Severe Thunderstorm Warning 40, NWS Flagstaff, AZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
944 AM MST SUN AUG 3 2008

.SYNOPSIS...SOUTHEAST FLOW ALOFT WILL BRING ADDITIONAL MOISTURE TO
NORTHERN ARIZONA CONTINUING THROUGH MUCH OF NEXT WEEK. AS A
RESULT...THE CHANCE OF AFTERNOON AND EVENING THUNDERSTORMS WILL
INCREASE. DAYTIME TEMPERATURES WILL ALSO DROP TO NEAR SEASONAL
NORMALS.

&&

.DISCUSSION...MOISTURE HAS INCREASED AGAIN THIS MORNING ACROSS THE
FORECAST AREA AS A RESULT OF PERSISTENT SOUTHERLY FLOW IN THE MID
LEVELS...AND SOME CONVECTIVE OUTFLOW FROM STORMS SATURDAY EVENING.
SURFACE DEWPOINTS HAVE RISEN INTO THE LOW TO MID 50S SOUTH OF A
GRAND CANYON TO SAINT JOHNS LINE...WITH SOME LOW 60S BEING REPORTED
ACROSS THE LOWER ELEVATIONS OF YAVAPAI AND GILA COUNTIES. THIS
MOISTURE...COMBINED WITH SOME STEEP LAPSE RATES IN THE LOW TO MID
LEVELS...SHOULD RESULT IN HIGHER STORM COVERAGE TODAY COMPARED TO
SATURDAY. IN ADDITION...IF SURFACE DEWPOINTS CAN BE MAINTAINED IN
THE MID 50S SOUTH OF THE MOGOLLON RIM...SOME STRONGER STORMS WILL BE
POSSIBLE WITH MIXED LAYER CAPE VALUES EXCEEDING 1200 J/KG. STORM
MOTION SHOULD TAKE THE ACTIVITY TOWARD THE WEST OFF THE MOGOLLON
RIM/WHITE MTNS TOWARD EASTERN YAVAPAI AND NRN GILA COUNTY BY
MID-LATE AFTERNOON. FORECASTS WILL BE UPDATED SHORTLY TO INCREASE
STORM CHANCES THIS AFTN/EVE BY 10-20 PCT MOST AREAS.

BY TONIGHT AND MONDAY...FORECAST MODELS INDICATE THE TROUGH AXIS
CURRENTLY MOVING NORTHWESTWARD TOWARD THE STATE FROM MEXICO WILL
MOVE UP INTO CENTRAL ARIZONA. THIS FEATURE MAY CAUSE AN ADDITIONAL
INCREASE IN MOISTURE...AND AN ENHANCEMENT IN THUNDERSTORMS FROM THE
MOGOLLON RIM SOUTHWARD. THE GFS MODEL APPEARS TO OVER-DEVELOP THIS
DISTURBANCE...SO WE WILL KEEP RAIN CHANCES A BIT LOWER THAN IT WOULD
INDICATE.

TUESDAY THROUGH THE END OF THE WEEK...A RIDGE TO OUR EAST IS
FORECAST TO KEEP THE REGION UNDER FAIRLY MOIST SOUTHERLY FLOW. A
CONTINUATION OF SCATTERED AFTERNOON AND EVENING THUNDERSTORMS IS
EXPECTED EACH DAY.

&&

.AVIATION...FOR THE 18Z PACKAGE...EXPECT SCATTERED THUNDERSTORMS TO
DEVELOP OVER HIGHER TERRAIN BY 19Z. GENERALLY WEAK AIRFLOW ALOFT
THIS AFTERNOON WILL PRODUCE SLOW MOVING STORMS PUSHING INTO LOWER
ELEVATIONS BY LATE AFTERNOON AND EVENING...WITH MVFR/IFR CONDITIONS
AND GUSTY WINDS WITH THE STRONGEST STORMS. EXPECT THUNDERSTORM AND
SHOWER ACTIVITY TO DIMINISH AFTER 04Z. AVIATION DISCUSSION NOT
UPDATED FOR AMENDMENTS.

&&

.FIRE WEATHER...SEE FIRE WEATHER FORECAST (FWFFGZ) FOR DISCUSSION OF
DAYS 1 AND 2.

TUESDAY THROUGH THURSDAY...EXPECT ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS EACH AFTERNOON AND EVENING. STORM COVERAGE WILL
DIMINISH OVERNIGHT.

&&

PUBLIC.............JJ
AVIATION/FIRE WX...BAK

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

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
1004 AM MST SUN AUG 3 2008

AZZ004>018-037>040-040430-
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-
1004 AM MST SUN AUG 3 2008

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

MOISTURE VALUES HAVE INCREASED ACROSS MUCH OF NORTHERN ARIZONA
TODAY. AS A RESULT...SCATTERED THUNDERSTORMS ARE EXPECTED TO
DEVELOP ACROSS THE HIGHER TERRAIN BY EARLY THIS AFTERNOON. THE
STORMS WILL MOVE SLOWLY TOWARD THE NORTH AND WEST...AFFECTING
LOWER ELEVATION AREAS BY MID TO LATE AFTERNOON. THE MAIN THREAT
WITH STORMS TODAY ALONG AND SOUTH OF THE MOGOLLON RIM WILL BE
HEAVY RAIN AND GUSTY WINDS...ALONG WITH A LOCALIZED RISK OF HAIL
TO AROUND ONE-HALF INCH IN DIAMETER. NORTH OF THE MOGOLLON RIM...A
FEW STORMS WILL BE CAPABLE OF WIND GUSTS UP TO 50 MPH.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

A DISTURBANCE MOVING NORTHWARD TOWARD THE REGION MONDAY MAY CAUSE
A FURTHER INCREASE IN MOISTURE FROM THE MOGOLLON RIM SOUTHWARD.
THUNDERSTORMS WITH LOCALLY HEAVY RAINFALL WILL BE POSSIBLE IN THIS
AREA. TUESDAY THROUGH SATURDAY...MOISTURE WILL REMAIN ACROSS THE
REGION WITH SCATTERED AFTERNOON AND EVENING THUNDERSTORMS EACH DAY.

.SPOTTER INFORMATION STATEMENT...

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

JJ