Monthly Review » Stu's Weather Blog

Rainlog.org

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Jul 082011

The monsoon season seems to be going well. My electronic rain gauge has been giving me fits, but it is finally working properly. Also, I have added a CoCoRaHS rain gauge to my measurement portfolio. CoCoRaHS is a volunteer network run by the National Weather Service to monitor rain and snow fall with greater detail. Good program.

But more important to me is the Arizona-run rainlog.org. CoCoRaHS is more rigid in what data they will except. My electronic gauge on my weather station isn’t sufficient for their standards. So, I augmented it with one of the CoCoRaHS gauges which does have higher resolution and the potential to use with snowfall. Rainlog will accept my electronic data.

Also, Rainlog is local. It is run by the University of Arizona Extension. Their goal is to enhance the knowledge about how much rain fell where in order to help drive more efficient use of our natural resource, water. It is a scarce and expensive commodity in Arizona.

I would like to make a plea to folks to use rainlog.org. If you have a good rain gauge, please register and report your data. If you have a garden or landscaping, please check the sight to see how much has fallen in your area, and use your water more efficiently. Here is a look at the month of July so far from rainlog.org.

Month to date rainfall for Flagstaff Area - July 2011, from rainlog.org

If you don’t own a gauge, you can find links at rainlog and CoCoRaHS for buying relatively inexpensive ones.

How windy was June?

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Jul 022011

It seems to me that accurately comparing wind between monthly time periods is insurmountable. The amount of data needed and local variability can be huge. But, didn’t June seem unusually windy?

I took a quick look at daily maximum wind speed, maximum wind gust and mean wind speed for June 2011, 2010 and 2009. They all show a similar trend, so I will just show the mean data. A graph of the mean wind speeds for these 3 time periods is below.

: Comparison of daily mean winnd speed for June 2011, 2010, and 2009

I included a trend line for each month. While they maybe not the most elaborate analysis, the trend lines show a decreasing trend throughout the month in 2010 and 2009. June 2011′s wind data show a steady to slightly decreasing trend. The decreasing trend becomes even clearer after the middle of June for 2009 and 2010. But, for 2011, the daily mean speed remained elevated. This seems like plenty of analysis for verifying the feeling of “Will the winds ever stop?”

Looking just a little deeper, here are how the averaged daily values look for the last 3 years.

	Average daily max wind speed	Avereage daily mean wind speed	Average max wind gust
2009	23.4	7.4	31.1
2010	24.3	7.8	31.7
2011	27.9	9.6	37.0

In all three categories, daily maximum wind speed, daily mean wind speed and maximum wind gust, last month ruled over the others. This isn’t enough data to make a statisitical analysis. Still, compared to recent history, I think it makes sense that most of us felt like June was windier than normal. 2010 and 2009 are nearly the same when compared to 2011.

We already knew May was chilly.

Monthly Review, Northern Arizona Weather Comments Off

Jun 022011

The preliminary look from the National Weather Service for May is out. It was chilly, in the lowest quartile of historic temperatures for May in Flagstaff.

From the graph below, you can see that the beautiful days were just barely above average, but the cold, wet days were way below average. Many days were 4-6 degrees below average. Three days were 13 or 14 degrees below average.

Flagstaff's May 2011 weather history - Weather Underground

While a few warm days are ahead, the temperature profile for the next few weeks continues to have periods with temperatures below normal, too.

March and Winter Review

Monthly Review, Northern Arizona Weather 1 Response »

Apr 162011

Preliminary March Summary

March was warm and dry for Northern Arizona. This winter has been a see-saw for us. February was cold and wet. January was dry, with near-normal temperatures. And, not to be left out from the oscillations, December was warm and wet. What the heck?

If I carefully pick the months I include in my definition for winter, I can get the results I want to justify my forecast from last fall. So, let’s take a look at all the data from October through March. Here are the departure from the historic averages.

Departure from averages for winter 2010-2011

Idare you to find a trend in that data. Maybe a trend to drier than normal, but even that’s a stretch. And look at the temperature variation. We had some unusual global conditions that drove our winter this year. I have mentioned many of them. A big factor is that with the shift in the Pacific sea surface temperatures to cold levels, global temperatures erased the global warming of the last century.

: Global Temperatures – AMSU Discover Data

That drop in global temperatures shifted weather patterns. Also, the only place that was really warm on the planet was the Arctic. Again, this shifted the storm track farther south. This brought us our several large storms.

