Area Forecast Discussion
Issued by NWS Flagstaff, AZ

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000
FXUS65 KFGZ 200422
AFDFGZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
920 PM MST TUE AUG 19 2014

.SYNOPSIS...A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE SOUTHWEST
UNITED STATES OVER THE NEXT FEW DAYS ENHANCING THE MOIST SOUTHERLY
FLOW OVER ARIZONA AND BRING CONTINUED SHOWERS AND THUNDERSTORMS
THROUGH FRIDAY. SOME OF THESE STORMS WILL PRODUCE VERY HEAVY RAIN
AND CONTINUE THE POSSIBILITY FOR LOCALIZED FLASH FLOODING.

&&

.DISCUSSION...A MESOSCALE CONVECTIVE SYSTEM DEVELOPED OVER SOUTHERN
YAVAPAI COUNTY THIS MORNING WITH THUNDERSTORMS PRODUCING EXTREMELY
HEAVY RAINFALL WITH 4 TO 6 INCHES OBSERVED ON THE GROUND.

AREAS OF FLOODING WERE ALSO REPORTED MAINLY NEAR BLACK CANYON CITY
AS THE AGUA FRIA RIVER PEAK FLOW AS MEASURED AT THE ROCK SPRINGS
GAUGE WAS ROUGHLY 23 FEET ABOVE BASELINE FLOW WITH A VOLUME OF 40000
CUBIC FEET PER SECOND...THAT IS ROUGHLY 40000 BASKETBALLS FULL OF
WATER PASSING BY PER SECOND.

HISTORICALLY FOR THE ROCK SPRINGS AGUA FRIA RIVER GAUGE THIS WAS THE
5TH LARGEST FLOW ON RECORD GOING BACK TO 1919 AND THE HIGHEST FLOW
EVER REPORTED FOR A SUMMER EVENT. THE LAST TIME ROCK SPRINGS GAUGE
REPORTED A HIGHER FLOW WAS THE HISTORIC WINTER STORM ON JANUARY 21ST
2010 WITH 55000 CUBIC FEET PER SECOND OF WATER FLOW.

FOR TONIGHT...THE TROUGH OF LOW PRESSURE MOVING DOWN THE WEST COAST
WILL CONTINUE TO PROVIDE LIFT THROUGH THE NIGHT SO SOME STORMS WILL
LAST AFTER DARK. STRONG STORMS ARE POSSIBLE AGAIN ON WEDNESDAY AS
THE LOW CENTER APPROACHES ARIZONA...UPWARD MOTION AND COOLING ALOFT
WILL CONTINUE.

FOR THURSDAY AND BEYOND...MUCH DEPENDS ON THE PROGRESS OF THE
CALIFORNIA LOW. TIMING DIFFERENCES STILL EXIST BETWEEN MODELS. THE
GFS BRINGS A FAIRLY STRONG UPWARD MOTION BULLS-EYE ACROSS NORTHERN
ARIZONA FROM LATE WEDNESDAY NIGHT INTO THURSDAY. THE EUROPEAN BRINGS
THE UPWARD MOTION MAXIMUM THROUGH FROM THURSDAY NIGHT INTO FRIDAY.
MODELS ARE CURRENTLY DOWNPLAYING ANY CONNECTION BETWEEN THIS UPWARD
MOTION MAXIMUM AND MOISTURE TO THE SOUTH. THE RESULT IS A FAIRLY
COMMON LOOKING PRECIPITATION FORECAST. HOWEVER...IF A TAP IS MADE TO
DEEPER MOISTURE JUST TO THE SOUTH WATCH OUT.

IN ANY EVENT...KEEP ABREAST OF THE SITUATION. STRONGER STORMS THIS
WEEK WILL BE CAPABLE OF PRODUCING EXTREMELY HEAVY RAINFALL.

&&

.FOR THE 06Z PACKAGE...EXPECT SCATTERED SHRA/TSRA ACROSS NORTHERN
ARIZONA TO DECREASE IN COVERAGE OVERNIGHT. AREAS OF MVFR WILL BE
COMMON WITH ISOLATED IFR DUE TO PRECIP AND OR LOW CLOUDS AND FOG
THROUGH 18Z WEDS. SCATTERED THUNDERSTORMS TO REDEVELOP AFTER 18Z
WEDS. AVIATION DISCUSSION NOT UPDATED FOR AMENDMENTS.

&&

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

&&

$$

PUBLIC.........BOHLIN/MAS
AVIATION.......DL

FOR NORTHERN ARIZONA WEATHER INFORMATION VISIT
WEATHER.GOV/FLAGSTAFF











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