7/24/05: TALK: GREAT LAKES

[nickgrillo]

Tomorrow holds the potential for a MI chase for myself...

For tomorrows setup... Winds across MI are pretty much unidirectional, and will be supportive of isolated to scattered severe thunderstorms; capable of producing damaging wind gusts. We will have alot of factors supporting severe weather, including very strong instability (CAPES AOA 3500J/KG), strong deep layer shear, high theta-e, very strong unidirectional wind fields, so we shall see...

Tomorrows temperatures could reach record breaking status as well, GRR is saying that we will see some of the highest temps/heat indexes since 1999. With all that said, I think tomorrow could hold a pretty decent risk for storms across MI.

Rob Dewey, whatcha think?

 

[Andrew Khan]

Looks to me like their could very well be damaging winds, with possible minor flooding. Looks to me like the storms will flare up over the night...Looks good so far...

 

[Andrew Khan]

Now when you say GRR, what are you reffering to? Finally found a ride, thats good.

 

[J West]

Originally posted by Andrew Khan
Now when you say GRR, what are you reffering to? Finally found a ride, thats good.

GRR is NOAA/FAA-ese for Grand Rapids, MI.

 

[Robert Dewey]

Originally posted by nickgrillo
I am pretty surprised that DTX makes pretty much no mention of storms developing in the evening with the cold front, but GRR does, and hits it in their HWO.

Probably because:

1) Morning/early afternoon convection will reduce instability
2) As the day progresses, a thermo-nuclear CAP will develop
3) Very weak convergence along the front

The main threat appears to be in the 12-18Z timeframe across lower MI. The 00Z NAM is doing an amazing job with the convection that just developed over MN/WI just recently. It develops this into a very intense MCS and blasts it eastward with a sharp turn to the southeast, setting it's eyes right on the DTX CWA. Given the degree of shear, forcing, and moderate instability, things should develop quite nicely.

The real race will be tomorrow mornig - Will the SFC-based instability be able to advect in right before the line comes through? The NAM says so, with SBCAPE's climbing near 2000J/KG with almost 500M2/S2 of helicity available (thanks to backed SFC winds, veering rapidly to the northwest at 700MB with a jet max of nearly 55KNTS).

The overal setup resembles what happened yesterday (or today, depending on time) in regards to that long tracked bow echo/derecho.

Either way, after that stuff blow through, 850-700MB temps increase dramatically and CAP everything off, not to mention any subsidence as a result from the MCS.

EDIT: Was just pulling up some forecast soundings from the NAM for various sites around the MI area - At 15-18Z, LAN shows 2500J/KG of CAPE with 0-3KM shear values of nearly 70KNTS - This brings 0-3KM EHI values of 4.5. If storms get their act together tonight, they should be able to survive the trip southward, if not intensity along the way.

 

[Jeremy Lemanski]

IF areas can get some sun later on, the combo of outflow boundries, the weak front and lake breeze could just break the cap and if it does break, watch out for the storms will be isolated and in areas with good shear/very unstable air.

 

[Andrew Khan]

I'm watching the storm on radar, their are some meso rings embedded in this storm as well. Is anyone chasing yet? The NWS in Pontiac/Detroit has issued a severe thunderstorm warning.

 

[Robert Dewey]

Well, I am not 100% convinced that things won't refire later this evening. The CAP still has me concerned quite a bit, but there is at least a small chance things could pop. Latest NAM and RUC both show this happening, with ample instability and shear present. If storms develop, they will obviously be severe.

EDIT: NAM soundings for 21-00Z across the area shows in excess of 4K J/KG of SBCAPE (and 3K J/KG of MLCAPE) to work with. In addition, low level shear (0-2KM and 0-3KM) is 61KNTS and 59KNTS respectively. That is more than sufficient for organized severe thunderstorms, particularly bow echoes. EHI's also get up to 5.9, but with a real lack of directional shear, I don't see a widespread threat for tornadoes. Of interest, increasing the storm relative motion by 5-10KNTS yields effective storm relative helicity of over 300M2/S2, and increases EHI to just over 7. So, the parameters certainly support severe thunderstorms... This of course is assuming that convection even redevelops - but at 00Z, the NAM doesn't even have a hint of CINH. If the NAM and RUC are correct, and the CINH completely errodes, thunderstorm develop is very possible.