The weather service track September to September precipitation. As of March 31, 2011, they were reporting 13.17 inches since September 1, 2010. This is 1.67 inches below normal. Since January 1, they reported 4.26 inches, or 3.10 inches below normal. So, I could claim I was right about the winter, but I think that would be misleading. Especially given the drought monitor data from NOAA.

US Drought Monitor

If I had been forecasting for any place but Flagstaff, I may have gotten it right. If you add December into the January-March data, we have had 6.5 inches of precipitation, which is roughly 1.5 inches below normal. So, less than normal, but we didn’t end up with a drought. But, the snow definitely has had staying power. Also, the word is that Arizona Snowbowl had new and better capabilities for managing their snow this year. That led to a very long season.

I think my forecast was a near miss for this winter.

Quick Look at February

Monthly Review, Northern Arizona Weather 1 Response »

Mar 022011

For Flagstaff, and most of Arizona, February was a cold, cold month. Compared to the 30 year average from 1971-2001, Flagstaff’s temperature was 4.4 degrees below average. That makes it the 27th coldest winter on record since they started keeping records in 1898. Even that one Beautiful weekend wasn’t able to pull us out.

I think the excessive cold weather helped drive our precipitation in the month. We were 0.69 inches above average. This makes last month the 18th wettest February on record. A cold wet month!

With January’s very dry weather, we are still lacking water for the year. As of the end of February, we are 1.43 inches below average for precipitation. For the water year since September 1, 2010, we are 0.36 inches below average. that’s not terribly far from average. If you look at December – February, we are 0.34 inches above average. I think this makes it pretty clear that I, and just about everyone else, missed the precipitation forecast for the winter. March is still forecasted to be warm and dry. We’ll see. I’ll post more details some time soon.

Looking back over recent history since 2004, we see that December was very warm, and February marked a significant pendulum swing to cold.

Average Monthly Temperatures since 2004

Early December Review

Monthly Review, Northern Arizona Weather Comments Off

Jan 022011

December of 2010 is probably going to be one of the warmest on record for Flagstaff. The start of the month was amazing! After a snowy Thanksgiving, the first half of the month saw sunny skies and warm temperatures. Through December 14, the daily highs were almost always in the mid- to upper 50′s. December 13 saw a high of 67F, which broke the previous reecord of 66F.

December Average Daily Temperatures compared to Normal Average

The graph above tells the temperature story. It was all fun and games until the storm door opened December 22. And it opened in a big way. We ended up the month with 3.40 inches of precipitation, 1.57 inches above normal. A very damp end to the month, and probably one of the wetter Decembers on record.

Over the last few days a fair number of aggressive low temperature records were set. Notice many of these weren’t a degree or two colder, but as many as 9-15 degrees lower. What a weird month! Will it continue? More on this tomorrow, but the models show the storm door shutting for a while, but the Arctic Oscillation staying negative.

...RECORD LOW HIGH TEMPERATURES FOR NORTHERN ARIZONA ON DEC 31 2010...

CITY (PERIOD OF RECORD)          NEW LOW HIGH    PREVIOUS RECORD/YEAR
BAGDAD (1929 - 2010)                   31          42         IN  1936
COTTONWOOD-TUZIGOOT (1977 - 2010)      32          47         IN  1982
FLAGSTAFF (1898 - 2010)                17          18         IN  1918
FORT VALLEY (1909 - 2010)              13          20         IN  1918
MCNARY 2N (1920 - 2010)                16          25         IN  1972
PRESCOTT (1898 - 2010)                 22          31         IN  1982

...RECORD LOW TEMPERATURES FOR NORTHERN ARIZONA ON JAN 01 2011...

CITY (PERIOD OF RECORD)            NEW LOW       PREVIOUS RECORD/YEAR
BAGDAD (1930 - 2011)                   12          19         IN  2007
COTTONWOOD-TUZIGOOT (1977 - 2011)      13          20         IN  1983
FORT VALLEY (1909 - 2011)             -28          -19        IN  1912
MCNARY 2N (1921 - 2011)               -12          -9         IN  1976

...RECORD LOW HIGH TEMPERATURES FOR NORTHERN ARIZONA ON JAN 01 2011...

