Check out the image below. The little pink dot over the Flagstaff means that there is still a chance for March to have normal, or even a bit above normal precipitation. Even with the warm temperatures over the weekend, there is a change coming. The storm track will be crossing Arizona for the rest of the month. Temperatures will drop slowly during the rest of the month. This means the first storm will start as rain on Wednesday. Any snow will probably be wet. Future storms should be colder and snowier.
July and August are the wettest. They are followed by December and March. This is based on the average precipitation values at the Flagstaff Airport since 1950. The average precipitation for March is just barely over 2 inches. But wait! It’s been sunny and warm all month.
Way back when, it was sunny and warm through all of March after a pretty long wet winter. On March 31, it started to snow. It kept snowing for 5 days. 5 days. The city pretty much shutdown.
Will we have a repeat this year? I mentioned last week a chance for storm around March 23-24. Now it looks more like a pattern change. The end of the month will be colder and wetter. But, will it hit the average after a dry start?
Maybe. Around March 21-22, the first round of moisture will arrive. By the end of the month, one or two more storms should blow through Flagstaff. Below is the projected total precipitation through the end of the month. It’s right on the edge of 2 inches. Go figure!
Flagstaff has above average precipitation amounts for both the calendar year, and the water year (since 1 September). February had a final big storm at the end of the month to just cross the normal for the month. So far, March has been effectively dry.
It looks like it’s going to stay the way for most of the month. However, it might go out with a bit of precipitation. A storm showed up in the GFS model on March 22-23. It’s not a huge storm, and it is a long way out, but it’s the first real shot that has been in the computer model for quite a while.
With the Flagstaff Airport coming in at 16.3 inches, and many locations reporting similar results, for 8-12 inches in the actual Weather Service Forecast, this was a heck of a foot on snow. This last storm was tricky to forecast with plenty of variability of the computer models. Also, the track of the storm was a bit unusual. The low pressure came from the northwest, with a strong moisture flow behind it. In the end, a seemingly dry, warm February finishes nearly exactly on average for precipitation.
Unfortunately, that looks like the end of the precipitation for a while. All of the outlooks from the Climate Prediction Center are showing below average precipitation through the end of March. Maybe there is a chance for something in the middle of the month.
Finally, the models have aligned. We’ll see if it holds.
As you see below, heavy snowfall is on the way to the Flagstaff area. A winter storm warning is in effect from Monday evening through Tuesday morning. As you look at the image below, you will notice that Flagstaff is under the greenish section of the color scale. That should comfortably put it in the 12 inch or better range. The National Weather Service is forecasting 8-12 inches. Temperatures are going to be fairly warm during the snowfall, which could mean denser, less deep accumulations.
URGENT - WINTER WEATHER MESSAGE National Weather Service Flagstaff AZ 507 PM MST Sun Feb 26 2017 AZZ015-271200- /O.CON.KFGZ.WS.W.0003.170227T1800Z-170228T1800Z/ Western Mogollon Rim- Including the city of Flagstaff 507 PM MST Sun Feb 26 2017 ...WINTER STORM WARNING REMAINS IN EFFECT FROM 11 AM MONDAY TO 11 AM MST TUESDAY ABOVE 6000 FEET... * TIMING...The first flake of snow will occur by midday Monday. The heaviest period of snow will be between 11 PM Monday to 5 AM Tuesday. Snow should taper off by midday Tuesday. * GENERAL EVENT TOTAL SNOW ACCUMULATIONS... Elevations 6000 to 7000 feet: 5 to 10 inches (mainly west of Flagstaff). Elevations 7000 to 8000 feet: 10 to 13 inches. Elevations above 8000 feet: 13 to 18 inches. For the most up to date information consult the point specific forecast at: WEATHER.GOV/FLAGSTAFF. * SNOWFALL FORECAST FROM 11 AM MST Monday UNTIL 11 AM MST Tuesday... Doney Park 1 to 3 INCHES Flagstaff 8 to 12 INCHES Williams 6 to 8 INCHES * OTHER IMPACTS...Gusty winds will develop causing reduced visibilities in blowing and drifting snow at times during this event. PRECAUTIONARY/PREPAREDNESS ACTIONS... A Winter Storm Warning means severe winter weather conditions are expected or occurring...due to significant amounts of snow and strong winds producing limited visibilities. Driving will be extremely dangerous during this storm. For the latest road conditions and closures...call the adot freeway management system at 1 888 411 7623 or visit their web site at www.az511.com. Additional weather information is on the web www.weather.gov/flagstaff.
