Area Forecast Discussion
Issued by NWS Phoenix, AZ

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FXUS65 KPSR 262118
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
215 PM MST SUN APR 26 2015

.SYNOPSIS...
A LOW PRESSURE SYSTEM WILL EXIT INTO NEW MEXICO TONIGHT WITH A
FEW LINGERING SHOWERS OVER EASTERN ARIZONA INTO MONDAY AFTERNOON.
DRY WEATHER WITH A SIGNIFICANT WARMING TREND WILL COMMENCE RAPIDLY
THIS WEEK...WITH TEMPERATURES IN THE LOWER ELEVATION
POPULATION CENTERS APPROACHING THE 100 DEGREE MARK DURING THE
MIDWEEK TIME FRAME.

&&

.DISCUSSION...
THE WELL ADVERTISED TROUGH AXIS...CIRCULATION CENTER...AND COLD CORE
ALOFT HAS TRANSLATED INTO SOUTHWEST NEW MEXICO THIS AFTERNOON. AN
ASSOCIATED ELONGATED LOBE OF PV HAS BEEN FILLING INTO THE TROUGH
BASE...AND DELINEATING A SHARP MIDTROPOSPHERIC FRONT AND AREAS OF
ASCENT/DESCENT THROUGH CENTRAL ARIZONA. MEANWHILE...A SECONDARY WING
OF VORTICITY HAS ROTATED BACK SOUTH TOWARDS THE COLD CORE ACTING
UPON LOW LEVEL DESTABILIZATION...AND FORCING CONVECTIVE SHOWERS
WITHIN THE COLD CORE CYCLONIC CURVATURE REGION. WHILE LOSS OF
DAYTIME HEATING WILL LIMIT FURTHER CONVECTIVE GROWTH (ESPECIALLY
ALONG THE WESTERN PERIPHERY THROUGH THE PHOENIX METRO)...AMPLE
MIDLEVEL MOISTURE AND SYNOPTIC SCALE ASCENT WILL KEEP SOME SHOWERS
GOING THROUGH PARTS OF SRN GILA COUNTY.

HIGHER HEIGHTS ALOFT WILL GRADUALLY PROPAGATE EASTWARD MONDAY AS
UPSTREAM WEST COAST RIDGING AMPLIFIES. HOWEVER...NORTHERLY FLOW
ALOFT AND COOLER MIDTROPOSPHERIC TEMPERATURES COINCIDENT WITH
RESIDUAL MOISTURE AND MORE INTENSE SPRING INSOLATION WILL SUPPORT
MORE ISOLD/SCT CONVECTIVE SHOWERS OVER FAR EASTERN
ARIZONA...POTENTIALLY CLIPPING THE SAN CARLOS REGION OF SRN GILA
COUNTY. OTHERWISE...THE VAST MAJORITY OF THE FORECAST AREA WILL
FALL UNDER STRONGER SYNOPTIC SCALE SUBSIDENCE AS H5 HEIGHTS INCREASE
TO 573-579DM YIELDING AFTERNOON HIGHS 5-10F WARMER THAN TODAY.

STRONG RIDGING WITH H5 HEIGHTS IN EXCESS OF 580DM WILL FOLD OVER
INTO THE FORECAST AREA TUESDAY THROUGH THURSDAY. WHILE SOME THIN
CIRRUS IS POSSIBLE...MUCH OF THE REGION WILL BE CHARACTERIZED BY
FULL INSOLATION AND MIXING DEPTHS AOA 600MB. WITH H8 TEMPERATURES
REACHING THE +25C LEVEL...AFTERNOON HIGHS FLIRTING WITH (OR
EXCEEDING) THE 100F THRESHOLD WILL BE COMMON WEDNESDAY AND THURSDAY.
THIS IS WELL SHORT OF RECORD HIGHS AND NOT UNCOMMON FOR THIS TIME OF
YEAR...WITH THE AVERAGE FIRST 100F DAY IN PHOENIX OCCURRING ON MAY
2ND...AND IN YUMA APRIL 23RD.

A WEAK SHORTWAVE SHOULD SETTLE OVER THE EASTERN PACIFIC ALONG THE
CALIFORNIA COAST LATE IN THE WEEK...HELPING EDGE THE CORE OF THE
HIGHEST HEIGHTS ALOFT INTO THE SOUTHERN PLAINS. THIS WILL ALLOW FOR
A CONTINUATION OF DRY CONDITIONS OVER THE SWRN CONUS...AND ONLY A
SLIGHT COOLING SOMEWHAT CLOSER TO THE CLIMATOLOGICAL NORMAL FOR THE
BEGINNING OF MAY.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...
SCT LIGHT SHOWERS WILL MOVE EAST OF TERMINALS AND DISSIPATE
THIS EVENING...WITH LOWER CIGS AND MOUNTAIN OBSCURATION ON EASTERLY
APPROACHES THE PRIMARY AVIATION CONCERN. CIGS IN A 5K-7K FT LEVEL
WILL LIFT AND SCT WITH SUNSET THIS EVENING...THOUGH SOME SCT-BKN
CLOUDS ABV THE 10K FT LEVEL WILL BE POSSIBLE INTO THE OVERNIGHT.
NORTHWEST WINDS WITH SOME GUSTS WILL WEAKEN AND EVENTUALLY TURN
EASTERLY TOWARDS SUNRISE MONDAY...HOWEVER ONLY MODEST CONFIDENCE
IN TIMING WIND SHIFTS EXISTS.


SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA INCLUDING KIPL AND
KBLH...
OCCASIONALLY GUSTY N/NW WINDS WILL BE THE PRIMARY AVIATION CONCERN
THROUGH MONDAY UNDER MOSTLY CLEAR SKIES. WHILE GUSTS MAY ABATE WITH
SUNSET...A STRENGTHENING NLY LLJ TOWARDS SUNRISE MAY MIX TO THE SFC
AT KBLH. OTHERWISE...SFC WINDS IN A 10-20KT RANGE WILL BE COMMON
ACROSS SE CALIFORNIA.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
TUESDAY THROUGH SATURDAY...
SOME PERIODS OF ELEVATED NORTHEASTERLY BREEZES ARE POSSIBLE OVER
SOUTH-CENTRAL AZ THRU MIDWEEK... LIKELY DURING THE EARLY MORNING
HOURS ENHANCING THE ALREADY TYPICAL DRAINAGE PATTERN. TEMPERATURES
WILL BEGIN TO WARM SUBSTANTIALLY AND APPROACH THE TRIPLE DIGIT MARK
DURING THE MIDDLE OF THE WEEK AS HIGH PRESSURE STRENGTHENS.
AFTERNOON HUMIDITIES WILL DROP INTO THE LOWER TEENS AND UPPER
SINGLE DIGITS WITH FAIR OVERNIGHT RECOVERIES. DURING THE LATTER HALF
OF THE WEEK...WINDS WILL GENERALLY BE LIGHT FOLLOWING TYPICAL
DIURNAL PATTERNS.

&&


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

DISCUSSION...MO
AVIATION...MO
FIRE WEATHER...MO/NOLTE


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