Michigan Radio & TV Buzzboard

This may come back to bite me, but I do think that today's rain chances are pretty decent today. The NAM is a bit more aggressive than the HRRR/RAP, but the HRRR/RAP seems to be overestimating the amount of planetary boundary layer (PBL) to free troposphere mixing. You can tell this by looking at model soundings, as well as what the projected dewpoints will be this afternoon according to each model. The NAM has dewpoints closer to the mid 60s with the HRRR hovering in the upper 50s/low 60s. That dewpoint differential in each model implies a few hundred J/kg difference in surface-based CAPE, with higher PBL moisture supporting higher CAPE values.

I think part of the reason that the mixing will be suppressed (and we'll see higher dewpoints verify this evening) is because of the hazy skies from the western US/Canada wildfires filtering out some of the sunlight from reaching the ground. See below:

The HRRR and NAM does not account for these aerosols and assumes a "clean" atmosphere, thus the HRRR is probably too warm and too dry and the NAM is probably closer to being right for the wrong reasons. I would expect high temps today to reach the mid 80s with dewpoints in the low-to-mid 60s, which is enough to support scattered thunderstorm development along the front this afternoon generally along and east of Telegraph/Lapeer Rd and along and south of I-69.

It's worth noting that we're in a much drier airmass than have been the past weeks, so while brief heavy rain is possible, flooding isn't a concern today.

MWmetalhead wrote: ↑Mon Jul 19, 2021 5:16 pm I think I saw a chance of showers and thundershowers Tuesday evening into very early Wednesday morning and again Friday. Otherwise, partly cloudy to mostly sunny. Temps near average except upper 80s tomorrow and mid to upper 70s Wednesday.

No big heat in sight for this part of the country, just as I stated nearly a week ago. A pretty boring weather pattern for a change! Flood drenched homeowners will finally see some relief.

There are only Thunderstorms. There is no such thing as a "Thundershower". It's a made-up term. Many many years ago, I had a college meteorology Prof who threatened failing grades over any use of "Thundershower" or "Heat Lightning". Both are misnomers, and are, in fact, thunderstorms.

Class dismissed.

Colonel Flagg wrote: ↑Tue Jul 20, 2021 4:13 pm

MWmetalhead wrote: ↑Mon Jul 19, 2021 5:16 pm I think I saw a chance of showers and thundershowers Tuesday evening into very early Wednesday morning and again Friday. Otherwise, partly cloudy to mostly sunny. Temps near average except upper 80s tomorrow and mid to upper 70s Wednesday.

No big heat in sight for this part of the country, just as I stated nearly a week ago. A pretty boring weather pattern for a change! Flood drenched homeowners will finally see some relief.

There are only Thunderstorms. There is no such thing as a "Thundershower". It's a made-up term. Many many years ago, I had a college meteorology Prof who threatened failing grades over any use of "Thundershower" or "Heat Lightning". Both are misnomers, and are, in fact, thunderstorms.

Class dismissed.

I don't know why some stations still use it then.

radioandtventhusiast wrote: ↑Tue Jul 20, 2021 10:28 pm

Colonel Flagg wrote: ↑Tue Jul 20, 2021 4:13 pm

MWmetalhead wrote: ↑Mon Jul 19, 2021 5:16 pm I think I saw a chance of showers and thundershowers Tuesday evening into very early Wednesday morning and again Friday. Otherwise, partly cloudy to mostly sunny. Temps near average except upper 80s tomorrow and mid to upper 70s Wednesday.

No big heat in sight for this part of the country, just as I stated nearly a week ago. A pretty boring weather pattern for a change! Flood drenched homeowners will finally see some relief.

There are only Thunderstorms. There is no such thing as a "Thundershower". It's a made-up term. Many many years ago, I had a college meteorology Prof who threatened failing grades over any use of "Thundershower" or "Heat Lightning". Both are misnomers, and are, in fact, thunderstorms.

Class dismissed.

I don't know why some stations still use it then.

Could you give an example?
I admit that I only really watch one local station, but I watch a LOT of the weather forecasts on that station and I don’t recall hearing these terms on-air.

