Stu

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A different look at the numbers.

 Models, Monsoon  Comments Off on A different look at the numbers.
Sep 032016
 

I friend of mine reported heavy, torrential downpours in Flagstaff on Friday. This is typically good news. When I looked for the rainfall total at the Flagstaff Airport, the weather station had reported no rain for the day. When I looked at a couple of downtown weather stations, KAZFLAGS42 and KAZFLAGS82, on Wunderground.com, I found 0.57 and 0.32 inches reported. Location matters.

The Flagstaff area is subject to large variances in precipitation depending on location. Prevalent winds, changes in terrain and typography can all change the locally measured rainfall amounts. KAZFLAGS42 and KAZFLAGS82 reported 3.16 and 2.61 inches of rain for the month of August. Looking at Rainlog.org, the monthly self-reported totals are below, the variation is clear.

Rainfall totals from August 2016 on rainlog.org.

Rainfall totals from August 2016 on rainlog.org.

If you have lived in the area, you have experienced. In 1950, the the Weather Service movedFlagstaff weather station moved from downtown Flagstaff, to the current location at the airport. It still baffles me when the National Weather Service references historic data from before 1950. Here is their monthly summary for August 2016:

Monthly Temperature and Precipitation review for August 2016 from the National Weather Service in Flagstaff.

Monthly Temperature and Precipitation review for August 2016 from the National Weather Service in Flagstaff.

Notice the period the reference. It was cool and wet in August, but when you take measures from two different environments, equipment and measurement techniques, care is required making comparisons and claims. At a minimum, it should be made clear every time it is done. A more careful review for Flagstaff would include 1950 until present.

When considering 1950 to present, August 2016 was the second wettest, and tied as fourth coldest. Interestingly, since 2010, 6 of the 7 years have had rainfall above the 1950-present average. And, 3 of the last 4 years have been more than one standard deviation above the 1950-present average. Two of the last 4 years have been more than one standard deviation below the 1950-present average temperature.

 Posted by at 4:36 am

Second wettest August since 1950

 Hurricane, Record  Comments Off on Second wettest August since 1950
Aug 272016
 

With two days of record rainfall, 1.41 inches on Friday, 0.94 inches on Saturday, the total precipitation for August at the Flagstaff airport is 6.34 inches. Since placing the National Weather Service placed the weather station at the Flagstaff Airport in 1950, only August of 1986 had higher rainfall at 8.06 inches. This brings the 12 month precipitation over 26 inches, and the two-year total to over 52 inches.

The computer models keep projecting a drying trend, which never shows up. We’ll see what happens. I haven’t written in a while because the model outlooks have been in flux. Watching the potential development of tropical storms and hurricanes in the Atlantic has been very perplexing. Over the last week, one system has shifted between a band of organized thunder storms to a very powerful hurricane in and around Florida several times. Hurricanes, and forecasts of hurricanes, can affect the weather, and forecasts of the weather, for thousands of miles around. For some reason, there is a huge amount of variability in the computer models now. It will probably persist for the next few weeks as a very powerful storm is in the longer term outlooks.

 Posted by at 11:10 pm

Weather is always odd

 Models, Monsoon, Northern Arizona Weather, Outlooks  Comments Off on Weather is always odd
Aug 112016
 

As the most recent batch of moisture, which was left over from a tropical system, starts to leave Arizona, the outlooks have switched. We still have a dry period ahead, but then more moisture will return in about a week. At least, it looks that way today.

Yesterday, NOAA increased it’s outlook for Atlantic hurricane activity for the rest of this season. As if to point out who’s in charge, the computer models and Mother Nature removed any hint of future development in the next two weeks. Still, we are in the season and tropical activity can spin our monsoon season any which way. Hurricanes affect the weather for thousands of miles. With none in the plans, after the upcoming dry spell, thunderstorms should make a comeback.

To date in August, the Flagstaff Airport has received 2.32 inches of rain. an average or above average month is at hand. By comparison, Munich has received nearly 3 inches in August, and close to 11 inches in the last 30 days.

 Posted by at 9:35 pm

Don’t get too used to being dry

 Monsoon, Northern Arizona Weather  Comments Off on Don’t get too used to being dry
Aug 062016
 

With July finishing nearly on average for precipitation and over two inches falling already in August, the next few days should be mostly drier. But, don’t get used to it.

I think the current break in the action is due to a couple of tropical systems moving around Southern and Central Mexico. These have shutdown the flow of new moisture into Arizona. One Wednesday through Friday, some of their moisture and storm energy will move into Arizona. From the computer models, storms could double the current precipitation amount for August. The has been a consistent forecast for a couple of days now. We will see.

Beyond that, the monsoon flow looks shaky. For the calendar year and for the water  year, Flagstaff is well above average. This is interesting given how dry last winter was.

For those of you wondering, we have also had over 2 inches of rain in Munich this month. That’s on top of the nearly 7 inches of rain in July. Supposed to clear up today.

 Posted by at 9:52 pm

Strong precipitation outlook for the next month

 Models, Monsoon, Outlooks  Comments Off on Strong precipitation outlook for the next month
Jul 222016
 

The Climate Prediction Center released new 6-1o day, 8-14 day and 1 month outlooks on Thursday. Even though Flagstaff’s July precipitation is half of normal for this point in the month, the next month of the monsoon season should be above average. Below is an animation of these outlooks.

