Nov 132014

Or, will we see rain Friday night.

Over the last week, the homegrown forecast at has included a 30-40% chance of rain for Friday. No place else has been as consistent. All of the computer models(GFS, NoGAPs, NAM) have not shown rain until today. I can not remember another time where this has been the case. Yesterday, the National Weather Service predicted a 10% chance. This morning they have accelerated that to 30%.

So, we will see. Did Wunderground get it right? Are they ahead of the pack?

 Posted by at 6:35 am
Nov 102014

I usually shoot for the end of September to write my first post for the winter. Historically, this is because Arizona Snowbowl was dependent on natural snow. Now, they make their own snow. As a result, making the early decision about buying a season pass at a discount doesn’t matter so much.

As early as last spring, the media started to hype an oncoming “Monster El Nino.” A body of warm water moved across the Pacific Ocean from west to east, deep below the surface. To many it looked like a sure bet that this would be the first of many such warming events. I watched and waited.

There are two key components to having a successful El Nino. First, you need the warmer than normal water in the equatorial Pacific. Second, you need the equatorial trade winds to shift from their normal westerly direction to the east. The equatorial waters did warm. The trade winds did not shift. I’m going to go a bit deeper. If you want to go much deeper I strongly recommend Bob Tisdale’s 2014-2015 El Nino Series. He goes into deep detail and you can watch the entire evolution. I am going to use Anthony Watt’s ENSO Page at WattsUpWithThat site for a data source. He has collected a great deal of data from around the world that is difficult to find.

The equatorial Pacific has warmed. Occasionally, it has warmed above the El Nino threshold of 0.5 degrees above normal in the ENSO 3.4 region. The map below shows this region.

El Nino regions

El Nino regions

The warm water did arrive over the summer. The 3.4 region temperature anomaly did turn positive. The graph below from the Australian Bureau of Meteorology shows the anomaly. Over the summer, the anomaly barely crossed above the half degree line. It then fell almost all the way back to zero.

Niño 3.4 Region Sea Surface Temperature Index - 5 Years

Niño 3.4 Region Sea Surface Temperature Index – 5 Years

The problem causing the fall was that the trade winds did not reverse to support full El Nino conditions. As summer went on, more warm water arrived and the temperature trend reversed again.

Australia’s Bureau of Meteorology (BOM) monitors the difference in surface air pressure between Darwin, Australia and Tahiti. From this data, they calculate the Southern Oscillation Index (SOI). The pressure difference is indicative of which direction the winds are blowing. A negative value of the SOI indicates that the winds have shifted to support El Nino conditions. The threshold for El Nino conditions is -8. A graph below shows the SOI over the last 5 years. In the last 3 months shown, the SOI has been negative and at least close to -8. (August -11.4, September -7.5, October -8)

Graph of the Southern Oscillation Index

Southern Oscillation Index from the Australian Bureau of Meteorology.

It looks like the winds may have finally shifted. The sea surface temperatures are shifting. But, is it sustainable. Keep in mind that El Nino means the boy, and refers to the Christmas celebration of Jesus Christ’s birth. The warm waters would be recognized around Christmas time. There is another body of warm water transiting beneath the surface of the Pacific. This should arrive before Christmas. It could be the icing on the El Nino cake. Before you get your hopes too high, most of the outlooks are for weak El Nino conditions at best.

 Posted by at 7:08 am
Oct 122014

If you know me or my blog, you know I watch Lake Powell. Most of my posts are about the water level increase expected each spring and early summer. But many boaters have reported weather problems at the lake that weren’t related to dust storms, thunderstorms or wind storms. Triple digit temperatures are a common occurrence on Lake Powell. The high temperatures can cause engine problems.

Waterskiing at Lake Powell

Waterskiing at Lake Powell

On of the intended benefits of fuel injection was to prevent vapor lock. The gut reaction of most “gear-heads” and marine mechanics is that a fuel injected engine can not suffer vapor lock. I’m now a believer that there is a mechanism for vapor lock in a marine engine.

Marine engines run in a tough environment. The stern drive motors are typically inside a small engine compartment with limited ventilation and exceptional noise insulation. It’s a great environment for containing heat. The lower unit of the stern drive takes up fresh water and pumps it to the engine and support systems. It’s a great way to cool a motor while it’s running. But when you shut down a boat’s engine, there isn’t a natural heat release path. You can run the engine compartment bilge blowers to provide air flow. But there is no radiator like in a car. In the Lake Powell’s summer temperatures, blowing 110 degree air over a 155 degree engine has little effect.

