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Monsoon season to start in earnest next weekend

 Climate, El Nino/La Nina, Models, Monsoon, Northern Arizona Weather, Outlooks  Comments Off on Monsoon season to start in earnest next weekend
Jul 022017
 
Dew point temperature outlook for Saturday afternoon, July 8, 2017, from the GFS model at TropicalTidbits.com.

In June, there have already been several thunderstorms and rain showers. But, a sustained monsoonal flow has been mostly absent. Dew point temperatures will rise throughout the week, with most Arizona being in the mid-40s by next weekend.

Dew point temperature outlook for Saturday afternoon, July 8, 2017, from the GFS model at TropicalTidbits.com.

Dew point temperature outlook for Saturday afternoon, July 8, 2017, from the GFS model at TropicalTidbits.com.

While isolated thunderstorms would be come more frequent this week, next saturday is the first day that seems to have pretty good areal coverage.

24-hour total rainfall forecast for next Saturday, July 8, 2017, from the GFS model at TropicalTidbits.com.

24-hour total rainfall forecast for next Saturday, July 8, 2017, from the GFS model at TropicalTidbits.com.

One last note, the start of the season should be strong. The 6-10 and 8-14 day outlooks from the Climate Prediction Center show above average precipitation. The longer range 1 and 3 month outlooks only show normal precipitation chances. I think these may change the next time they are run since the El Niño outlook has a decreased likelihood of it occurring this year.

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 Predication Center.

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

 Posted by at 9:13 am

Unsettled weather could delay fire season

 Northern Arizona Weather  Comments Off on Unsettled weather could delay fire season
May 042017
 

Next Tuesday through Thursday, a low pressure system is currently in the forecast to move across Northern Arizona. It should bring considerable water, but spread across the three day period. That should help with fire season after several weeks with high winds.

I don’t write much about the spring winds. The driving force is the passage of storms north of Arizona. We get the winds. Utah gets the rain. This storm is dropping farther to the south, so we get the rain this time. Over an inch could fall across Flagstaff and surrounding areas above the Mogollon Rim. There could be large gaps in time where no rain falls. Also, it is a cut-off low pressure system, which means there is high variability in the forecast.

60-hour total precipitation from the GFS model, ending Thursday, May 11, 2017.

60-hour total precipitation from the GFS model, ending Thursday, May 11, 2017.

 Posted by at 8:04 pm

Major Snowstorm to Hit Flagstaff Tonight

 Northern Arizona Weather  Comments Off on Major Snowstorm to Hit Flagstaff Tonight
Apr 012017
 
GFS Precipitation Model from US Navu NOGAPS site. For Thursday night to Friday morning.

Welcome to April!

Unbelievably, all of the computer models have changed overnight. Flagstaff will receive 5-7 feet of snow overnight! The National Weather Service is clearly scrambling to get a grip what they should do about this. No severe weather warnings have been issued. Expect temperatures to drop severely this afternoon and early evening. Snow should start to fall right at sunset. Be ready to not be able to travel for several days.

What a way to start April!

GFS Precipitation Model from US Navu NOGAPS site. For Thursday night to Friday morning.

GFS Precipitation Model from US Navy NOGAPS site. For Saturday night to Sunday morning.

 

 

 

 

 Posted by at 8:58 am

Little pink dot means?

 Northern Arizona Weather, Winter Storms  Comments Off on Little pink dot means?
Mar 202017
 
Total precipitation outlook for the rest of March 2017,from the GFS Model. (Tropicaltidbits.com)

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.

Total precipitation outlook for the rest of March 2017,from the GFS Model. (Tropicaltidbits.com)

Total precipitation outlook for the rest of March 2017,from the GFS Model. (Tropicaltidbits.com)

 Posted by at 11:40 am

Don’t Forget! March is one of the wettest months.

 Northern Arizona Weather  Comments Off on Don’t Forget! March is one of the wettest months.
Mar 152017
 
8-14 day precipitation anamoly outlook from the Climate Prediction Center from April 14, 2017..

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!

Total precipitation projected through the end of March. (GFS Model at Tropical Tidbits)

Total precipitation projected through the end of March. (GFS Model at Tropical Tidbits)

8-14 day precipitation anamoly outlook from the Climate Prediction Center from April 14, 2017..

8-14 day precipitation anamoly outlook from the Climate Prediction Center from April 14, 2017..

 Posted by at 11:05 am

Finally, a chance of snow creeps into the long-range March outlook

 Northern Arizona Weather  Comments Off on Finally, a chance of snow creeps into the long-range March outlook
Mar 092017
 
GFS model precipitation outlook for March 23, 2017. (From TropicalTidbits.com)

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.

GFS model precipitation outlook for March 23, 2017. (From TropicalTidbits.com)

GFS model precipitation outlook for March 23, 2017. (From TropicalTidbits.com)

 Posted by at 12:00 pm

One of the deeper 8-12 inch snowfalls

 Northern Arizona Weather  Comments Off on One of the deeper 8-12 inch snowfalls
Feb 282017
 
March 2017 precipitation outlook from the Climate Prediction Center.

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.

March 2017 precipitation outlook from the Climate Prediction Center.

March 2017 precipitation outlook from the Climate Prediction Center.

 Posted by at 9:55 pm

Heavy snow to finish February

 Northern Arizona Weather  Comments Off on Heavy snow to finish February
Feb 262017
 
Total snowfall projection from the North American Mesoscale model through Tuesday evening. (From Tropical Tidbits)

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.

Total snowfall projection from the North American Mesoscale model through Tuesday evening. (From Tropical Tidbits)

Total snowfall projection from the North American Mesoscale model through Tuesday evening. (From Tropical Tidbits)

***************************************************

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.
 Posted by at 11:30 pm

Yet again, the computers can’t make up their minds

 Northern Arizona Weather  Comments Off on Yet again, the computers can’t make up their minds
Feb 242017
 
US Navy NAVGEM computer model forecast of precipitation rate for Monday night, February 27, 2017. (from Tropical Tidbits)

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.

US Navy NAVGEM computer model forecast of precipitation rate for Monday night, February 27, 2017. (from Tropical Tidbits)

US Navy NAVGEM computer model forecast of precipitation rate for Monday night, February 27, 2017. (from Tropical Tidbits)

 

 Posted by at 11:43 pm

Here’s an animation that makes the point.

 Climate, Models, Northern Arizona Weather, Outlooks  Comments Off on Here’s an animation that makes the point.
Feb 162017
 
Animation of total precipiation from 4 different computer models runs for the same storm. (From Tropical Tidbits)

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.

Animation of total precipiation from 4 different computer models runs for the same storm. (From Tropical Tidbits)

Animation of total precipiation from 4 different computer models runs for the same storm. (From Tropical Tidbits)

 Posted by at 11:33 am
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