A low pressure center over northwestern Arizona brought abundant moisture and dynamics to central and eastern parts of northern Arizona. This lead to thunderstorms producing a tornado, large hail, heavy rain, and flash flooding.
Every event with a place to put it. 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 low pressure center over northwestern Arizona brought abundant moisture and dynamics to central and eastern parts of northern Arizona. This lead to thunderstorms producing a tornado, large hail, heavy rain, and flash flooding.
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 Sep 14, 9:30 AM MST, 4 hours 40 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE FLAGSTAFF AZ 930 AM MST WED SEP 14 2011 .SYNOPSIS...A LOW PRESSURE SYSTEM OVER THE SOUTHWESTERN STATES WILL BRING A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS TO THE AREA UNTIL LATE THURSDAY. SOME THUNDERSTORMS MAY BE SEVERE. COOLER THAN NORMAL TEMPERATURES WILL ALSO CONTINUE. EXPECT A SIGNIFICANT DRYING TREND BY FRIDAY...WITH HIGH TEMPERATURES WARMING BACK TO AROUND SEASONAL AVERAGES OVER THE WEEKEND. && .DISCUSSION...THE UPPER LEVEL LOW IS SEEN WELL THIS MORNING ON WATER VAPOR IMAGERY SPINNING OVER NORTHWEST AZ. THIS FEATURE THAT HAS BROUGHT UNSETTLED WEATHER OVER THE PAST SEVERAL DAYS AND WILL CONTINUE TO AFFECT THE WEATHER ACROSS NORTHERN AZ TODAY. ALSO SEEN ON WATER VAPOR IMAGERY THIS MORNING IS A DRY SLOT THAT PUSHED INTO NORTH CENTRAL AZ OVERNIGHT. MORNINGS SOUNDINGS ALSO SHOW A GOOD AMOUNT OF DRY AIR ALOFT HAS MOVED IN. DESPITE THIS DRYING...SURFACE DEW POINTS HAVE SHOWN LITTLE CHANGE OVER THE PAST 24 HOURS AND SOUNDINGS STILL SHOW ADEQUATE BOUNDARY LAYER MOISTURE. WITH THE UNCERTAINTY IN HOW MUCH OF A ROLE THIS DRY AIR WILL PLAY...WILL CONTINUE WITH GOOD CHANCES FOR SHOWERS/THUNDERSTORMS THIS AFTERNOON AND EVENING AS THE UPPER LEVEL COLD POOL MOVES OVERHEAD AND WE'LL CONTINUE TO MONITOR HOW CONVECTIVE TRENDS PROGRESS. && .PREVIOUS DISCUSSION (310 AM)...THE AREA OF BEST SHEAR...INSTABILITY AND DIVERGENCE ALOFT WILL MOVE NORTHEAST INTO THE NORTHEAST PLATEAUS AND WINDOW ROCK AREA THIS AFTERNOON AND EARLY EVENING...WITH THE BIGGEST THREAT OF STRONG THUNDERSTORMS DEVELOPING WITHIN THIS AREA. THE LOW IS FORECAST TO WEAKEN AND MOVE NORTHEAST WEDNESDAY NIGHT... AND CONVECTION SHOULD DIE OFF. ON THURSDAY...EVEN THOUGH THE LOW HAS WEAKENED AND MOVE NORTHEAST...A LINGERING TROUGH REMAINS OVER PORTIONS OF NORTHERN ARIZONA...LEAVING A MOIST AND SOMEWHAT UNSTABLE AIRMASS IN PLACE. WE SHOULD STILL SEE SCATTERED SHOWERS AND THUNDERSTORMS...ALTHOUGH NOT AS STRONG AS IN PREVIOUS DAYS. BY FRIDAY...THE TROUGH OVER THE AREA FILLS AND WEAKENS EVEN MORE WITH A MORE DRY AND STABLE WESTERLY FLOW...WITH ONLY ISOLATED TO WIDELY SCATTERED SHOWERS AND THUNDERSTORMS AT BEST. SATURDAY HEIGHTS CONTINUE TO RISE...ALONG WITH DRIER AIR. THERE IS STILL A SLIGHT CHANCE OF AN AFTERNOON SHOWER OR THUNDERSTORM MAINLY ALONG THE ARIZONA AND UTAH BORDER WHERE THE BEST MOISTURE AND INSTABILITY LINGER WITHIN THE DECAYING TROUGH OVER THE REGION. SUNDAY INTO TUESDAY...HEIGHTS CONTINUE TO RISE ACROSS THE SOUTHWEST WITH A DRIER WESTERLY FLOW. EXPECT DRY CONDITIONS AND A WARMING TREND FOR DAYTIME HIGHS. && .AVIATION...FOR THE 18Z PACKAGE...SCT TO NMRS SHRA/TSRA...AND ISOLD +TSRA WILL DEVELOP TODAY. EXPECT ISOLD IFR CONDITIONS WITH ANY +TSRA. SOME STORMS MAY CONTAIN LARGE HAIL AND STRONG WIND GUSTS TO 60KT. CONVECTION WILL DECREASE TO ISOLD/SCT COVERAGE AFT 02Z-04Z THURSDAY. AVIATION DISCUSSION NOT UPDATED FOR AMENDMENTS. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && PUBLIC..................MCS AVIATION................MAS FOR NORTHERN ARIZONA WEATHER INFORMATION VISIT WEATHER.GOV/FLAGSTAFF.
