A strong low pressure system moved across Arizona with widespread rain and snow. Most of the accumulating snow was above 5000 feet elevation.
Every event with a place to put it; 4 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS FGZ wrote it up.
A strong low pressure system moved across Arizona with widespread rain and snow. Most of the accumulating snow was above 5000 feet elevation.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Flagstaff, AZ wrote its last area forecast discussion before the first event at Apr 13, 9:15 PM MST, 3 hours 45 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE FLAGSTAFF AZ 915 PM MST FRI APR 13 2012 .SYNOPSIS...A STRONG LOW PRESSURE SYSTEM WILL MOVE ACROSS ARIZONA TONIGHT AND SATURDAY. AREAS OF RAIN AND SNOW WILL DEVELOP AND MOVE ACROSS THE NORTHLAND LATE THIS EVENING...THROUGH SATURDAY. MODERATE SNOW ACCUMULATION WILL BE POSSIBLE OVER HIGHER TERRAIN...MAINLY ABOVE 5000 FEET. UNSETTLED...BUT IMPROVING CONDITIONS WILL LINGER THROUGH SUNDAY...WITH RAPID WARMING AND DRYING BY NEXT WEEK. && .DISCUSSION...A STRONG COLD FRONT HAS CROSSED THE LOWER COLORADO RIVER VALLEY AND WAS MOVING TOWARD WESTERN YAVAPAI COUNTY THIS EVENING. IMPRESSIVE RAINFALL TOTALS FROM NEEDLES AND BULLHEAD CITY ARE NOW TRACKING TOWARD KINGMAN. 00Z MODELS BRING THE SWEET SPOT OF THIS FRONT DUE EAST ALONG I-40...AND THEN THE FRONT FRAGMENTS PARTIALLY AFTER PASSING THROUGH FLAGSTAFF...AND WILL MOVE THROUGH THE EASTERN RIM AND WHITE MOUNTAINS IN A WEAKENED FORM. WE EXPECT SNOWFALL TO BEGIN IN WESTERN YAVAPAI COUNTY ABOVE 5000 FEET SHORTLY...REACHING FLAGSTAFF RIGHT AROUND MIDNIGHT. PRECIPITATION WILL NOT START IN THE WHITE MOUNTAINS UNTIL AROUND SUNRISE. THERE WILL BE A 2-4 HOUR PERIOD OF VERY STRONG DYNAMICS...AND A RAPIDLY DESTABILIZING ATMOSPHERE DURING THIS FRONTAL PASSAGE. THIS 2-4 HOUR PERIOD WILL LIKELY BE RESPONSIBLE FOR MUCH OF THE SNOW FORECASTED TONIGHT. AFTER THE FRONT PASSES...A DRY SLOT WILL TEMPORARILY BRING A LULL TO THE ACTIVITY OVER CENTRAL ARIZONA...WITH THE FRONT OVER EASTERN ARIZONA. THEN...THE VERY COLD AIR IN THIS LOW WILL BRING WIDESPREAD AND OCCASIONALLY HEAVY INSTABILITY SHOWERS TO THE AREA SATURDAY AFTERNOON. THESE SHOWERS WILL COMBINE WITH UPSLOPE FLOW ALONG THE WESTERN MOGOLLON RIM...WHERE SNOWFALL RATES COULD REACH 2 INCHES PER HOUR. THIS SYSTEM WILL THEN EXIT THE AREA SATURDAY NIGHT AND SUNDAY...ALTHOUGH JUST ENOUGH INSTABILITY REMAINS SUNDAY AFTERNOON FOR A FEW MORE SHOWERS ALONG AND EAST OF THE RIM. WE HAVE ALREADY MADE MANY UPDATES THIS EVENING...SO WHAT IS OUT NOW LOOKS GOOD. UPDATES WILL BE SENT FOR THE WSWFGZ TEXT PRODUCT SOON. && .AVIATION...FOR THE 06Z PACKAGE...A COLD FRONT WILL MOVE WEST TO EAST ACROSS NORTHERN ARIZONA