Flood in Arizona, July 25, 2002

NORTHERN ARIZONA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
230 PM MST THU JUL 25 2002

.SYNOPSIS...WESTERLY FLOW ALOFT WILL REMAIN ACROSS NORTHERN ARIZONA
OVER THE NEXT FEW DAYS. THIS WILL BRING A DRIER AIR MASS TO THE
REGION. LOOK FOR A DOWN TREND IN THE DAILY SHOWERS AND THUNDERSTORMS
ACTIVITY THROUGH THE WEEKEND.

.DISCUSSION...MID-LEVEL TROUGH WAS LOCATED OVER THE GREAT BASIN THIS
AFTERNOON WITH THE SUBTROPICAL RIDGE SHIFTED SOUTHWARD. TROUGH WILL
REMAIN OVER THE GREAT BASIN THROUGH AT LEAST SUNDAY. AS A
RESULT...DEEP WESTERLY FLOW WILL REMAIN OVER NORTHERN ARIZONA. IN
RESPONSE...DRY AIR AND A MID-LEVEL WARM CAP WAS BEING ADVECTED
ACROSS NORTHERN ARIZONA ABOVE THE 600 MB LEVEL. BELOW THE 600 MB
LEVEL MOISTURE WILL BE SLOW TO BUDGE. VERTICAL MIXING WILL BE SLOW
TO PENETRATE THE CAP ALOFT (THE VERY DRY AIR IS ABOVE THE CAP) AND
DEEP MOISTURE REMAINS IN THE BOUNDARY LAYER TO THE WEST. AS A
RESULT..ON FRIDAY...EVEN THOUGH WESTERLY FLOW WILL CONTINUE TO
STABILIZE THINGS THERE WILL BE THUNDERSTORMS AROUND. LOOKING AT 20
POPS OVER THE FAR WESTERN COUNTY WARNING AREA (CWA) ON FRIDAY WITH
50 POPS NEAR THE NEW MEXICO BORDER. WESTERLY FLOW CONTINUES INTO
SATURDAY WITH FURTHER SLOW DRYING. THERE IS SOME UNCERTAINTY BETWEEN
MODELS AS TO HOW MUCH DRYING. THE AVN IS VERY DRY WITH NO STORMS
OVER THE WESTERN THIRD OF THE CWA BUT THE ETA KEEPS THINGS MORE
MOIST. AS A RESULT...WILL GO WITH ISOLATED TO LOW SCATTERED POPS
OVER MUCH OF THE WESTERN TWO-THIRDS OF THE CWA BUT OVER THE FAR EAST
STICK WITH 40 TO 50 POPS. HAVE DECIDED TO TAKE ALL POPS OUT OF AREAS
SUCH AS THE GRAND CANYON...KAIBAB PLATEAU...COCONINO
PLATEAU...MARBLE CANYON ON SATURDAY AND SUNDAY. SUNDAY SHOULD SEE SOME
FURTHER STABILIZATION BUT IT WILL NOT COMPLETELY DRY OUT WITH A
STRONG MOISTURE GRADIENT LINGERING OVER SOUTHERN ARIZONA AND
NORTHERN MEXICO.

IN THE EXTENDED...FOR THE PERIOD MONDAY THROUGH WEDNESDAY THE
SUBTROPICAL RIDGE EXPANDS NORTHWARD. MONSOON MOISTURE WILL BE LURKING
OVER THE SOUTHERN PORTIONS OF ARIZONA AND EXPECT MOISTURE WILL
RAPIDLY MOVE NORTHWARD WITH THE NORTHWARD SHIFT OF THE SUBTROPICAL
RIDGE. WILL BROAD BRUSH THE EXTENDED WITH PARTLY CLOUDY WITH A
CHANCE OF SHOWERS AND THUNDERSTORMS.

