Area Forecast Discussion
Issued by NWS Phoenix, AZ

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
064
FXUS65 KPSR 100357 AAA
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
900 PM MST TUE FEB 9 2016

.UPDATE... UPDATED AVIATION SECTION.

.SYNOPSIS...
HIGH PRESSURE WILL REMAIN THE DOMINANT WEATHER FEATURE OVER THE
SOUTHWESTERN UNITED STATES THIS WEEK. THIS WILL RESULT IN A
PROLONGED PERIOD OF SUNNY SKIES...MUCH ABOVE NORMAL
TEMPERATURES...RELATIVELY LIGHT WINDS...AND LOW HUMIDITY VALUES.

&&

.DISCUSSION... ANOTHER VERY MILD EVENING FOR THIS TIME OF YEAR
ACROSS THE REGION...AS VERY STRONG RIDGING ALOFT ALLOWED HIGHS
ACROSS THE LOWER DESERTS TO RISE WELL UP INTO THE 80S. PHOENIX SKY
HARBOR REACHED 86...WHICH BROKE THE PREVIOUS RECORD BY 2 DEGREES.
TEMPERATURES AT THIS HOUR ARE ACTUALLY RUNNING 1-3 DEGREES WARMER
THAN WHAT WE SAW AT THIS TIME YESTERDAY. GIVEN THESE WARMER
TEMPERATURES AND THE LOWS WE SAW LAST NIGHT...DECIDED TO RAISE OUR
OVERNIGHT LOWS TONIGHT A BIT. OUTSIDE OF THESE WARMER
LOWS...INHERITED FORECASTS/TRENDS ARE HOLDING UP WELL...AND NO OTHER
UPDATES ARE PLANNED.

&&

.PREVIOUS DISCUSSION... QUASI-BLOCKED HIGH AMPLITUDE FLOW REMAINS
ENTRENCHED ACROSS THE WRN HEMISPHERE WITH RIDGING EXTENDING ALONG
THE WEST COAST OF NORTH AMERICA WHILE DEEP TROUGHING ENVELOPES ERN
CONUS. UNUSUALLY HIGH HEIGHTS ALOFT (H5 HEIGHTS 2-3 NORMALIZED
STANDARD DEVIATIONS ABOVE AVERAGE) AND 12Z KTWC SOUNDING SAMPLED H8
AND H7 TEMPERATURES ABOVE THE 90TH PERCENTILE (APPROACHING OR
SLIGHTLY EXCEEDING DAILY RECORDS) HAVE RESULTED IN NEAR TO ABOVE
RECORD HIGHS THIS AFTERNOON.
THIS GENERAL PATTERN CONFIGURATION WILL PERSIST THROUGH THE
REMAINDER OF THE WEEK UNTIL MORE ROBUST PACIFIC SHORTWAVE ENERGY
DAMPENS THE RIDGE AXIS...AND NEGATIVE ERN CONUS HEIGHT ANOMALIES
TRANSLATE INTO THE NORTH PACIFIC.

THROUGHOUT THE FORECAST AREA...LITTLE CHANGE IN THE THERMODYNAMIC
PROFILE WILL OCCUR OVER THE NEXT 84 HOURS WITH A NEAR PERSISTENCE
FORECAST MOST APPLICABLE. WITH 1000-850MB THICKNESSES REGULARLY
TOUCHING 140DM AND OTHER HEIGHT AND THERMAL PROFILES CONTINUING TO
FALL IN THE 2-3 NORMALIZED STANDARD DEVIATIONS ABOVE NORMAL
RANGE...AFTERNOON HIGHS FLIRTING WITH RECORD TERRITORY WILL BE
TYPICAL. (PLEASE REFERENCE THE CLIMATE SECTION BELOW FOR FORECAST
AND RECORD DETAILS). MODEL SPREAD ON ALL ACCOUNTS IS QUITE SMALL
YIELDING EXCELLENT FORECAST CONFIDENCE AND POINTING TOWARDS FRIDAY
AS THE WARMEST DAY OF THE WEEK.

THE SWIFT PASSAGE OF THE SOUTHERN END OF A DRY PAC NORTHWEST
SHORTWAVE WILL SUPPORT A DEGREE OR TWO OF COOLING SATURDAY AND
SUNDAY WITH THE COMBINATION OF SLIGHTLY LOWER UL HEIGHTS AND SOME
HIGH LEVEL CLOUDINESS. RIDGING WILL QUICKLY REBOUND EARLY NEXT WEEK
AND THE WARMTH AND ABOVE-NORMAL TEMPERATURES RETURN. HOWEVER ONE
POTENTIAL AREA OF INTEREST...A SHEARED PORTION OF THIS PAC NW TROUGH
MAY FORM A CUTOFF LOW OFF THE SAN DIEGO COAST SUNDAY...DEEPENING
SOUTH TO OFFSHORE SOUTHERN BAJA MONDAY NEAR THE NORTHERN EDGES OF
WARM EL NINO WATERS. WHILE THERE IS SOME ENSEMBLE SPREAD IN THE
ORIENTATION OF THESE FEATURES...THIS AREA OFFSHORE COULD PRESENT
ALMOST LIKE THE SOUTHERN BRANCH OF A REX BLOCK WITH LOWER
HEIGHTS/GENERAL WEAKNESS PERSISTING.