CITY (PERIOD OF RECORD)          NEW LOW HIGH    PREVIOUS RECORD/YEAR
COTTONWOOD-TUZIGOOT (1977 - 2011)      36          42         IN  1979
PAGE (1958 - 2011)                     26          28         IN  1991
PRESCOTT (1899 - 2011)                 26          30         IN  1960

...RECORD LOW TEMPERATURES FOR NORTHERN ARIZONA ON JAN 01 2011...

CITY (PERIOD OF RECORD)            NEW LOW       PREVIOUS RECORD/YEAR
COTTONWOOD-TUZIGOOT (1977 - 2011)      -3          20         IN  1983
FORT VALLEY (1909 - 2011)             -28          -19        IN  1912
GRAND CANYON NP N RIM (1926 - 2011)   -14          -11        IN  1976
PAYSON (1949 - 2011)                    1          6          IN  1976
SPRINGERVILLE (1912 - 2011)           -25          -15        IN  1960

Will November’s cold continue?

Monthly Review, Northern Arizona Weather, Outlooks, Winter Storms Comments Off

Dec 122010

November started out absolutely beautiful! The daily temperatures were as much as 10 and 12 degrees above normal. But, by the end of the month, daily temperatures were as much as 15-17 degrees below normal.

November 2010 departure from daily temperatures for Flagstaff

The cold came with roughly 6 inches of snow for most of the Flagstaff area. Snow stuck around for quite a while, too. There is still a drift outside of my office entrance. Compared to the 30-year mean, Flagstaff was 2 degrees below normal and the 28th coldest on record. It was also the 33rd wettest. In the graph below, the temperatures are compared to the mean of temperatures going back to 2004.

Departure from average for 2004-present for monthly mean temperatures in Flagstaff

After a brief break over the summer and early fall, Flagstaff has fallen back below normal. The question is whether this trend is going to continue. If we continue to see significantly colder than normal temperatures, we cold see closer to normal precipitation.

So far, December has been beautiful! Every day has seen daily temperatures above normal with the last 3 days being 11-12 degrees above normal. This is the how I originally foresaw the winter playing out. Looking ahead to the next two weeks, there is a chance that the storm track will drop south. But, the extent of the drop has been variable. Temperatures appear to be headed toward a cooling trend, but only back to normal levels until around Christmas. So, while the possibility of a White Christmas exists, I remain skeptical.

One other consideration is that it looks like the high number of hurricanes had an impact on Atlantic sea surface temperatures. Much of the North Atlantic has returned to near normal temperatures. This could play a role in moderating how warm and dry the winter will be. At the same time, the Pacific off the coast of California and Baja continues to grow cooler.

Global Sea Surface Temperatures

October Update From Rainlog.org

Climate, Monthly Review, Northern Arizona Weather, Outlooks Comments Off

Nov 132010

If you have your own rain gauge, I strongly encourage you to supply your data to Rainlog.org.

<from Rainlog.org> Rainlog.org is a cooperative rainfall monitoring network for Arizona. Data collected through this network will be used for a variety of applications, from watershed management activities to drought planning at local, county, and state levels. Precipitation amounts are highly variable across Arizona due to topography and seasonal weather patterns. This is especially true during the monsoon season, when thunderstorms can produce heavy rainfall that is very localized.

Here is a graphic of the data for the Flagstaff Area in October 2010. Their monthly report is attached below. You can see the variability that makes this such a great service. If you don’t have a rain gauge, you can look on this site and find someone near you. This can help you decide if you need to water your plants, or not.

October 2010 Rainfall - Flagstaff

Rainlog Climate Summary for October 2010

Sorry for the delay in sending the October summary. November snuck up on us.

October was full of weather surprises including a record number of tornadoes and unusually wet conditions across the northern half of Arizona. Several strong low pressure systems moved through the Southwest during October, bringing unsettled weather, cooler temperatures and widespread precipitation to parched areas of northern Arizona. Several of these storm systems dropped one-day totals of over an inch of rain in the Kingman and Flagstaff areas.

Rainloggers in northern Arizona reported two-day totals in excess of 3 inches from large thunderstorm complexes that moved from north to south on October 4th and 5th. October 5th was the busiest day with the development of several severe thunderstorms and eight confirmed tornadoes that touched down from Cottonwood to Flagstaff, destroying several homes and flattening over 5,000 acres of forest.

October precipitation amounts were two to four times greater than average across the northwest quarter of the state. The southern half of Arizona has seen far less precipitation with most locations reporting only 50-75% of normal rainfall.