To protect the fuel, a fuel cooler is a part of the cooling system. The fuel cooler’s intent is prevention of fuel vaporization due to high engine compartment temperatures. The water comes in from the outdrive, flows through the power steering cooler, then the fuel cooler, before going to the engine’s thermostat housing. This doesn’t work after the engine is shutdown, either.

Over the last few years our boat driving habits at the lake have changed. We used to spend lots of time on the beach with brief runs for water-skiing or wake boarding, or sightseeing. Now, we tend to do longer runs with plenty of canyon exploring and trips to Rainbow Bridge with friends. This means we run our engine longer and the compartment and engine gets thoroughly hot. Here is a temperature profile of the engine during a summer weekend trip. I measured the temperature on the top of the thermostat housing lifting eye. So, it wasn’t in direct contact with the housing or engine.

Engine compartment temperature profile, July 18-19, 2014.

Engine compartment temperature profile, July 18-19, 2014.

The heat build up is fairly quick. Idling the engine after a run provides a fair amount of cooling. But after shutting down the engine, the cool-down is much slower. Opening the engine hatch provides a better cool down of the top of the engine. Shorter runs result in a much faster cool down. We had to open the hatch because the engine wouldn’t start; we hypothesized vapor lock. But the engine compartment temperature had cooled much at this point. Shouldn’t it have started?

There is a theory about some marine engines. The theory is that some of the engine cooling water flows backwards after engine shutdown. This takes very hot water out of the engine and back the way it came. The first stop on the way out is the fuel cooler.

My son and I tried to replicate the outcome. We took our boat on a long, roughly 40 mile round trip. We went straight back to our slip at Wahweap Marina and shut down the engine as quick as possible. We watched the temperature on top of the thermostat housing lifting eye, and the air temperature inside the fuel cooler box, just an inch or so away from the real heat exchanger.

Thermostat housing and fuel cooler temperature

We watched the fuel cooler temperature quickly move from 101.5 degrees F to 121F at 15 minutes, and hit a top temperature of 124F by 30 minutes. At 45 minutes, we thought the temperature had stabilized and attempted to start the engine. It turned over, but didn’t start. We took a video the fuel being injected at the throttle body when cool, and again when it failed to start.

The fuel spray in the hot video is quite different with spurts, drips and gaps in the flow. The cool fuel spray is well atomized. What a difference!

On other trips, I tried to measure the temperature of the cooling hose that allows back-flow to the fuel cooler. Since the data logger I used had a self-protection turn off at 140F degrees, it only produced a few minutes of data as the temperatures climbed above 140F. Back-flow was the likely issue.

Mercruiser is the manufacturer of my engine. They have provided a tech bulletin about this vapor locking issue on their V-8 engines.

Mercruiser Vapor Lock Tech Bulletin

One of the solutions Mercruiser gives is to insert a check valve in the cooling system to prevent back-flow. I opted for this option. I installed the check valve in the cooling line between the fuel cooler and the thermostat housing. When I removed the existing hose, I found that it was mostly empty. To me, this validated the back flow problem as an issue. The top part of the engine coolant drained out via the fuel cooler. With the included instructions, the valve was remarkably easy to install. An experienced mechanic could do it in probably five minutes. I invested 45 minutes. Here’s a picture of the installed valve.

Cooling line check valve installed. Blue with yellow in the lower right.

Cooling line check valve installed. Blue with yellow in the lower right.

To test the repair, we did a high-speed run to Rainbow Bridge. When we shut down the engine, I watched the fuel cooler temperature. At 15 minutes, the temperature had dropped by 0.3 degrees. In other trips since then, it has occasionally increased, but never above 103F.

Every pump has a low pressure intake, and high pressure discharge. The fuel pump takes it suction on the outlet of the fuel cooler. The pump’s suction can vaporize the heated fuel, even if it is below boiling point. I wanted to record this some place because many boaters at Lake Powell to get hit by this phenomena.

 Posted by at 6:35 pm
Oct 062014

The remnants of Hurricane Simon are on their way to Arizona. The big question is still around which path he will take. The Navy NoGAPs computer model has the bulk of the storm going to the west and north of Flagstaff. The GFS model has the storm going to the south and east of Flagstaff. Which way will he go?

You can see the subtle differences in the two models below. The National Weather Service’s chances of rain peak at 50% right. Wunderground peaks at 80%. Accuweather is forecasting rain and thunderstorms. I think we are going to get wet. I think we need to keep an eye on this storm because it can bring heavy rain and flooding…again.

6 hour precipitation outlook at 48 hours from the US Navy's NoGaps model.

6 hour precipitation outlook at 48 hours from the US Navy’s NoGAPs model.

6 hour precipitation outlook at 48 hours from the National Weather Service's GFS model.

6 hour precipitation outlook at 48 hours from the National Weather Service’s GFS model.

