Flash Flood Warning 18, NWS Flagstaff, AZ

412 
WGUS75 KFGZ 282041
FFSFGZ

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
141 PM MST SUN JUL 28 2013

AZC005-282049-
/O.CAN.KFGZ.FF.W.0018.000000T0000Z-130728T2145Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
COCONINO AZ-
141 PM MST SUN JUL 28 2013

...THE FLASH FLOOD WARNING HAS BEEN CANCELLED FOR CENTRAL COCONINO
COUNTY...


GRAND CANYON NATIONAL PARK OFFICIAL INDICATE THAT FLASH FLOODING 
ON GARDEN GARDEN CREEK HAS ENDED. 

LAT...LON 3610 11213 3607 11186 3602 11180 3597 11196
      3601 11212

$$

41

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
1022 AM MST SUN JUL 28 2013

.SYNOPSIS...MONSOON MOISTURE WILL CONTINUE TO BRING A GOOD CHANCE OF
THUNDERSTORMS TODAY...A FEW CAPABLE OF PRODUCING HEAVY RAIN.
STARTING MONDAY...DRIER AIR WILL MOVE INTO NORTHERN ARIZONA WITH A
DECREASE IN STORM ACTIVITY.

&&

.DISCUSSION...A WEAK SHORTWAVE OVER SOUTHERN NEVADA IS EVIDENT ON
WATER VAPOR/IR AND APPEARS TO BE SHEARING (PULLING APART) AS IT
MOVES NORTHEAST ACROSS NORTHWEST ARIZONA. EVIDENCE OF LIFT
ASSOCIATED WITH THIS FEATURE IS THE RADAR ECHOES EXTENDING FROM
NAVAJO NATIONAL MONUMENT SOUTHWEST TO AROUND KINGMAN. THIS LIFT WILL
DRIFT INTO CENTRAL COCONINO COUNTY AND JUST SOUTH OF THE BLACK MESA
BY THIS AFTERNOON AND IT WILL HAVE WEAKENED CONSIDERABLY AND MAY NOT
SUPPORT ENOUGH LIFT TO HAVE ANY DISCERNIBLE INFLUENCE AFTER THAT
POINT ON TODAY'S WX.

NEXT FEATURE TO AFFECT WESTERN ARIZONA IS AN UPPER LEVEL SHORTWAVE
SEEN IN THE MODEL DATA AT 300 MB. THIS FEATURE WILL TRACK NNW ACROSS
WESTERN ARIZONA AND INTO NW COCONINO COUNTY. THIS FEATURE WILL
PROVIDE LIFT IN ASSOCIATION WITH UPPER LEVEL VORTICITY ADVECTION.
THE SHEAR OVER ARIZONA TODAY IS IN RESPONSE TO THE INCREASED HEIGHT
GRADIENT OVER THE SOUTHWEST U.S. AS THE SOUTHWEST SITS BETWEEN A
HIGH TO THE EAST AND A TROUGH OF LOW PRESSURE ALONG THE CALIFORNIA
COAST. THE BEST SHEAR IS AT ANVIL LEVEL WHICH WILL HELP SUPPORT A
FEW ORGANIZED THUNDERSTORMS MAYBE STRONG ENOUGH TO PRODUCE LARGE
HAIL ALONG AND NORTHWEST OF A KPRC TO KRQE LINE. THE BEST PW IN THE
FORECAST AREA IS ALONG AND NORTH OF THE I-40 CORRIDOR LATE THIS
MORNING AND AFTERNOON. THERE IS THE POSSIBILITY OF MAYBE A FEW
TRAINING STORMS IN THE SHEARED ENVIRONMENT THAT MAY POSE A HEAVY
RAIN THREAT. STORMS WILL BE MOVING TO THE NORTHEAST TODAY BETWEEN 10
TO 20 KTS AND GIVEN THE RAPID MOVEMENT OF CELLS AND THE LOWER PW
ENVIRONMENT WOULD NOT MAKE IT FAVORABLE FOR NUMEROUS AREA OF HEAVY
RAIN AND OR FLASH FLOODING...EXCEPT FOR NW COCONINO COUNTY WHERE THE
WEAK SYNOPTIC LIFT COULD FAVOR AN ENVIRONMENT FOR NUMEROUS
THUNDERSTORM AND WITH THE UNIDIRECTIONAL SHEAR AN ANCHORED LINE OF
STORMS WITH TRAINING CELLS.

