Area Forecast Discussion
Issued by NWS Flagstaff, AZ

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FXUS65 KFGZ 161647
AFDFGZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
945 AM MST TUE SEP 16 2014

.SYNOPSIS...EXPECT SCATTERED SHOWERS AND THUNDERSTORMS ALONG AND
SOUTH OF THE I-40 CORRIDOR TODAY...SOME STORMS WILL PRODUCE VERY
HEAVY RAIN. ISOLATED STORMS ARE EXPECTED NORTH OF I-40...WITH THE
LEAST COVERAGE NEAR THE UTAH BORDER. DEEP MOISTURE WILL CONTINUE TO
MOVE INTO THE AREA WEDNESDAY AND THURSDAY...WITH INCREASING AND
POTENTIALLY PROLONGED PRECIPITATION. A FLASH FLOOD WATCH IS IN
EFFECT FOR AREAS ALONG AND SOUTH OF I-40 ON BOTH OF THOSE DAYS.
SCATTERED SHOWERS AND THUNDERSTORMS WILL THEN CONTINUE THROUGH NEXT
WEEKEND AS MOISTURE LINGERS OVER THE REGION.

&&

.DISCUSSION...

SHORT TERM FORECAST IS IN GOOD SHAPE AND DISCUSSION BELOW COVERS WX
SITUATION WELL. LEADING EDGE OF THE CLOUD SHIELD IS ALONG A LINE
FROM GALLUP TO FLAGSTAFF TO PRESCOTT WITH CLEAR SKIES NORTHWARD.
RADARS SHOW A BAND OF STEADY PRECIP ACROSS SRN AZ INTO NEW MEXICO
NOW...THIS BAND SHOULD MOVE INTO THE SOUTH SIDE OF THE MOGOLLON RIM
LATER THIS AFTERNOON.

&&

.PREV DISCUSSION 335 AM...SHOWERS AND THUNDERSTORMS ALREADY BREAKING
OUT ALONG THE LEADING EDGE OF A DEEP MOISTURE GRADIENT APPROACHING
CENTRAL ARIZONA. THIS GRADIENT AND UPPER LEVEL DIVERGENCE AHEAD OF
ODILE WILL BE THE FOCUS FOR STRONGER CONVECTION TODAY...WHICH SHOULD
BE LOCATED ROUGHLY ALONG AND SOUTH OF THE I-40 CORRIDOR FOR OUR CWA.
BEHIND THIS GRADIENT...THERE IS CONSIDERABLE CLOUDINESS ASSOCIATED
WITH ODILE...AS WELL AS SOME MID-LEVEL WARMING AND SUBSIDENCE. THIS
MAY AFFECT OUR ABILITY TO GENERATE DEEP CONVECTION BY WEDNESDAY AND
THURSDAY...ALTHOUGH WIDESPREAD AND FREQUENT SHOWERS WILL STILL BE
OCCURRING.

CURRENT MODELS TRENDS AND OFFICIAL FORECASTS ARE MOVING EASTWARD
WITH ODILE...WITH THE PRECIPITATION SHIELD PRIMARILY AFFECTING SE
ARIZONA. IN ADDITION...THIS TRACK MAY GENERATE SIGNIFICANT EASTERLY
OR NORTHEAST WINDS ACROSS THE AREA...WHICH MAY IMPORT DRIER AIR FROM
THE NORTH. THE CURRENT FLASH FLOOD WATCH WILL NEED TO BE MONITORED
FOR THESE TRENDS...AS WELL AS THE POSSIBILITY FOR STRONG CONVECTION
TODAY...THAT IS WELL IN ADVANCE OF THE WATCH TIME FRAME.

AFTER ODILE EXITS THE SOUTHWEST LATER THURSDAY...MODELS ARE IN
DISAGREEMENT ON A NEW TROUGH DEVELOPING OVER THE SOUTHWEST BY NEXT
WEEKEND. THIS MAY OR MAY NOT DRAW DEEP MOISTURE BACK INTO THE AREA
WHERE IT WILL THEN INTERACT WITH COLDER TEMPERATURES ALOFT AND SOME
SHEAR. GFS DEPICTS THIS AS POSSIBLY A MORE SERIOUS SITUATION THAN
THE NEXT FEW DAYS...WHILE ECMWF TAKES THIS NEW LOW AND RETROGRADES
OUT TO SEA...AWAY FROM ARIZONA. TIME WILL TELL ON THIS AND WE HAVE
LEFT SCATTERED POPS IN THE FORECAST THROUGH NEXT WEEKEND UNTIL THE
SITUATION BECOMES A BIT MORE CLEAR.

&&

FOR THE 18Z PACKAGE...EXPECT AFTERNOON TSRA/SHRA PREDOMINANTLY OVER
HIGH TERRAIN LOCATIONS. SOME STORMS WILL BE CAPABLE OF PRODUCING
MVFR/IFR CIG/VSBY AND SOME SMALL HAIL. EXPECT INCREASING LIGHT-MDT
RAIN ACTIVITY FROM THIS EVENING ONWARD AS WELL AS SOME LOW VFR
CEILINGS. AVIATION DISCUSSION NOT UPDATED FOR AMENDMENTS.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...

FLASH FLOOD WATCH FROM 11 AM MST WEDNESDAY THROUGH 6 PM MST THURSDAY
FOR AZ PUBLIC ZONES 007-008-012>018-037-038.

&&

$$

PUBLIC.........DL / PETERSON
AVIATION.......AT

FOR NORTHERN ARIZONA WEATHER INFORMATION VISIT
WEATHER.GOV/FLAGSTAFF







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