October’s wild, wet weather gave way to a dry and warm weather pattern in early November. This most likely will be the main story for the rest of the winter. A strong La Nina event is underway in the Pacific Ocean and is expected to steer winter storms north, away from the Southwest, leaving us with unusually dry weather and the threat of rapidly emerging short-term drought conditions.

October 2010 Review

Monthly Review, Northern Arizona Weather Comments Off

Nov 062010

Tornadoes. I think that sums up the big news maker of the month. If you still haven’t seen these images, check them out.

The monthly summary from the National Weather Service (NWS), October Month In Review, reports on 8 tornadoes that struck the area on October 6. What a day!

Overall, October was wetter than average. According to the National Weather Service, the Flagstaff Airport received a full inch above the average historic precipitation (total of 2.93 inches). This historic average, 1.93 inches, is based on 1971-2001. Looking at the average of 1953-2007, the average October precipitation is lower, 1.63 inches. In any case, October was a wet month, the 21st wettest since 1898.

It was warm too. Wait a minute, how could it have been warm? It was wet. Wetter weather means more clouds. It seemed to be a fairly cool and cloudy month, didn’t it. Clouds also stabilize daily temperatures. They reflect sunlight during the day, and act as a blanket at night. This can be seen in the weather history graph from Weather Underground.

October 2010 Weather History - Wunderground.com

A handful of days had the daily highs above average. The daily lows were rarely below normal. Overall, the daily average was 1.7 degrees above normal, according to the NWS. This made it the 28th warmest since 1898. However, the average of the daily highs was 0.5 degrees below the historic average. The daily lows were a whopping 3.7 degrees above the historic average. September and October reversed a significant trend from mostly below average(2004-2010) monthly temperatures.

Departure from Normal Monthly Temperatures 2004-2010

Since May of 2009, the departure had been on a downward trend. Over the summer this had reversed, with September and October peaking. I am still wondering, with the strong, negative PDO and rapidly falling global temperature predictions, if this trend will continue.

So, back in August, I predicted that August-October precipitation would be above normal. (Fall and Winter Precipitation Outlook 2010-2011) How did I end up? I quoted an average 3-month total precipitation of 7.61. In August, September and October, we received 3.56, 0.79 and 2.93 inches. That is a total of 7.28 inches. So, I missed it. September was oddly dry in the middle of a string of wet months.

September Review

Hurricane, Monthly Review, Record Comments Off

Oct 032010

The National Weather Service hasn’t published their review for the month of September, yet. But, I think it’s a pretty easy month to summarize. Here is the monthly climate graph from Weather Underground.

September 2010 Climate History - Weather Underground

There were two stormy times, from September 6-9 and September 22-23. These provided us with significantly cooler temperatures for several days. The rest of the month was absolutely beautiful. It was the best month this year to get outdoors and enjoy. As you can see the last week of the month was well above normal for temperatures and drove us firmly into an above average temperature month. Overall, according to the National Weather Service, we were 2.4deg F above normal with precipitation coming in at a meager 0.79 inches, 1.33 inches below normal. This shift in temperature represents a strong move in the departure from normal temperatures since 2004.

Departure from normal mean temperatures, 2004-2010

Temperatures have been mostly below normal since the fall of 2009.

September 1998 doesn’t match September 2010. I think this is due to the timing and rapidity of the shift from El Nino to La Nina, and the accompanied change from a warm Pacific Decadal Oscillation Index to a cool one. I think this has led to a faster return of dry, and possibly warmer conditions. Notice the large cool body of water in the Equatorial Pacific.

Global sea surface temperature anomaly - 1 October 2010 (NOGAPS)

Also note the warm North Atlantic Ocean. As an aside, there are a couple cooler patches of water in the North Atlantic. One from the coast of Africa stretching north of the Caribbean towards the East Coast of United States. The other from the coast of Nova Scotia to the east. These are under the tracks of Hurricanes Earl and Danielle, and Tropical Storms Colin and Fiona. Tropical storms provide this cooling.

The warm Atlantic and the cool Pacific are going to be the drivers for our upcoming dry winter.

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Switzer Canyon, Flagstaff, AZ
temp:	63.0 F (17.2 C)
humidity:	16%
wind:	From the SW at 4.3 MPH Gusting to 6.0 MPH
pressure:	30.24" (1023.9 mb)
station:	KAZFLAGS23
hardware:	Oregon Scientific WMR-100a
updated:	May 23, 7:11 PM MST
local forecast