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I disagree with our weather forecasters on TV

Discussion pertaining to Detroit, Ann Arbor, Port Huron, and SW Ontario
jadednihilist
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Re: I disagree with our weather forecasters on TV

Post by jadednihilist » Tue Aug 10, 2021 9:40 pm

00Z sounding for DTX shows 35 kt winds at 850 mb, which is robust enough to support MCS maintenance. I'm a bit concerned about instability though. Lots of dry air in the sounding compared to the 19Z Green Bay sounding. We would need a bit more moisture aloft to steepen those mid-level lapse rates, but that'll eat away at this storm as it moves east. This increases the impact surface cooling would have on overall instability.

Image

It's worth noting that CAPE represents an upper bound on available thermodynamic energy. It assumes no dry air mixes with a saturated parcel (bad assumption, especially in a dry airmass) and also ignores drag forces. With dry air in place, actual buoyancy of parcels is substantially lower. I'm downgrading my expectations for tonight.


I'm here for a good, hearty debate, to agree and disagree respectfully, and commiserate on the current state of terrestrial radio.

jadednihilist
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Re: I disagree with our weather forecasters on TV

Post by jadednihilist » Tue Aug 10, 2021 9:57 pm

The HRRR doesn't really give the atmosphere an opportunity to recover tomorrow as it develops deep convection to the south, limiting moisture transport up here. It seems like the CAMs are pushing the jet stream a bit farther south than the GFS/Euro, which would support that conclusion.

I'm looking at the 588 dm 500 mb height isohypse as a proxy for southward extent of the 500 mb jet stream. The 00Z soundings show a bit of deepening of the jet with the 588 line between Davenport, Iowa and Springfield Illinois (closer to Davenport). At 700 mb, pretty wide area of 35 kt winds would also support convection farther south as well. I would argue that a southward miss is definitely in the cards tomorrow.


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WOHO
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Re: I disagree with our weather forecasters on TV

Post by WOHO » Wed Aug 11, 2021 9:36 am

Severe Tstorms that rolled-thru Toledo during the night, 2:45am, didn't come from the NW like it looked like during the 11pm forecasts, but snuck-up from the SW into the area, and one that rolled thru Wood County at 8am came (pretty fast-like 50mph straight out of the west). Wood County storm was probably the first one all season that had any sort of electrical activity in the way of nearby strikes.



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MWmetalhead
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Re: I disagree with our weather forecasters on TV

Post by MWmetalhead » Wed Aug 11, 2021 1:16 pm

I-80 corridor saw some good action for sure.

Toledo is in line to get more nasty storms in next 2 to 3 hours. Expect a watch to be issued soon.

Parts of SE Michigan, especially I-94 south, will likely also get in on the action.

Monster squall line is forming over WI as we speak. That one could cause serious issues for western Michigan after the dinner hour.



km1125
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Re: I disagree with our weather forecasters on TV

Post by km1125 » Wed Aug 11, 2021 2:43 pm

As I was watching the radar signatures as the storms rolled across Lake Michigan, I thought it was interesting that when they were leaving the Wisconsin shore, their shape mimicked the shoreline of the state. As they rolled across the lake, it appears they "adjusted" so by the time the made landfall on the Michigan side, they actually mimicked the Michigan shoreline. I don't know what they call that, but how the geography impacts the formation and direction of storms is very interesting. It's very obvious around mountains, but I think it's really interesting how the lakes affect it. I've watched storms roll across the Detroit Metro area and it's interesting what happens to them as they hit the area around Lake St Clair.

I've also wondered how much this really impacts the storm. I've noticed some storms rolling over the Ann Arbor area and it seems like they split when they go over that valley, with some of the storm trending north and some south. Not that they really GO north and south, just that the development peters out going over the valley instead of strengthening like the areas to the north and south. A couple weeks ago I was in the Bay City area the morning after a bunch of storms rolled though there. Ask a couple people how bad they were and some said "Well, it wasn't too bad. Since we're in a valley they kind of skip over us"

Makes me wonder. If there's a valley, is the influence different if the storm is going over them perpendicular to the valley vs parallel to it? How much of a valley (or a hill) does it take to make an influence to the weather pattern and affect storm development?

EDIT: Here's an example I caught today as the storms were rolling over AA:
Image



jadednihilist
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Re: I disagree with our weather forecasters on TV

Post by jadednihilist » Wed Aug 11, 2021 9:20 pm

km1125 wrote:
Wed Aug 11, 2021 2:43 pm
As I was watching the radar signatures as the storms rolled across Lake Michigan, I thought it was interesting that when they were leaving the Wisconsin shore, their shape mimicked the shoreline of the state. As they rolled across the lake, it appears they "adjusted" so by the time the made landfall on the Michigan side, they actually mimicked the Michigan shoreline. I don't know what they call that, but how the geography impacts the formation and direction of storms is very interesting. It's very obvious around mountains, but I think it's really interesting how the lakes affect it. I've watched storms roll across the Detroit Metro area and it's interesting what happens to them as they hit the area around Lake St Clair.

