Jan 082013
 

somewhat. A storm system will move across Northern Arizona on Thursday night into Friday. Here is the Weather Story image from the National Weather Service:

Weather Story from National Weather Service - Flagstaff. December 8, 2013

Weather Story from National Weather Service – Flagstaff. December 8, 2013

I don’t agree with the 3-7 inches of snowfall by Friday night. I guess it’s possible, but I doubt we will see more than 2 inches. Two things are probably fairly certain. It will be cold, continuing our long-term below average temperatures. (But 2012 was warm overall. Try to remember the warm times.)  It will be windy. To me, wind in the winter means dry.

 Posted by at 1:07 pm
Dec 182012
 

Let’s deal with today very quickly. It’s going to snow tonight. Once again, there is a chance it will start around rush hour in Flagstaff. We will get 3-8 inches. Altitude will play an important role as to how much different spots receive. Today’s weather story, from the National Weather Service, nicely maps the situation.

Weather Story from National Weather Service, 12-18-2012

Weather Story from National Weather Service, 12-18-2012

More importantly, We are on track for a real WHITE CHRISTMAS!!! It’s a long ways out, and the NoGAPs model doesn’t agree, but it has consistently been in the AccuWeather, Intellicast and Wunderground forecasts, the GFS model and the GEFS model. Christmas is still a week away, but 4-8 inches could become a reality.

GFS 48-hour precipitation model ending 5pm, December 25, 2012

GFS 48-hour precipitation model ending 5pm, December 25, 2012

 Posted by at 6:54 am
Dec 172012
 

Tuesday night we will receive another round of snow. This next storm will move past us more quickly and drop only 4-8 (maybe fewer) inches of fresh snow. The real news is that a stronger storm may hit us on Christmas Eve through Christmas Day. While far out in the future, most models include this in their forecast. However, I think the models often change on Monday afternoons when the meteorologists have had the day to add their tweaks to the forecast models. Keep your fingers crossed.

 Posted by at 6:50 am
Dec 152012
 

If you read yesterday’s blog, today’s winter storm warning (shown below) shouldn’t be a big surprise… I don’t understand why we only had a winter weather advisory yesterday. So, what are all the definitions of the winter advisories and warnings? Here they are:

Winter Storm Warning: Issued when hazardous winter weather in the form of heavy snow, heavy freezing rain, or heavy sleet is imminent or occurring. Winter Storm Warnings are usually issued 12 to 24 hours before the event is expected to begin.

Winter Storm Watch: Alerts the public to the possibility of a blizzard, heavy snow, heavy freezing rain, or heavy sleet. Winter Storm Watches are usually issued 12 to 48 hours before the beginning of a Winter Storm.

Winter Storm Outlook: Issued prior to a Winter Storm Watch. The Outlook is given when forecasters believe winter storm conditions are possible and are usually issued 3 to 5 days in advance of a winter storm.

Winter Weather Advisories: Issued for accumulations of snow, freezing rain, freezing drizzle, and sleet which will cause significant inconveniences and, if caution is not exercised, could lead to life-threatening situations.

Snow Flurries: Light snow falling for short durations. No accumulation or light dusting is all that is expected.

Snow Showers: Snow falling at varying intensities for brief periods of time. Some accumulation is possible.

Snow Squalls: Brief, intense snow showers accompanied by strong, gusty winds. Accumulation may be significant. Snow squalls are best known in the Great Lakes region.

Blowing Snow: Wind-driven snow that reduces visibility and causes significant drifting. Blowing snow may be snow that is falling and/or loose snow on the ground picked up by the wind.

I remember that these definitions had snowfall amounts in the past. These are more about the impact of a storm that the amount of snow expected. Enjoy the snow. Another, lighter round is due on Tuesday or Wednesday.

