 Speaker would be Lance Boser. Lance also gave a talk at the colloquium. So thanks again, Lance. When are you ready? Okay. I'm doing this at Rob Bell's house because there was a massive internet failure at my house about an hour and a half ago. Naturally, the atmosphere knows what I was up to or not up to is the same to be. All right. So I'm going to talk about it's not getting full screen Lance, sorry. I always forget to do that. I always forget something. It's the one next to this sliding climate. Hold it there. There we go. Okay. First of all, I want to thank you and Judith for putting on this remarkable colloquium. Having done this, I know just how much work it is, especially behind the scenes to make it work. I also want to acknowledge my co-authors, two of them are students in the colloquium, Tyler Light and Alex Mitchell, and other Albany graduate student, Minghao Chao. All right. So I want to talk about the contributions of Recurving East Pack and West Pack Cropical Cyclones to an extreme weather event over the Western Conus in September 2020. And the event in question is it had a lot of California wildfires, the antecedent conditions and widespread drought. So this is becoming a regular occurrence on the West Coast, but this was quite the event last year. And if we look at, say, the water, some of the patterns that led up to this was the trough off the shore that allowed moisture from mid-levels to reach the West Coast and steep lapse rates that favored dry thunderstorms with lots of lightning. So in California, it was the 30th dry of August in 126 years in through here. And you look at the Western Conus vapor pressure deficit is near the 100th percentile pretty much everywhere. The monsoon season this year are sure different than last summer. So what do Recurving and Transitioning Western Pacific Tropical Cyclones have to do with everything in through here? Well, they lead to downstream barriclic development and, in this case, deep dateline trough formation, upper-level ridging in Eastern Alaska and Western Canada, surface anti-cyclogenesis over Southwest Canada that drove the easterly flow to the coast and called strong sea-level pressure rises across the Great Basin and the in the strong West Coast easterly flow. And there was eventually a big cold outbreak that followed the heat wave. So everything was happening all at once. All right, there were three West-packed TCs in particular, Bavi, Mesaik and Haishen in there. And they all were moving mostly northward. And these are the kinds of TCs that you have to pay attention to because as they move northward, they can perturb the North Pacific jet stream. And that can lead to downstream barriclinic development. So we're going to show you some overview maps first. We're going to look at it from a dynamic tropopause perspective on the two potential vorticity unit surface. And we'll look at PV and the 300 to 200 hectopascal irrotational wind and 250 millibar winds. Take away from these maps is going to be that West-packed TCs perturb the downstream flow. And the maps I'm going to show you are courtesy of Heather Archambault. So here's the first one, a 12C in the August 26th of August 2012. This dynamic, we're going to see these dynamic tropopause maps. The colors, the warm colors, the higher potential temperature. So here's the TC right in here. Here's a trough to the West. And then you see this big anisoclinic mushroom type cloud. This is the impact of anisoclinic wave breaking when a TC interacts with the mid-latitude barriclinic trough. That was Bavi. Here's May 2nd, 0C the 3rd, September. You again see the trough to the West. The TC isn't here. And here's Haishen coming in, coming in to join the party. Negatively tilted trough to the West. These are the winds on the dynamic tropopause. And again, a big anisoclinically curved outflow and with a further downstream trough. So if we go now to TC Haishen, on the 7th of September at 0C, this is getting look old. Another trough to the West of the TC as the TC interacts with the trough. Big anisoclinically curved outflow, wave break, anisoclinic wave breaking and a downstream trough. So instead, if we look at, go back and look at now the PV, the 250 millibar winds and the 300 to 200 millibar hectopascal, irrotational wind vectors. So the solid contours are PV and the wind vectors are the irrotational winds and the 300 to 200 millibar layer. The red area is the asset, the 6 to 400 millibar layer. So this is the weakest storm. This is Bavi in through here. But notice the PV max is up here. Bavi is in here. Note that there's negative PV infection by the irrotational wind, which is helping to build the ridge. Now we look at Masek. Again, it's a stronger TC. You can see the upstream trough here. Here's Masek right here. The upstream trough, it's interacting the trough, but note the strong negative PV infection by the irrotational wind, which is contributing to the ridge building. Now in a rerun, here's Haishen four days later. These are identical. This is just the western one. The left one is in the western Pacific and this is the north Pacific. So you can see the downstream impacts. Again, strong negative divergent outflow from the irrotational wind and that is being driven by latent heat release. So that's the connection between between the the perturbation to the PV waveguide and the deep tropical moisture associated with the tropical storm. And here's the same thing down here, but further east and you can see the effect of the downstream bear clinic development. You have this big deep trough building the ridge on the off along the west coast and again with negative PV infection by the irrotational wind and strong divergent outflow. So the takeaway from that part, recurring West Pact TC is perturbed to Westerlies and induced downstream bear clinic development. Negative PV infection by the irrotational wind further resists downstream bear clinic development and ridge building. And if you don't get the moisture distribution right and you don't have the vertical distribution of diabetic heating properly done, your forecast is going to contain a lot of errors. Okay, but wait, there's more. East Pact TC's joined the party. So we had Polward moving and weakening East Pact TC's Elida, Fosto and Genevieve in August 2020. There are the tracks in through here, but the East Pact TC's