Sep 272014
 

A strong cold front is crossing Arizona from west to east today. While the moisture is coming from the south, the cold front is a winter weather phenomenon for Arizona. We are expecting fast-moving thunderstorms with heavy rain and other severe weather. This is reminiscent of the storms on October 6, 2010.

The National Weather Service isn’t taking any chances. They have posted severe weather watches and warnings. Check their website for updates.

 

Weather Story from the National Weather Service (Septemer 27, 2014)

Weather Story from the National Weather Service (Septemer 27, 2014)

 Posted by at 7:02 am
Mar 122014
 

For the last week or so, the computer models have generated a storm forming to the east of Flagstaff tomorrow. This morning, everything seems to have changed. We are now looking at a nice round of rain and snow for tomorrow. Even though the storm appears pretty strong in the models, the National Weather Service is only projecting a 40-50% chance of precipitation. Here is the North American Mesoscale model of precipitation for the next couple days.

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

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

 

 Posted by at 8:13 am
Mar 022014
 

The radar summary below from Intellicast tells the story. As band of rain and thunderstorms moved across the state, they were too far south. I don’t know about how you feel, but I don’t like being stuck in the middle between storm paths. There isn’t much more in the next week or so. Sorry.

Daily radar precipitation summary from Intellicast.com

Daily radar precipitation summary from Intellicast.com

 Posted by at 7:08 am
Feb 282014
 

As expected, temperatures around Flagstaff are warm this morning; in the upper 30s and low 40s. The outlook for snow is pretty weak because of the high temperatures. However, Arizona Snowbowl could receive 2-3 feet of new snow with this storm. The National Weather Service hasn’t posted any alerts, yet. If temperatures drop, our outlook could change.

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
418 AM MST FRI FEB 28 2014

AZZ004>018-037>040-010900-
KAIBAB PLATEAU-MARBLE AND GLEN CANYONS-GRAND CANYON COUNTRY-
COCONINO PLATEAU-YAVAPAI COUNTY MOUNTAINS-
NORTHEAST PLATEAUS AND MESAS HWY 264 NORTHWARD-CHINLE VALLEY-
CHUSKA MOUNTAINS AND DEFIANCE PLATEAU-
LITTLE COLORADO RIVER VALLEY IN COCONINO COUNTY-
LITTLE COLORADO RIVER VALLEY IN NAVAJO COUNTY-
LITTLE COLORADO RIVER VALLEY IN APACHE COUNTY-
WESTERN MOGOLLON RIM-EASTERN MOGOLLON RIM-WHITE MOUNTAINS-
NORTHERN GILA COUNTY-YAVAPAI COUNTY VALLEYS AND BASINS-
OAK CREEK AND SYCAMORE CANYONS-BLACK MESA AREA-
NORTHEAST PLATEAUS AND MESAS SOUTH OF HWY 264-
418 AM MST FRI FEB 28 2014

THIS HAZARDOUS WEATHER OUTLOOK IS FOR APACHE...COCONINO...
NORTHERN GILA...NAVAJO...AND YAVAPAI COUNTIES IN NORTHERN
ARIZONA.

.DAY ONE...TODAY AND TONIGHT

SHOWERS WILL SPREAD INTO COCONINO AND YAVAPAI COUNTIES BY THIS
AFTERNOON AS A STORM SYSTEM APPROACHES. STEADY PRECIPITATION WILL
THEN DEVELOP OVERNIGHT...WITH THE HEAVIEST AMOUNTS FROM THE
MOGOLLON RIM SOUTHWARD INTO YAVAPAI AND GILA COUNTIES. A FEW
THUNDERSTORMS ARE POSSIBLE OVERNIGHT. SOUTHWEST WINDS OF 15 TO 30
MPH WITH GUSTS UP TO 40 MPH WILL ALSO CONTINUE THIS AFTERNOON
THROUGH TONIGHT. SNOW LEVELS REMAIN ABOVE 8000 TO 9000 FEET.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

SATURDAY AND SATURDAY NIGHT...MODERATE TO LOCALLY HEAVY
PRECIPITATION WILL CONTINUE WITH RAIN AND HIGH ELEVATION SNOW. A
FEW THUNDERSTORMS ARE ALSO EXPECTED SATURDAY.

