UPDATED (9:52AM, January 22): Winter Storm Warning in effect. See below
Answers: I don’t know. And, on the ground, of course.
The National Weather Service provides two great products for looking at Flagstaffs weather. The Daily Climate Report and the Preliminary Monthly Climate Data Report. Yesterday, both reports were showing MM, or missing data for snowfall on both days. This has been repaired in the Monthly, but the Daily for January 20 still shows MM. The total snow fall was 12.6 inches. In the January 20 report, the record snowfall for the date was 7.1 inches in 1954. I wonder if it is still a record. Also, a Record Event Report archive is available. There is no report for January 20 or 21. I hope we don’t lose the data. This was a significant event.
Another interesting aspect, the snowfall amount broke the record, but the total precipitation amount did not. Must have been a warmer storm in 1954.
The bigger question is how deep will the next chunk of snow be? The GFS model caps it at a foot. The NAM model shows more, around 18 inches. You can see the difference in the image below. The Navy’s NoGaps model doesn’t run a snowfall calculation. But adding up the individual precipitation amounts and going with a rough 10 inches of snow for 1 inch of water, it looks like it is on the 18 inch side of the discussion. In any of these cases, it looks like the snow starts in earnest again on Sunday evening and goes through Tuesday. Current a Winter Winter Storm Watch is in effect. I would expect a that to change to a warning.
URGENT - WINTER WEATHER MESSAGE NATIONAL WEATHER SERVICE FLAGSTAFF AZ 945 AM MST SUN JAN 22 2017 ...THE THIRD AND FINAL STORM IS EXPECTED TODAY INTO LATE MONDAY NIGHT... .THE NEXT STORM HAS ALREADY BEGUN TO AFFECT THE WESTERN HALF OF ARIZONA THIS MORNING...AND WILL SPREAD EASTWARD LATER THIS EVENING THROUGH MONDAY NIGHT. THERE IS A THREAT OF HEAVY SNOW ACCUMULATION FOR AREAS ABOVE 6000 FEET ELEVATION...WITH LIGHTER ACCUMULATIONS DOWN TO NEAR THE 5000 FOOT LEVEL. AZZ004-006>008-015-230300- /O.EXT.KFGZ.WS.W.0002.170122T1645Z-170124T1200Z/ KAIBAB PLATEAU-GRAND CANYON COUNTRY-COCONINO PLATEAU- YAVAPAI COUNTY MOUNTAINS-WESTERN MOGOLLON RIM- INCLUDING THE CITIES OF...JACOB LAKE...GRAND CANYON VILLAGE... VALLE...FLAGSTAFF 945 AM MST SUN JAN 22 2017 ...WINTER STORM WARNING NOW IN EFFECT UNTIL 5 AM MST TUESDAY ABOVE 6000 FEET... * TIMING...LIGHT TO MODERATE SNOW WILL CONTINUE THROUGH LATE THIS AFTERNOON...INCREASING IN INTENSITY AND CONTINUING THROUGH EARLY TUESDAY MORNING. SNOW WILL SPREAD FROM WEST TO EAST SUNDAY AFTERNOON AND EVENING...CONTINUING THROUGH TUESDAY MORNING. * GENERAL EVENT TOTAL SNOW ACCUMULATIONS...8 TO 15 INCHES FOR AREAS ABOVE 6000 FEET ELEVATION. HIGHER AMOUNTS POSSIBLE ALONG SOUTHWEST FACING SLOPES OF THE MOGOLLON RIM AND THE KAIBAB PLATEAU. CONSULT POINT SPECIFIC FORECAST AT: WEATHER.GOV/FLAGSTAFF. * SNOWFALL FORECAST FROM 9 AM MST TODAY UNTIL 5 AM MST TUESDAY... DONEY PARK 5 TO 9 INCHES FLAGSTAFF 9 TO 15 INCHES GRAND CANYON 9 TO 15 INCHES JACOB LAKE 11 TO 17 INCHES NORTH RIM 20 TO 26 INCHES VALLE 4 TO 8 INCHES WILLIAMS 6 TO 10 INCHES * WINDS...GUSTY WINDS ARE EXPECTED THROUGHOUT THE EVENT...WITH THE STRONGEST WINDS LATE TONIGHT THROUGH MONDAY AFTERNOON. SUSTAINED WINDS OVER 20 MPH WITH GUSTS UP TO 45 WILL SEVERELY REDUCE VISIBILITIES IN BLOWING AND DRIFTING SNOW. * OTHER IMPACTS...DANGEROUS TRAVEL CONDITIONS ARE LIKELY DUE TO SNOW PACKED AND SLICK ROADS. VISIBILITY COULD ALSO BE SEVERELY REDUCED DUE TO BLOWING AND DRIFTING SNOW. 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. 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.