 

URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
414 AM MST SAT DEC 15 2012

AZZ015-016-018-151915-
/O.UPG.KFGZ.WW.Y.0010.000000T0000Z-121216T0100Z/
/O.NEW.KFGZ.WS.W.0002.121215T1114Z-121216T0100Z/
WESTERN MOGOLLON RIM-EASTERN MOGOLLON RIM-NORTHERN GILA COUNTY-
INCLUDING THE CITIES OF...FLAGSTAFF...WILLIAMS...MUNDS PARK...
HEBER...HAPPY JACK...FOREST LAKES...PAYSON...STRAWBERRY...YOUNG
414 AM MST SAT DEC 15 2012

...WINTER STORM WARNING IN EFFECT UNTIL 6 PM MST THIS EVENING
ABOVE 5000 FEET...

THE NATIONAL WEATHER SERVICE IN FLAGSTAFF HAS ISSUED A WINTER
STORM WARNING FOR HEAVY SNOW WHICH IS IN EFFECT UNTIL 6 PM MST
THIS EVENING ABOVE 5000 FEET. THE WINTER WEATHER ADVISORY WAS
UPGRADED TO A WINTER STORM WARNING.

* TIMING...SNOW SHOWERS WILL WILL CONTINUE THROUGH THE DAY
  TODAY...AND BECOME HEAVIER AND MORE CONSISTENT BY LATE MORNING
  AND AFTERNOON.

* ADDITIONAL ACCUMULATIONS...4 TO 8 INCHES ABOVE 5000 FEET...8 TO
  12 INCHES ABOVE 6000 FEET. LOCALLY HIGHER AMOUNTS OF 10 TO 14
  INCHES MAY BE FOUND ALONG THE SOUTHERN EDGE OF THE MOGOLLON RIM
  SOUTH OF FLAGSTAFF.

* IMPACTS...REDUCED VISIBILITIES AND SNOW COVERED ROADWAYS WILL
  MAKE TRAVEL CONDITIONS HAZARDOUS AT TIMES.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WINTER STORM WARNING MEANS SEVERE WINTER WEATHER CONDITIONS ARE
EXPECTED OR OCCURRING...DUE TO SIGNIFICANT AMOUNTS OF SNOW AND
STRONG WINDS PRODUCING LIMITED VISIBILITIES. DRIVING WILL BE
EXTREMELY DANGEROUS DURING THIS STORM. IF POSSIBLE...POSTPONE
TRAVELING IN THE WARNING AREA UNTIL THIS STORM PASSES. IF YOU
MUST TRAVEL TAKE EMERGENCY SUPPLIES THAT INCLUDE WINTER
CLOTHING...FOOD...WATER AND A FLASHLIGHT. TELL FAMILY AND FRIENDS
YOUR TRAVEL ROUTE...THE PLANNED ARRIVAL TIME AT YOUR
DESTINATION...AND THE TYPE AND COLOR OF VEHICLE YOU ARE DRIVING
IN CASE YOU GET STRANDED. 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 5:41 am
Dec 142012
 

Check out the next 48 hour precipitation forecasts in the high-resolution models. Click on the images to see the full size versionThere’s still more to come.

While there were flurries last night at rush hour, this storm is still just starting up this morning. Looks like I picked the wrong rush hour.

Nested Window Run high resolution forecast model for 48 hour total precipitation (HRW_NMM) - NOAA

Nested Window Run high resolution forecast model for 48 hour total precipitation (HRW_NMM) – NOAA

Nested Window Run high resolution forecast model for 48 hour total precipitation (HRW-ARW) - NOAA

Nested Window Run high resolution forecast model for 48 hour total precipitation (HRW-ARW) – NOAA

 

 Posted by at 6:31 am
Dec 122012
 

So, I am trending my forecast from several inches to a lot. I think 7-12 inches is possible with this storm. Interstate 17, and lots of other roads, will be a mess. Currently, I think it will start around 9pm Thursday night, but my fear is that we could have one of those rush-hour storms that starts as the sun is low in the sky. Oddly, the National Weather Service has not issued any warnings or watches for our area at this time. Check the daily Weather Story in the right side-bar of this webpage. If I see one, I will append it to this post or a future post.

