Severe Thunderstorm Warning 97, NWS Flagstaff, AZ

NORTHERN ARIZONA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
1040 AM MST FRI SEP 14 2001

.SYNOPSIS...A RIDGE OF HIGH PRESSURE OVER NORTHERN MEXICO AND A WEAK
AREA OF LOW PRESSURE IN THE EASTERN PACIFIC WILL CONTINUE TO PUSH
MOISTURE NORTHWARD INTO ARIZONA. EXPECT SCATTERED SHOWERS AND
THUNDERSTORMS TO DEVELOP AGAIN TODAY AND INTO THE WEEKEND. A DRYING
TREND WILL BEGIN ON MONDAY AND LAST THROUGH THE WEEK.

.DISCUSSION...FLASH FLOOD WATCH TODAY AND INTO THIS EVENING...WATCH
EXTENDS ROUGHLY ALONG AND SOUTH OF A LINE FROM WINDOW ROCK TO
FLAGSTAFF TO SELIGMAN.

PRECIPITABLE WATER FROM THE GOES SOUNDER DPI IS CLOSE
TO REALITY...WITH AROUND .6 IN AT THE UTAH ARIZONA BORDER WITH
NEARLY AN INCH AND A HALF ALONG SOUTHERN SECTIONS OF THE FLG
FORECAST AREA. 300MB JET WITH ITS AXIS RUNNING FROM NORTHEAST NEW
MEXICO TO FLAGSTAFF FOR GOOD VENTILATION AT STORM TOP. GOOD SOLAR
HEATING WITH THE DRY AIR ALOFT...A SHALLOW STABLE LAYER AROUND 600
MB FOR CONVECTION TO BREAK...VIS IMAGERY ALREADY SHOWING THAT
HEATING OVER THE HIGHER TERRAIN HAS BEEN ENOUGH TO BREAK THROUGH AND
BEGIN CONVECTION. THETA E AXIS EXTENDS NORTH AN SOUTH THROUGH MOST
OF NORTHERN ARIZONA...DEPENDING ON WHICH MODEL. WIND PROFILE 5 TO 10
KNOTS FROM THE SW AT 700MB INCREASING TO 15 KNOTS AT 500MB...SO MAIN
CONCERN WILL BE THE POSSIBILITY OF BACK BUILDING CELLS. WILL BE
ISSUING A FLASH FLOOD WATCH FOR SOUTHERN PART OF THE FLG FORECAST
AREA.
CLEMMONS

.FGZ...FLASH FLOOD WATCH UNTIL 10 PM MST FOR
ZN 008-011-013>018-038-037.

AZZ004>018-037>040-141930-
HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
1105 AM MST THU SEP 13 2001

...FLASH FLOOD WATCH THROUGH THIS EVENING ALONG AND SOUTH OF A LINE
   FROM WINDOW ROCK TO SELIGMAN...
...SOME THUNDERSTORM WILL PRODUCE LOCALLY HEAVY RAIN WHICH COULD
    PRODUCE RAPID RUNOFF INTO SOME OF THE DRY WASHES...
...A FEW THUNDERSTORMS WITH LARGE HAIL AND GUSTY WINDS...

HIGH PRESSURE CIRCULATION JUST SOUTHWEST OF THE BIG BEND REGION IN
TEXAS WILL CONTINUE TO PRODUCE A MOIST SOUTHERLY FLOW ACROSS ARIZONA
TODAY. LOOK FOR AN INCREASE IN SHOWERS AND THUNDERSTORMS BY LATE
MORNING...BECOMING MORE NUMEROUS DURING THE AFTERNOON. THE MAIN AREA
OF CONCERN FOR HEAVY RAIN RUNS ALONG AND SOUTH OF A LINE FROM
WINDOW ROCK TO FLAGSTAFF TO SELIGMAN. IN THIS AREA...SOME
THUNDERSTORMS WILL PRODUCE LOCALLY HEAVY RAIN...ON THE ORDER OF TWO
TO THREE INCHES IN A SHORT PERIOD OF TIME...ALONG WITH RAPID RUNOFF
INTO NORMALLY DRY WASHES. THUNDERSTORMS NORTH OF THE WINDOW ROCK TO
SELIGMAN LINE HAVE THE POTENTIAL TO PRODUCE RAINFALL AMOUNTS OF 1 TO
2 INCHES. SLOT CANYONS WILL ESPECIALLY BE PRONE TO FLOODING IF THE
CONDITIONS ARE RIGHT. EXPECT A FEW THUNDERSTORMS WITH LARGE HAIL AND
GUSTY WINDS BETWEEN 20 TO 40 MPH FROM SOME OF THE THUNDERSTORMS AS
WELL.