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00:00:00:26 – 00:00:17:29
Speaker 1
Welcome to today’s visit Satellite Chat and 15th May 2013. And we’ll start off today with guest from is Ken Pryor. We’ll be talking about down burst convective down burst. So take it away Ken okay.
00:00:17:29 – 00:00:47:01
Speaker 2
Yes. Thank you Dan. And, yes, I will be briefly discussing a down burst event that occurred this past Saturday, May 11th. There were reports of high winds and wind damage scattered along the Atlantic Coast region during the afternoon of May 11th, and we’ll go ahead and move on and show the SPC storm report for, May 11th, 2013.
00:00:47:03 – 00:01:37:20
Speaker 2
And we can see scattered reports of wind damage and high winds, from the New York City area and northern new Jersey south to the central Florida coast. And I will be discussing a couple of the most significant wind events, demonstrating the performance of those derived products, for Denver’s potential assessment, specifically the, microburst wind Speed Potential Index and the, vertical data, a different index and how they performed in any event that occurred, both over northeastern Maryland and the Chesapeake Bay region, as well as in the Cape Canaveral region of Florida.
00:01:37:23 – 00:02:14:16
Speaker 2
So first, let’s get started and discuss a more northern event. That occurred, over a, upper Chesapeake Bay region and, northeastern Maryland, in the Baltimore metro area, a line of convective storms or thunderstorms developed ahead of a cold front that was crossing the Appalachian Mountains Saturday afternoon. And isolated storms embedded within the larger frontal rain band.
00:02:14:26 – 00:02:47:14
Speaker 2
And produce some marginal burst activity. First, over northeastern Maryland, there were some reports of scattered wind damage, trees down. Even though the only measured wind gust that I could find from this event was actually over the Chesapeake Bay, measured by the NOAA, Tabasco. Bui, here in this image, the white diamond marks the location of the NOAA Patapsco.
00:02:47:14 – 00:03:20:22
Speaker 2
Bui which is about, 50 miles southeast of Baltimore, over the upper Chesapeake Bay. We can see in this animation a embedded thunderstorm cell that first begins as an a long gated spearhead type echo pattern that evolves into a small bow echo as it moves over the upper Chesapeake Bay. And that would be a tip off that this particular cell had the potential to produce strong winds, as it moved over the Chesapeake Bay.
00:03:20:22 – 00:03:57:01
Speaker 2
I will go ahead and stop the animation here and go through this a little more slowly to show you the evolution of the storm. But first, we begin here, right around 2200 Greenwich Mean Time. And just to point out the cell of interest here that is moving just south of the city of Baltimore, and you can see that, this particular echo has evolved into a spearhead or arrowhead pattern, which has been strongly correlated with burst activity in progress.
00:03:57:01 – 00:04:34:11
Speaker 2
But what I found interesting with this particular cell was that as it continued to move eastward over the Chesapeake Bay, the cell eventually elongated and then, bailed out or took on a bow echo configuration. As we can see here, as it was moving over the Patapsco. Bui that was the imagery that I am showing here is a composite of mixed red imagery from Sterling, Virginia, overlying water vapor, minus infrared brightness, temperature difference product.
00:04:34:14 – 00:05:14:21
Speaker 2
And I will highlight the deeper convective storm activity here has a magenta shading indicating the coldest cloud tops associated with the thunderstorm activity. Dry air in the mid troposphere. Outside of the storm, activity can be indicated anywhere from a dark blue shading that we see here to gave for a, magenta shading as well. So what we see here is an area of thunderstorms moving into a region with very dry mid tropospheric air over the middle and upper Chesapeake Bay.
00:05:14:23 – 00:05:52:10
Speaker 2
So at the time that the SPO echo was moving over the Bui, the Bui did record a wind gust of 36, not that this was good, because this measurement to validate or verify a central marine warning, which had been issued over an hour and a half prior to this event, although it was a what I would consider to be a marginal event, a goes MWP and vertical data in different algorithms.
