615
FXUS65 KPSR 161121
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
420 AM MST WED OCT 16 2013
...UPDATED AVIATION...
.SYNOPSIS...
DRY CONDITIONS WILL CONTINUE INTO NEXT WEEK WITH CLEAR SKIES AND
AT OR JUST BELOW NORMAL TEMPERATURES. A FEW WEAK WEATHER
DISTURBANCES WILL PASS THROUGH THE REGION LEADING TO BREEZY TO WINDY
CONDITIONS AT TIMES...MAINLY OVER SOUTHEAST CALIFORNIA AND FAR
WESTERN ARIZONA.
&&
.DISCUSSION...
TODAY...LATEST BATCH OF SHORTWAVE ENERGY ALONG THE MEAN TROUGH
BASE...THAT STRETCHES FROM THE GREAT LAKES INTO THE SOUTHWEST...IS
MOVING THROUGH SOUTHERN UT/NORTHERN AZ PER WV IMAGERY. WEAK AND
SUBTLE COOL FRONT ASSOCIATED WITH THIS SHORTWAVE BROUGHT SOME SLIGHT
DRYING TO SURFACE DEWPOINTS LAST NIGHT AND THIS MORNING...WITH MANY
LOWER DESERT SITES OBSERVING VALUES 3 TO 7 DEGREES DRIER THAN THIS
TIME TUESDAY.
SLIGHTLY ELEVATED NORTHERLY BREEZES LINGER ALONG THE COLORADO RIVER
VALLEY AND WILL CONTINUE INTO THE MIDDAY HOURS TODAY WHILE THE
SHORTWAVE AND ASSOCIATED JET STREAK MOVE INTO NM/CO. TUESDAY EVENING
RAOBS FROM OUR NORTHERN NEIGHBORS SHOW 10C COOLING JUST ABOVE 700MB
FOR KVEF OR LAS VEGAS AND 7C OR SO ABOVE 600MB FOR KFGZ OR
FLAGSTAFF. EFFECTS OF THAT COOLING WILL NOT RESULT IN NOTICEABLE
CHANGES TO OUR DAYTIME TEMPS FURTHER SOUTH...WITH ANOTHER DAY OF
WIDESPREAD 80S EXPECTED FOR PHOENIX...YUMA...GILA BEND AND EL
CENTRO. MORNINGS WILL CONTINUE TO BE ON THE COOL SIDE AND BELOW
MID-OCTOBER NORMALS.
THURSDAY THROUGH THE LATE WEEKEND...ADDITIONAL SHORTWAVE ENERGY WILL
CONTINUE TO DROP OUT OF THE CANADIAN PROVINCES...WITH A WEAK WAVE
BRUSHING WELL TO OUR NORTH THURSDAY...AND ANOTHER SLIGHTLY STRONGER
TRAILING WAVE INTO ARIZONA FOR FRIDAY. ANOTHER ROUND OF ELEVATED
NORTHERLY BREEZES POSSIBLE FROM BULLHEAD CITY THROUGH YUMA DURING
THE DAY FRIDAY WITH ISOLATED GUSTS OF 20 MPH POSSIBLE. EACH OF THESE
SHORTWAVE FEATURES REMAIN DRY...WITH AREA PWATS TO REMAIN 0.30
INCHES OR DRIER THROUGH THE PERIOD. BULK OF THE COOLER AIR
ASSOCIATED WITH THESE FEATURES WILL REMAIN NORTH AND EAST OF OUR
AREA...RESULTING IN A PERSISTENCE FORECAST OF STILL BELOW NORMAL
TEMPERATURES ACROSS SOUTH CENTRAL ARIZONA AND READINGS POSSIBLY A
FEW DEGREES WARMER ACROSS SOUTHWEST ARIZONA AND SOUTHEAST
CALIFORNIA.
EARLY NEXT WEEK AND BEYOND...LARGE AREA OF MILD PACIFIC RIDGING HELD
AT BAY BY LONGWAVE TROUGHING OVER MUCH OF THE WEST WILL SLOWLY BEGIN
TO SLIDE ON-SHORE MONDAY AND INTO NEXT WEEK. OUR DRY FALL PATTERN
WILL CONTINUE...WITH POTENTIAL TO SEE A FEW DEGREES OF WARMING OVER
OUR RECENT COOL SPELL OF BELOW NORMAL TEMPERATURES. MEDIUM RANGE
MODELS STILL DIVERGE ON THE SCALE OF THE WARMING...WITH LATEST ECMWF
PAINTING READINGS IN THE LOW 90S FOR THE WARMER DESERT LOCALES.
LATEST GFS GUIDANCE HAS A MUCH COOLER SOLUTION IN THE LOW 80S FOR
TUESDAY AND BEYOND. WENT WITH A NEAR OR JUST ABOVE CLIMO FORECAST
FOR EARLY NEXT WEEK WHICH ESSENTIALLY SPLITS THE FORECAST MODEL
DIFFERENCES.
&&
.AVIATION...
SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA AND KSDL...
CLEAR SKIES WILL CONTINUE THROUGH THURSDAY MORNING. SFC WINDS WILL
STAY BELOW 8KT AND GENERALLY FOLLOW TYPICAL DIURNAL TRENDS. GIVEN
THE WEAK PRESSURE GRADIENT...PERIODS OF LIGHT AND VARIABLE OR CALM
WINDS CAN BE EXPECTED.
SOUTHEAST CA AND SOUTHWEST AZ...INCLUDING KIPL AND KBLH...
A FEW NORTHERLY SFC WIND GUSTS UP TO 20 KT WILL BE POSSIBLE AT KBLH
LATE THIS MORNING/EARLY AFTERNOON...HOWEVER A WEAKENING PRESSURE
GRADIENT WILL ALLOW SPEEDS TO DECREASE MARKEDLY BY LATE THIS
AFTERNOON. OTHERWISE...CLEAR SKIES AND NO AVIATION IMPACTS THROUGH
THURSDAY MORNING.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
FRIDAY THROUGH TUESDAY...
A WEAK TROUGH WILL MOVE THROUGH THE AREA ON FRIDAY...BRINGING
AFTERNOON BREEZINESS DOWN THE COLORADO RIVER...ALONG WITH LOWER
HUMIDITIES. LOOKS LIKE WINDS WILL BE WELL SHORT OF CRITICAL
THRESHOLDS HOWEVER AND NO HEADLINES APPEAR NECESSARY AT THIS POINT.
OTHERWISE WEAK HIGH PRESSURE WILL SETTLE OVER THE AREA ON SATURDAY
AND REMAIN IN PLACE THROUGH EARLY NEXT WEEK. THROUGH THE
PERIOD...AFTERNOON HUMIDITY VALUES WILL FALL INTO THE SINGLE DIGITS
AND TEENS...WITH FAIR TO GOOD OVERNIGHT RECOVERY.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...NOLTE
AVIATION....MO
FIRE WEATHER...LEINS/MO