Maybe one computer has made up it’s mind. The Navy computer model is predicting a wet end to the February on a consistent basis. NOAA’s GFS model is not repeatably predicting anything. On Friday, two runs of the GFS model shows very light precipitation through the end of the month. Then, there were two other runs that showed over an inch of water coming to the Flagstaff are by the end of the month. Given the recent misses in forecast heavy rain or snow for Arizona, I am doubtful we will see a big storm for the start of next week.
If the most recent runs are accurate, there could be significant snowfall by next Wednesday. A little snow or rain could fall during the day on Sunday. Then, Monday afternoon through Tuesday night, Flagstaff could receive 8-12 inches of snow. So, be ready.
February has been warm and dry. It probably won’t be the warmest or driest since 1950, but it will be in the top 5 warm Februaries since 1950. If the precipitation comes through, there is still a chance to be at the average for the month. I’m doubtful.
The computer GFS computer model is all over the place. Here is an animation of 4 images. All 4 images report total project precipitation through next Tuesday evening. Notice, it hasn’t started to rain or snow at this time, so that the start time doesn’t matter. The precipitation amounts are widely different. It looks like Flagstaff is in the 0.5 to 3 inches range, depending on which run you like.
The current Navy model, which doesn’t automatically calculate totals from more than 6 hours, appears to forecast a couple inches of precipitation. Currently, the GFS model has predicted more snowfall than earlier this week.
Reader: Stu, that title is in German.
Stu: I know, but it will make sense later on.
Bis Freitag scheinen sich die Wettermodelle noch sehr einig zu sein, was am Wetterhimmel passiert. Aber schon am Wochenende sind sie sich schon nicht mehr einig, die Temperaturspanne wird breiter. Und in der nächsten Woche liegen die Prognosen derzeit sogar 20 Grad auseinander. Das Wetter weiß noch nicht, wohin die Reise geht. Winter oder Frühling? Beides ist noch möglich. (wetter.de)
The computer models have been crazy with changes lately. As I read this brief story yesterday on wetter.de, it appeared very relevant to me. The computer models for the Southwestern US have been subjects to wild swings when predicting precipitation for the rest of the month, let alone this weekend. According to this brief article, there is a 20 degree C difference between computer model runs. That means it could be sunny and 68 degree F on Saturday, or it could be freezing. I’m hoping for warm, and we are heading to Bamberg to test drive smoked beer.
This weekend will be wet, and the rain and possible snow will continue through Tuesday. Snow levels will start high, but drop through this time. Snowbowl should get a nice recharge. Somewhere between 1 and 2 inches of precipitation will probably fall between now and the middle of next week.
If you go to Google translate, you can copy and past the German text above and get a rough translation.
The computer GFS computer model has been changing the precipitation outlook for the rest of the month quite a bit between runs. On Friday, the rest of the month, through Sunday evening, February 26, looked fairly wet. This image is reposted below.Flagstaff was in the 1.5 to 2 inch range.
This Sunday morning, everything looks remarkably wetter!!! Flagstaff is in the 3-4 inch, if not more, range. The series of storms for the rest of the month, including the current one, are proving very tricky for the model. Similar effects are showing up in the navy model. Still, the snow levels are projected to remain high for a while. A little snow could fall on Wednesday, and next weekend.
But first, what is average? In the grand view, we have limited data. The National Weather Service maintains a record going back to 1898. Between 1898 and 1950, the weather station site moved 4 times. This complicates the precipitation record because of the effects terrain can play on precipitation amounts. Precipitation has been measured at the Flagstaff airport since 1950.
In the back of my head, I thought average February precipitation was about 2 inches. As I looked quickly at the last few years, 2 inches seemed like a stretch. The last ten years averaged out at 1.47 inches. Ouch! What about the rest of the data? I went back, 10 years at a time, to look at how the averages change.
Wow! The last decade was less than half of the 1987-1996 average. The standard deviation was 0.7 inches across this set of data. Since 1950, the average is 1.98 inches.
Back to the simply question, will Flagstaff get average precipitation in February? From a total water precipitation point of view, yes. Below is the total projected precipitation through the end of the month from the GFS model via Tropical Tidbits. It looks like Flagstaff is in the 1.5-2.0 inches range.
On the other hand, much of it will be rain, not snow. That doesn’t seem to be average. For this weekend’s storm, the snow levels are projected to be high, 8000-9000 feet.