are different. They're typically weakening TC's. They're not like the category three and category four ones in the Western Pacific. And so the tendency is to dismiss them because they weaken the colder sea surface temperatures. And as they get away from the warmer sea surface temperatures, they tend to weaken, but they have other impacts in terms of moisture. So what I call trough off the coast pattern between the eighth and 21st of August 2020. So let's look at some mean 500 millibar height for this period on the top, anomaly on the bottom, on the right hand column is precipitation water anomaly on the bottom. So you see there's a big ridge over the western part of the United States in the core of the anomalies over Nevada, Northern California and Southern Oregon in here, a trough offshore. So there's anomalous southeastally flow. That will help facilitate moisture polward moisture infection from those recovering Eastern Pacific tropical cyclones. In the terms of precipitation water anomalies, positive anomalies almost everywhere along the California coast and offshore. Big negative anomalies you might imagine with the wave in the ridge and the very dry air inland. So here's the effect of the offshore anomalous trough in there and the track of the anomalous of the tropical cyclones up the coast. Now, what does that do indirectly? It's not like a category one TC, but watch what happens. And this is the case of the first one fasto in here. So you can see the moisture if we play this late again, notes how the moisture is streaming forward into California, mid-level moisture in Northern and Central California. And what is that going to do? It's going to support some elevated convection. So if we look at the North Pacific flow evolution subsequent to the recurrence of those three Eastern Pacific TC's. And we have it in a loop in through here in the Pacific. And now you can see the effect of the TC's. You can see how the jet amplifies in the downstream trough and ridge builds on the left-hand side. The thickness is there, 250 millibar winds. On the right hand side is the 500 millibar flow. And you can see towards the end, the big ridge of the TC's as the whole pattern flow pattern amplifies. Now, if you're here and lead to this big ridge on the west coast, and then a trough drops down to the east, that was the subsequent cold wave during that period. So here's an intermediate synopsis about the TC's. The recurring west-pack TC's induce downstream flow amplification, mid-Pacific trough and an Alaska Northwest Canada ridge. Decaying poleward moving east-pack TC's enable mid-level tropical moisture to reach Northern or California and Oregon. The tropical mid-level moisture fuels the outbreaks of dry lightning storms that sparks an outbreak of wildfires. So let's look briefly at some impacts in here. There's this spectacular image of lightning over the Bay Bridge, San Francisco Oakland Bay Bridge. This is a very unusual site for mid-August. Here's a radar lightning loop in California showing all the lightning and the convective cells. You would think it would be a lot of rain reaching the surface, but it wasn't in there. And here's like lightning complexes on the air, the lightning and the storm fire complexes on the left and on the right. They have the tracks of the lightning cloud to grow out lightning during this period. So over very dry soil, that's that mid-level moisture, which is supporting that. And these are what was going on. Wildfire spread by flying embers. And I love this image because this is taken by the Reno National Weather Service Doppler radar. Here's the California Nevada border here. So you're looking west. Here you have an anisoclinic tornado. Flow away from the radar, towards the radar, in through here. Likely fire tornado, according to, noted by the radar operator in there. And there's a ground truth verification of the anisoclinic tornado at the same time. That is just a spectacular image. So now let's look at the during the ridge building on the western conus ridge building in through here. This is 12Z in August. You're going to see some maps that look like this. Sea level pressure is in solid. 1,005 thickness decometers in red and blue. And then principle water is the grayscale shady. So back on the 12th of August in through here, you can see some of the moisture sort of sneaking up. Here's the first of the TC's in there. And that's Alita. Then the remnant moisture in through here. This will be Fausto coming in trough off the west coast. Here comes the next one in there. So that's remnant of Genevieve. Again, with the weak trough off the west coast, the moisture sneaks up along the coast at mid levels, but it's not enough to produce. And this is all remnant from the tropical cyclones, but it just goes into the ridge building with the trough offshore in through here, 28th of August in there. And then you can see what we described earlier as the big ridge builds in through here. At this time, ridging in substance, that's a result of the recovering western Pacific tropical cyclones. And as that ridge, whoops, and as that ridge builds, you can see the ridge poking its way into the Pacific Northwest, and you get the easterly flow gradient to the south. And that's driving the wildfires towards the towards the coast. Now then there was a cold surge that followed. And so we look at some standardized anomaly maps for this period. On the left is the 500 millibar height, height and standardized anomalies. On the right are the 850 millibar heights and black contours. And the temperatures are dash red contours. And that standardized height, standardized 850 millibar temperatures on the right, standardized 500 millibar temperature on the left. You can see you're looking at three and four sigma ridge here on the 6th of September. All across the west of the United States, it's very anonymously warm between two and three sigma standardized anomalies. So as we go through, one day later, I'll go back, watch how the ridge builds in this final act from the last of the western Pacific typhoons, tracking it, pushing it up, folds over, trough treatments on the east as the ridge folds over, and it's the chronic way breaking tries to get going. The trough drops down the eastern side, and then it comes down across the Great Basin, bringing significant cold spell to that area. And