Hot Weekend…And Why Do Clouds Stick Together? (Pt 3)

It looks like the first week of June will be solidly in the “summery” column. A ridge of high pressure will give us a sunny Friday with valley highs in the upper 80s. The 80s will stay through the weekend, although Sunday will bring a slight cool down with breezy conditions. Those breezes will create the first tenuous fire condition of the summer, so be very careful with any of those campfires.

Clouds 2

So why do clouds “stick together?” Perhaps the easiest way to answer is to talk about why those kinds of clouds form in the first place. First, the cloud doesn’t really “stick together”; because if you look carefully at time-lapse imagery you will see parts of the clouds evaporate, while other parts seem to form out of clear air. So the make-up of the cloud itself doesn’t contain a single group of water molecules, but rather the actual cloud is always “recirculating” the water through it.


Cumulus form because small columns air rise and the water vapor condenses as the air cools. It is where this lifting occurs that the clouds seem to be sticking together, whereas in reality, it is a dynamic process of formation and dissipation. This happens with all cloud types. More on that tomorrow.


Warming Back Up…And Why Do Clouds Stick Together? (Pt. 2)

We are going to ring in June on an appropriately summery note. After the trough of low pressure dropped valley temperatures into the lower 70s Wednesday, highs will bounce back into the low 80s Thursday, and climb into the upper 80s by the weekend. Skies will be mostly sunny through Friday, with a few afternoon heat induced clouds popping up Saturday Afternoon. Conditions remain dry and a bit on the warm side of average through the middle of next week at least.

Clouds 2

Yesterday, Richard wondered why clouds “stick” together…Did it have anything to do with ion charges or molecular attractions?  He poses an interesting question. But it’s not one that is especially easy to answer. Let me start by saying that clouds do have negative and positive ions, although those charges are usually grouped such that negative ions tend to group with negative and vice versa, so that wouldn’t provide any attraction there. And on an atomic level, there are inter-molecular attractions that hold individual water droplets together, but don’t really account for a significant attraction between separate water droplets. Water droplets will coalesce (stick together and form bigger droplets), but that doesn’t hold an entire cloud together. Tomorrow, I’ll approach it from another angle.


Cooler Midweek, Warmer Weekend…And Why Do Clouds Stick Together? (Pt. 1)

As we bid a fond farewell to the month of May, we have a little dip in the road temperature-wise as a weak trough of low pressure moves through the region Wednesday. Mostly cloudy skies and scattered to isolated showers will dot the area Wednesday and the valley temperatures will drop to the low to mid-70s. The trough passes through the area fairly quickly, and skies should clear out by Thursday, with high temperatures back into the low 80, continuing to climb to the mid-80s on Friday and the upper 80s by Saturday.


We are now pretty firmly in the time of year where we spend a lot of our afternoons dodging thunderstorms. And even if we don’t get enough buildup for showers and/or lightning, it’s a rare hot summer day around here where we don’t at least see some afternoon clouds build up. Perhaps with that in mind, Richard had the following question for me: “Why do the big white puffy clouds tend to stay together? What keeps them from spreading out and disappearing? The shape will change, but for the most part the cloud seems to stay as a cloud. Does it have to do with negative and positive ions? Or water molecules attracting to each other? Or something else?”  I’ll tackle this tomorrow.


Hot Memorial Day…And What Are The Driest Cities In The US?

The Memorial Day weekend will finish on a summery note, with mostly sunny skies and high temperatures in the valleys near 90 degrees. That’s enough heat to possibly pop up some cumulus clouds over the mountains in the afternoon, but there’s only a slight chance of getting an isolated afternoon thunderstorm. Things stabilize on Tuesday, and the temperatures tail off just a bit before a weak low pressure system brings cooler temperatures and isolated showers to the region on Wednesday. That clears out quickly, and mostly sunny and warm temperatures return for the rest of the week.

Reno arch

Last week I wrote about the rainiest cities in the country. How about the driest cities in the country? How does Reno stack up on that scale?

Well, Reno doesn’t do too badly. The Biggest Little City slides in safely as the fourth driest city in the nation, with an average of about seven and a half inches of precipitation per year (this year notwithstanding). Topping the dry list is our neighbor to the south, Las Vegas, with only four and a half inches of rain annually. Vegas is followed by Bakersfield, CA; Winslow, AZ; Reno; Phoenix, AZ; Winnemucca, NV; Yakima, WA; Grand Junction, CO; Albuquerque, NM; and El Paso, TX.



Heating Up For Memorial Day…And Why Summer Is Wetter Than Winter (In Some Places)

We are going to cool things down a bit going into the Memorial Day weekend, but the temperature trend reverses itself once the weekend proper starts, and we will be looking at mid-summer conditions by the time you go back to work on Tuesday. The ridge of high pressure will strengthen through the weekend, taking Friday’s high in the mid-70s and sending then into the low 80s Saturday, the mid-to-upper 80s on Sunday and to about 90 degrees on Memorial Day Monday. Skies should stay mostly sunny throughout.

Gulf moisture

Yesterday, I listed the ten rainiest cities in the lower 48 states. Besides the fact that it doesn’t include any cities that are publicly perceived as being rainy places, the interesting thing is most of the precipitation that occurs in these areas doesn’t fall in the winter months… but during the summer. That’s because most of their precipitation comes from thunderstorms. If you have ever been caught in a Deep South thundershower, you know that the inches of rain can pile up in a real hurry.