I looked at the sea surface temperatures this morning when it became clearer that the moisture supply was to the south, not the southwest, like Hawaii. The waters to the south, and the southwest, have warmed recently. Our recent cooling in Arizona will help bring the moisture to us.

Time lapse sea surface temperatures and anomalies from the Climate Prediction Center

Time lapse sea surface temperatures and anomalies from the Climate Prediction Center

 Posted by at 7:10 am
Dec 112012
 

The forecast details vary by site. Wunderground is forecasting a meager 3 inches with their “BestForecast” tool. AccuWeather is forecasting 4-8 inches. The National Weather Service is stepping out and forecasting 6-10 with a couple more on Friday. I’m sticking to my forecast from yesterday for “several inches.”

There are salient differences in all these forecasts and the models behind them. This morning the North American Mesoscale model shows the bulk of the storm hitting the eastern parts of Arizona, with Flagstaff expecting less than half an inch of water, or about 6 inches of snow.

North American Mesoscale model total precipitation forecast through midday Friday, from NOAA

North American Mesoscale model total precipitation forecast through midday Friday, from NOAA.

The US Navy’s NoGAPs model shows the storm hitting more of the central part of the state with up to an inch of water, which could be a foot of snow.

US Navy NoGAPs precipitation forecast for Thursday night.

US Navy NoGAPs precipitation forecast for Thursday night.

The NAM model is a higher resolution model that takes into account more detail of time and place. The National Weather Service forecasting up to a foot of snow makes me wonder. Looking at their forecast discussion, I think the NWS is wondering to:

FORECAST CONFIDENCE…THE LATEST FORECAST MODEL RUNS CONTINUE TO BE FAIRLY CONSISTENT ON THE TRACK AND INTENSITY OF THIS LOW…HOWEVER THE PRECIPITATION AMOUNTS IN THE SAME MODEL RUNS HAVE A HIGH DEGREE OF VARIABILITY. WHILE OUR CONFIDENCE IN WIDESPREAD MEASURABLE PRECIPITATION IS HIGH…OUR CONFIDENCE IN THE AMOUNTS OF RAIN AND SNOW ARE ONLY FAIR AT THIS TIME. THIS MEANS WE SHOULD EXPECT SOME ADJUSTMENTS TO THE PRECIPITATION AMOUNTS AS THE TIME PERIOD GETS CLOSER.

So, I am sticking with my forecast for “several inches.” It’s going to snow, it will affect driving conditions. The NAM model shows the snowfall starting later in the evening on Thursday, and tapering off on Friday afternoon.

 Posted by at 6:52 am
Dec 102012
 

Or, “Out of the frying pan and into the Freezer”

November was simply beautiful! Count your blessings. We had a warm November. The United Kingdom had one of their coldest autumns in recent history. Arizona’s data for November is below. Click on the image for a full report.

We should expect a shift in the jet stream to the south. We have colder temperatures today. Several inches of snow should fall on Thursday night into Friday. Maybe more snow during the weekend. Hopefully, this begins a wetter, colder, snowier pattern.

Temperature and precipitation data for Arizona, November 2012. National Weather Service, Flagstaff

Temperature and precipitation data for Arizona, November 2012. National Weather Service, Flagstaff

 Posted by at 7:01 am
Dec 082012
 

First the first time I can remember, the GFS, NoGAPs and GEF (Global Ensemble Forecast) models are all aligning around now for next Thursday. Not a lot, but maybe enough to give us a bit of white for the holidays. More importantly, it might help filling around the trees at Snowbowl for better ambiance. I rarely see this level of alignment across models, particularly for a smaller sized storm.

US Navy NoGAPs model for 6-hour precipitation next Thursday night.

US Navy NoGAPs model for 6-hour precipitation next Thursday night.

NOAA's GFS 12-hour precipitation model for next Thursday night.

NOAA’s GFS 12-hour precipitation model for next Thursday night.

NOAA's Global Emsemble Forecast for precipitation next Thursday night.

NOAA’s Global Ensemble Forecast for precipitation next Thursday night.

 Posted by at 8:22 am
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
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