Flood in Arizona, July 25, 2002

NORTHERN ARIZONA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
900 AM MST THU JUL 25 2002

.SYNOPSIS...WESTERLY FLOW ALOFT WILL DEVELOP 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...CURRENT FORECAST IN GOOD SHAPE WITH NO UPDATES.
MID-LEVEL TROUGH WAS MOVING OVER THE GREAT BASIN THIS MORNING WITH
THE SUBTROPICAL RIDGE SHIFTING SOUTHWARD. TROUGH WILL THEN REMAIN
OVER THE GREAT BASIN THROUGH AT LEAST SATURDAY. AS A RESULT...DEEP
WESTERLY FLOW (5 TO 10 KNOTS THROUGH A DEEP LAYER) WAS BEING
OBSERVED OVER NORTHERN ARIZONA. IN RESPONSE...DRY AIR WAS BEING
ADVECTED ACROSS THE AREA ABOVE THE 500 MB LEVEL. BELOW THE 500 MB
LEVEL MOISTURE WILL BE SLOW TO BUDGE. DEEP LOW-LEVEL MOISTURE
EXTENDS WELL TO THE WEST INTO NEVADA AND CALIFORNIA. THINK NORTHERN
ARIZONA WILL SEE ANOTHER ACTIVE DAY TODAY. LOOKS LIKE THE MAIN
THREAT WILL BE HEAVY RAIN PRODUCING STORMS SINCE CELL MOVEMENT WILL
BE SLOW (WEAK FLOW ALOFT) AND FLOW FAVORS TRAINING OF CELLS OVER THE
TERRAIN. ON FRIDAY...WESTERLY FLOW CONTINUES TO SLOWLY DRY THINGS
OUT. SHOULD BE A DOWNTURN IN ACTIVITY AS VERTICAL MIXING BEGINS TO
DRY THINGS FURTHER IN THE BOUNDARY LAYER. 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 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 THE WESTERN
TWO-THIRDS OF THE CWA BUT OVER THE EAST STICK WITH 40 TO 50 POPS.

MCCOLLUM

.FGZ...NONE

.CODED TEMPERATURES/POPS FOR SELECTED CITIES IN NORTHERN ARIZONA

CITY             TEMPERATURES HI/LO           PROBABILITY OF PRECIP
                 TDY TON   FRI     SAT        TDY TON   FRI   SAT
FLAGSTAFF        078/056 080/052 080/050      050 020 040 020 020 020
WINSLOW          089/066 090/060 091/058      050 030 030 020 020 020
PRESCOTT         086/064 089/062 090/060      040 020 020 020 020 020
PAGE             092/072 096/071 096/069      050 020 020 000 000 000
WINDOW ROCK      080/055 080/054 082/052      060 040 050 040 030 030
CANYON DE CHELLY 086/061 086/060 088/058      050 030 040 030 020 020
COTTONWOOD       097/072 100/070 101/068      030 020 020 020 020 020
GRAND CANYON     080/055 082/051 082/049      040 020 030 020 020 020
GREER            074/052 076/048 076/046      080 040 070 040 040 040
HEBER            083/057 085/053 085/051      070 030 060 030 030 030
JACOB LAKE       076/056 078/052 078/050      040 020 030 020 020 020
NAVAJO N.M.      080/059 080/058 082/056      050 030 040 030 020 020
PAYSON           091/065 094/063 095/061      040 020 020 020 020 020
SEDONA           095/070 098/068 099/066      030 020 020 020 020 020
SELIGMAN         089/057 092/055 093/053      030 010 010 010 010 010
SHOW LOW         084/064 086/060 086/058      050 030 040 030 020 020
ST. JOHNS        083/061 084/055 085/053      070 040 040 030 030 030
WUPATKI N.M.     091/069 092/063 093/061      060 030 030 020 020 020

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.