Feb 222014
 

As we closer to the start of March, the storm track shifts to the south. A couple of storms had faded in and out of the models. Currently, the GFS and NoGAPs models for Saturday, March 1, align and show moderate storm moving quickly across Arizona.

Below is an image for the GFS model run by the National Center for Atmospheric Research. It shows up to half an inch of water falling around the Flagstaff area next Saturday.

GFS model for 6-hour precipitation outlook on Saturday, March 1, 2014.

GFS model for 6-hour precipitation outlook on Saturday, March 1, 2014.

We still have a week, so the outlook could change.

 Posted by at 6:47 am
Feb 192014
 

There are a couple of curious things to note about Lake Powell. First, it’s at its lowest level for this date since 2005. Outflows from the lake are around the historic average.

Lake Powell water levels since 2010 - http://lakepowell.water-data.com/

Lake Powell water levels since 2010 – http://lakepowell.water-data.com/

Second, the snow pack above Lake Powell is well above normal for this time of year.

Upper Colorada Basin Snowpack - http://lakepowell.water-data.com/

Upper Colorada Basin Snowpack – http://lakepowell.water-data.com/

Unlike Arizona, this year’s storm track has hit the Upper Colorado River Basin. If this year ends up similar to 2011, lake levels could recover considerably. In 2011, level lake increase by roughly 60 feet. We are still well before the peak in snowfall.

Here is the Bureau of Reclamation’s outlook for this summer. I have highlighted the max, likely and min lake level projections.

Based on the current forecast, the February 24-Month study projects Lake Powell elevation will peak near approximately 3,611 ft next summer and end the water year near 3,604 feet with approximately 12.16 maf in storage (50% capacity).  Note that projections of elevation and storage have significant uncertainty at this point in the season, primarily due to uncertainty regarding the season’s total snowpack and the resulting inflow to Lake Powell.  Under the minimum probable inflow scenario, updated in January, the projected summer peak is 3,592 ft and end of water year storage is 9.7 maf (40% capacity).  Under the maximum probable inflow scenario, updated in January, the projected summer peak is 3,631 ft and end of water year storage is 15.0 maf (62% capacity).  There is a 10 percent chance that inflows will be higher, resulting in higher elevation and storage, and 10 percent chance that inflows will be lower, resulting in lower elevation and storage.  The minimum and maximum probable model runs will be updated again in April.  The annual release volume from Lake Powell during water year 2014 is projected to be 7.48 maf under all inflow scenarios. 

Seems odd to be thinking about Lake Powell in February, but the weather has been so nice. That could all change. Here is a new graphic from the National Weather Service for spring precipitation following dry winters. Near normal spring amounts seem to the highest likelihood. Currently, the weather pattern seems to be shifting across North America. The Eastern US is going to see a warming trend. There is a strong storm for Arizona in the long-range outlook.

Spring precipitation following dry winters - National Weather Service Flagstaff

Spring precipitation following dry winters – National Weather Service Flagstaff

 Posted by at 4:11 am
Feb 112014
 

As most of the world seems buried in snow, Flagstaff and Sochi are basking in the sun. The East Coast is getting beat-up again today by another major winter storm. We shouldn’t see any snow for a while. We will see lost of sun courtesy of our friendly local high pressure system. Over the next few days, our high temperatures will climb from about 50 degrees today to the mid-60s for the weekend. Most of the records for this time frame are in this range. Wednesday’s is a bit lower at only 58. It could be close or we could easily blow past a couple.

Wednesday, February 12     58F
Thursday, February 13      68F
Friday, February 14        64F
Saturday, February 15      65F
Sunday, February 16        70F

Below is the temperature anomaly outlook for the next 3-7 days. New England suffers while the Southwest has an early taste of spring. Arizona is comfortably in the 15 degree F above average region. This could change at the end of next week.