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE FLAGSTAFF AZ 525 AM MST WED SEP 14 2011 AZZ004>018-037>040-150700- 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- 525 AM MST WED SEP 14 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EAST CENTRAL ARIZONA...NORTH CENTRAL ARIZONA...NORTHEAST ARIZONA AND WEST CENTRAL ARIZONA. .DAY ONE...TODAY AND TONIGHT A LOW PRESSURE SYSTEM OVER SOUTHERN CALIFORNIA SOUTHERN NEVADA WILL MOVE EAST EARLY THIS MORNING...AND INTO NORTHWESTERN ARIZONA BY LATE MORNING. EXPECT SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS TO RE-DEVELOP AHEAD OF THIS LOW LATER THIS MORNING. THE STRONGEST STORMS WILL OCCUR FROM WESTERN AND CENTRAL YAVAPAI COUNTY...AS WELL AS COCONINO COUNTY FROM FLAGSTAFF WESTWARD. A FEW STORMS IN THESE REGIONS WILL HAVE THE POTENTIAL TO BECOME STRONG PRODUCE LARGE HAIL FROM ONE INCH OR LARGER WITH THE POSSIBILITY OF A TORNADO FROM ONE OF THESE STORMS. THE SEVERE WEATHER POTENTIAL IN THIS REGION WILL PARTIALLY DIMINISH DURING THE AFTERNOON. THEN...THE SEVERE WEATHER POTENTIAL WILL LIKELY SHIFT TOWARD THE EASTERN AND NORTHEASTERN SECTIONS OF THE STATE DURING THE AFTERNOON. ELSEWHERE...EXPECT FREQUENT STORM ACTIVITY WITH SOME HAIL AND THE POSSIBILITY OF HEAVY RAIN. HOWEVER...IN GENERAL...STORMS OUTSIDE OF THE REGIONS MENTIONED ABOVE WILL NOT BE AS STRONG OR ORGANIZED...BUT THEY WILL BE NUMEROUS. LOCALIZED HEAVY RAIN PRODUCING STORMS...AS WELL AS STORMS CROSSING THE SAME AREA MORE THAN ONCE...WILL ALSO BRING THE THREAT FLASH FLOODING. THIS THREAT WILL BE MAXIMIZED OVER OUR BURN AREAS...SUCH AS THE SCHULTZ...LOCUST...AND WALLOW FIRE BURN SCARS. THUNDERSTORM ACTIVITY WILL SLOWLY DIMINISH TONIGHT. HOWEVER...SOME AREAS OF LIGHT TO MODERATE RAIN WILL LIKELY CONTINUE...ESPECIALLY OVER THE NORTHEAST. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY THE ATMOSPHERE WILL REMAIN MOIST AND UNSTABLE INTO THURSDAY AS THE LOW MOVES VERY SLOWLY TO THE EAST. SHOWERS AND THUNDERSTORMS ARE POSSIBLE ONCE AGAIN ON THURSDAY...WITH THE STRONGER STORMS MOST LIKELY LOCATED FROM FLAGSTAFF NORTH AND NORTHEAST. BY FRIDAY...EXPECT A SIGNIFICANT DOWNWARD TREND IN THUNDERSTORM ACTIVITY AS DRIER AND MORE STABLE AIR COMES IN FROM THE WEST. THIS DRYING...AND WARMING TREND...WILL LAST INTO THE COMING WEEKEND. SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE FLAGSTAFF AZ 1253 PM MST WED SEP 14 2011 AZZ004-005-009-142015- COCONINO AZ- 1253 PM MST WED SEP 14 2011 THE NATIONAL WEATHER SERVICE IN FLAGSTAFF HAS ISSUED A SIGNIFICANT WEATHER ADVISORY FOR... NORTH CENTRAL COCONINO COUNTY IN NORTH CENTRAL ARIZONA UNTIL 115 PM MST AT 1245 PM MST...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A LINE OF STRONG THUNDERSTORMS APPROACHING ROUTE 89A IN THE HOUSE ROCK VALLEY. THIS IS BETWEEN HOUSE ROCK AND MARBLE CANYON. THESE STORMS WERE MOVING NORTH AT 15 MPH. HAIL UP TO THE SIZE OF PENNIES IS EXPECTED WITH THIS STORM...ALONG WITH VERY HEAVY RAIN. LOCATIONS IMPACTED INCLUDE... RURAL NORTHERN COCONINO COUNTY... PRECAUTIONARY/PREPAREDNESS ACTIONS... IF YOU ARE IN THE ADVISORY AREA AND STORMS APPROACH...TAKE SHELTER IN A STURDY BUILDING. && LAT...LON 3677 11205 3681 11173 3662 11169 3657 11199 TIME...MOT...LOC 1952Z 178DEG 12KT 3666 11186
The Flagstaff radar (KFSX), 55 km away, was scanning. The volume nearest the first event began at 21:07 UTC.
5 flash flood, 1 hail, 1 tornado. Local standard time, as filed.
Quarter sized (1 inch diameter) hail covered the ground 1 mile south of Schnebly Hill Road Exit on I-17.
An official from the Sedona Police Department reported that creeks in the Tlaquepaque area had overflowed. The flood water covered road ways and forced the closure of several roads.
An official with the Lake Powell Tribal Park reported flash flooding of Rattle Snake and Owl Canyons.
Law Enforcement officials reported flooding on Zalesky Road.
Law Enforcement officials reported an ongoing swift water rescue on Spring Creek.
A storm survey revealed that significant forest damage occurred along the Humpherys Trail near the Snowbowl Ski Area around 10,000 feet elevation. Preliminary rating was EF2.
A trained spotter reported flash flood debris covering roadways in Page Springs.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Arizona in 2011Every state in 2011This day in weather historyThe tornado archive for Arizona, 2011Warnings in Arizona, September 2011
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: 349037, 349038, 349039, 349324, 349325, 349327, 349326.