TONIGHT WITH STEADY RA/SN AND MVFR/IFR CONDITIONS. ISOLD TSRA/TSSN ARE EXPECTED ALONG THE COLD FRONT. SFC WINDS TONIGHT 10-20 KT GUSTS TO 30 KT. AFT 12Z SAT...THE FRONT AND STEADY PRECIPITATION SHOULD BE ACROSS APACHE COUNTY AND HEADING EAST. BEHIND THE FRONT...AN UNSTABLE AIRMASS WILL PRODUCE NUMEROUS MODERATE TO HEAVY SHOWERS WITH MVFR AND IFR CONDITIONS. SHOWERS SHOULD TAPPER OFF FROM WEST TO EAST AFT 02Z SUNDAY. AVIATION DISCUSSION NOT UPDATED FOR AMENDMENTS. && .FGZ WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 10 PM MST TONIGHT UNTIL 11 AM MST SATURDAY FOR AZ PUBLIC ZONE 015. WINTER WEATHER ADVISORY ABOVE 5000 FEET UNTIL 11 AM MST SATURDAY FOR AZ PUBLIC ZONES 004-006. WINTER WEATHER ADVISORY ABOVE 4500 FEET UNTIL 8 AM MST SATURDAY FOR AZ PUBLIC ZONES 007-008. WINTER WEATHER ADVISORY FROM MIDNIGHT MST TONIGHT UNTIL 11 AM MST SATURDAY FOR AZ PUBLIC ZONE 016. && PUBLIC.........PETERSON AVIATION.......MAS FOR NORTHERN ARIZONA WEATHER INFORMATION VISIT WEATHER.GOV/FLAGSTAFF
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE FLAGSTAFF AZ 205 PM MST FRI APR 13 2012 AZZ004>018-037>040-140815- 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- 205 PM MST FRI APR 13 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHERN ARIZONA. .DAY ONE...THIS AFTERNOON AND TONIGHT A VIGOROUS STORM SYSTEM WILL AFFECT NORTHERN ARIZONA TONIGHT THROUGH SATURDAY EVENING. SOUTHWEST WINDS GUSTS TO 45 MPH ARE EXPECTED THROUGH THIS EVENING ALONG AND NORTH OF THE MOGOLLON RIM...AND A WIND ADVISORY IS IN EFFECT FOR MUCH OF NORTHERN ARIZONA. RAIN AND SNOW WILL DEVELOP IN WESTERN YAVAPAI COUNTY THIS EVENING AND SPREAD EASTWARD TONIGHT. A WINTER ADVISORY HAS BEEN ISSUED FOR PORTIONS OF NORTHERN ARIZONA ABOVE 4500 FEET VALID TONIGHT THROUGH SATURDAY MORNING. SEE PHXWSWFGZ FOR ADDITIONAL DETAILS. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY SHOWERS WILL PERSIST ON SATURDAY...WITH LOCALLY HEAVY SNOW SHOWERS PRODUCING A QUICK INCH OF ACCUMULATIONS AND LOW VISIBILITIES. THE MAIN THREAT FOR ACCUMULATING SNOWFALL WILL END BY SATURDAY EVENING...WITH JUST A SLIGHT CHANCE OF LIGHT SHOWERS ON SUNDAY.
The national radar mosaic for the moment the first event began.
4 heavy snow. Local standard time, as filed.
Twelve inches of snow fell at the North Rim of the Grand Canyon on the Kaibab Plateau.
Eight to twelve inches of snow fell in and around Flagstaff.
Seven inches of snow fell 5 miles west of Prescott.
Seven inches of snow was reported in Pinetop-Lakeside.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Arizona in 2012Every state in 2012This day in weather historyWarnings in Arizona, April 2012
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 375850, 375862, 375861, 375863.