December has been low on moisture compared to normal, and near normal for the average temperature. Low precipitation in an El Niño December probably is not very unusual. I’ll have to look. But, it all changes in the start of January. A series of storms is due next week. Arizona will get plenty of moisture with seasonal normal temperatures. Enjoy this week’s sun while it’s here.
I haven’t seen any forecasts that without a high likelihood of a white Christmas for Flagstaff. As it is often the case, the exact timing and total snowfall amounts are changing in the forecast, but several inches in or around Christmas Day are very likely. The 6-10 precipitation outlook is below. I don’t see a huge storm coming to Northern Arizona. Precipitation will be strong to the north and east. Travel across the Southwest could be difficult.
2 or 3 storms are on their way to Arizona. The next two weeks will be mostly, seriously, cold with occasional snow. It looks like the storm track is shifting to the south and splitting, as we expect for an El Niño winter.
The sea surface temperature and temperature anomaly animation from the Climate Prediction Center shows 3 interesting features. First, the current strong El Niño conditions in the Equatorial Pacific are clear. Second, the North Atlantic cold conditions between the UK and Canada are persisting. Last, the blob off the West Coast is slowly disappearing. Interesting animation.
I keep looking at the longer range forecasts, the GFS computer model and the Climate Prediction Center outlooks. It seems like the 6-10 day outlooks have a huge amount of variability. Last weeks snow was never clearly in any of them. One day the 6-10 would be dry. The next day it would be wet. Nothing solid. Yesterday everything had next weekend looking very wet. Today, Thanksgiving weekend looks dry.
I bet it is harder to run the models with the current conditions. There isn’t a great analog available between the Blob, El Nino and the very cold North Atlantic. So, hang on, it could be a rough ride with unexpected storms and dry periods.
The 3-month outlook from the Climate Prediction Center seems to have Flagstaff in the greater than 50% chance of above average precipitation. Southern Arizona could be even wetter.
And now, news from Munich, DE. We had our first snow on Saturday night. No real accumulation. We had an early dinner, then we went to an organ concert at Saint Peter’s Church near Marienplatz. When we came outside, huge flakes were falling. We walked across Marienplatz and went up to the Café Glockenspiel and watched the snow fall as we had dessert. It was beautiful.
The Christbaum on Marienplatz isn’t very healthy. It had a very dry summer that weakened it. It will be hard for it to make it through Christmas. The needles are falling off.
Today will start wet in Northern Arizona. Around night fall, maybe a bit later, the rain should change to snow and start our El Nino winter. Almost an inch of water could fall from the skies in various forms. As it is often the case for these early winter storms, timing of the switch to snow is everything. A fairly dry period will follow as the winter storm pattern continues to develop.
My current frame of reference is Munich. It’s been mostly foggy with cool clear nights cause the still relatively warm moist ground to product fog. But, rainfall and first snow have been on my mind.
3.68 inches of rain have fallen in Flagstaff in October. This is more than double the normal amount. Below is the rainlog.org picture for October in the Flagstaff Area. As always, there is much variability. Overall, it was a wetter than normal month for Flagstaff, but very far from a record. This make the 12 month precipitation total 27.39 inches.
My weather station here in Munich has measured 3.5 inches of rain. Munich’s average precipitation is 2.68 inches at the airport. So, both Flagstaff and Munich have had a wet October, but I think Flagstaff has been wetter.
I continue to be interested in the Atlantic Multidecadal Oscillation(AMO) impact of Flagstaff precipitation. It surprises me that there could be a link between the sea surface water temperatures in the North Atlantic and the rain and snow amounts on the other side of North America, in a desert.
I past posts, I have discussed the image below and the link of AMO and Flagstaff precipitation.
The basic summary is that if the Atlantic is cool (AMO Negative) and the Pacific is warm (PDO Positive), Northern Arizona should have a lower risk of drought. But, does the AMO alone have a noticeable effect on Flagstaff precipitation. Using the data from NOAA at their Earth Systems Research Library, and the precipitation data for Flagstaff since 1950, a potential match in the data sets appears. (I only use the data back to 1950 because the National Weather Service’s Flagstaff measurement location moved from downtown to the airport in 1950.) To help reduce short-term effects, I used the smoothed data for the AMO and last 12 months precipitation total. Here is the resulting graph:
Looking at the AMO data, I see three zones In the first zone, the AMO is mostly positive and ends around January 1963. In the second zone, it is mostly negative and goes through July 1995. In the last zone, it is mostly positive. Here is another graph with those zone highlighted.
Looking at the each of these zones, there also appears to be a difference in the 12 month precipitation amounts.The first and last zones have a lower average. But is that enough?
Looking at a histogram of the precipitation data shows the trend more clearly.
The first and last zones have their peaks at lower precipitation amounts. There is still plenty of overlap between the zones, but the 1963-1995 zone has a higher average and a longer tail at the higher amounts. The Atlantic sea surface temperatures seem to have an effect on Flagstaff’s precipitation.
One lingering point concerns me. The is a recent upward trend since about 2010. The AMO data above includes the entire North Atlantic, from the Equator to 70 degrees North. This view might not be the best. There has been a persistent band of cold water in the far northern region of the Atlantic for about the last two years. This matches a move to a higher average precipitation recently. A better subset of the North Atlantic might be worth considering.
Yesterday I occasionally watched the weather radar as events emerged across Arizona. I could tell Flagstaff was going to get an early morning wake-up call from Mother Nature. And Mother Nature did not disappoint.
I did miss being in Arizona to see it first hand. October storms like this are often some of the most interesting to me. To me, if not the data, October is often a drier month with lots of wind. The occasional storm is more fun than wind.
With the recent precipitation, October is well above average for precipitation. With 3.21 inches, Flagstaff is roughly double the monthly average since 1950. The Northland can expect more rain today, but then a drier trend is on the way with lower chances through Friday, and a clear fall weekend.
It’s been a while since my last post. This is all thanks to Apple. I bought a new laptop because using my big MAC in Germany isn’t practical anymore. We just don’t have the room for it. After a week of using the new laptop, the arrow keys broke. The first chance I had, I took it to the Apple Store to have it replaced or fixed. They wanted to fix it, but the part would take some time. I could still use the computer, but not easily. Then I took it back when the part came in. They said I would receive a message in 3-5 days. After a week I called. They told me it would be another week before they got to it. Sheesh. I feel like just gave Apple a loan of over a thousand bucks for a month! This is not Steve Jobs’ Apple!
Deep cleansing breath in…and out.
So, I missed blogging about the rain last week. With the airport receiving 1.27 inches of rain, Flagstaff is well on its way to an above average rainfall month. The average October precipitation in Flagstaff since 1950 is 1.54 inches. With the outlooks for the next few weeks, we should easily surpass the average.
I’ve taken the current 6-10 day, 8-14 day, 3-4 week, 1 month and 3 month outlooks and made an animated gif. This is below.Most of Arizona is comfortably inside the above normal chances for above average rainfall for all time periods. El Nino and the disappearance of the Ridiculously Resilient Ridge are driving this. I wonder when the first big snow will show up. It could be this month.
Also, the North Atlantic is colder than normal. This can also mean a wetter than normal winter. I plan to do some more on this topic when I get my laptop back. The spreadsheets are on the laptop.