I've also wondered how much this really impacts the storm. I've noticed some storms rolling over the Ann Arbor area and it seems like they split when they go over that valley, with some of the storm trending north and some south. Not that they really GO north and south, just that the development peters out going over the valley instead of strengthening like the areas to the north and south. A couple weeks ago I was in the Bay City area the morning after a bunch of storms rolled though there. Ask a couple people how bad they were and some said "Well, it wasn't too bad. Since we're in a valley they kind of skip over us"

Makes me wonder. If there's a valley, is the influence different if the storm is going over them perpendicular to the valley vs parallel to it? How much of a valley (or a hill) does it take to make an influence to the weather pattern and affect storm development?

EDIT: Here's an example I caught today as the storms were rolling over AA:
Image

Off the top of my head, there are a couple factors at play as mesoscale convective systems (a broad term to describe thunderstorm complexes that are roughy 100 to under 1000 km in horizontal length) move over large bodies of water like the Great Lakes:

1.) Water surface temperatures. Since water has a specific heat capacity of roughly 4000 J/kg, about 4x higher than land, it takes roughly 4x more energy to raise the temperature of the water surface. That's why as you drive towards the beaches in the early summer, the lake breezes are so cool. However, during the fall/winter as cold air masses move into the region, it takes much longer for the lakes to cool off and we get lake effect precip.

In the summer, these relatively cooler water temps create a shallow layer of stability which inhibit storm development. If the atmosphere aloft is unstable (that is, the vertical temperature gradients are steep) and there's a steady supply of warm moist winds in the presence of a lifting mechanism (like a front), the air parcels in these storms airmass originate above the stable surface layer. That's called elevated convection - and this type of convection can still be quite robust. As the storms approach land, they encounter a horizontal thermal gradient once again, which can affect storm circulation.

2.) Friction. Just like with automobiles and planes, storms are also shaped by aerodynamic flows. Near the surface (about 1 km and below), there's a bunch of turbulence because of air interacting with trees, buildings, hills, etc. This turbulence slows down air flow, which is why winds at the ground tend to be gusty, but winds aloft tend to be more continuous. We call this turbulent surface region the boundary layer, similar to what you would see in water flows in pipes or rivers. Rough surfaces over land produce more friction than flatter water surfaces. The impacts from friction affect internal storm dynamics. These affects are especially pronounced during lake effect season where you'll see friction lead to sinking air upstream of lake effect precip, and rising air downstream. Example:

Image


I'm here for a good, hearty debate, to agree and disagree respectfully, and commiserate on the current state of terrestrial radio.

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Robert Faygo
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Re: I disagree with our weather forecasters on TV

Post by Robert Faygo » Thu Aug 12, 2021 5:36 am

We've quickly devolved from major annoyance into major disaster all across Metro Detroit over the last 18 hours with no real sign these training downpours are going to abate.

1/2 million DTE customers in the dark and growing.

While everyone predicted the chance of rain, the amount of widespread damage from wind and rain seems to have caught everyone that forecasts the weather for a living by surprise.


Wellllll... la de frickin da

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MWmetalhead
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Re: I disagree with our weather forecasters on TV

Post by MWmetalhead » Thu Aug 12, 2021 6:36 am

SE Michigan was upgraded to an elevated risk of severe relatively early yesterday (mid-morning, I want to say), so the wind damage threat was properly forecast a good 6+ hours in advance. Unfortunately, the upgrade occurred after most of the morning TV newscasts concluded, so people who headed out the door to work thought we were still in a slight risk.

The flooding rains and training elevated storms over a widespread area did indeed catch me off guard. The longevity of the rain along the I-96 and I-696 corridors was surprising. I had on & off thunderstorms for a good four hours total overnight and early this morning.

Downriver's turn is coming, perhaps. Big cluster of storms with history of severe winds over Hillsdale and southern Jackson County right now. Both the North Webster, IN and White Lake radars are showing a big core of 90 mph+ winds several thousand feet above the surface. That could certainly translate to 70 mph+ winds at the surface in the form of downbursts.

Storms do tend to weaken quickly around and shortly after sunrise, so not a sure thing these will hold together to slam the US-23 and I-275 corridors, but it is definitely possible. Folks in those areas should be on guard for rapidly deteriorating conditions.

Update: I see NWS DTX has preemptively issued a severe tstorm warning for all of Washtenaw County and the NW half of Lenawee County just now. They describe storm movement as "NE." I would describe it as more of an ENE pattern, and as it catches up with the outflow boundary from the existing storms over Metro Detroit, I think this pattern at some point will veer due east. This is very bad news for folks along the I-94 corridor in Wayne County if the storms hold together.