00:05:52:20 – 00:06:29:00
Speaker 2
It did capture, wind gust potential quite effectively with this event just to review, what these parameters entail, the microburst wind speed potential index. Is a multi parameter algorithm based on Cape temperature lapse rate and the difference in dew point depression between two layers, in the middle to lower troposphere, over this region, the MWP is calculated for the layer between 670 and 850 millibars.
00:06:29:03 – 00:07:20:16
Speaker 2
The other index here, being considered is a vertical equivalent potential temperature difference. And this is simply the difference between, say, a, the maximum value, measured near the surface compared to the minimum value found in the middle troposphere, typically between the 507 hundred millibar levels, the vertical TDE differences. And there’s an important parameter, for it detecting a favorable environment for down to earth, because it’s because of its ability to detect the presence of a significant troposphere air layer that I did point out in the previous image, basically derived from the brightness temperature difference between the water vapor and infrared channels.
00:07:20:19 – 00:07:46:15
Speaker 2
Now, let’s go ahead. Take a look again here at a composite image from 2200 Greenwich Mean Time. And this shows I go sounder and derived, say the difference and MWP values plotted over the satellite and radar composite image and what we see here, vertical, say the heat difference value of 14 just to the south east of the Bui.
00:07:46:15 – 00:08:24:09
Speaker 2
This is about 20km south east of the Patapsco. Bui. And, previous research has found that on vertical theta difference values of 28 or greater would indicate a significant risk of wet microburst. However, values between 14 and 19 would be considered marginal, perhaps indicating a slight risk or a low risk for weaker type two activity. For values 13 or lower, which would be 13°C or Kelvin.
00:08:24:18 – 00:08:54:04
Speaker 2
Basically the downpours potential is still and we wouldn’t consider, there to be a risk for the outburst at all. But in this case, we had, marginal values of 14, the MWP value here, 15.7 around that up to 16 is also marginal. Previous correlation a regression analysis has found that values around 15 can correspond to wind gusts potential.
00:08:54:22 – 00:09:24:03
Speaker 2
35 to 40. So again, this would indicate a potentially for a marginal down burst event with winds that would be below severe thunderstorm warning criteria. However, in this case, these winds did satisfy the criteria for a special brief warning. Now we will go ahead and compare this to a burst event that occurred just shortly before the Chesapeake Bay event.
00:09:24:16 – 00:10:05:25
Speaker 2
This storm burst event over the Cape Canaveral area of Florida occurred around 2100 Greenwich Mean Time. So a little over an hour before the, Baltimore area event and again, we can see here lines and clusters of thunderstorms that have developed, along the seabreeze front and are now moving eastward over the Atlantic coast. And I will go ahead and stop the animation here again to point out the location of the seabreeze front that we can see here as a fine line identified in red imagery from Melbourne, Florida.
00:10:06:01 – 00:10:43:04
Speaker 2
Again, the radar imagery is overlying bright temperature difference of imagery, similar to the imagery that I showed that I had shown previously over a bit Atlantic region. But what we see here are clusters of storms developing just to the west of the Seabreeze front and moving over the Cape Canaveral region. The first down burst, severe down burst that was recorded was by a tower, mounted observing station.
00:10:43:05 – 00:11:23:19
Speaker 2
This is an Air Force tower, just south of cocoa, Florida, that measured a wind gust of 54 tons. Okay. This would have been at 2050, UTC 2050 Greenwich Mean Time. And then the next down burst event, that was observed was actually over, Cape Canaveral for very close to the, shuttle facility, where wind gust of 54 knots was also measured about 15 minutes later.
00:11:23:21 – 00:11:56:03
Speaker 2
But again, I want to point out here in the radar imagery that just prior to the observance of the first down burst near cocoa, that the parent storm had evolved again into a spearhead type echo configuration. And, that was all always a signature that Ted Fujita found to be a red flag for Denver activity. And we can see that type of echo here in, radar reflectivity.
00:11:56:05 – 00:12:34:12
Speaker 2
Now, comparing, the previously calculated MWP and PD difference values over the Chesapeake Bay region to what was observed over Cape Canaveral. We can see, both index values here are more than double, over the Cape Canaveral region as compared to the Chesapeake Bay region. And, it wouldn’t be surprising that, down versus related wind gusts, over the Cape Canaveral region were significantly higher, in excess of 50 knots.
