appalachians, but nothing significant. The shortwave and primary low are likely going to be too far north to avoid an eventual flip to rain for all of PA/NJ and into the lower Hudson Valley and southern New England, barring wholesale changes. The EPS has continued to trend a little stronger with the N Atlantic thumb ridge and slower with the 50/50 low, resulting in higher pressure over the top and in front of the storm still, along with a stronger cold press in front of it. If I had to recklessly throw out some really early numbers, more for amusement, but based on the relative model consistency and the overall setup... Boston: 2-4" Worcester: 4-8" Albany: 4-7" New York City: 1-3" NW NJ: 3-6" Allentown: 2-5" Philly: 1-3" Atlantic City: T-1" Lancaster, PA: 2-4" Baltimore: 1-2" DC: T-1" Roanoke: 1-3" Richmond: T-1" Bonus: Cleveland 2-4", Columbus 1-3", Detroit 3-6", Indianapolis 1-3", and Chicago 3-6"
  13. I think all of the points you mention are correct...if there's one thing I like, it's that the airmass ahead of the storm is nothing to scoff at...dew points below 0 on the Euro and some radiational cooling Friday night, with 850mb temps of -5C with some room to wet bulb when precip moves in. The high north of the storm has overall trended somewhat stronger over the last few days and the airmass in front of it has not trended warmer yet. A strong low tracking well to the north will eventually warm us up and the flow is not good for cold air damming (just some brief in-situ damming due to how cold/dry the airmass is ahead of this). Basically, I think everyone changes to rain (obviously, to the south and near the coast first), but I do think many start as snow, and with a good shot of QPF there is some thump potential. I'd keep expectations low outside of the interior/northern Mid Atlantic, Upstate NY and New England, but the airmass in front of it makes it somewhat interesting.
  14. The reason we’re seeing the upcoming -EPO is because of the momentum being added in the Pacific. Whoooo boy...
  15. Quoting part of this from yesterday for comparison of today's 12z EPS to yesterday's valid at the same time...note how literally all of the things that I said could bring snow farther south have occurred on the ensemble mean today... Today's 500mb mean at 168 hours (yesterday's quoted for reference): We have a more robust north Atlantic thumb ridge, along with a stronger and farther southwest 50/50 low. We have a more robust -EPO. We have the trough centered a bit farther off the West Coast in response to the EPO ridge, allowing heights to rise a little more over the Rockies. We also have higher heights over Hudson Bay. This all results in a slightly more muted SE ridge, our shortwave in question digging/tracking a bit farther south, colder air pressing in from the NW, and also more confluence over SE Canada, the latter two resulting in higher pressures over the top. These trends have been in motion for a few cycles...first, the 500mb trend since Thursday's 12z run: Here are the SLP trends...note the much stronger ridging over the top on today's run: These changes when taken together would increase the potential for front end snow (and then some CAD in the interior) farther south into the Mid-Atlantic, and would also increase the potential for some snow along and east of I-95. It would also increase the potential for substantial snow from a Miller B in New England, and would perhaps inch that potential slightly farther southwest towards the Hudson Valley and MAYBE N NJ/NYC if the trends were to continue. As it is, this is still less than ideal for the Mid Atlantic, especially east of the fall line, but trends have been favorable today. I think the baseline remains the Upper Midwest, Great Lakes, Upstate NY and New England being favored for a light to moderate snow, with a lesser risk for light snow into the Mid Atlantic (favoring interior/northern), and some risk for a substantial Miller B snow in New England. However, the odds of snow have nudged up in the Mid Atlantic, including along/east of I-95, with higher odds of substantial snow in New England..with those odds ticking south towards areas like NE PA and the Hudson Valley. We're still pretty far out so this can trend less favorably, though nearly every trend in the EPS today is definitely good if you want snow next weekend. Here are the updated 1" and 6" probs, note that they're somewhat incomplete over eastern New England.
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