 Posted by at 5:27 pm
Oct 042014

Something new for my blog readers. I’m going to occasionally add reviews for product that are weather related to my blog. First up is the new WR-299 Weather Radio. Please watch the video for details.

This is a great compact emergency weather radio that offers AM/FM and Weather bands. It also have an Alert Mode to let you know when severe weather is on the way. The WR-299 has multiple power options:

*Solar Charger
*Hand Crank Charger
*USB Charger
*AAA batteries

It can also be used to charge your iPhone or other smart device. The speaker is clean and crisp. I can’t believe how good the sound is coming out for such an inexpensive radio.

The flash light is bright and will easily guide you through the dark.

This is an excellent addition to my Lake Powell kit.

 Posted by at 2:19 pm
Sep 302014

I’ve struggled the last few days with a broken internet connection, malfunctioning iPhone and a rainy weekend. The weekend struggle was the wonderful malaise that can hit Arizonans when it rains all day. Nonetheless, the Climate Prediction Center issued new outlooks for October and the 3-month period October to December.

The outlooks point to El Nino developing. I’m still not sure this is a reasonable expectation. Last spring and early summer, the sea surface temperatures in the Pacific Ocean near the equator appeared headed for a strong El Nino. Unfortunately, the trade-winds did not shift to support it and the sea surface temperatures fell. There is another burst of warm water headed towards Peru now. If the winds shift, we will have El Nino conditions and a high likelihood of a wet winter. If they don’t shift, we will see La Nada neutral conditions(I think this is what will happen). Here is NOAA’s narrative about the outlooks:



Here are the outlooks:

One-month precipitation outlook for October 2014 from the Climate Prediction Center

One-month precipitation outlook for October 2014 from the Climate Prediction Center

Three-month precipitation outlook for October- December 2014  from the Climate Predicction Center.

Three-month precipitation outlook for October- December 2014 from the Climate Prediction Center.

 Posted by at 7:10 am
Sep 272014

A strong cold front is crossing Arizona from west to east today. While the moisture is coming from the south, the cold front is a winter weather phenomenon for Arizona. We are expecting fast-moving thunderstorms with heavy rain and other severe weather. This is reminiscent of the storms on October 6, 2010.

The National Weather Service isn’t taking any chances. They have posted severe weather watches and warnings. Check their website for updates.


Weather Story from the National Weather Service (Septemer 27, 2014)

Weather Story from the National Weather Service (Septemer 27, 2014)

 Posted by at 7:02 am
Sep 162014

I have zoomed in and cropped the image below. There is still a pronounced boundary to the heavy precipitation area. The precipitation scale is the same as in the earlier image in my last post. This is from a shorter range, high-resolution model. I think Flagstaff ends up in the 3/4 to 1 inch range. Notice that another boundary is forming along I-40 to the east. Stay tuned! There will be areas of Arizona receiving large amounts of precipitation over the next few days.

Cropped 72-hour total precipitation forecast from the North American Mesoscale computer model by the National Centers for Environmental Prediction. 16 September, 2014.

Cropped 72-hour total precipitation forecast from the North American Mesoscale computer model by the National Centers for Environmental Prediction. 16 September, 2014.

 Posted by at 6:49 am
Sep 152014

Watching the GFS animation for the next 7 days this morning, I noticed a curious flow in the precipitation pattern. This flow reminded me of our last interaction with the remnants of a hurricane. Hurricane Norbert’s moisture missed us by traveling barely south of us. Next up for us are the remnants of Hurricane Odile. Currently, Odile is hitting Baja Mexico. Model predictions call for Odile’s moisture to move across most of Arizona. But, this morning’s GFS model for NOAA shows that a thin line might separate seriously wet areas from damp areas. We will have to keep watching to see where the water goes.

In the image below, I have added a yellow arrow to show the movement of precipitation. There is a large difference in the amounts to the southeast of the line and to the northwest of the line.

5-day total precipitation from the GFS model. Yellow arrow added for emphasis.

5-day total precipitation from the GFS model. Yellow arrow added for emphasis.

 Posted by at 6:34 am
Sep 112014

The newest 6-10 and 8-14 day precipitation outlooks show wet conditions continuing. We should be dry today and Friday. There is a chance for showers over the weekend and into early next week. Sometime in the second half of next week, tropical storm, soon hurricane, Odile will deliver more moisture to Arizona.

8-14 day precipitation outlook form the Climate Prediction Center, September 10, 2014.

8-14 day precipitation outlook from the Climate Prediction Center, September 10, 2014.

5-day outlook for Tropical Storm Odile. From, September 11, 2014.

5-day outlook for Tropical Storm Odile. From, September 11, 2014.

 Posted by at 6:28 am
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