MCCOLLUM

.FGZ...NONE

.CODED TEMPERATURES/POPS FOR SELECTED CITIES IN NORTHERN ARIZONA

CITY             TEMPERATURES LO/HI           PROBABILITY OF PRECIP
                 TON FRI   SAT     SUN        TON FRI   SAT     SUN
FLAGSTAFF        053/081 053/081 050/081      020 040 020 030 020 020
WINSLOW          066/091 064/093 061/093      020 020 020 020 020 020
PRESCOTT         064/088 062/090 059/090      020 020 020 020 020 020
PAGE             072/094 071/096 068/096      020 020 020 000 000 000
WINDOW ROCK      059/084 057/086 054/086      030 050 030 030 020 030
CANYON DE CHELLY 065/090 063/092 060/092      020 040 020 020 020 020
COTTONWOOD       072/099 070/101 067/101      020 020 020 020 020 020
GRAND CANYON     052/083 052/083 049/083      020 030 020 000 000 000
GREER            049/077 049/077 046/077      040 060 040 050 030 040
HEBER            054/086 054/086 051/086      030 050 030 040 030 030
JACOB LAKE       053/079 053/079 050/079      020 030 020 000 000 000
NAVAJO N.M.      063/084 061/086 058/086      020 040 020 020 020 020
PAYSON           065/093 063/095 060/095      020 020 020 020 020 020
SEDONA           070/097 068/099 065/099      020 020 020 020 020 020
SELIGMAN         057/091 055/093 052/093      010 010 010 010 010 010
SHOW LOW         061/087 061/087 058/087      020 040 020 030 020 020
ST. JOHNS        061/085 059/087 056/087      030 030 030 030 030 030
WUPATKI N.M.     069/093 067/095 064/095      020 020 020 020 020 020

AZZ004>018-037>040-251930-
HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
945 AM MST THU JUL 25 2002

...SCATTERED SHOWERS AND THUNDERSTORMS TODAY OVER PORTIONS OF
ARIZONA. SOME STORMS MAY PRODUCE HEAVY RAINFALL...

DISCUSSION...TROPICAL MOISTURE WILL REMAIN ACROSS NORTHERN
ARIZONA TODAY WITH A CHANCE OF THUNDERSTORMS ACROSS ALL OF
NORTHERN ARIZONA. THE DEEPEST MOISTURE
WILL BE LOCATED ALONG AND SOUTH OF THE MOGOLLON RIM. AS A
RESULT...THE STRONGEST
STORMS WILL BE LOCATED FROM THE GRAND CANYON...MOGOLLON RIM AND
WHITE MOUNTAINS SOUTHWARD...ESPECIALLY OVER YAVAPAI AND
NORTHERN GILA COUNTIES.

LIGHT WESTERLY FLOW ALOFT WILL RESULT IN SLOW MOVING THUNDERSTORMS
WHICH WILL INCREASE THE CHANCE OF HEAVY RAINFALL ACCUMULATIONS IN
SOME AREAS. THIS WILL BE ESPECIALLY TRUE FROM THE MOGOLLON RIM
SOUTHWARD WHERE THUNDERSTORMS CELLS ARE EXPECTED TO REDEVLOP OVER THE
SAME AREAS.

BURNED AREA RAIN OUTLOOK...
SMALL AMOUNTS OF RAIN CAN CAUSE FLASH FLOODING IN BURNED OUT AREAS.

CHEDISKI-RODEO BURN AREA...NUMEROUS SHOWERS AND THUNDERSTORMS
ARE EXPECTED THIS AFTERNOON AND EVENING. SOME STORMS WILL
PRODUCE RAINFALL AMOUNTS APPROACHING TWO INCHES.

INDIAN BURN AREA...NUMEROUS SHOWERS AND THUNDERSTORMS ARE
EXPECTED THIS AFTERNOON AND EARLY EVENING. SOME STORMS WILL
PRODUCE RAINFALL AMOUNTS APPROACHING ONE INCH.