Gary Lezak and "The LRC"........ever hear of him?

jd

jd

Administrator
Staff member
I do not have any recollection of hearing about him, so I cannot make too much of a commentary on him, other than to say if someone really could make a reliable forecast out 12 weeks, his name would be about as well known as anyone in the weather business!

-John
 
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frnash

Active member
Lezak has a credibility problem!

In my humble opinion, Mr. Lezak has a credibility problem. His web site was a bit of a disappointing read. So much so that I have posted the following "web mail" note on his Contact page:

I have only recently discovered your site.

My first impression? You have a credibility problem. To wit:

Excerpts from: Gravity Waves & Can you find the outflow boundary?
by Gary | Jul 25, 2015 | General

"This is the radar image from 8:30 AM this morning."
[I'm sure glad it wasn't from 8:30 AM this evening! — Aren't "AM" and "morning" redundant?]

"It really should be plotted right now that thin line …" [Now that thin line?]

"What is an atmospheric gravity wave? They are similar to waves on the surface of the ocean …"
[It (singular)? They (plural)? Which are you referring to, "A gravity wave, or gravity waves? Please be grammatically consistent!]

"This morning we had thunderstorm complexes to over northeastern Missouri … and now these disturbances have produced gravity waves go billowing out from these systems …"
[To over? "… have produced gravity waves go billowing out …"?]

"When these waves interact with thunderstorms they can intensify them with enhanced rising motion." ["… they can intensify them …"? Which can intensify which?]

Bottom line: You learned English where?

Yes, I have known plenty of competent engineers that couldn't write their way out of a wet paper bag, but that sort of writing does affect the credibility of your whole work product. Sad but true.

Then there's this (on a more technical note):

Excerpt from: Extreme Humidity Over The Missouri River Valley

by Gary | Jul 24, 2015 | General |

"… If we were in Death Valley, CA and it was 129° with extremely low humidity, believe me it would feel a lot hotter in Death Valley. It would be 34° higher and it would feel that much hotter. It will be ridiculously humid and the human body would react to the 94° as if it were 129°, but it would still “feel like” 94°, but very uncomfortable with the body’s inability to evaporate moisture. The body would lose it’s ability to cool off. Hopefully this makes sense. What do you think?"

[What I think: It makes no sense whatsoever. (Perhaps it's still an issue with English.)]

It would feel a lot hotter than what?

I will say this: If we were in Death Valley at 129° with say 8% humidity, it would "feel" like a mere 122°.

I may not have experienced that situation in Death Valley, but I have seen plenty of days in Phoenix, AZ at 112° and above with humidities in the single digits, (typically in June, before the monsoon season brings higher humidities). Not to mention record temperature days of:

1. 122 (26 Jun 1990)
2. 121 (28 Jul 1995)
3. 120 (25 Jun 1990)
4. 119 (29 Jun 2013)

… and including a run of 18 days with high temperatures of 110° or above (12 Jun 1974 - 29 Jun 1974).

Where T = Temperature in °F and R = Relative Humidity in %:
Heat Index = -42.379 + (2.04901523 x T) + (10.14333127 x R) - (0.22475541 x T x R) - (6.83783x10-3 x T2) - (5.481717x10-2 x R2) + (1.22874x10-3 x T2 x R) + (8.5282x10-4 x T x R2) -(1.99x10-6 x T2 x R2)

But of course that's just my humble opinion, not as a meteorologist, but as a pilot/aviation weather aficionado and retired software engineer with a BS in Mathematics, and oh yes, an amateur linguist and philologist.
Click to expand...

Um… was that a bit harsh? :confused:
 
S

sweeperguy

Active member
frnash said:
In my humble opinion, Mr. Lezak has a credibility problem. His web site was a bit of a disappointing read. So much so that I have posted the following "web mail" note on his Contact page:



Um… was that a bit harsh? :confused:[]
Click to expand...

Not harsh, if he is presenting himself as a educated professional meteorologist, he should not be talking nonsense. I applaud your taking the time to put that out on his contact page.
 
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frnash

Active member
Lezak has a credibility problem!

I should hasten to add, for any professional meteorologists that may be reading this (Hi John! ;)):

I realize that no true equation for the Heat Index exists. The equation shown in my previous post is fairly well known, but it only approximates the Heat Index, and because this equation is obtained by multiple regression analysis, the resulting heat index value (HI) has an error of ±1.3°F.

I included the equation only as a means of verifying my assertion, from my experience with the Phoenix AZ climate, that "If we were in Death Valley at 129° with say 8% humidity, it would 'feel' like a mere 122°."