then we can look at it here in loop mode. On the left, sea level pressure, 1,005 thicknesses of 250 millibar winds. And on the right, 700 millibar heights, precipitation water is shaded and what temperatures are in dash red contour. But you can see in the 700 millibar circulation, and when it reloops and through here, northerly flow circulation comes down in there. The moisture is directed to the east of the continental divide. All right. This is remarkable. This is the 24 hour forecast temperature change, verifying 21Z on the 8th of September by the European center model. There's a 59, a couple of 59 degree Fahrenheit temperature drops in a 24 hour change. That's how impressive that cold air surge was that followed that followed that. And I love this image. These are taking one day apart. This is the sky on fire literally the day before. And then there's snow on the ground is 101 and four columns. And the next day, there's snow on the ground. Talk about changeable weather in there. All right. So say something about the conus extreme weather events and the wildfire impacts as we get towards the end here. Really hot in California. Look at these temperatures on the coast and the areas above 100, 110. And through here, 106, 102, 109, 117 in there. Very, very hot. Heat and fire where the active wildfires. And you can see pretty much all throughout the northern and central parts of the state and the hills. And this is a remarkable pyrocumulus in there. Mono lake is in the foreground in there. And you can see the outflow of smoke, hay, edge, edge in through here. Pyrocumulonimbus with anvil. Remarkable picture. Another view of it. And you would think of looking down a massive thunderstorms going on, but you can see there's very little shear because the anvil is spreading out in both directions in there in the, in the ridge. So what were some of the impacts in the poor air quality in here? Here's a remarkable image. While the flow was off shore, you can see the fires burning in Oregon. The flow was off shore. And then it would come in, come inland when it reloops in through here. Really, really thick smoke. So there's poor out air quality up and down the west coast, a day without sun, the golden gate bridge in the red orange looking like the end of the world. I mean, look at that image of San Francisco. That's ridiculous. And the poor air quality three days later, off the charts, poor air quality pretty much everywhere up and down the west coast and parts of inland areas of Washington and Oregon. Acreage bird. Okay, I'm almost done. Acreage bird record in 2020. And an operational model forecast issue here, erroneous progressive flow. So I want to compare the GS 15, which was then operational, which was the GFS v 16, which was coming into play. So here's the 156 hour forecast. And here's verification, the lower right corner, the new GFS current operational there. The model of 156 hours could not get the trough to cut back into the mountains. And that's the difference field of the lower left, because it couldn't get the ridging right on the western coast. At 168 hours, you can see the the newer model was even worse than the operational model in having a two progressive a trough compared to reality. 180 hour forecast was even worse. So it's the systematic bias of being too progressive in the in the in the in the forecast. And that had a huge impact on what happened in the in the west. So the conclusions would be that the east pack top of the TC moisture field thunderstorms that initiated west coast wildfires, it missed a heat wave. West pack ET events resulted in a Western North America Ridge and multiple western conas extreme weather events. Troughs cresting the ridge facilitated a cold surge that ended a record breaking heat wave over the Great Basin and Rockies, which produced record breaking low temperatures. A couple days later, anacyclogenesis behind the cold surge drove hot dry gusty down slope winds that further fueled the West Coast wildfires and widespread wildfires resulted in masses spoke plumes that spread across much the conas and the North Atlantic. And the NCEP models, a GF model, GFS model struggled to predict the large scale flow that drove multiple Western conas extreme weather events. I'm done. Thank you, Lance. It's really interesting. Any questions for Lance? So I had one, Lance, in terms of tropical variability and Eric had mentioned this in terms of like the MJOs, teleconnection into the East Pacific and modulating the TC activity there during this event. Was there a connection to the tropical waves? That I don't know the answer to that question yet. Okay. What I do know is what I showed you. Yeah. But that obviously is the next step. Right. Great. Yeah, I don't see other questions, Lance, on the chat or the raised hand. If there are other questions, they can be posted on Slack and then we can mention it to you for a response. Sure. I think everyone's tired and not a lot of people like to look at weather maps these days. Oh, no, it's great to bring in the, oh, Jan has a question. Go ahead, Jan. Yeah, thanks for, can you hear me? Yes. Yeah, thanks for this very interesting talk. I learned a lot. You showed the prediction at the end, I think five or six days ahead of the cold air coming down from the north. So you said the ridge wasn't predicted. Well, do you have an idea what, where the errors are and is it because it relates to the TC. It all originates back to the TC's in the western Pacific and the negative PV advection by the irrotational wind due to a strong diabetic heating in ridge building and downstream barric link development. Okay. Thanks. We follow up to that, Lance, in terms of uncertainty in prediction of the TC's, was there a large uncertainty in terms of like the cone of the ensemble spread for the individual TC's? Yeah. That's a good question, Anish. I don't know the answer to that question but the errors are growing rapidly downstream and they're related to the release of latent heat which is manifest by the strength of the irrotational wind and the associated negative PV advection by the irrotational wind. Okay. Great. Yeah. Thanks, Yan, for the question again and thank you again, Lance, for the interesting talk. With that, we'll end today's session for the workshop. Thanks again to all the speakers, both Modming and the second session.