FXUS65 KFGZ 300406
AFDFGZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
905 PM MST THU JUL 29 2010

.SYNOPSIS...AN EXTREMELY MOIST SOUTHEASTERLY FLOW WILL CONTINUE TO 
BRING SHOWERS AND THUNDERSTORMS TO THE AREA...PRIMARILY DURING THE 
AFTERNOON AND EVENING HOURS. LOCALLY HEAVY RAINFALL AND THE 
POSSIBILITY OF FLASH FLOODING WILL CONTINUE FOR THE NEXT SEVERAL 
DAYS.

&&
.DISCUSSION...A LINE OF SHOWERS AND THUNDERSTORMS IS MOVING EAST TO 
WEST ACROSS APACHE AND NAVAJO COUNTIES THIS EVENING. SOME AREAS 
NORTH AND SOUTH OF HOLBROOK RECEIVED 2-3 INCHES OF RAIN IN A HOUR 
WITH THESE STORMS. A FLASH FLOOD WARNING WAS ISSUED FOR THIS AREA. 
RAINFALL RATES AND COVERAGE OF VERY HEAVY RAINFALL AS DECREASED SOME. 
HOWEVER...SOME STORMS COULD STILL PRODUCE LOCALIZED FLOODING THIS 
EVENING AND OVERNIGHT. WILL UPDATE GRIDDED FORECAST AFTER 06Z FOR 
THESE STORMS. NO CHANGES NEED AFTER TONIGHT. 

&&

.PREV DISCUSSION /230 PM MST/...HIGH PRESSURE WILL REMAIN OVER THE 
SOUTHERN THIRD OF THE UNITED STATES OUT AS FAR AS THE EYE CAN SEE. 
THE POSITION OF THE HIGH WILL PLACE SOUTHEASTERLY FLOW ACROSS 
ARIZONA WHICH WILL LEAVE THE DOOR OPEN TO A VERY MOIST AIR MASS WITH 
ORIGINS FROM OVER THE GULF OF CALIFORNIA. PRECIPITABLE WATER VALUES 
WILL CONTINUE TO RANGE FROM 1 INCH OVER FAR NORTHEAST ARIZONA TO 
NEARLY 2 INCHES SOUTH OF THE MOGOLLON RIM EXTENDING INTO THE LOWER 
DESERT. 

FOR TONIGHT...ISOLATED TO SCATTERED STORMS WILL CONTINUE..MAINLY 
DRIVEN BY THUNDERSTORM OUTFLOW. THE MAIN OUTFLOW PUSH LOOKS TO BE 
FROM STORMS OVER NEW MEXICO WHICH WOULD IMPACT NORTHEAST AND EAST 
CENTRAL ARIZONA THIS EVENING. ANY STORMS WILL BE CAPABLE OF 
PRODUCING EXTREMELY HEAVY RAINFALL. STORMS AND SHOWERS WILL 
GRADUALLY DIMINISH OVERNIGHT HEADING INTO EARLY FRIDAY. 

FOR FRIDAY THROUGH SUNDAY...A LOW PRESSURE SYSTEM ALOFT...NOW OVER 
NEW MEXICO...WILL HAVE IT'S PRIMARY AFFECT ON NORTHERN ARIZONA FROM 
FRIDAY INTO SUNDAY. IN ANY EVENT...THE HIGH PRECIPITABLE WATER 
VALUES OVER NORTHERN ARIZONA ENSURE THAT HEAVY RAIN PRODUCING 
THUNDERSTORMS AND LOCALIZED FLASH FLOODING WILL REMAIN A THREAT 
THROUGH THE WEEKEND. THE GREATEST THREAT FOR FLASH FLOODING APPEARS 
TO BE ON FRIDAY OR SATURDAY WITH THE PASSAGE OF THE MID-LEVEL LOW 
PRESSURE CIRCULATION. THE FLOW ALOFT COULD BECOME BETTER SUITED FOR 
THE DEVELOPMENT OF ORGANIZED STORMS DURING THIS PERIOD IN ADDITION 
TO INCREASED UPWARD LIFT AND A MORE UNSTABLE AIR MASS.   

MONDAY INTO NEXT WEEK...MODELS FAIRLY CONSISTENT IN SOME DRYING OF 
THE AIR MASS ACROSS NORTHERN ARIZONA. HOWEVER...THE CURRENT MODEL 
RUNS ALSO SUGGEST...EVEN WITH DRYING...THAT AMPLE MOISTURE WILL 
REMAIN FOR A CHANCE OF THUNDERSTORMS EACH DAY. NO REAL BREAK IN 
MONSOON ACTIVITY IS ANTICIPATED AT THIS TIME.

&&

.AVIATION...FOR THE 06Z PACKAGE...A LINE OF SHOWERS AND 
THUNDERSTORMS WILL CONTINUE TO MOVE WEST THROUGH KINW AND 40NM NORTH 
AND SOUTH THROUGH 08Z. HEAVY RAINFALL WITH MVFR VISIBILITIES AND 
CEILINGS CAN BE EXPECTED IN THIS LINE. SURFACE WINDS MAY BECOME 
ERRATIC AND GUSTY IN AND AROUND THE STRONGER STORMS. SHOWERS AND 
THUNDERSTORMS WILL REDEVELOP AROUND 17-18Z FRIDAY. AVIATION 
DISCUSSION NOT UPDATED FOR AMENDMENTS.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...NONE.

$$

PUBLIC.......MCCOLLUM/MAS
AVIATION.....MAS

VISIT WEATHER.GOV/FLAGSTAFF FOR NORTHERN ARIZONA WEATHER INFORMATION.