PATTERN PREDICTABILITY DROPS OFF AND ENSEMBLE SPREAD INCREASES
TOWARDS THE LATTER END OF THE EXTENDED PERIOD AS SOME TROPICAL
PACIFIC CONVECTION AND JET STREAKING TAKE ADVANTAGE OF THOSE
PERSISTENT LOW HEIGHT ANOMALIES OVER THE EAST PACIFIC/BAJA PENINSULA.
AS PREVIOUS SHIFTS NOTED...THIS ATMOSPHERIC SET-UP HAS OCCURRED IN
PREVIOUS EL NINO YEARS /CUTOFF LOWS IN THIS EL NINO REGION HAVE SPUN
UP INCREDIBLY FAST DUE TO THE PHASING OF A SUBTROPICAL JETSTREAM/
RESULTING IN EVENTUAL PRECIP ACTIVITY DOWNSTREAM OVER THE SOUTHWEST
DESERTS. DETERMINISTIC MODEL RUNS ARE BROADLY AGREEING ON THE IDEA
OF STRONGER AND DEEPER PACIFIC TROUGH SWEEPING INTO SOUTHERN WEST
COAST TOWARDS THE LATTER PART OF NEXT WEEK AND MODTREND GUIDANCE
FROM THE GFS POINTS TO SOME PERSISTENT WEAKENING OF 500MB HEIGHTS
OVER THE CENTRAL PACIFIC UPSTREAM BY THU-FRI NEXT WEEK. WE ARE JUST
OUTSIDE THE WINDOW OF GETTING IVT/AR GUIDANCE BUT BROAD MODEL
AGREEMENT ON THE UPPER LEVEL PATTERN NEVER HURTS TO SEE THIS FAR OUT.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND SDL...AND
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH...

HIGH PRESSURE ALOFT...AND A VERY DRY AIRMASS...TO KEEP SKIES CLEAR
AT ALL OF THE TAF SITES THROUGH THE NEXT 24 HRS...AND BEYOND.
WEAKENING SFC PRESSURE GRADIENTS TO KEEP WINDS FOR THE MOST PART ON
THE LIGHT SIDE...8 KTS OR LESS...AND ALLOW THEM TO FOLLOW TYPICAL
DIURNAL TRENDS...WITH THE EXCEPTION OF A A PERIOD OF SLIGHTLY
STRONGER EASTERLY BREEZES AT KPHX DURING THE LATE MORNING/EARLY
AFTERNOON PERIOD ON WEDNESDAY.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
THURSDAY THROUGH MONDAY...
AN UNSEASONABLY STRONG HIGH PRESSURE RIDGE WILL REMAIN IN PLACE OVER
THE WESTERN STATES THIS WEEK AND INTO EARLY NEXT WEEK. THIS WILL
LEAD TO A PERSISTENT PERIOD OF WELL ABOVE NORMALS HIGH
TEMPERATURES...WITH READINGS PEAKING 10 TO 15 DEGREES ABOVE SEASONAL
NORMALS. MANY LOWER ELEVATION AND DESERT SITES WILL SEE A STRETCH OF
DAYS WITH HIGH TEMPERATURES WARMING PAST THE 80 DEGREE MARK. RH`S
WILL ALSO REMAIN ON THE DRIER AND BELOW NORMAL SIDE DURING THE WEEK
WITH MIN VALUES TYPICALLY IN THE LOW TO MIDDLE TEENS.

LIGHT WINDS ARE EXPECTED THURSDAY THROUGH SATURDAY...AND WILL
GENERALLY FOLLOW TYPICAL DRAINAGE/SLOPE DRIVEN HEADINGS WITH LIGHT
SPEEDS. INCREASED NORTHERLY BREEZES ARE EXPECTED OVER THE WESTERN
DESERTS...ESPECIALLY ALONG THE LOWER COLORADO RIVER VALLEY...SUNDAY
INTO MONDAY. SUNNY DAYS AND CLEAR NIGHTS WILL BE REPLACED BY
VARIABLE HIGH CLOUDINESS STARTING FRIDAY AND CONTINUING THROUGH THE
WEEKEND.

&&

.CLIMATE...


AFTERNOON SATELLITE IMAGERY INDICATES MOSTLY CLEAR TO SCATTERED
SKIES OVER THE REGION. EXPECT MOSTLY CLEAR SKIES WITH A FEW
SCATTERED...MOSTLY HIGH CLOUDS IN ALL AREAS. IN THE PHOENIX
AREA...WINDS WILL BE LIGHT OR LIGHT AND VARIABLE AND FOLLOW NORMAL
DIURNAL SWINGS. HOWEVER...AT KBLH OCCASIONAL NORTHERLY AFTERNOON
WIND GUSTS UP TO 25 KNOTS ARE EXPECTED. OTHERWISE...SOUTHEAST
CALIFORNIA LOCALES CAN EXPECT NORTHERLY WINDS THIS AFTERNOON AND
LIGHTER WESTERLY WINDS TONIGHT. VISIBILITIES WILL REMAIN GOOD
THROUGHOUT THE PERIOD.
                   PHOENIX         |        YUMA
             FCST | RECORD (YEAR)  | FCST | RECORD (YEAR)

TUE FEB 9      84 | 84 (1987)      |   84 | 90 (2015)
WED FEB 10     84 | 87 (1951)      |   84 | 93 (1951)
THU FEB 11     85 | 83 (1951)      |   85 | 86 (1971)
FRI FEB 12     86 | 84 (1988)      |   85 | 87 (1957)
SAT FEB 13     86 | 88 (1957)      |   85 | 93 (1957)
SUN FEB 14     83 | 85 (2014)      |   83 | 94 (1957)

&&

.SPOTTER INFORMATION STATEMENT...
SPOTTERS ARE ENCOURAGED TO REPORT BASED ON STANDARD OPERATING
PROCEDURES.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.

&&

$$

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

DISCUSSION...PERCHA/MO/NOLTE
AVIATION...PERCHA
FIRE WEATHER...NOLTE/CB
CLIMATE...NOLTE



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.