00:12:34:12 – 00:13:33:07
Speaker 2
And this did, in fact satisfy for the, special marine warning as well as severe thunderstorm warning criteria. So you can see, even though we had acquired more widely scattered outburst events over the land and coast region, it goes MWP and a different, product output effectively indicated relative wind gust potential with these events. And finally, here to compare the general characteristics of the pre convective environment over, the upper Chesapeake Bay in Maryland to to Cape Canaveral region of Florida, in both cases, we can see significant cape here and the vertical sounding profiles, these Saudi profiles were calculated using rapid refresh model analysis step first over the Cape Canaveral region at
00:13:33:09 – 00:14:09:00
Speaker 2
20 Greenwich Mean Time. About 50 minutes prior to the first down burst event over the Cape Canaveral area, we can see large Cape, Cape that was significantly larger than what was observed, over and east of the Baltimore area and also a region here, highlighted or shaded in blue that indicates the mid troposphere dry air layer, especially where we see orange dew points, depressions between the 406 hundred millibar levels.
00:14:09:02 – 00:14:37:16
Speaker 2
We can see that the dry air layer over the Cape Canaveral area was, quite a bit deeper and had a larger, in general, larger dew point depression. In a deeper layer. Three of us here, so it wouldn’t be surprising that stronger down burst winds. But it did, in fact result from these storms over at the Cape Canaveral Air Region.
00:14:37:18 – 00:14:48:18
Speaker 2
And that’s, pretty much a summary of it, this, down burst event over the Atlantic coast. Last Saturday, the 11th. Are there any question?
00:14:48:20 – 00:14:53:02
Speaker 1
I have a question for you. Can can you go back to slide four?
00:14:53:04 – 00:14:55:28
Speaker 2
Certainly.
00:14:56:01 – 00:15:08:15
Speaker 1
And I see in your downdraft calculation, you use, the temperature minus the dew point at 850. Do you use something? Different out west for higher elevation location?
00:15:08:24 – 00:15:43:20
Speaker 2
Good question. Dan. Yes. And in fact, the calculation over the, Rocky Mountain Great Basin region uses the use of the 500 to 700 millibar, level, layer. So, the upper level or, basically the upper boundary is 500 millibar level. The lower boundary is 700 millibar level. And that has also been the traditional calculation for the dry microburst index.
00:15:43:20 – 00:16:02:14
Speaker 2
So yes, certainly over the western U.S., especially the Great Basin region, the layer of consideration is much higher. Edward flexing climatology as well as the higher surface elevations prevalent in that area.
00:16:02:17 – 00:16:04:29
Speaker 1
Okay. Great. Are there any other questions?
00:16:05:07 – 00:16:38:25
Speaker 2
Sister Scott, I have a question. We had some down burst here in Wisconsin yesterday, and I saw that. Yes. So how can I can is this microburst wind speed potential index available in a what. Not yet. And that is another issue I’ve been trying to address. Through my visit lessons. And the only I would say the only means currently that you can obtain microburst output, is by accessing a sounding profile.
00:16:38:25 – 00:17:38:08
Speaker 2
Now this is a what’s one and I give to give an example in my visit lesson. But that the, Windex blend index parameter, which I didn’t discuss today, and the microburst potential index, which is the key difference, is divided by 30. Both of those parameters are calculated and listed on a sounding profile. That is the only up close, derived microburst, data that would be available on a with now, I am highly encouraging, my, stakeholders and potential users, in the National Weather Service to submit an official request for these microburst products, for, the SP, RV, Satellite Products and Services Review Board.
00:17:38:08 – 00:18:07:10
Speaker 2
And that way I can obtain the, funding and contract support to transition these, products to operations. So definitely, I do want to get these products into, a with, but it hasn’t happened as of yet. Okay. Thank. Yes, but the experimental products are available, are still available. On these star like first products web page, if you can see my screen here.