The only nod to common perception is Olympia, Washington. While it doesn’t make the top ten in total precipitation, it did lead the way with the most rainy days per year with 63.


Heating Back Up Memorial Day…And The Top Ten Rainiest Cities in the US

It is looking like we will get a little cooling going into the Memorial Day Weekend, but things will heat up quickly as we go through the weekend. A weakening ridge of high pressure will allow our temperatures to fall back to near 80 on Thursday and then to the upper 70s (with a few afternoon clouds) on Friday. As we go into the weekend, the ridge reasserts itself, and high temperatures will climb back into the low 80s Saturday, the upper 80s Sunday and then to near 90 degrees on Monday.


Yesterday I mentioned that Mobile, Alabama was the rainiest city in the Lower 48 states. What about the rest of the top 10? The results may surprise you.

After Mobile, you have: Pensacola, FL., New Orleans, LA., West Palm Beach, FL., Lafayette, LA., Baton Rouge, LA., Miami, FL., Port Arthur, TX., Tallahassee, FL. and Lake Charles, LA. round out the list.

Besides the fact that it doesn’t include any cities that are publicly perceived as being rainy places, the interesting thing is most of the precipitation that occurs in these areas doesn’t fall in the winter months… but during the summer. I’ll tell you why tomorrow.



Not As Hot…And What’s The Rainiest City In America?

It’s all relative. While we are going to see high temperatures Wednesday about 10 degrees above average for this time of year, we are still “cooling down.” The large and hot ridge of high pressure will shift a bit as a low pressure trough passes by our northeast. The high temperature in Reno will fall to the mid-80s under mostly sunny skies, and then drop to the upper 70s by Friday.

As we head into the holiday weekend temperatures will rebound a bit as the ridge builds back in, reaching the low 80s on Saturday and the mid-to-upper 80s by Sunday and Monday.


We know it isn’t Reno, but just what is the rainiest city in the United States?

Most people have their preconceived answers to that question. Seattle? Wrong. It doesn’t even make the top ten. (The Emerald City actually ranks 41st in the country.) Portland? Not even close. It comes in 42nd place.

Mobile AL

Believe it or not, the rainiest city in the United States is Mobile, Alabama. Mobile averages about five feet (67 inches to be exact) of rainfall every year. Seattle and Portland limp in at about three feet of rain (36 inches and change). I’ll give more of the list tomorrow.


First 90? And Some Encouraging News for the Walker River

\A lot of sunshine and very warm temperatures will still make for a very uneasy time downstream of all the local rivers, although the news appears to be improving for the Walker River, which was feared to be threatened with major flooding, and has since been downgraded to minor to moderate flooding.

A very strong ridge of high pressure will push the jet stream well into British Columbia, and high temperatures in Reno could reach 90 degrees for the first time this year on Tuesday. The temperatures ease off a bit as we go through the week, but stay in the 80s until Friday when they drop back into the 70s.

The Memorial Day Weekend looks to stay clear with high temperatures starting in the upper 70s Saturday and finishing back in the mid-80s on Monday.

flood walker3

Speaking of the Walker River, the flooding situation is looking a little less dire according to the latest forecasts from the Hydrologic Center. The latest forecasts have dropped the expected flooding from major to somewhere between minor and moderate. Some slight changes in temperatures, additional monitoring from emergency gauges and snowmelt that has been slightly less than originally expected has eased the pressure a bit, although care should still be taken near all the area rivers this week.



Much Warmer…And Flooding Concerns

A whole lotta sunshine…that’s the forecast for the next week in a nutshell. A ridge of high pressure will build onshore keeping the skies clear, and will help boost our temperatures into the mid-70s for Friday, the low 80s through the weekend, and then into the mid-80s through the middle of next week. Winds will generally be light in the morning, and then may pick up to about 10 mph in the afternoons.

Spring Snowmelt

The warming trend will also cause runoffs from the area rivers to increase. The region is under an Areal Flood Watch starting Sunday and running for the next couple of days at least. While any flooding on the Truckee River will likely be quite minor (thanks to adequate upstream storage) there is some minor lowland flooding concern on the Carson River, it is the Walker River that is generating the most concern. Since there is almost no storage in the upstream basin of the Walker, moderate flooding is expected along the Walker from Antelope Valley through the Mason Valley next week. This includes the towns of Yerington and Smith Valley. With the extended heat in the forecast, the flooding could be an issue for quite some time.


Sunshine and Warming…And The Difference Between Burn Codes and Air Quality Codes

The forecast over the next several days gets pretty simple. A building ridge of high pressure will result in mostly clear skies and warming temperatures through the weekend. After a chilly start to Thursday morning (a light frost is possible in some of the colder valley micro-climates) the sunshine should warm the afternoon up to nearly 70s degrees, and continue the warming into the low 80s by Saturday. Highs in the low 80s will stay with us through the middle of next week.

ozone 1

Yesterday I talked about the color codes used to describe the days air quality. This is not to be confused with our local burn code, although they are similar and there can easily be some confusion. Our burn code uses AQIs, and also assigns a green color (no burning restrictions) to good air quality and yellow (voluntary cutbacks) to moderate air quality. But the red burn code (no burning allowed) kicks in as soon as the AQI gets above 100.

smog reno

When I first came to Nevada back in the 80s, Reno’s air quality was quite poor, and we were even on the EPA’s “hit list.”  But aggressive pollution mitigation programs (including the Green, Yellow and Red burn codes) have helped to take us off the EPA’s radar.