Area Forecast Discussion
Issued by NWS Phoenix, AZ

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FXUS65 KPSR 221659
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
956 AM MST FRI AUG 22 2014

.SYNOPSIS...
LOW PRESSURE WILL CONTINUE TO MOVE THROUGH THE AREA TODAY...HOWEVER
ONLY A FEW ISOLATED SHOWERS ARE EXPECTED ACROSS THE REGION. DRIER
CONDITIONS ARE EXPECTED THROUGH THE WEEKEND ALONG WITH SLIGHTLY
COOLER THAN NORMAL TEMPERATURES. A RETURN TO A MORE TYPICAL MONSOON
PATTERN IS EXPECTED EARLY NEXT WEEK...WITH AFTERNOON AND EVENING
SHOWERS AND THUNDERSTORMS RETURNING TO THE REGION.

&&

.DISCUSSION...
SATELLITE IMAGERY SHOWS SOME MID-LEVEL CUMULUS DEVELOPMENT OVER THE
EASTERN HALF OF ARIZONA THIS MORNING...THE ENHANCEMENT OF THE CLOUDS
DUE TO THE POSITION OF THE 700-500MB TROUGH AXIS OF THE UPPER LEVEL
LOW MOVING ACROSS THIS STATE. SURFACE CONDITIONS CWA-WIDE REMAIN
COOL AND MOIST FOR THE MOST...CURRENT TEMPERATURES ARE BALMY...IN
THE 70S WITH DEW POINTS HOVERING IN THE 60S.

THE MOISTURE WILL NOT LINGER LONG OVER OUR FORECAST AREA AS A DRIER
WEST-NORTHWESTERLY FLOW ALOFT WILL SET UP BEHIND THE DEPARTING
TROUGH AND EFFECTIVELY SHUNT MONSOON MOISTURE EASTWARD INTO NEW
MEXICO FOR THE WEEKEND. FOR TODAY...THE BOUNDARY LAYER WILL RETAIN
ITS MOIST CHARACTERISTICS...HOWEVER THE LACK OF UPPER LEVEL SUPPORT
OVER SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA SHOULD KEEP SHOWER
AND THUNDERSTORM DEVELOPMENT CONFINED INTO THE HIGHER TERRAIN AND
MOUNTAINS NORTH/EAST OF PHOENIX THIS AFTERNOON. ENTIRELY POSSIBLE TO
GET A FEW ISOLATED THUNDERSTORMS OVER THE LOWER CENTRAL DESERTS...
BUT ONCE WE LOSE THE PEAK INSOLATION/HEATING OF THE DAY...STORMS
WILL QUICKLY DISSIPATE. HOLISTICALLY...MUCH OF THE SAME IS EXPECTED
FOR SATURDAY AND SUNDAY AS LOW LEVEL MIXING RATIOS BOTTOM OUT AROUND
5-6 G/KG. DAYTIME TEMPERATURES WILL CONTINUE TO BE BELOW NORMAL AS
WE END THE WEEK...HOLDING IN THE MID TO UPPER 90S OVER THE LOWER
DESERTS THIS AFTERNOON...BARLEY BREAKING THE 100 DEGREE MARK
SATURDAY...AND A FEW MORE DEGREES OF WARMING FOR SUNDAY.

NEXT WEEK WILL SEE A RETURN TO A MORE TYPICAL MONSOON SETUP AS HIGH
PRESSURE SLIDES EAST AND LOW LEVEL WINDS TURN AROUND OUT OF THE
SOUTHEAST. WHILE THERE ARE SOME DIFFERENCES IN THE MODELS REGARDING
A TROUGH MOVING THROUGH UTAH BY THE MIDDLE OF NEXT WEEK...BOTH THE
GFS AND EUROPEAN...AS WELL AS THE 12Z NAEFS INDICATE A NOTEWORTHY
INCREASE IN MOISTURE ACROSS THE AREA MONDAY/TUESDAY NEXT WEEK. THIS
COULD BE THE RESULT OF THE PASSAGE OF A TROPICAL SYSTEM WELL SOUTH
OF THE GULF OF CALIFORNIA...OR IT COULD SIMPLY BE OUTFLOW DRIVEN
FROM CONVECTION OVER SONORA. REGARDLESS...MIXING RATIOS EXPECTED TO
RETURN TO THE 10-12 G/KG RANGE EARLY NEXT WEEK WHICH SHOULD SET THE
STAGE FOR AFTERNOON SHOWERS AND THUNDERSTORMS EACH DAY THROUGH AT
LEAST FRIDAY. TOUGH TO PICK OUT ONE ACTIVE DAY OVER ANOTHER...BUT
POPS HAVE BEEN NUDGED TOWARD CLIMO /AND SLIGHTLY HIGHER EAST OF
PHOENIX/ FROM TUESDAY THROUGH FRIDAY.

&&

.AVIATION...
SOUTH-CENTRAL AND SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA
INCLUDING KPHX...KIWA...KSDL...KIPL...AND KBLH...
A WEAKENING UPPER LOW WAS CENTERED JUST WEST OF PHX AT 12Z AND WILL
CONTINUE SHIFTING EAST DURING THE DAY WITH FURTHER WEAKENING.
ANTICIPATE FEW-SCT BASES AT 8-10 KFT MSL...BECOMING SCT-BKN BY
MIDDAY OVER HIGHER TERRAIN NEAR AND EAST OF PHOENIX METRO. A STRAY
SHOWER CANNOT BE RULED OUT OVER SOUTH-CENTRAL ARIZONA INCLUDING
PHOENIX AREA...MORE LIKELY FURTHER EAST...BUT PROBABILITY TOO LOW TO
REFLECT IN TAFS. EXPECT CLEAR SKIES THIS EVENING AS THE SYSTEM
SHIFTS INTO NEW MEXICO AND WEAKENS EVEN FURTHER. SURFACE WINDS OVER
PHOENIX AREA WILL FAVOR EAST AND SOUTHEAST DIRECTIONS THIS MORNING
BEFORE TRANSITIONING TO WESTERLY AROUND MIDDAY. SURFACE WINDS OVER
SOUTHWEST AZ AND SOUTHEAST CA WILL HOLD ON TO SOUTHERLY COMPONENT
LONGER BEFORE TRENDING TOWARD SOUTHWEST AND WEST THIS
EVENING...LOCAL GUSTS TO 20 KTS THIS EVENING IMPERIAL VALLEY.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
SUNDAY THROUGH THURSDAY...
HUMIDITIES WILL TREND UPWARD MONDAY AND TUESDAY BEFORE STARTING TO
TREND DOWNWARD THURSDAY. OVERNIGHT RECOVERY WILL REMAIN GOOD THROUGH
THE WEEK. STORM CHANCES WILL REMAIN SLIGHT AND FAVOR THE HIGHER
TERRAIN OF SOUTH-CENTRAL ARIZONA HOWEVER THEY WILL EXPAND SLOWLY
WESTWARD TO NEAR THE LOWER COLORADO RIVER VALLEY BY WEDNESDAY.
HAINES INDEX VALUES PEAK AT 5 OVER PORTIONS OF SOUTHEAST CALIFORNIA
AND SOUTHWEST ARIZONA SUNDAY AND MONDAY BEFORE TRENDING DOWNWARD.
EXPECT LOWER VALUES OVER SOUTH-CENTRAL ARIZONA DUE TO BETTER
ATMOSPHERIC MOISTURE CONTENT.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...MEYERS/LEINS
AVIATION...AJ
FIRE WEATHER...AJ




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