00:18:07:22 – 00:18:16:24
Speaker 2
This is iQOS MWP product page where you can take experimental versions of these images.
00:18:16:26 – 00:18:19:25
Speaker 1
Okay. Do you have any are there any other questions?
00:18:19:27 – 00:18:40:15
Speaker 2
Yeah. This is, Hi, Ken, this is Tony back in, in Boulder. Hi, Tony. Yeah. And while you were, giving the, talk, you know, looking for, any kind of verification data, you’re saying that you have trouble finding I. What would you say you did actually find a buoy out there over the bay? Yes.
00:18:40:15 – 00:19:11:15
Speaker 2
The Chesapeake Bay has a brewing system, a network of boogies. It’s called the Chesapeake Bay interpretive Brewing System. Yeah, it’s a network, yes. Yeah. I’m not too aware of that, but I don’t know that you. I’m a big fan of the Weather Underground. Why? You were, talking. I looked up a couple of the observations, and I did find one, and 44 043 email sent it a link.
00:19:11:28 – 00:19:47:15
Speaker 2
That is, it’s called, Fort Howard, Maryland, but it’s also out over the water. Okay. Are you aware of that one? Later. The report. August of, 40. Okay. Yes. Tony, that is the same station that I’ve been working to. Another and another label for it. I think you’re right. The Tabasco Brewing NTPC. Dave, the name for 4043 are number two that we said that it’s the same observation.
00:19:48:02 – 00:20:18:23
Speaker 2
Okay. But I do also check Weather Underground observations. Well, I figured okay, I figured I think I did see one other one further north somewhere. Okay. But I can find it later that was. That would be great, Tony. It really over over 30. It was, in the 30s. One more. Okay. Okay. That would be great. The challenge with a lot of these, you know, especially just the official sites in between, you’re not going to get the observation, but out there in the East, it shouldn’t be too hard, you would think.
00:20:18:26 – 00:20:35:28
Speaker 2
Well, no, we do have plenty of networks. The only issue becomes the data quality of the serving station. So that’s that’s a whole other area, a whole other topic to get into is surface data quality. Right? Okay.
00:20:36:00 – 00:20:37:09
Speaker 1
Okay. Any other. Great.
00:20:37:11 – 00:20:41:18
Speaker 2
Thanks. Thank you.
00:20:41:21 – 00:20:53:28
Speaker 1
Okay. Let’s get it over to Scott Lindstrom at Simmons in Madison, Wisconsin.
00:20:54:00 – 00:21:13:07
Speaker 2
I wasn’t knowing I was coming in right now, but here we go. This is just something that’s been going on. There’s been a lot of, email chatter on the negative side about the difficulty with straight life. This is the time of year when stray light gets. And this is just an example. I’ll explain how stray light happens.
00:21:13:09 – 00:21:36:14
Speaker 2
So this is an a weird scene, from our a here at Sims. And you know, this is step four. This is at 4401 image. There’s bad data. It goes bad data goes away at 430. It comes back at 501C. So there. So the question is, you know, how does this data become bad. What’s actually happening here that’s causing the bad data.
00:21:37:12 – 00:22:09:22
Speaker 2
This is actually from the National Weather Service in Blacksburg. And there is stray light occurring. This this is the visible images at five C. So you notice up at the top there, sunlight is peeking in over the into the visible image in the middle of the night. And that’s causing, problems for the calibration. So it’s not necessarily that radiation is getting into the 3.9 micron channel, but there is a difficulty here with calibration, as I’ll show you an example.
00:22:09:22 – 00:22:38:02
Speaker 2
And because it gets into three point, the calibration issue is getting to 3.9. It gets into the, fog and low stratus product, for example, which is shown here. The low IFR probability has all these regions of higher, probabilities because of stray light. So here’s the visible band, at 415 and at 430, and at 445, and at 502, and at 515.
00:22:38:02 – 00:22:59:19
Speaker 2
And the difficulty is, is when the satellite is scanning, it looks out in space, to get a blackbody look. And the problem is it’s looking right at the sun when it does this. And when we had goes 12, for example, you might remember the eclipse season and the keep out zones. Well, the eclipse season is gone because of the longer batteries.