&&
.PREVIOUS DISCUSSION /300 AM MST/...MONSOON MOISTURE WILL REMAIN
ACROSS NORTHERN ARIZONA TODAY. STRENGTHENING WESTERLY FLOW WILL
BRING DRIER AIR TO THE AREA OVER THE NEXT 24 HOURS BUT THIS WILL BE
A GRADUAL PROCESS. MORE THAN ENOUGH MOISTURE WILL REMAIN FOR HEAVY
RAIN PRODUCING STORMS. STORM MOTION WILL GENERALLY BE FROM WEST TO
EAST. THE STRENGTHENING FLOW ALOFT INCREASES THE POSSIBILITY OF
TRAINING OF THUNDERSTORM CELLS AND THE THREAT FOR LOCALIZED FLASH
FLOODING WILL CONTINUE.

FOR MONDAY THROUGH WEDNESDAY...A WEAK LOW PRESSURE SYSTEM WILL BRUSH
THE PACIFIC NORTHWEST MOVING FROM WEST TO EAST. IN RESPONSE...HIGH
PRESSURE WILL BE SUPPRESSED TO THE SOUTH AND EAST OF ARIZONA. THE
SHIFT IN THE HIGH WILL ALLOW A SLIGHTLY DRIER AND MORE STABLE AIR
MASS FROM OVER THE EASTERN PACIFIC TO MOVE ACROSS NORTHERN ARIZONA.
AS A RESULT...SHOWERS AND STORMS WILL BECOME MORE ISOLATED.

FROM THURSDAY AND INTO NEXT WEEKEND...THE BREAK IN THE MONSOON LOOKS
SHORT LIVED. AS THE PACIFIC NORTHWEST LOW PRESSURE SYSTEM HEADS
EASTWARD MODELS CONTINUE TO SHOW HIGH PRESSURE MOVING BACK TOWARD
THE FOUR CORNERS REGION. THE DOOR WOULD LIKELY THEN OPEN TO
SOUTHERLY FLOW AND THE RETURN OF DEEP MONSOON MOISTURE.

&&

.AVIATION...FOR THE 18Z PACKAGE...SCT-NMRS TSRA/SHRA WITH MVFR/IFR
CONDITIONS. OVER NW AZ...SOME STORMS MAY PRODUCE LARGE HAIL AND
STRONG WINDS. CONVECTIVE ACTIVITY SLOWLY DIMINISHING OVERNIGHT.
AVIATION DISCUSSION NOT UPDATED FOR AMENDMENTS.

&&

.FIRE WEATHER...A MOIST AND UNSTABLE AIR MASS WILL REMAIN OVER
NORTHERN ARIZONA TODAY PRODUCING AFTERNOON HEAVY RAIN SHOWERS AND
THUNDERSTORMS. THE MAIN THREATS TO OPERATIONS WILL BE FROM LOCALIZED
FLASH FLOODING AND LIGHTNING. DECREASING MOISTURE LEVELS ARE
FORECAST STARTING ON MONDAY WITH LOWER CHANCES FOR STORM ACTIVITY.

TUESDAY THROUGH THURSDAY...A DOWNWARD TREND IN THUNDERSTORM ACTIVITY
WILL CONTINUE THROUGH WEDNESDAY. EXPECT INCREASING CHANCES FOR
THUNDERSTORMS OVER NORTHEASTERN ARIZONA ON THURSDAY.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...FLASH FLOOD WATCH UNTIL 10 PM MST
THIS EVENING FOR AZZ004>007..

&&

PUBLIC.........TC/MCCOLLUM
AVIATION.......DB
FIRE WEATHER...BOHLIN

FOR NORTHERN ARIZONA WEATHER INFORMATION VISIT
WEATHER.GOV/FLAGSTAFF

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
335 AM MST SUN JUL 28 2013

AZZ004>018-037>040-290745-
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-
335 AM MST SUN JUL 28 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR APACHE...COCONINO...
NORTHERN GILA...NAVAJO...AND YAVAPAI COUNTIES IN NORTHERN
ARIZONA.

.DAY ONE...TODAY AND TONIGHT

MONSOON MOISTURE WILL REMAIN OVER NORTHERN ARIZONA. STORMS WILL BE
MOST NUMEROUS FROM THE MOGOLLON RIM NORTHWARD. THE MAIN THREAT
FROM STORMS WILL CONTINUE TO BE HEAVY RAIN.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

FROM MONDAY THROUGH WEDNESDAY...DRIER AIR WILL MOVE OVER THE AREA
WITH THUNDERSTORM AND SHOWER ACTIVITY BECOMING ISOLATED. FOR
THURSDAY AND THE END OF THE WEEK...SOUTHERLY FLOW AND MONSOON
MOISTURE WILL RETURN TO NORTHERN ARIZONA.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.