Dec 022016
 
Global Tropical Sea Surface Temperature Animation from the Climate Prediction Center. (23 November 2016)

Over the last week, I’ve watched the computer models bounce around. For the most part, the precipitation part of the models has calmed down to indicate two weeks of mostly dry weather for Arizona…or so I thought. The temperature models have been worse the last few days. Devastating cold and wonderful warmth are the walls the models are bouncing off. Yesterday, I almost wrote a post about how incredibly warm it would be next week. This morning, December 8 shows up in the computer models with Flagstaff 7-10 degrees below normal. By the following weekend, temperatures are 4 or 5 degrees above normal. I’m positive it will look different again tomorrow. But, why?

So, a few years ago, in a place off the western coast of North America, an anomalous blob of warm water (aka The Blob) gathered. It was following the Ridiculously Resilient Ridge. (How can a resilient ridge of high pressure, and a blob of warm water can get Wikipedia pages, and I can’t?) Both of these features interfered with forecasting because of the alterations they made to the weather patterns.

Well, the ridge is gone. Most likely this is because it ran out of ridiculousness. The warm blob is now gone, too. Not only gone, but currently replaced by a “cold blob.” The cold blob has yet to ascertain Wikipedia status. Below is the global sea surface temperature and temperature anomaly animation from the Climate Prediction Center.

Global Tropical Sea Surface Temperature Animation from the Climate Prediction Center. (23 November 2016)

Global Tropical Sea Surface Temperature Animation from the Climate Prediction Center. (23 November 2016)

You can watch the remnants of the warm blob fade away as the cold blob migrates from Eastern Russia to the east. Also, you can see the weak La Niña grow across the Equatorial Pacific. Both of these cold water features are going to make forecasting more complex. I think that’s why the forecasts keep bouncing around.

The Navy’s NoGaps forecast model has a bit of moisture in the forecast for the middle of next week. The GFS model has none, as of this post. This will be an interesting winter.

6-hour precipitation rate for Wednesday morning, December 7, 2016. From the US Navy

6-hour precipitation rate for Wednesday morning, December 7, 2016. From the US Navy

 

 Posted by at 11:30 pm

Everything changes on the Monday after Thanksgiving

 Models, Northern Arizona Weather, Outlooks  Comments Off on Everything changes on the Monday after Thanksgiving
Nov 292016
 
6-10 day precipitation anomaly outlook from the Climate Prediction Center on November 28, 2016

Computer models need tweaking to adjust to what’s really going on in the world. It looks like quite a bit changed between Sunday and Monday. The real timeline is probably between last Wednesday and Monday. On weekends and holidays, the computer models more or less independently produce the 6-10 and 8-14 day outlooks at the Climate Prediction Center. On normal workdays, they are adjusted by real humans. Like every Monday after Thanksgiving, huge adjustments were required.

I saved the outlooks from Sunday, and they are below.

6-10 day precipitation anomaly outlook from the Climate Prediction Center on November 28, 2016

6-10 day precipitation anomaly outlook from the Climate Prediction Center on November 27, 2016

8-14 day precipitation anomaly outlook from the Climate Prediction Center on November 28, 2016

8-14 day precipitation anomaly outlook from the Climate Prediction Center on November 27, 2016

Wow, Flagstaff was going to pretty much get clobbered with snow according to these maps. But, then Monday comes along and adjustments are made.

6-10 day precipitation anomaly outlook from the Climate Prediction Center on November 28, 2016

6-10 day precipitation anomaly outlook from the Climate Prediction Center on November 28, 2016

8-14 day precipitation anomaly outlook from the Climate Prediction Center on November 29, 2016

8-14 day precipitation anomaly outlook from the Climate Prediction Center on November 28, 2016

Looks like the future storm track will shift well to the north, and oddly to the south. Flagstaff ends up in the dry middle for two weeks.

 Posted by at 5:40 am

Advisory, watch, warning?

 Northern Arizona Weather  Comments Off on Advisory, watch, warning?
Nov 272016
 
48 hour total snowfall forecast from the GFS model at Tropical Tidbits. (tropicaltidbits.com)

With 5-10 inches of snow on the way for Flagstaff, and more for other areas, what the heck do all the National Weather Service’s key words and catchy phrases mean.

Advisories mean, “Hey, there’s something you should probably keep in the back of your mind as you plan your activities.” From a kid’s point of view, a Winter Weather Advisory can mean you will most likely see snow, and have to go to school.

Watches mean, “Hold-on there, there’s a chance of some serious hazards possible over the next two days. You should consider changing your plans.” From a kid’s point of view, a Winter Storm Watch means there’s a good chance you won’t have school in a few days. It’s not sure enough to where you shouldn’t get your homework done and study for your test.

Warnings mean, “Stop, change your plans. There will probably be serious impacts from the weather.” From a kid’s point of view, a Winter Storm Warning means it’s almost positive that you won’t be going to school, but not guaranteed. Only shoveling snow will get you out of homework. The more snow you shovel, the less homework you have to do.