00:22:59:26 – 00:23:19:27
Speaker 2
The keep out zones are much reduced. So this is a error that’s been introduced by giving you a little bit more data. So this is something to keep in mind when you have this data and they’re working on they’re discussing workarounds with this that go from, you know just flagging the data to not even sending the data.
00:23:20:00 – 00:23:39:24
Speaker 2
So kind of regressing back to what it was with Goes 12 and not sending the data when you have the difficulty, when you’re looking off to the left or the right to do the calibration because you want a space look and you’re looking instead at the sun that screws up the calibration. So that it’s that time of year when that happens.
00:23:40:06 – 00:24:02:26
Speaker 2
And should go away in a couple couple of weeks. It’ll come back again in six months. But just wanted to kind of explain what is how it’s happening. And this is this visible image is really telling you because you can imagine if you’re if you’re putting the 3.9 sensor in the middle here, you’re not getting, you’re not going to have any issues until you look off to the side to do your deep space calibration.
00:24:02:26 – 00:24:27:29
Speaker 2
You’re looking right into the sun. So that’s all I have. Any questions? No. Very interesting. Sky is. Yeah, I guess so. One question, Scott, in terms of, is there like a message or something we could do as part of a blog, or have you done a blog and explain? It is on my list of things. There will be a blog entry on this.
00:24:28:01 – 00:24:51:03
Speaker 2
All right. Because I think the the issue is, one way to try to figure out how to do that is to certainly alert the users that you see any kind of a jump and an image or other derived product around this time times, an area that we’re dealing with here. To certainly then question at that time.
00:24:51:08 – 00:25:10:25
Speaker 2
Right. Any kind of discontinuity, it’s more than likely that a meteorological phenomena. Right. More likely an instrument artifact of, you know, this, straight like and and and it’s around. I would I would think most users aren’t aware of it at all. That would be my first guess. And that’s around 530 if it goes east and around nine efficiency for it goes west.
00:25:10:29 – 00:25:20:06
Speaker 2
And so there would be actually a great block, whenever you have time. Yeah. Okay. Thanks.
00:25:20:09 – 00:25:31:27
Speaker 1
Okay. Next, we’ll turn it over to, Scott Meyer, also at Sims and Madison.
00:25:31:29 – 00:25:34:21
Speaker 2
Okay. Is my screen up on everyone’s.
00:25:34:24 – 00:25:35:18
Speaker 1
Yes.
00:25:35:21 – 00:26:12:13
Speaker 2
Okay. I thought I’d talk just a little bit about the fact that we’re sort of entering, the, the, the time of the year when burning becomes an issue. And if we look at the SPC outlook, they highlight an area in Arizona which, you know, they had been having a few, in that area. But if you look at how much of the just that the whole whole western half of the U.S is in a drought.
00:26:12:13 – 00:26:49:13
Speaker 2
I mean, there’s a lot of areas that are dry and we can have an issue with, a burning problem and in fact, even up in our area here, you can see that a lot of areas are still in a bit of a drought. So if you look at what happened here, here yesterday afternoon and evening before the ellipse, so here is the images where we’re looking at the,
00:26:49:15 – 00:27:30:18
Speaker 2
At I think those imagery, where we can see the hot spots, here’s one, hot spot here in northern Wisconsin and also the one in Minnesota. The, I think with the, the, the average enhancement that maybe you could call up when you have have this so the hot spots will be black. I personally like to apply an enhancement where the hot spots, have a little bit of color.
00:27:30:20 – 00:27:57:20
Speaker 2
That’s not the one I wanted. This one here. Okay, so if I apply an enhancement here to the hottest, ones. Oh, yeah. Well, we’ll see. Well, we’ll be highlighted with a little bit of color. So the eye is drawn to that hot spot. So you see on this one here, we hold the cursor over it.
00:27:57:20 – 00:28:09:18
Speaker 2
It’s got a very, hot value. However, if it’s still hard, if you’re.