6-10 day, 8-14 day, and one month precipitation outlooks from the Climate Prediction Center (June 21, 2016)

6-10 day, 8-14 day, and one month precipitation outlooks from the Climate Prediction Center (June 21, 2016)

 Posted by at 8:40 am

After a long sigh, the monsoonal flow will return

 Monsoon  Comments Off on After a long sigh, the monsoonal flow will return
Jul 162016
 

It’s been chilly an draining in most of Europe for the last few weeks. It’s been warm and dry for a couple of weeks in Northern Arizona. Thunderstorm activity will increase over the next few days and hopefully continue for most of the rest of the month. I think I mentioned July 19th in my last post. This should be right on time. It’s going to change for Northern Arizona, but I don’t think it will change for Europe.

The southwesterly flow on the monsoon season is returning to Arizona. It looks like a return to normal, but I’m not sure it will be enough. Currently, July is 0.58 inches below average for the month to date. It looks like Flagstaff will receive over an inch by the end of the month. This would leave us short of the normal roughly 2.5 inches.

10 day total precipitation forecast from the Climate Prediction Center's GFS model.

10 day total precipitation forecast from the Climate Prediction Center’s GFS model.

 Posted by at 12:04 pm

Strong start, but now the monsoonal flow will stall

 Hurricane, Monsoon, Northern Arizona Weather, Outlooks  Comments Off on Strong start, but now the monsoonal flow will stall
Jul 022016
 

With over 1.25 inches of rain since June 15, Flagstaff has enjoyed a strong start to the monsoon season. However, that will change. A series of strong, Eastern Pacific tropical storms far to the south are going to distract the moisture flow. These storms are not going to head northward along the coast. The current forecasts have them moving to the west-northwest almost due north of Hawaii before looping back towards Washington State. After today, the changes for rain drop substantially. Isolated thunderstorms will start this week. By next weekend and through July 19, the chances for precipitation drop to nearly zero.

The Climate Prediction Center published a new 1-month outlook on June 30. It shows most of Arizona with better than normal chances for above average July precipitation.

 Posted by at 10:25 pm

Thunderstorm season to start early and with a boom

 Models, Monsoon, Northern Arizona Weather  Comments Off on Thunderstorm season to start early and with a boom
Jun 252016
 

We all know that the 4th of July is the typical “start” of monsoon season in Northern Arizona. So, anything earlier in my mind is early. As I sit in Munich and enjoy an even thunderstorm and a cool (not cold) weißbier, the computer models are telling me it is going to start very wet.

From the Climate Prediction Center, Friday’s 6-10 and 8-14 day outlook are strongly on the side of a very wet start to the season. Personally, I don’t believe they have the best record on monsoon forecasts, but I hope they are correct. And that they are correct because they have improved their modeling capability.

6-10 and 8-14 day precipitation outlooks from the Climate Prediction Center.

6-10 and 8-14 day precipitation outlooks from the Climate Prediction Center.

Here is the total precipitation forecast from their GFS model for the next 10 days. Notice some areas are to receive as much as 2-3 inches of rain.

I still worry that a strong start will result in a quick season.

gfs_namer_240_precip_ptot

 Posted by at 9:32 am

Wet Outlook for Monsoon Season Start

 Northern Arizona Weather  Comments Off on Wet Outlook for Monsoon Season Start
Jun 222016
 

With the already wetter than normal June (over half an inch above average), the start of the monsoon season should be wetter and earlier than average. Yesterday’s rain in the Flagstaff area is just a taste. It should dry out one more time before next week. While the 1-4 week outlooks all call for above average precipitation, I’m not sure how long it will last with the on-coming La Nina.

Below are  the outlooks for 6-10 days, 8-14 days and 3-4 weeks. They all show above average expectations of above average precipitation. After last winter’s dry conditions, this should help the Northland. As La Nina emerges, I am afraid that the season will start strong, but finish quickly and lead to a long dry phase.

6-10 day precipitation outlook from the Climate Prediction Center.

6-10 day precipitation outlook from the Climate Prediction Center.

 

8-14 day precipitation outlook from the Climate Prediction Center.

8-14 day precipitation outlook from the Climate Prediction Center.

3-4 week precipitation outlook from the Climate Prediction Center.

3-4 week precipitation outlook from the Climate Prediction Center.

 Posted by at 6:31 pm

One More False Start

 Northern Arizona Weather  Comments Off on One More False Start
Jun 182016
 

I mentioned to a few people I saw in Flagstaff yesterday that I thought there was a chance the monsoon season would start in earnest next week. The warm/hot temperatures we will experience over the next few days will drive formation of the thermal low pressure system in southwestern Arizona. (Visit my Monsoon Mechanics website for more detail)

Watching the computer models, the monsoon flow from Mexico has come in and out of the outlooks. Yesterday, I thought that Wednesday or Thursday would kick of the season with some level of regular storms. Today, it doesn’t look so certain. In most years, the computer models poorly predict of the thunderstorm activity during monsoon season. I still think it will be a bit early. In any case, the typical 4th of July start looks certain.

UPDATE:

Here is the newest 8-14 day precipitation outlook. Since it comes on a weekend day, I have doubts about its accuracy. But, it does point to an pre-4th of July start of monsoonal storms.

8-14 day precipitation outlook from the Climate Prediction Center. (18 June 2016)

8-14 day precipitation outlook from the Climate Prediction Center. (18 June 2016)

 

 Posted by at 6:33 am
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