Severe Thunderstorm Warning 1, NWS Flagstaff, AZ

NORTHERN ARIZONA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
250 PM MST SUN JUL 11 1999

SYNOPSIS...SHOWERS AND THUNDERSTORMS WITH LOCALLY HEAVY RAINFALL
WILL CONTINUE ACROSS MUCH OF NORTHERN ARIZONA INTO THE START OF THE
WORK WEEK. DRIER AIR WILL CONTINUE TO MOVE INTO NORTHEAST ARIZONA
TONIGHT AND MONDAY WHICH WILL DECREASE THE SHOWER ACTIVITY IN THIS
AREA. THE HIGH PRESSURE SYSTEM NEAR THE FOUR CORNERS AREA WILL MOVE
EASTWARD INTO NEW MEXICO BY MIDWEEK.  HOWEVER...THERE WILL BE
ENOUGH MOISTURE IN THE LOW LEVELS OF THE ATMOSPHERE FOR SCATTERED
SHOWERS AND THUNDERSTORMS TO CONTINUE THROUGH THE WEEK.

DISCUSSION...FORECAST FOCUS FOR TONIGHT CONTINUES TO BE LOCALLY
HEAVY RAINFALL IN WESTERN COCONINO COUNTY...YAVAPAI COUNTY AND THE
RIM AREA.  A TONGUE OF 1.5 TO 2.0 INCHES OF PRECIPITABLE WATER
STRETCHES FROM THE SOUTHWEST DESERT NORTHWARD TO THE GRAND CANYON
AREA. THIS COMBINED WITH WEAK VORT MAX AND 7H THETA RIDGE OVER
WESTERN THIRD OF FA IS PROVIDING FOCUS FOR LOCALLY HEAVY RAINFALL
OCCURRING TODAY. HAVE ISSUED FFW FOR SUPAI VILLAGE WITH 0.75 INCHES
IN 30 MINUTES AT GCN AND REPORTS OF FLOW COMING UP RAPIDLY IN
CATARACT CREEK. ONLY SUBTLE CHANGES EXPECTED NEXT TWO
DAYS...PRIMARILY DRY AIR MOVING INTO NE SECTION OF FA...BUT HIGH
THETA AIR REMAINS ENTRENCHED OVER WESTERN THIRD OF FA. ABUNDANT
MOISTURE REMAINS FOR SCATTERED TO LIKELY POPS OVER MOST OF THE
FA...WITH THE EXCEPTION OF FAR NE.

EXTENDED...FOUR CORNERS HIGH MOVES EASTWARD MIDWEEK WITH MRF
SHOWING HINT AT SOUTH TO SOUTHWEST FLOW DEVELOPING. HOWEVER...AS
NEARBY OFFICES MENTIONED IN BLAST-UP COORD CALL...WILL HAVE TO
WATCH INVERTED TROF OVER BIG BEND AREA MOVING INTO THE STATE AROUND
WED TIME FRAME.  FOR NOW...CONFIDENCE NOT HIGH ENOUGH TO INTRODUCE
ANY DRYING TREND...SO WILL GO WITH CONTINUED CHANCE SHOWERS/TSTORMS
THROUGH THE PERIOD.

TW

.FLG...FLASH FLOOD WATCH UNTIL 600 PM MST FOR ZONES
       4/6/7/8/15/37/38.  SEE FLASH FLOOD WATCH STATEMENT FOR
       SPECIFIC DETAILS.