00:28:09:20 – 00:28:49:26
Speaker 2
It’ll, it’ll show up as it ain’t no data. Because it’s actually hotter than what you believe that be so, you know, I if there are, you can put em an enhancement on here that will will make these hot spots, a little bit more obvious. However, let me go back to this other enhancement here, and let’s watch what happens as we go from the F the afternoon hours into the evening hours.
00:28:49:26 – 00:29:22:25
Speaker 2
And you see that the, hot spots began to become not as hot and not quite as obvious. So if you want to know exactly where these hot spots are, it gets a little bit harder to tell on. The goal is because of the, your resolution is,
00:29:22:27 – 00:29:55:06
Speaker 2
Or kilometers. So if you go to some old arbitrary imagery, which is high res, we are able to see these hot spots with a little more detail here. I’m going to do a. Looking at the one kilometer here from the Morris’s experiment. Let me get to the right time here. What we’re having to look at. Where are these hotspots and the the overnight hours?
00:29:55:06 – 00:30:28:20
Speaker 2
Where is where it was it was a little bit hard to see where they were on the, of those imagery. So here we are at oh eight. See, and we can see that there is a little bit of a hotspot here in Wisconsin. And we can also see this little hotspot here. And Minnesota. If we compare to what we see at this exact time on the gold image, can we see, wow, that hotspot is not here at all.
00:30:28:23 – 00:31:00:06
Speaker 2
And this hotspot here. Well, we can kind of. Say it, but it appears to be in a different part of the county. There is a navigation problem when we’re trying to see where these hotspots are on because imagery, in fact, you can see that here looking at state, the boundary of the land and water, you see that, you know, there is a little bit of a problem here.
00:31:00:07 – 00:31:40:18
Speaker 2
And yeah, in fact, and the mapping, because every so, you know, you can if it’s often, you have to have an idea of exactly what part of the county or counties the hotspots are. So you get a lot more accurate idea if you look at, the polar orbit or imagery, which also allows you to see the data at a one kilometer.
00:31:40:25 – 00:31:54:12
Speaker 2
So this is what it looks like when we compare it, it goes and even notice if we look at a comparison of the areas imagery.
00:31:54:14 – 00:32:11:09
Speaker 2
And let me get to the right time area where we were in the overnight hours. And it was hard to see those.
00:32:11:12 – 00:32:20:16
Speaker 2
Things went past my time here.
00:32:20:19 – 00:32:48:27
Speaker 2
All right. So it’s look here. So, that there is imagery here and here we see, this area of hotspots in Wisconsin and an even hotter area in Minnesota. And if we compare again, what did this look like at this time on the goes imagery? Well, you know, yeah, you can kind of see that hotspot. But again, it’s in the wrong area of this county and also this hotspot.
00:32:48:29 – 00:33:16:14
Speaker 2
You know here it isn’t as hot on goes. And it really is not where it’s supposed to be ongoing. So if it’s important to tell people, you know, what part of the county, the actual hotspots are right to be as accurate as possible, you really need to look at the pole or polar orbit or imagery from either the bears instrument or the forest estimate.
00:33:16:14 – 00:33:30:12
Speaker 2
And you can add this into the in to your ellipse, via the LDM. And so that’s all I have on this particular topic.
00:33:30:15 – 00:33:32:03
Speaker 1
Any questions?
00:33:32:05 – 00:33:41:23
Speaker 2
I’ll just this is the biggest fire to hit Wisconsin since 2005, and it’s almost contained. No.
00:33:42:02 – 00:33:49:08
Speaker 3
Scott, does this Madison or Solomon have this severe imagery? And there, you know Sullivan.
00:33:49:08 – 00:33:57:09
Speaker 2
Yes. I don’t know if Duluth does. This is still right. Yeah. Anyway,
00:33:57:11 – 00:34:05:07
Speaker 3
Although they should see it on the regional scale, I would imagine, from Sullivan. Yeah.
00:34:05:10 – 00:34:11:09
Speaker 1
Okay. Any other questions?
00:34:11:12 – 00:34:16:28
Speaker 1
Okay. Well, so very interesting. Okay. Well, thanks, everybody for participating.