STORM TOTAL PRECIPITATION AMOUNTS OF 1 TO 2 INCHES ARE EXPECTED
ALONG AND SOUTH OF THE MOGOLLON RIM...WITH LOCALLY HIGHER AMOUNTS.
WHILE WIDESPREAD FLOODING IS NOT EXPECTED...LOCALIZED MINOR
FLOODING OF POORLY DRAINED AREAS IS POSSIBLE...AS WELL AS RISES ON
CREEKS AND WASHES.

SNOW LEVELS ARE FORECAST TO REMAIN ABOVE 8000 FEET EARLY SATURDAY
MORNING...THEN FALL TO 6500 TO 7500 FEET BY SATURDAY AFTERNOON.
SNOW ACCUMULATIONS FROM SATURDAY TO SUNDAY MORNING BETWEEN 6000 TO
8000 FOOT ELEVATION WILL RANGE FROM 2 TO 6 INCHES...WITH MUCH
HEAVIER SNOW AMOUNTS EXPECTED OVER THE HIGHEST MOUNTAINS PEAKS.

DETAILS REGARDING SNOW LEVELS AND SNOW AMOUNTS ARE STILL SOMEWHAT
UNCERTAIN...PLEASE STAY TUNED FOR THE LATEST UPDATES AT
WWW.WEATHER.GOV/FLAGSTAFF
 Posted by at 4:38 am
Feb 262014
 

As our storm approaches, the computer models are predicting more precipitation. The 5-day precipitation outlook from the Weather Prediction Center shows a peak of 4.4 inches. This would completely reverse our deficit since September 1, 2013.

5-day precipitation outlook, ending Monday morning, 3-3-2014. From the National Weather Service's Weather Prediction Center

5-day precipitation outlook, ending Monday morning, 3-3-2014. From the National Weather Service’s (NWS) Weather Prediction Center

But, forecast temperatures remain above average. The daily minimum temperature anomaly for the next 5 days is +9 degrees F. Our typical average low this time of year is 21 degrees. That gives us an average temperature over the next 5 days of 30 or more. The NWS forecasts high temperatures in the low 40s and lows in the mid-20s. Snow or rain? Some of each? A lot of both.

I’m also thinking of the pictures in the Flagstaff Athletic Club’s East Facility. I think it was March of 1991. Flagstaff received a bunch of snow, then a bunch of rain which flooded the area near the bubble. Could we be looking at a similar scenario?

5-day minimum temperature anomaly from the NWS's Weather Prediction Center.

5-day minimum temperature anomaly from the NWS’s Weather Prediction Center.

 Posted by at 4:10 am
Feb 252014
 

Thursday will usher in a wetter pattern. With the “polar vortex” moving into the Midwest and Eastern United States, our temperatures are going to stay warm until the weekend. We probably won’t see significant precipitation until Friday night. While the precipitation will continue until Monday, the intensity will drop during the day on Sunday. Since temperatures will be warm, I don’t know how much of the precipitation will fall as snow.

There will be a significant amount of moisture with this system. Here is the 5-day precipitation outlook from the National Weather Service’s Weather Prediction Center. Notice the 2.5 inch peak precipitation amount. This won’t make up our 4 inch precipitation deficit to average since September, but it could nearly cut it in half. On another note, this storm will proceed to the east. It could be come a major spring storm.

5-day precipitation outlook, ending Sunday morning, 3-2-2014. From the National Weather Service's Weather Prediction Center

5-day precipitation outlook, ending Sunday morning, 3-2-2014. From the National Weather Service’s Weather Prediction Center

 Posted by at 4:22 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 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
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