Aug 172014
 

In my last post, I pointed out that a drier period was ahead. What I had meant, and what the models foretold, was no rain for a week or so. That has not been the case. Thursday evening, a storm moved across the west side of Flagstaff dumping heavy rain across the area. Friday evening a storm hit central Flagstaff. I got about 1/3 of an inch of rain. I got more rain on Saturday, a mere 0.03 inches. This is drier than earlier in the week when I received over an inch.

This dry trend will continue for the next few days with a 30-60% chance of rain each day through Thursday. I think that in wet years, the forecast models run on the dry side, especially at long lead times. In dry years, they run on the wet side. The result is that more is on the way for this week.

 Posted by at 10:16 pm
Jul 182014
 

This morning the Climate Prediction Center issued a new 90-day precipitation outlook. All of Arizona is in the above average precipitation zone.

Three-month precipitation outlook from the Climate Prediction Center.

Three-month precipitation outlook from the Climate Prediction Center.

 Posted by at 7:14 am
Jul 152014
 

Looking out 2 weeks, you might think so. Today is the last day in the current forecasts and outlooks when Northern Arizona can strongly expect rain. The winds are going to shift back to a southwesterly origin and bring dry air. Below are the 6-10 and 8-14 day outlooks. The Climate Prediction Center issues new 30 and 90-day outlooks on Thursday.

As a side note, it looks more and more like El Nino is going to fail before it is up and running. I get in to that detail later. However, this probably isn’t the driver behind our monsoon season.

6-10 day precipitation outlook from the Climate Prediction Center. (14 July 2014)

6-10 day precipitation outlook from the Climate Prediction Center. (14 July 2014)

8-14 day precipitation outlook from the Climate Prediction Center. (14 July 2014)

8-14 day precipitation outlook from the Climate Prediction Center. (14 July 2014)

 Posted by at 6:33 am
Aug 242013
 

Ivo. Well, my iPad recognizes Ivo as a proper noun. Given the rain we expect Ivo to bring this weekend, I thought the name could be derived from some archaic rain god. Nope.

Meaning & History
Germanic name, originally a short form of names beginning with the Germanic element iv meaning "yew".
Alternative theories suggest that it may in fact be derived from a cognate Celtic element. 
This was the name of several saints (who are also commonly known as Saint Yves or Ives).

Anyway, the air is wet today. Moisture is already surging northward. The Valley of the Sun had heavy rains and lightning over night. It will be wetter tomorrow. It still looks like Tropical Storm Ivo will end our August drought.

Infrared satellite image from Saturday morning. National Weather Service.

Infrared satellite image from Saturday morning showing Tropical Storm Ivo off the tip of the Baja Peninsula. Tropical moisture is already surging up from the south from this storm. National Weather Service.

 Posted by at 8:25 am
Aug 192013
 

According to the long-range outlooks and GFS model,¬† an intense low pressure system(now identified as 94E) will move up the west coast of Mexico and bring plenty of moisture next Sunday and Monday. It’s still a long ways out, but the GFS model and the 6-10 day outlook predict above average precipitation. It has been consistent for several model runs.

6-10 day precipitation outlook from the Climate Prediction Center. Monday Afternoon, August 19, 2013

6-10 day precipitation outlook from the Climate Prediction Center. Monday Afternoon, August 19, 2013

The last GFS model had the bulk of the precipitation falling in western Arizona. It’s not a sure bet, yet.

 Posted by at 5:41 pm
Dec 022012
 

Not the Model-T, but my very own weather forecasting model. Some of you may remember the intense accuracy it provided years ago. It just seems to work.Since I don’t have a super computer and years of training and education on developing models for predicting weather, the model has a lot of manual tweaks in it to get it to give decent output. I spend a considerable amount of time just figuring out the inputs and boundary conditions to make it work.

The GFS and NoGAPS models have output similar results to mine for this next week. But the results are inconsistent, run after run. So, I thought it was time to give my model a try. Here is the output. While not definitive and with some variability, my experience points to a reasonable likelihood of some snowfall this week. Unless you are me, you are probably silly to use my model. I would stick with the pros, but I feel pretty good about my historic knowledge. There is a good chance of snow this week. My forecast doesn’t match anything else out there.

Stu's T-model output for the week of december 2, 2012

Stu’s T-model output for the week of december 2, 2012

If you are a serious meteorologist, you should express no interest in the details of how I work this thing, but you can still send me an email (stu@stu-in-flag.net) and ask. It is a curiosity.

 

 Posted by at 6:52 am
Nov 192012
 

Looks like the NoGAPs model failed. The current storm track is far to the north. Instead, the Pacific Northwest is getting pretty beat up. The GFS model is forecasting a more southern route for the storm track starting with next week. We will see if that sticks.

This week’s weather will be mostly beautiful! Enjoy!

 Posted by at 6:55 am
Nov 152012
 

Sorry for missing the first real accumulation of snow for the year. But, I was basking in tropical sunlight last week. Ahhhh.

Early next week we could receive another round of snow, depending on which forecast model is correct. The NoGAPs model forecast precipitation for Northern Arizona on Monday morning. The Navy’s model project a quarter to a half-inch of precipitation for the Flagstaff Area.

US Navy NoGAPs precipitation model for Monday, November 19, 2012.

US Navy NoGAPs precipitation model for Monday, November 19, 2012. (Update: Sorry, I don’t know where this image went. Now it is gone forever.)

However, this doesn’t match the outlook from the GFS Model at NOAA. This model projects the moisture from the same storm misses Northern Arizona.

GFS Precipitation model for Monday morning, November 19, 2012

GFS Precipitation model for Monday morning, November 19, 2012

Which model is better tuned for this year? Of the forecast websites I routinely use, none are forecasting rain or snow on Monday. We’ll have to wait and see.

 Posted by at 7:04 am
Apr 042012
 

Just when I condemn us to a dry spring, the GFS and NoGAPs Models align around a storm for next week. It’s unusual for both models to align at long time points. In the current case, both are predicting a significant storm around next Wednesday or Thursday. NoGAPs predicts the storm’s arrival 6-12 hours earlier than GFS. We will see.

We have wind on tap for the next few days

NoGAPs precipitation forecast for Wednesday afternoon, April 11, 2012

NoGAPs precipitation forecast for Wednesday afternoon, April 11, 2012

 Posted by at 6:37 am
Oct 022011
 

Both GFS and NoGAPS models are predicting a wet, continuously cooler week  ahead. AccuWeather has predicted temperatures in the low 30s and upper 20s for Thursday and Friday. The pattern from the last few days for Arizona has been more of a monsoonal flow. With the jet stream dropping down, Pacific storms moving from the west to the east will be responsible for the next few precipitation events.

US Navy NoGAPS model precipitation outlook for 6 hours, Thursday morning, October 6, 2011

US Navy NoGAPS model precipitation outlook for 6 hours, Thursday morning, October 6, 2011

NoGAPS and GFS models are in agreement with a wet start to the week. Then, they indicate a bit of a break on Wednesday before the big cold push on Thursday and Friday.

US Navy NoGAPS temperature outlook, 5am Friday, October 7, 2011

US Navy NoGAPS temperature outlook, 5am Friday, October 7, 2011

I haven’t done a big winter outlook this year. I think we could see a similar year to last year. We have a weak La Nina, a more active, but still anemic, Sun, and a generally cold Pacific. For the winter overall, it will probably be warmer than average, drier than average, with scatter times of heavy snow and very cold temperatures.

 Posted by at 7:37 am
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