Colonel Flagg wrote: ↑Tue Jul 20, 2021 4:13 pm

MWmetalhead wrote: ↑Mon Jul 19, 2021 5:16 pm I think I saw a chance of showers and thundershowers Tuesday evening into very early Wednesday morning and again Friday. Otherwise, partly cloudy to mostly sunny. Temps near average except upper 80s tomorrow and mid to upper 70s Wednesday.

No big heat in sight for this part of the country, just as I stated nearly a week ago. A pretty boring weather pattern for a change! Flood drenched homeowners will finally see some relief.

There are only Thunderstorms. There is no such thing as a "Thundershower". It's a made-up term. Many many years ago, I had a college meteorology Prof who threatened failing grades over any use of "Thundershower" or "Heat Lightning". Both are misnomers, and are, in fact, thunderstorms.

Class dismissed.

As a degreed Meteorologist myself, the term Thundershower drives me up a wall. There is no such thing as a thundershower, if you want to make it sound like periodic precip, call it showers and thunderstorms. Anything with lightning is a storm.

I'm in overall agreement with your assessment, MW. There's a nice boundary in mid-Michigan from this morning's MCS in Northern Lower with thick cloud cover that's kept temps in the lower 70s to the north and 80s to the south. This boundary is lessentially traversing in an east-west line from Saginaw Bay to Lake Michigan. Upper level pattern suggests that surface low north of the UP will continue to strengthen, which will aid in pushing through a cold front this evening into tonight across Metro Detroit.

The atmosphere across the Great Lakes is quite saturated. Precipitable Water values across Detroit, Gaylord, and Green Bay are between 1.8-2", which is quite high for this region. This should keep mid-level lapse rates fairly stable/neutral, so any instability that develops will be surface-based from daytime heating.

For reference, I consider steep mid-level lapse rates to be anything greater than 7ºC/km and low-level lapse rates at about 8ºC or greater. Unsaturated adiabatic lapse rates are 9.8ºC/km and saturated (cloudy/rainy) lapse rates are a bit lower at roughly 6ºC/km. To generate instability, you need a parcel to be warm than the surrounding environment, so environmental lapse rates (measured by weather balloons) should be approximately dry adiabatic near the surface, up until reaching the base of the cloud deck (ballpark around 850 mb), and a bit steeper than the moist adiabatic lapse rates aloft. Low level lapse rates are computed roughly from 1000-700 mb, so there's some often saturation within that level, so its okay for the lapse rates not to be exactly 9.8ºC/km or higher. Mid-level lapse rates are computed from the 700-500 mb level. The latest SPC mesoanalysis shows low-level lapse rates peaking around 7ºC/km in mid-Michigan and shallow moist adiabatic lapse rates of around 6-6.5ºC/km in the mid-levels. Thus today's instability is quite sensitive to any surface cooling via clouds, outflow boundaries, and the loss of daytime heating tonight.

I do think there is enough upper-level support for organized severe thunderstorms across all of lower Michigan today, with damaging winds bring the primary threat. However, as you pointed out, the tornado threat (albeit still on the low end), is maximized in Mid-Michigan today where the best axis of instability, upper shear from the 500 mb jet, and low level shear from the messy MCS boundaries coincide. Good call by the SPC putting out a mesoscale discussion in that area. Hail will also be possible in the strongest updrafts.

The storms that form up north will consolidate into a nice hefty line with torrential downpours. I think storm movement should be quick enough that the flooding threat is not nearly as bad has it has been with recent storms. The wind profile certainly supports sustaining a strong-to-severe line of storms with scattered areas of damaging winds. There's enough low-level spin (helicity) to support a brief spin-up tornado, but that threat is still quite low.

Thanks MW -- I appreciate your compliments and enjoy the conversation.

There was a tornado warning for a confirmed tornado near Port Austin and moved east across Huron County in the thumb. A funnel cloud was also spotted in Saginaw. The Marine Warnings in Saginaw Bay all include mentions of possible waterspouts as well.

The tornadoes/funnel clouds have been reported in the areas where the latest SPC mesoanalysis has the best 0-3 km CAPE coinciding with surface vorticity. The surface vorticity is generally being aided by the front and it's moving into a decently unstable airmass, so I still wouldn't rule out additional spin-ups tonight.