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MWmetalhead
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Re: I disagree with our weather forecasters on TV

Post by MWmetalhead » Thu Aug 12, 2021 7:00 am

Indeed, the complex over Washtenaw is moving due east now. A gust front is pushing northeastward from the northern flank, however. So, folks in Salem Twp, Northville, etc. could still see damaging winds, even though the guts of the storm should stay mostly south of there.



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MWmetalhead
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Re: I disagree with our weather forecasters on TV

Post by MWmetalhead » Thu Aug 12, 2021 7:45 am

The wind field has weakened dramatically over last 20 minutes. Isolated gusts to 60 mph remain possible. The line is moving very fast fortunately.



km1125
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Re: I disagree with our weather forecasters on TV

Post by km1125 » Thu Aug 12, 2021 9:23 am

Just heard Michael Estime say something like "one inch of rain over one square mile is 17 million gallons of water"

I did a little math and come up with over 2.5 billion gallons. Is my math wrong or his??



BKRPDM
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Re: I disagree with our weather forecasters on TV

Post by BKRPDM » Thu Aug 12, 2021 10:49 am

To jaded or MW, or anyone who might know:
*Customarily, storms of a severe nature seem to lesson in intensity towards the late evening or overnight. I wonder why this hasn’t been the case lately….
*Has this been a relatively rough storm season? It seems like we’ve had some calm summers the last few years. I do remember some stormy summers in the early 1980s.



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Rate This
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Re: I disagree with our weather forecasters on TV

Post by Rate This » Thu Aug 12, 2021 10:54 am

BKRPDM wrote:
Thu Aug 12, 2021 10:49 am
To jaded or MW, or anyone who might know:
*Customarily, storms of a severe nature seem to lesson in intensity towards the late evening or overnight. I wonder why this hasn’t been the case lately….
*Has this been a relatively rough storm season? It seems like we’ve had some calm summers the last few years. I do remember some stormy summers in the early 1980s.
For what it’s worth 1980 was a particularly bad July… there was a Derecho that smacked southeast Michigan with 140+ mph straight line winds. The eruption of St. Helens that year messed with the weather for a couple years. Winter 1982 was very very old.

As late as 10pm the NWS auto forecast box was giving a 10% chance of storms and the hazardous weather outlook was saying storms should be confined around the Tri-cities. When the storm complex hit Kzoo and started dipping down I knew we were gonna get hammered. I did not expect the training and freeway flooding. Lots of branches down and power out. Fortunately I’m unaffected so far.



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WOHO
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Re: I disagree with our weather forecasters on TV

Post by WOHO » Thu Aug 12, 2021 11:22 am

According to Cleveland NWS, they had NOT issued a single severe weather warning thru the entire "Meteorological Spring" of 2021, which is unheard of since Doppler Weather Radar. So not jack anything this spring.
June 20th/21st were the very first Severe Thunderstorm Warnings issued for Lucas County since October of 2020.
Then nothing, until the three warnings this week, so only this past week have we seen anything resembling severe weather this summer in NW Ohio, and yesterday saw some significant wind damage for the first time in a long time.

Agree on the 70's having many more severe weather events up thru 1980.
Then a another lull until about July 1992, June 1998, (a year with no summer in 2004?) and a
lull again until June 5, 2010 killer tornado in Wood County, OH and a June 2012 derecho.
Oddities were the two November Tornado events: Nov.10, 2002 VanWert/Tiffin Tornadoes & Nov.17, 2013 P-Burg/Oregon Drive-in tornado).

As far as winter goes, Jan/Feb of 1977, 1978 and 1982 sucked big time along with Dec83/Jan84 and Jan2014 being record cold.



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MWmetalhead
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Re: I disagree with our weather forecasters on TV

Post by MWmetalhead » Thu Aug 12, 2021 8:35 pm

Regarding storminess this season - yes, this has turned into a rather active storm season. Last year was extremely quiet compared to normal. The big heat dome out west has been sending spokes of energy to the upper MS valley and Great Lakes regions. When other ingredients interact, the environment is ripe for storms. Backdoor cold fronts from Ontario have been sinking into Michigan and the northern OH region from time to time. In other cases, systems that are the summertime equivalent of Alberta clippers have touched off storms.

What we saw last night is a great example of elevated convection.

In terms of the "why haven't they been weakening at night?" question, instability doesn't vanish immediately after sunset. Heck, two nights ago I opened the door at 1 AM to let the dog take a leak, and I about jumped out of my pants at how oppressively muggy the air mass was. Even at that late hour, I bet the heat index was near 90 in my locale. The most unfavorable time for storm sustenance, if we're talking heat fueled storms, is usually early morning near sunrise.

I will note that at least two big storm systems out west lost a lot of their punch over the past couple weeks in Michigan due to a combination of factors, one of which is overnight arrival.

Chicagoland has had a much tougher go than us stormwise these past several weeks, believe it or not.



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