Flash Flood Warning 11, NWS Flagstaff, AZ

NORTHERN ARIZONA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
230 PM MST TUE AUG 19 2003

.SYNOPSIS...HIGH PRESSURE ALOFT WILL REMAIN NEAR THE FOUR CORNERS
REGION THIS WEEK. THIS WILL RESULT IN A MORE SOUTHEASTERLY FLOW AND
AN INCREASE IN MOISTURE LASTING INTO THE WEEKEND. A WEATHER
DISTURBANCE WILL MOVE ACROSS YAVAPAI AND WESTERN COCONINO COUNTIES
TONIGHT CAUSING SCATTERED SHOWERS AND THUNDERSTORMS THROUGHOUT THE
NIGHT. FOR THE REST OF THE WEEK...EXPECT SCATTERED SHOWERS AND
THUNDERSTORMS...MAINLY DURING THE AFTERNOON AND EARLY EVENING HOURS.

.DISCUSSION...SATELLITE IMAGERY SHOWS THE CONVECTIVE VORTEX SOUTH OF
PHX FILLING IN WITH CONVECTION THIS AFTERNOON. REMNANT CLOUD COVER
FROM MORNING CONVECTION IS STILL INHIBITING CONVECTIVE DEVELOPMENT
OVER YAVAPAI COUNTY. NORTH OF THIS VORTEX...CONVECTION IS BREAKING
OUT ALONG THE MOGOLLON RIM AND OTHER HIGHER TERRAIN WHERE MORE
AFTERNOON HEATING WAS OCCURRING. 18Z FGZ SOUNDING INDICATED WEAK CAP
BETWEEN GULF SURGE/OUTFLOW BOUNDARY LOW-LEVEL AIRMASS AND REMNANT
MIXED LAYER FROM YESTERDAY. THIS WEAK CAP CAN BE EASILY BROKEN BY
ANY OUTFLOW BOUNDARIES FROM CONVECTION...THUS EXPECT CONVECTIVE
ACTIVITY TO LINGER INTO THE EVENING AS NEW THUNDERSTORMS DEVELOP
ALONG OUTFLOW BOUNDARIES. ADDITIONALLY...EXPECT CONVECTION TO LINGER
ALL NIGHT OVER YAVAPAI AND WESTERN COCONINO COUNTY AS THE CONVECTIVE
VORTEX SOUTH OF PHX MOVES NORTHWARD AROUND THE WESTERN EDGE OF THE
HIGH PRESSURE SYSTEM IN NM.

MODELS INDICATE THAT ONCE THIS VORTEX MOVES NORTHWARD THROUGH THE
FORECAST AREA...FLOW BECOMES SOUTHERLY AND WILL CONTINUE TO ALLOW
ANY MOISTURE AND DISTURBANCES FROM ADDITIONAL CONVECTIVE COMPLEXES
TO MOVE OVER THE AREA. GFS WEAKENS THE HIGH BY THE END OF THE WEEK
AND MOVES IT OVER THE STATE FOR A POSSIBLE SLOW DRYING TREND BY THE
WEEKEND. ECMWF MODEL INDICATES THE HIGH MOVING INTO THE MIDDLE
PORTION OF THE US. WILL CONTINUE MODERATE-GRADE MONSOON PATTERN
THROUGH THE FORECAST PERIOD UNTIL A MORE CONSOLIDATED SOLUTION
EMERGES. STAUDENMAIER

.CODED TEMPERATURES/POPS FOR SELECTED CITIES IN NORTHERN ARIZONA

CITY             TEMPERATURES LO/HI           PROBABILITY OF PRECIP
                 TON WED   THU     FRI        TON WED   THU     FRI
FLAGSTAFF        054/077 051/077 053/075      040 040 030 040 030 040
WINSLOW          064/089 062/088 063/087      030 030 030 030 020 030
PRESCOTT         063/084 061/084 063/084      050 040 030 040 030 040
PAGE             072/094 068/093 071/093      020 020 020 020 020 020
WINDOW ROCK      056/084 052/081 051/078      030 040 030 040 020 040
CANYON DE CHELLY 065/092 060/087 059/084      030 030 020 030 020 030
COTTONWOOD       072/095 069/095 071/095      040 030 030 040 020 030
GRAND CANYON     052/081 051/080 054/076      030 030 030 030 020 030
GREER            049/072 048/072 050/070      040 050 040 050 030 060
HEBER            055/082 053/082 055/080      030 040 040 040 030 040
JACOB LAKE       053/075 051/075 053/073      020 040 030 040 030 030
NAVAJO N.M.      058/083 057/081 056/078      020 030 030 030 020 030
PAYSON           067/088 062/088 064/088      030 040 030 040 030 040
SEDONA           068/093 067/092 069/092      030 040 030 040 020 030
SELIGMAN         062/087 060/087 062/087      030 030 030 030 020 030
SHOW LOW         057/082 059/082 061/080      040 040 040 040 030 040
ST. JOHNS        063/089 059/089 060/087      030 040 030 040 030 040
WUPATKI N.M.     068/091 063/090 064/089      030 030 030 030 020 030

AZZ004>018-037>040-200200-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
1000 AM MST TUE AUG 19 2003

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

.DAY ONE...TODAY

ADDITIONAL MOISTURE HAS MOVED INTO THE AREA FROM THUNDERSTORM ACTIVITY
TO THE SOUTH OVERNIGHT. AN AREA OF THUNDERSTORMS HAS ALREADY DEVELOPED
AROUND PHOENIX AND WILL MOVE NORTHWEST INTO SOUTHERN YAVAPAI COUNTY.
ADDITIONAL SHOWERS AND THUNDERSTORMS WILL DEVELOP THROUGHOUT THE
MORNING HOURS...ESPECIALLY ALONG THE MOGOLLON RIM AND LOCATIONS SOUTH
WHERE THE DEEPER MOISTURE RESIDES. A CIRCULATION CENTER OVER
SOUTHWEST ARIZONA WILL HELP TO ORGANIZE CONVECTION AND ENHANCE
THE SOUTHEASTERLY WIND FLOW OVER THE WESTERN PORTION OF THE FORECAST
AREA. THIS WILL RESULT IN STORM MOVEMENT GENERALLY TOWARD THE WEST. OVER
NORTHEASTERN PORTIONS OF THE FORECAST AREA...LIGHTER WINDS WILL RESULT IN
LITTLE STORM MOVEMENT. THE MAIN THREAT FROM THUNDERSTORMS TODAY WILL
BE HEAVY RAIN...ALONG WITH THE THREAT OF HAIL.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.
A MOIST AND UNSTABLE AIR MASS WILL REMAIN OVER ARIZONA RESULTING IN
A CHANCE OF SHOWERS AND THUNDERSTORMS EACH DAY.

.SPOTTER INFORMATION STATEMENT...

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

DEFINITION OF HAZARDOUS WEATHER...A WEATHER EVENT POSING A THREAT
TO LIFE AND PROPERTY.