Flash Flood in Arizona, August 18, 2010

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
805 PM MST WED AUG 18 2010

.SYNOPSIS...SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE IN
NORTHEASTERN ARIZONA THIS EVENING...WITH A SLIGHT CHANCE OF SHOWERS
AND THUNDERSTORMS DEVELOPING OVERNIGHT IN FAR NORTHERN ARIZONA. ON
THURSDAY AND FRIDAY...SLIGHTLY DRIER AIR WILL LOWER BUT NOT END
THUNDERSTORM CHANCES. THUNDERSTORM ACTIVITY SHOULD INCREASE THIS
WEEKEND THROUGH TUESDAY AS MOIST SOUTHERLY FLOW RETURNS.

&&

.DISCUSSION...A SHORTWAVE TROUGH CONTINUES TO EJECT NORTHEASTWARD
ACROSS NORTHERN AZ THIS EVENING...BRINGING WIDESPREAD SHOWER AND
THUNDERSTORM ACTIVITY TO THE NORTHEAST CORNER OF THE STATE...WHILE
SKIES ARE CLEARING TO THE WEST BEHIND THIS FEATURE. AN OUTFLOW
BOUNDARY MOVING SOUTHWARD THROUGH SOUTHERN UT WAS INITIATING
THUNDERSTORMS IN SOUTHWEST UT AND MAY AFFECT FAR NORTHERN AZ TONIGHT
IF IT CONTINUES TO PROPAGATE SOUTHWARD. HAVE UPDATED THE FORECAST
PACKAGE FOR MUCH LOWER POPS TONIGHT BEHIND THE NORTHERN AZ
SHORTWAVE. OTHERWISE...FORECAST PACKAGE IS IN GOOD SHAPE FOR
THURSDAY AND BEYOND.

&&

.PREV DISCUSSION/310 PM MST/...THUNDERSTORMS HAVE BEEN SLOW TO
DEVELOP THIS AFTERNOON ACROSS NORTHERN ARIZONA. THE STORM COVERAGE
AND INTENSITY IN NAVAJO AND APACHE COUNTIES IS LESS THAN EXPECTED.
WE WILL CANCEL THE FLASH FLOOD WATCH FOR NAVAJO AND APACHE COUNTIES.
SCATTERED THUNDERSTORMS SHOULD CONTINUE ACROSS THE NORTHLAND THROUGH
EARLY EVENING BEFORE DIMINISHING.

FOR THURSDAY THRU FRIDAY...LIGHT WESTERLY FLOW ALOFT IS FORECAST TO
RETURN TO NORTHERN AZ. THIS WILL ALLOW FOR SOME DRYING...BUT NOT
ENOUGH SHUT OFF DAYTIME THUNDERSTORM ACTIVITY. PW VALUES DROP TO
NORMAL FOR THIS TIME OF YEAR. AFTERNOON CHANCES OF THUNDERSTORMS ARE
RANGE FROM 10-20 PERCENT IN NW COCONINO COUNTY TO 40-50 PERCENT IN
THE WHITE MTNS.

FROM SATURDAY THROUGH EARLY NEXT WEEK. DEEP AND MOIST SOUTHERLY FLOW
IS FORECAST TO RETURN TO AZ DURING THIS TIME PERIOD. VERY HIGH
PRECIPITABLE WATER VALUES ARE SHOWN FOR THE NORTHLAND. WE HAVE
CONTINUED THE ABOVE CLIMATOLOGY CHANCES FOR PRECIPITATION...AND
EXPECT MORE CLOUDS THAN CLEAR FOR MUCH OF DAY 3 THROUGH 7 FORECAST
PERIOD.

&&

.AVIATION...FOR THE 06Z PACKAGE...SCT SHRA/TSRA WITH IFR CONDITIONS
IN THE STRONGER STORMS WILL CONTINUE UNTIL AROUND 09Z NORTHEAST OF A
KSJN-P14-0V7 LINE WITH PRIMARILY VFR CONDITIONS TO THE WEST. A
SLIGHT CHANCE OF -SHRA/-TSRA WILL DEVELOP IN FAR NORTHERN AZ
OVERNIGHT AS A LINE OF SHOWERS AND THUNDERSTORMS PUSHES SOUTHWARD
FROM SOUTHERN UT. ON THURSDAY...ISOLATED TO SCATTERED THUNDERSTORMS
ARE EXPECTED TO DEVELOP AFTER 18Z. AVIATION SECTION NOT UPDATED FOR
AMENDMENTS.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES... NONE.

PUBLIC.................DJO
AVIATION...............DJO

VISIT WEATHER.GOV/FLAGSTAFF FOR NORTHERN ARIZONA WEATHER
INFORMATION.

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
320 PM MST WED AUG 18 2010

AZZ004>018-037>040-190715-
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-
320 PM MST WED AUG 18 2010

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

TODAY FLASH FLOOD WATCH FOR NAVAJO AND APACHE COUNTIES HAS BEEN
CANCELLED. SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE ACROSS
THE NORTHLAND THROUGH MID EVENING. STORM COVERAGE SHOULD DIMINISH
BY LATE EVENING.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

ON THURSDAY...SLIGHTLY DRIER AIR SHOULD BEGIN TO MAKE ITS WAY
ACROSS NORTHERN ARIZONA...WITH PRECIPITATION CHANCES LOWERING BUT
NOT ENDING THROUGH FRIDAY. THUNDERSTORM CHANCES AND THE THREAT OF
LOCALLY HEAVY RAINFALL RETURN FROM SATURDAY THROUGH TUESDAY.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
702 PM MST WED AUG 18 2010

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0654 PM     FLASH FLOOD      3 N SALINA              36.07N 109.87W
08/18/2010                   APACHE             AZ   LAW ENFORCEMENT

            ROUTE 4 IMPASSABLE DUE TO HIGH WATER BETWEEN MILE
            MARKERS 40 AND 43.

&&

EVENT NUMBER FGZ1000182

JVC