 

[Kurt Hulst]

Wow i dont think i have ever seen a Super cell composite of 32 before over SW Michigan. IF things do fire it wont be till late. Looks like an area of strong convergence will form Just south west of me if not right over GRR. According to the RUC the CAP is supposed to errode away b/w 21 and 01z. Will see if that actually occurs. Temps up top are warming very rapidly but we already have dewpoints up to 73 and rising. With a cold front, lake breeze and outflow boundaries to work with its is not out of the question that something might devlope later this evening. Of course it will be working with unidirectional wind fields. Even with that ill take some majorly close lightning strikes. Even those 50 yard away strikes make your butt pucker i love them.

 

[Andrew Khan]

So this is a confirmed supercell? But it's practically all out of MI.

 

[Scott Olson]

Originally posted by Andrew Khan
So this is a confirmed supercell? But it's practically all out of MI.

No, nothing has formed. Everyone is just looking at the data and parameters such as the supercell composite parameters to see type/strength if and when storms fire.

 

[Aric Cylkowski]

If it fires in the next two hours, we'll be in for a real treat. If it fires after that, my money is on the usual: wind, hail, no tornadoes.

 

[nickgrillo]

Originally posted by Kurt Hulst
Wow i dont think i have ever seen a Super cell composite of 32 before over SW Michigan. IF things do fire it wont be till late. Looks like an area of strong convergence will form Just south west of me if not right over GRR. According to the RUC the CAP is supposed to errode away b/w 21 and 01z. Will see if that actually occurs. Temps up top are warming very rapidly but we already have dewpoints up to 73 and rising. With a cold front, lake breeze and outflow boundaries to work with its is not out of the question that something might devlope later this evening. Of course it will be working with unidirectional wind fields. Even with that ill take some majorly close lightning strikes. Even those 50 yard away strikes make your butt pucker i love them.

If convection does develop, there would certainly be some rocking storms...

It is warm aloft, but the RUC soundings show very little in the way of a CAP by mid-afternoon. Latest analysis shows temperatures pushing 95F in southwest MI, with dewpoints approaching 80F (really adding to the instability), with instability AOA 4000J/KG. In addition, helicity is >450M2/S2 across most of southern MI... Supercell composite is a whopping 40 in Calhoun county as of this moment, one of the highest in MI I have seen in a long time.

 

[Kurt Hulst]

Yeah Nick ain't it crazy freakn 40 SCP. Right now RUC has the CAPE at 4500 in my area with 5500-6000 just south of that. Sig tor is fairly high as well. I did notice with the 18z RUC run that Forecasted Pricp has lessend and the CAPE though weak may hold on. Mesoanylsis has shown it erroding away from two counties south of Calhoun. Now the question, is that actually happening? Theres good moisture convergance showing up just east of me with a good theta E tounge. Very good upper shear and lower shear just all veered. Getting reading of Temps reaching 90 on up now here and and dewpoints up to 76-77 in my local area. LCLs are riseing SW of me and continue to rise in a eastward propagation.

I would love it to go nutts on us but I have seen these parameters before and nothing has happened. When the RUC said the CAP was gone it was still there enough to keep initiation from occuring. but its only a matter of sitting and waiting. its not like i have driven 10 hours for it to only bust. today i can just sit here and say if it happens im ready for it. if it doesnt im that much closer to home because this is where i live hehe. it's almost to hot to venture out.

 

[Dan Robinson]

I know I'm probably committing a cardinal sin and a major meteorological pet peeve by even mentioning this, but the SCP is 48 and sig torn is 9 in lower Michigan. That's interesting to say the least.

The slight risk extending south into Ohio and WV probably has me a little more optimistic than I should be. None of the models are breaking precip out south of I-70 and not much in the way of Cu anywhere. RUC suggests things exploding along the lake around Cleveland later, but it looks like I'm not going to stay awake to watch this.