Navy says we may have a very White Christmas

 Northern Arizona Weather, Outlooks, Winter Storms  Comments Off on Navy says we may have a very White Christmas
Dec 182016
 
6-hour precipitation outlook from the U.S. Navy's NoGaps computer model for Friday evening, December 23, 2016.

I was feeling under the weather. Both because I have a cold, and the GFS computer model was not predicting any precipitation. Below is the 24 hour precipitation GFS model forecast for Friday, December 23, 2016. You’ll notice that the Arizona is covered in white, meaning no rain or snow. The rest of the intervening time has no snowfall predicted for Flagstaff.

24 hour total precipitation late Friday night, Dec. 23, 2016 forecast from the GFS computer model, via TropicalTidbits.com.

24 hour total precipitation late Friday night, Dec. 23, 2016 forecast from the GFS computer model, via TropicalTidbits.com.

So, I decided to check with the Navy to see if they thought the previously forecasted storm had vanished. They have a much different outlook for a similar time period. Their forecast below is for 6 hours, ending late Friday evening.

6-hour precipitation outlook from the U.S. Navy's NoGaps computer model for Friday evening, December 23, 2016.

6-hour precipitation outlook from the U.S. Navy’s NoGaps computer model for Friday evening, December 23, 2016.

This is a much different picture. The Navy has the precipitation starting on Friday morning and continuing through Saturday morning. If the Navy is correct, there could be significant snowfall during this time.

 Posted by at 6:29 am

This winter will be difficult to forecast

 Models, Northern Arizona Weather, Outlooks  Comments Off on This winter will be difficult to forecast
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

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

Strong precipitation outlook for the next month

 Models, Monsoon, Outlooks  Comments Off on Strong precipitation outlook for the next month
Jul 222016
 

The Climate Prediction Center released new 6-1o day, 8-14 day and 1 month outlooks on Thursday. Even though Flagstaff’s July precipitation is half of normal for this point in the month, the next month of the monsoon season should be above average. Below is an animation of these outlooks.

6-10 day, 8-14 day, and one month precipitation outlooks from the Climate Prediction Center (June 21, 2016)

6-10 day, 8-14 day, and one month precipitation outlooks from the Climate Prediction Center (June 21, 2016)

 Posted by at 8:40 am

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

Is winter on the way back to Northern Arizona.

 Outlooks  Comments Off on Is winter on the way back to Northern Arizona.
Apr 022016
 

At the end of last week, the outlooks for April shifted. I couldn’t bring myself to post about a change to upcoming wetter conditions on April Fool’s Day. The last 6 month’s we have seen a repeated disappearing act of storms. They would show up in the computer models as strong storms over a week away. Then they would slowly disappear into sunshine and warm conditions. Sigh.

So, here we are again. Two storms are over the horizon. One should arrive towards the end of next week. The second is about a week out. An animation of the 6-10 day, 8-14 day and one month outlooks is below. Each storm looks strong. It only takes a few to fill-in a precipitation deficit. Average April precipitation since 1950 is about 2 inches. The computer models snow just over two inches in the next two weeks.

We will see. This would help delay the fire season.

Animation of 6-10 day, 8-14 day and one month precipitation outlooks from the Climate Prediction Center.

Animation of 6-10 day, 8-14 day and one-month precipitation outlooks from the Climate Prediction Center.

 Posted by at 11:31 pm

It’s always just over the horizon.

 Northern Arizona Weather, Outlooks, Winter Storms  Comments Off on It’s always just over the horizon.
Feb 292016
 

The computer models keep dropping a significant storm into the long-range forecast. If you look at the image from my last post, it shows significant precipitation around March 4, 2016. The forecasts do point to some precipitation this weekend, but not the large amount in that image. The problem is that the big storm is always just over the horizon. Below is the outlook for Monday, March 14. It’s almost identical to the image in my last post.

As we move away from a very warm and dry February, we have to wonder if March will fulfill its historic reputation for the wettest time of year. The computer models keep pointing to a change in the storm track that will push storms over Arizona. We will see. Not much to blog about when it’s sunny and warm.

12-hour average precipitation rate (mm/hr) for Monday, March 14, 2016 from Tropical Tidbits.

12-hour average precipitation rate (mm/hr) for Monday, March 14, 2016 from Tropical Tidbits.

 Posted by at 8:48 pm
Feb 192016
 

Warm and dry has become the February story. The wet cold start has faded into sun and occasional high winds. There have be a few times the outlook was positive for wet conditions. It hasn’t happened.

Is it unusual for February to be dry during an El Niño winter. I think the data are pretty messy and there really isn’t enough to be very meaningful. Since 1950, the average for February precipitation in Flagstaff is about 2 inches. There are very wet and fairly dry Februaries during El Niño years.

Most of the areas that normally benefit from El Niños are benefiting this year. We continue to be way ahead on 12 and 24 month total precipitation.

The GFS model shows a possible weak storm at the end of the month, and a stronger storm at the start of March.

12-hour precipiation outlook ending noon, March 4, 2016. (Tropical Tidbits website.)

12-hour precipiation outlook ending noon, March 4, 2016. (Tropical Tidbits website.)

The 3 month outlook from the Climate Prediction Center continues to look positive from a precipitation point of view.

3-month precipitation outlook from the Climate Prediction Center.

3-month precipitation outlook from the Climate Prediction Center.

There is still time left this winter for more snow. March is typically the wettest month of the year. I think more is on the way.

 Posted by at 4:50 pm

Dry period in an El Niño Winter

 Outlooks  Comments Off on Dry period in an El Niño Winter
Nov 272015
 

Thanks to an Eastern Pacific hurricane and very strong northerly storm track, the next couple weeks will be very dry in Arizona.

6-10 and 8-14 day precipitation outlooks from the Climate Prediction Center (26 November 2015).

6-10 and 8-14 day precipitation outlooks from the Climate Prediction Center (26 November 2015).

 Posted by at 12:25 am
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