Area Forecast Discussion
Issued by NWS Flagstaff, AZ

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000
FXUS65 KFGZ 211657
AFDFGZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
957 AM MST THU AUG 21 2014

.SYNOPSIS...
A LOW PRESSURE SYSTEM WILL MOVE ACROSS ARIZONA TODAY AND
TONIGHT...ENHANCING SHOWER AND THUNDERSTORM ACTIVITY. DRIER AIR
BEHIND THIS LOW WILL FILTER INTO ARIZONA ON FRIDAY AND SATURDAY WITH
A GRADUAL DOWN TURN IN STORM ACTIVITY FORECAST INTO THE WEEKEND.

&&

.UPDATE/DISCUSSION...
PRECIPITATION CHANCES WERE INCREASED FOR TODAY NORTHEAST OF THE
MOGOLLON RIM...WHERE THERE SHOULD BE SOMEWHAT OF A RAIN SHADOW
EFFECT AT LEAST INITIALLY BUT UPWARD MOTION ASSOCIATED WITH THE
APPROACHING LOW SHOULD PRODUCE SOME RAIN. OTHERWISE...SOME MINOR
CHANGES WERE MADE TO WINDS FOR TODAY.

EXPECT MOST AREAS TO RECEIVE RAIN AT LIGHT TO MODERATE RATES
TODAY/TONIGHT...THOUGH SOME LOCATIONS COULD RECEIVE HEAVY
PRECIPITATION ESPECIALLY AT THE LEADING EDGE OF THE DEVELOPING
RAIN SHIELD. LOCATIONS WHICH HAVE SEEN LARGE AMOUNTS OF RAIN IN
RECENT DAYS SHOULD BE ALERT FOR THE POSSIBILITY OF LOCALIZED
FLOODING THROUGH THIS EVENING.

&&

.PREVIOUS DISCUSSION /330 AM MST/...
THE UPPER LOW IS CENTERED NEAR SAN DIEGO THIS MORNING
WITH PLENTY OF MID AND UPPER LEVEL MOISTURE FLOWING NORTHWARD INTO
ARIZONA AHEAD OF THE SYSTEM. SHOWER AND THUNDERSTORM ACTIVITY SHOULD
DEVELOP LATER TODAY AS THE LOW APPROACHES...WITH LIFT INCREASING
OVER YAVAPAI AND COCONINO COUNTIES BY LATE AFTERNOON. THE LOW CENTER
IS THEN FORECAST TO SLOWLY WEAKEN AS IT PASSES THROUGH NORTHERN AZ
LATE TONIGHT THROUGH FRIDAY. AS THE COLD CORE OF THE LOW MOVES
THROUGH...SCATTERED SHOWERS AND THUNDERSTORMS ARE LIKELY TO CONTINUE
OVERNIGHT AND INTO FRIDAY MORNING FOR MOST AREAS...SHIFTING INTO
MAINLY EASTERN AZ BY FRIDAY AFTERNOON. OVERALL MOISTURE LEVELS WITH
THIS EVENT ARE LOWER THAN OUR OTHER RECENT HEAVY RAIN EVENTS...BUT
THERE WILL STILL BE A THREAT OF LOCALIZED HEAVY RAIN WHICH COULD
LEAD TO FLOODING...ESPECIALLY SINCE MANY AREAS ALREADY HAVE
SATURATED GROUND CONDITIONS.

SATURDAY INTO EARLY NEXT WEEK...TROUGHING OVER THE NORTHWESTERN U.S.
WILL BRING DRIER WESTERLY FLOW INTO NORTHERN ARIZONA. DEEPER
MOISTURE IS PUSHED SOUTH OF OUR AREA...SO THE CHANCE OF STORMS LOOKS
LOW AT THIS TIME...IN THE 10-30 PERCENT RANGE. HOWEVER...SOME OF
THIS MOISTURE COULD GET PULLED NORTHWARD AS THE TROUGH DIGS DOWN
TOWARD THE SOUTHWEST...SO RAIN CHANCES INCREASE A BIT AS WE HEAD
INTO NEXT WEEK.

&&

.AVIATION...
FOR THE 18Z PACKAGE...NUMEROUS SHOWERS AND THUNDERSTORMS WILL DEVELOP
FROM SOUTH TO NORTH OVER NORTHERN ARIZONA TODAY AND THIS
EVENING...WITH REDUCED VSBY IN TSRA AND ERRATIC OUTFLOW WIND GUSTS
TO 30 KTS AS THE PRIMARY IMPACTS. AFTER 04Z...SCATTERED TO
NUMEROUS STORMS WILL CONTINUE NORTH AND EAST OF THE MOGOLLON
RIM...WITH SCATTERED STORMS ELSEWHERE. AVIATION DISCUSSION NOT
UPDATED FOR AMENDMENTS.

&&

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

&&

$$

PUBLIC.........AT/JJ
AVIATION.......BAK

FOR NORTHERN ARIZONA WEATHER INFORMATION VISIT
WEATHER.GOV/FLAGSTAFF




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