3-7 day maximum temperature anomaly outlook from the National Weather Service's Weather Prediction Center

3-7 day maximum temperature anomaly outlook from the National Weather Service’s Weather Prediction Center

 Posted by at 6:43 am
Feb 052014
 

UPDATED: 5:45pm AZ time – See below

The Weather service is being clear about their expectations for the end of the week. On their forecast, they have Thursday night as the period with the heaviest precipitation. This is their Weather Story for today.

Snowfall outlook for the rest of the week, from the National Weather Service in Flagstaff

Snowfall outlook for the rest of the week, from the National Weather Service in Flagstaff

But the North American Mesoscale(NAM) model has us drawing a blank for the next few days. The lower resolution GFS model shows a situation similar to the Weather Story above. Aaarrrggghhh!

2-5 Inches is probably a good guess. At this point, 4-8 seems like a stretch. The computer models are often and by large amounts. We’ll see. It’s possible the next few days could be just like the last few.

UPDATE - So, just to make the point…. The NAM model has shifted tonight. We are back in the 3-8 inch range for snowfall amounts between now and midday Friday. All I can say is “Be ready.” It will probably snow. We may receive a decent amount.

North American Mesoscale Model forecast for precipitation between Wendesday evening and midday Friday. NOAA's Climate Prediction Center

North American Mesoscale Model forecast for precipitation between Wendesday evening and midday Friday. NOAA’s Climate Prediction Center

 Posted by at 7:04 am
Feb 032014
 

We continue to have a chance for snow over the next couple days. We should only get light accumulations. Temperatures will remain cooler than what we had experienced in January. A stronger storm remains in the forecast for Friday and Saturday. It won’t be a drought buster, but should bring us several inches of snow.

 Posted by at 6:23 am
Jan 312014
 

Finally, I real break in the storm pattern appears to be at the other end of next week. In the current GFS model run, the precipitation starts Thursday night and lingers into Saturday afternoon. On the map below, there is a very nice dark blue area over Flagstaff. This represents 1/2 to 3/4 of an inch of water, or roughly 6-8 inches of snow. Welcome back winter!

20140201-072928.jpg

 Posted by at 5:29 pm
Jan 312014
 

The slow-moving system that will affect us for the next few days isn’t packing a huge punch. But, it should break our dry run. Today and tomorrow, we should get an inch or two each day. On Monday, it could happen again.  It looks like the long-awaited break in the pattern is happening.

 Posted by at 6:51 am
Jan 292014
 

Just, exactly far enough south to give us a break.I must’ve told half a dozen people over the next week that it looked like it would be weeks before we saw any wet weather. Looks like that did the trick. Please, if you could, do something to help it snow. Wash your car, put away your snow shovels and blowers.

It looks like this week’s storm will have two parts to it. The first part will hit on Friday. The second part will hit Saturday night into Sunday. Scattered light precipitation could fall in between and linger in the area afterwards. There isn’t much water in either part. At best, it looks like either storm could produce a few inches of snow. Any precipitation will occur only the higher elevations of Northern Arizona. The San Francisco Peaks could see more.

Hopefully, this will represent a longer term shift. Currently, when the storms leave, we return to high pressure and warm, sunny conditions. The very long-range output of the GFS model has wetter conditions.

 Posted by at 6:34 am
Jan 162014
 

Just as the long-range models started to look positive, the National Weather Service posts these three images on their Flagstaff webpage. If that doesn’t lock us into some precipitation in the next 7-14 days, nothing will. (Except maybe everyone washing their cars!)

Dry Spell Stats from National Weather Service - Flagstaff

Dry Spell Stats from National Weather Service – Flagstaff (1-16-14)

Late January Outlook from National Weather Service - Flagstaff

Late January Outlook from National Weather Service – Flagstaff

Dry Weather Pattern from National Weather Service Flagstaff

Dry Weather Pattern from National Weather Service Flagstaff

 Posted by at 7:36 pm
Jan 162014
 

I can’t say much yet, but both models have a hint of something over the horizon. About one to one and a half weeks out, the pattern could shift and our chances for snow could increase. The T-model has spikes around next Thursday and Friday, then again on the following Monday. Stay tuned.

 Posted by at 7:07 am
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