Q.E.D. :)


(Reference: http://www.srh.noaa.gov/images/ffc/pdf/ta_htindx.PDF)
 
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frnash

Active member
Well, he could beat me up about that sloppy copy & paste of the formula at the end of my original post, where some important symbols/mathematical operators were lost — (and my failure to proofread & edit it :p ) as reads:

"Where T = Temperature in °F and R = Relative Humidity in %:
Heat Index = -42.379 + (2.04901523 x T) + (10.14333127 x R) - (0.22475541 x T x R) - (6.83783x10-3 x T2) - (5.481717x10-2 x R2) + (1.22874x10-3 x T2 x R) + (8.5282x10-4 x T x R2) -(1.99x10-6 x T2 x R2)"

Or more correctly/neatly:

"Where T = ambient dry bulb temperature (°F) and R = relative humidity (integer percentage).
= -42.379 + (2.04901523 * T) + (10.14333127 * T) - (0.22475541 * T * T) - (0.00683783 * T^2) - (0.05481717 * T^2) + (0.00122874 * T^2 * T) + (0.00085282 * T * T^2) - (0.00000199 * T^2 * T^2)"
There is an utterly ridiculous number of biometeorological parameters involved in the calculation, all intended to determine the "sensible" temperature as felt by a "particular" human being under some very outrageously specific and individual/personal criteria[SUP]1[/SUP], each of which can be described by an equation but they are given assumed magnitudes(!) here (In parentheses) in order to simplify the model. (Note some of the improbable assumptions!)


  1. Vapor pressure. Ambient vapor pressure of the atmosphere. (1.6 kPa)
  2. Dimensions of a human. Determines the skin's surface area. (5' 7" tall, 147 pounds)!
  3. Effective radiation area of skin. A ratio that depends upon skin surface area. (0.80)!
  4. Significant diameter of a human. Based on the body's volume and density. (15.3 cm)!
  5. Clothing cover. Long trousers and short-sleeved shirt is assumed. (84% coverage)!
  6. Core temperature. Internal body temperature. (98.6°F)
  7. Core vapor pressure. Depends upon body's core temperature and salinity. (5.65 kPa)!
  8. Surface temperatures and vapor pressures of skin and clothing. Affects heat transfer from the skin's surface either by radiation or convection. These values are determined by an iterative process.
  9. Activity. Determines metabolic output. (180 W m² of skin area for the model person walking outdoors at a speed of 3.1 mph)!
  10. Effective wind speed. Vector sum of the body's movement and an average wind speed. Angle between vectors influences convection from skin surface (below). (Assumed to be 5 kts.)!
  11. Clothing resistance to heat transfer. The magnitude of this value is based on the assumption that the clothing is 20% fiber and 80% air.!
  12. Clothing resistance to moisture transfer. Since clothing is mostly air, pure vapor diffusion is used here.!
  13. Radiation from the surface of the skin. Actually, a radiative heat-transfer coefficient determined from previous studies.
  14. Convection from the surface of the skin. A convection coefficient also determined from previous studies. Influenced by kinematic viscosity of air and angle of wind.
  15. Sweating rate. Assumes that sweat is uniform and not dripping from the body.!
  16. Ventilation rate. The amount of heat lost via exhaling. (2-12%, depending upon humidity)!
  17. Skin resistance to heat transfer. A function of activity, skin temperature, among others.!
  18. Skin resistance to moisture transfer. A function of the vapor-pressure difference across the skin (and, therefore, relative humidity). It decreases with increasing activity.
  19. Surface resistance to heat transfer. As radiation and convection from the skin increases, this value decreases.
  20. Surface resistance to moisture transfer. Similar to heat transfer resistance but also depends upon conditions in the boundary layer just above skin's surface. These last five variables are used explicitly to derive the apparent temperature. By an iterative procedure which relies on the assumptions in the first list, the model is reduced to a relationship between dry bulb temperature (at different humidities) and the skin's resistance to heat and moisture transfer.

Even though temperature and relative humidity are the only two variables in the equation, all the variables on the lists above are implied.

A common perception is that wind is not taken into account in the Heat Index. In actuality it is. It is assumed to be 5 knots! This may seem trivial but a forecaster may be able to use this information creatively when writing Public Information Statements regarding heat stress, heat stroke, etc.

Since the resistances (the last four factors above) are directly related to skin temperature, we now have a relationship between ambient temperature and relative humidity versus skin (or apparent) temperature.

[[SUP]1[/SUP]So in fact virtually every individual may well experience a different and personal "feels like" temperature based on the individual and personal criteria shown above in addition to the intimately local ambient weather conditions!]

Can you tell this has been studied to death? Probably for someone's Doctoral thesis. But practical? Not so much, at least in such detail. ;)
 
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