Severe Thunderstorm Warning 56, NWS Flagstaff, AZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
1014 AM MST FRI AUG 7 2015

.SYNOPSIS...DEEP MOISTURE AND AN APPROACHING PACIFIC TROUGH WILL
PRODUCE SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS ACROSS
NORTHERN ARIZONA TODAY. THERE IS AN ELEVATED RISK FOR FLASH
FLOODING IN NORTHWESTERN ARIZONA THAT INCLUDES MUCH OF COCONINO
COUNTY. STORM ACTIVITY WILL THEN DECREASE IN COVERAGE ON SATURDAY
AND SUNDAY. DEEPER MOISTURE WILL RETURN NEXT WEEK RAMPING UP STORM
ACTIVITY FROM MONDAY ONWARD.

&&

.DISCUSSION...WE HAVE MADE NO MAJOR FORECAST UPDATES THIS MORNING.
STILL EXPECTING AN ACTIVE DAY OF SHOWERS AND THUNDERSTORMS IN
ASSOCIATION WITH A TROUGH MOVING INTO THE GREAT BASIN AND A
SUBSTANTIAL INCREASE IN MOISTURE OVER THE PAST 24 HOURS.

SOME WEAK FORCING AHEAD OF THE GREAT BASIN TROUGH IS ALREADY
FUELING AN AREA OF THUNDERSTORMS ACROSS NORTHWESTERN COCONINO
COUNTY. EXPECT THIS ACTIVITY TO CONTINUE THROUGH MUCH OF THE DAY
AND FILL IN ELSEWHERE ACROSS THE FORECAST AREA WHERE DAYTIME
HEATING INCREASES INSTABILITY. ANY STORMS THAT DEVELOP TODAY WILL
BE CAPABLE OF PRODUCING LOCALLY HEAVY RAIN. STORM MOTION WILL BE
SOUTHWEST TO NORTHEAST AT ABOUT 20 MPH OR EVEN FASTER TO THE
NORTHWEST. THIS SHOULD LIMIT SOME FLOODING CONCERNS...EXCEPT IN
AREAS WHERE STORMS REPEATEDLY MOVE OVER THE SAME SPOTS. THE
GREATEST THREAT FOR TRAINING STORMS LEADING TO FLASH FLOODING WILL
BE ACROSS NORTHWESTERN ARIZONA WHERE A FLASH FLOOD WATCH REMAINS
IN EFFECT. ENHANCED VERTICAL WIND SHEAR MAY LEAD TO A FEW STRONG
TO SEVERE STORMS CAPABLE OF DAMAGING WINDS AND HAIL UP TO 1.0 INCH
DIAMETER...THE GREATEST THREAT ACROSS NORTHERN COCONINO AND NAVAJO
COUNTIES.

&&

.PREV DISCUSSION /426 AM MST/...ON SATURDAY...STORM ACTIVITY WILL
DECREASE FROM WEST TO EAST AS DRIER PACIFIC AIR MOVES INTO THE
REGION. HOWEVER ENOUGH INSTABILITY AND MOISTURE WILL LINGER ACROSS
NAVAJO AND APACHE COUNTY FOR CONTINUED THUNDERSTORM ACTIVITY.

BY SUNDAY...A DRIER AND MORE STABLE ENVIRONMENT WILL LEAD TO
MOSTLY FAIR WEATHER CONDITIONS WITH JUST A FEW SHOWERS POSSIBLE
OVER THE WHITE MOUNTAINS REGION.

MONDAY THROUGH THURSDAY...A SEASONABLY STRONG PACIFIC LOW WILL
FORM JUST WEST OF THE CALIFORNIA COAST. THE INTERACTION BETWEEN
THE LOW AND THE SUBTROPICAL HIGH OVER NEW MEXICO AND TEXAS WILL
BRING A STRONG SOUTHERLY FLOW AND ADVECT DEEPER MOISTURE BACK INTO
ARIZONA. EXPECT INCREASING MOISTURE...CLOUDS AND A RETURN TO
THUNDERSTORM ACTIVITY FROM MONDAY ONWARD.

&&

.AVIATION...FOR THE 18Z PACKAGE...EXPECT SCT-NMRS SHRA/TSRA TO
DEVELOP ACROSS NORTHERN AZ AND PERSIST THROUGH THIS EVENING.
SCATTERED MVFR/IFR CONDS PSSBL IN STRONGER STORMS. THERE IS A
THREAT FOR STRONGER STORMS PRODUCING DAMAGING WIND AND HAIL UP TO
1 INCH ACROSS NORTHERN COCONINO/NAVAJO COUNTIES (INCLUDING KGCN
AND KPGA TERMINALS). STORMS DECREASING AND MOVING OFF TO THE EAST
BTWN 02-05Z SATURDAY. AVIATION DISCUSSION NOT UPDATED FOR
AMENDMENTS.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...FLASH FLOOD WATCH THROUGH THIS EVENING
FOR AZZ004>007-009-012- 015-038.

&&

PUBLIC...MCS/MCS
AVIATION...MCS

FOR NORTHERN ARIZONA WEATHER INFORMATION VISIT
WEATHER.GOV/FLAGSTAFF

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
442 AM MST FRI AUG 7 2015

AZZ004>018-037>040-080645-
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-
442 AM MST FRI AUG 7 2015

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

.DAY ONE...TODAY AND TONIGHT

SHOWERS AND THUNDERSTORMS WILL CONTINUE TO DEVELOP ACROSS NORTHERN
ARIZONA. A FEW OF THESE THUNDERSTORMS MAY BECOME SEVERE WITH LARGE
HAIL OR STRONG WINDS. HEAVY RAIN WITH SUCCESSIVE STORMS WILL
ELEVATE THE THREAT FOR LOCALIZED FLASH FLOODING IN NORTHWESTERN
ARIZONA INTO THE EVENING HOURS.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

SATURDAY...THUNDERSTORM ACTIVITY WILL CONTINUE ACROSS NAVAJO AND
APACHE COUNTIES.

SUNDAY...NO SIGNIFICANT THREATS.

MONDAY THROUGH THURSDAY...SHOWERS AND THUNDERSTORMS WILL RETURN.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
TO LOCAL LAW ENFORCEMENT...OR THE NATIONAL WEATHER SERVICE BY
CALLING 1-888-745-1637.