Atmosphere Comparison

[Jim]

The endless chatter of weather.

[chumley]

Kayaking on I-10 has historically been the result of the remnants of tropical systems moving into Arizona. Kayaking is fun.

[chumley]

Can we really count on widespread 1-2" rain totals from a forecast this far out, and as uncertain as tropical systems typically produce in Arizona? (I was hoping for more, but I think that historical tropical systems drop higher amounts of rain in pretty limited areas.) It will be interesting to see how this develops.

For now, here's the current "Hi Jim ;)" QPF map.

[Jim]

Yeah, a 168 hour QPF is typically not all that reliable, but we shall see. Even with a higher level of accuracy for a Pacific Low in January that will affect the Sierra Nevada, there tends to be a lot of variation over that time frame, as you know, Toddy. The models haven't been very reliable for the big predictions over the last month. We shall see.

Looking at the potential rainfall, and realizing that this is more the result of a low dropping into the state from the Great Basin, and moisture from the dead tropical storm, if this does pan out, it raises one question for me. Given how dry the state has been this summer, what kind of benefit will this bring? Flagstaff still reports only 1.24 inches of rain since July 1. How widespread was that kind of pattern?

Assuming other similarly dry areas picked up 1.5+ inches of rain, which would just about saturate most of the soil, with it being so late in the growing season for areas above 3,000 or 4,000', how great is this for most plants? In Phoenix, it probably would help wild flowers out for spring, but with several mid 30s low temperatures already recorded on the Colorado Plateau, it probably doesn't have as much ecological benefit as summer rain in early August would have had.

Then again, last year the early October storms were so wet, that the rocks were leaking trickles of water from their cracks in the Sierra Ancha, so the hydrologic benefits are obvious.

[chumley]

The current run of weather models result in an 11.5% chance of no measurable rain in Phoenix from now through Wednesday next week. I'm starting to think that this percentage will increase.

[DixieFlyer]

My rain gauge has recorded 3.9" of rain so far today. That is quite a bit when you consider that the average annual rainfall is around 9".

[Jim]

We beat the odds! It rained.

[sneakySASQUATCH]

accumulation and 21 degrees.

[Jim]

WOW! the dew point at Sky Harbor is -2 degrees. Thats dry!

[sneakySASQUATCH]

Woke up to the second snow of the season. Only about 2”.

[sneakySASQUATCH]

It snowed a little last night.

[Jim]

Someone is getting more early snow tonight and tomorrow. To think I thought April was his big snow month.

[DixieFlyer]

Someone is getting more early snow tonight and tomorrow.

Thankfully it is not me!!

[sneakySASQUATCH]

Yes we are! Global Warming.

[chumley]

The Flagstaff weather office just issued a post showing that parts of their forecast area are experiencing some of the lowest humidity values possible.

Prescott Airport is currently reporting a humidity of 1%.
The temperature is 72°F and the Dew Point is -63°F (yes, the dew point is 135 degrees lower than the air temperature! )

Here in the valley, most humidity values are in the single digits with dew points ranging from the negative single digits to the teens.

This explains why my contact lenses literally bounce right off my eyeball!

[Jim]

@chumley
While that is an impressive difference between temperature and dew point, the most interesting thing to me is the asymptote that seems to be created if you plotted a curve of the humidity level. Maybe this is due to them not being able to give a 1/4% humidity, or 0%, which would be nearly impossible? I'm pretty sure physics plays some role here, and it is not a linear relationship. Maybe Randy knows why?

Here is what I mean, for those that aren't familiar with this idea. In 2007 I remember living in Flagstaff and 1 June day we had a temperature in the high 80s and a dew point in the low single digits. Humidity was 2%. For an temperature difference of over 85 degrees between temp and dew point, it was 2% humidity. Yesterday, for difference of 135 degrees, 1%. Anyway,....

[azlaurie]

Hiking Brown's Peak tomorrow. First time. Super stoked, the weather looks to be real nice.
Thank you for your time.

**Hikebot edit in bold

[LosDosSloFolks]

@azlaurie
Have fun! We were there 3 weeks ago but chickened out in the chute. Knew we could get up but we both were anxious about coming back down. Lots of videos on YouTube of "schlubs" having no problems so it should be a piece of cake for you. Then you can focus on Joe's "Mother Lode".

[azlaurie]

@LosDosSloFolks
Ty. Can't say I'm not nervous. And I already have a mother loader. I just need to get on board.

[chumley]

@azlaurie Well the weather thread has gone off the rails a few times but this is a whole new level!
May you have good weather on your hike!

[rwstorm]

@chumley
I think Jim's comment short circuited some folk's interest levels, and they went to a default "let's hike" mode. But he is right, it is all based on physics and there are computations for such wild readings. Trouble is, there are no instruments that can accurately measure such values (almost theoretical at such low numbers), so the validity of any reading under about 2 percent is highly questionable. But of course, it plays well in our presently sensationalized social media world, where everyone seems to be trying to out hype and out do the other.