Okay, on the serious side, from the National Weather Service’s NWS Reference Guide:

  • Winter Weather Advisory – Snow and/or sleet and ice accumulations causing an inconvenience to society and commerce are imminent or occurring. (Specific criteria varies greatly per region.)
  • Winter Storm Watch – Possibility of accumulating snow, sleet and/or freezing rain causing severe impacts to society and commerce.
  • Winter Storm Warning – Heavy snow and/or sleet and ice accumulations are imminent or occurring. Society and commerce are expected to be greatly impacted. Precipitation may be accompanied by gusty wind. (Specific criteria vary by region)

Maybe that wasn’t clear. I looked at the NWS-Flagstaff site and couldn’t easily find their definitions for trigger points, such as 2-4 inches of snow for the Winter Weather Advisory.

Flagstaff is under a Winter Weather Advisory. I recommend full school preparedness for Monday.

From the National Weather Service in Flagstaff:

URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
1052 PM MST SAT NOV 26 2016

AZZ004-006>008-015-271415-
/O.CON.KFGZ.WW.Y.0006.161127T1900Z-161128T0700Z/
KAIBAB PLATEAU-GRAND CANYON COUNTRY-COCONINO PLATEAU-
YAVAPAI COUNTY MOUNTAINS-WESTERN MOGOLLON RIM-
INCLUDING THE CITIES OF...JACOB LAKE...GRAND CANYON VILLAGE...
VALLE...FLAGSTAFF
1052 PM MST SAT NOV 26 2016

...WINTER WEATHER ADVISORY REMAINS IN EFFECT FROM NOON SUNDAY TO
MIDNIGHT MST SUNDAY NIGHT FOR ELEVATIONS ABOVE 5500 FEET...

* TIMING...SNOW LEVELS WILL FALL AFTER MIDNIGHT AS SHOWERS
  DEVELOP ACROSS THE AREA...WITH MOSTLY SNOW ABOVE 6500 FEET BY
  EARLY SUNDAY MORNING. SHOWER ACTIVITY WILL DECREASE SUNDAY
  MORNING...BEFORE INCREASING AGAIN SUNDAY AFTERNOON. A PERIOD OF
  STEADIER AND HEAVIER SNOW WITH DROPPING SNOW LEVELS WILL THEN
  DEVELOP SUNDAY AFTERNOON THROUGH SUNDAY EVENING.

* GENERAL EVENT TOTAL SNOW ACCUMULATIONS...1 TO 4 INCHES OF SNOW
  BETWEEN 5500 FEET AND 6500 FEET AND 3 TO 6 INCHES OF SNOW
  ABOVE 6500 FEET. SEE DETAILS BELOW OR CONSULT POINT SPECIFIC
  FORECAST AT: WEATHER.GOV/FLAGSTAFF.

* SNOWFALL FORECAST FROM NOON MST SUNDAY UNTIL 12 AM MST
  MONDAY...

     DONEY PARK  2 TO 4  INCHES       FLAGSTAFF  3 TO 5  INCHES
   GRAND CANYON  1 TO 3  INCHES      JACOB LAKE  1 TO 3  INCHES
      NORTH RIM  2 TO 4  INCHES        PRESCOTT  1 TO 2  INCHES
       SELIGMAN  1 TO 2  INCHES           VALLE  1 TO 2  INCHES
       WILLIAMS  3 TO 5  INCHES

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WINTER WEATHER ADVISORY FOR SNOW MEANS THAT PERIODS OF FALLING
SNOW WILL CAUSE TRAVEL DIFFICULTIES. BE PREPARED FOR SLIPPERY
ROADS AND LIMITED VISIBILITIES.

PLAN EXTRA TIME FOR TRAVEL...AND USE CAUTION WHILE DRIVING. 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 AT
WWW.WEATHER.GOV/FLAGSTAFF.
 Posted by at 1:08 am

Wonderful December Weather Ahead!

 Northern Arizona Weather, Winter Storms  Comments Off on Wonderful December Weather Ahead!
Nov 242016
 
Western US 5 and 10 day total snowfall GFS model prediction from Tropical Tidbits.

For those that follow me on Facebook, you will notice the posts about the spreading snow in Siberia and what it means for the rest of the Northern Hemisphere this winter. I think the key point is that El Nino overrides the impact early Siberian snowfall. But, we are heading towards La Nina this winter. It could be important.

Looking at the 6-10 and 8-14 day outlooks, Flagstaff could be on it’s way to a White Christmas. Below are the outlook maps for precipitation and temperature anomalies. With above average precipitation, and below average temperatures in the outlooks, snow it probably likely for the Northland. Also, the total snowfall prediction for 5 and 10 days from the GFS model at TropicalTidbits.com is shown. I think Flagstaff could be in the 10 inch range by day 10. This does not necessarily mean that 10 inches will be present on December 3, or anytime between now and then. Also, the general disclaimer about variations with altitude and particular terrain producing more or less precipitation apply.

If you like my post, please share it on Facebook (see the buttons above and below this post.)

Temperature anomaly outlook maps for 6-10 and 8-14 days from the Climate Prediction Center.

Temperature anomaly outlook maps for 6-10 and 8-14 days from the Climate Prediction Center.

 

Temperature anomaly outlook maps for 6-10 and 8-14 days from the Climate Prediction Center.

Temperature anomaly outlook maps for 6-10 and 8-14 days from the Climate Prediction Center.

 

Western US 5 and 10 day total snowfall GFS model prediction from Tropical Tidbits.

Western US 5 and 10 day total snowfall GFS model prediction from Tropical Tidbits.

 Posted by at 11:15 am

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 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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