820
FXUS65 KPSR 282148
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
248 PM MST SUN FEB 28 2021
SYNOPSIS
COOLER AND WINDY CONDITIONS TODAY AS A DRY SYSTEM PASSES THROUGH.
A COLD MORNING IS EXPECTED TO START THE WEEK WITH SOME LOWER
DESERT SPOTS FALLING TO FREEZING. WARMER CONDITIONS ARE
ANTICIPATED HEADING INTO MIDWEEK AS HIGH PRESSURE MOVES THROUGH
THE INTERMOUNTAIN WEST. A LOW PRESSURE SYSTEM WILL BRING A CHANCE
OF RAIN TO THE AREA DURING THE WEDNESDAY INTO THURSDAY TIMEFRAME.
THEREAFTER, A RETURN TO ABOVE NORMAL NORMAL TEMPERATURES IS
LIKELY BY FRIDAY AND INTO NEXT WEEKEND.
DISCUSSION
IT IS PRETTY EASY TO PICK OUT WHERE THE SHORTWAVE TROUGH IS AND
ITS ORIENTATION ON SATELLITE THIS AFTERNOON. SCATTERED CUMULUS,
CLOSELY TIED TO THE TROUGH, HAS DEVELOPED WITH WHAT LITTLE MID
LEVEL MOISTURE EXISTS AND ARE PUSHING SOUTHEAST THROUGH CENTRAL
AND EASTERN AZ. THERE ARE EVEN A FEW WEEK ECHOES WITH SOME OF THE
CUMULUS, BUT WITH THE VERY DRY SURFACE CONDITIONS IT WILL LIKELY
BE AN INSURMOUNTABLE TASK FOR A RAIN DROP TO REACH THE SURFACE
BEFORE EVAPORATING. THE BIGGEST AND MOST NOTICABLE IMPACT FROM
THIS PASSING TROUGH TODAY HAS BEEN THE WINDS AND VERY DRY AIR. IT
HAS BEEN BREEZY FROM THE GET-GO TODAY WITH GUSTS GENERALLY UP TO
25-35 MPH, AND SOME LOCALIZED GUSTS UP TO 40 MPH, ACROSS OUR CWA.
GUST MAGNITUDES IN SOUTHEAST CA AND SOUTHWEST AZ, WHERE A WIND
ADVISORY IS STILL IN EFFECT, SHOULD GENERALLY LET UP OVER THE FEW
HOURS. WINDS MOST LOCATIONS SHOULD SUBSIDE LATE THIS EVENING.
WINDS ARE EXPECTED TO INCREASE ALOFT OUT OF THE NORTHEAST TONIGHT,
AS THE TROUGH PUSHES AWAY, BUT THESE STRONGER WINDS ARE UNLIKELY
TO DESERT FLOOR LOCATIONS GIVEN THE OVERNIGHT TIME PERIOD.
ANOTHER SENSIBLE IMPACT FROM THIS TROUGH HAS BEEN MUCH COOLER
CONDITIONS. TEMPERATURES EARLY THIS AFTERNOON ARE ROUGHLY 10
DEGREES COOLER THAN THIS TIME YESTERDAY. MOST LOWER DESERT
LOCATIONS ARE STRUGGLING TO EVEN REACH THE MID 60S. WE WILL SEE
THE ABNORMALLY COOL CONDITIONS EXTEND THROUGH MONDAY MORNING.
POTENTIALLY THE COLDEST TEMPERATURES IN ABOUT A MONTH ARE EXPECTED
TOMORROW MORNING. NBM IS PROJECTING LOWS ACROSS THE LOWER DESERTS
GENERALLY IN THE 35-40 DEGREE RANGE, WITH SOME OF THE TYPICAL COLD
SPOTS, LIKE PINAL COUNTY, LIKELY FALLING NEAR OR BELOW FREEZING.
ELEVATED WINDS THROUGH THE NIGHT COULD CERTAINLY KEEP TEMPERATURES
LOCALLY A LITTLE WARMER THAN ANTICIPATED, BUT ON THE FLIP SIDE
LIGHT WINDS PAIRED WITH THE VERY DRY CONDITIONS AND CLEAR SKIES
COULD ALSO PUSH TEMPERATURES EVEN A DEGREE OR TWO COOLER THAN
CURRENTLY FORECASTED. A FREEZE WARNING HAS BEEN ISSUED FOR
PORTIONS OF PINAL COUNTY FOR TOMORROW MORNING.
TEMPERATURES WILL REBOUND QUICKLY INTO THE AFTERNOON MONDAY AND
INTO MIDWEEK AS A RIDGE MIGRATES SWIFTLY ACROSS THE INTERMOUNTAIN
WEST. THE 80 DEGREE MARK IS NOT OUT OF THE QUESTION FOR PHOENIX
TUESDAY WITH AN EVEN BETTER CHANCE WEDNESDAY NOW WITH POTENTIAL
WARM AIR ADVECTION AHEAD OF OUR NEXT SYSTEM. THE NBM SUGGESTS
ROUGHLY A 20 PERCENT CHANCE OF REACHING 80 TUESDAY AND 65 PERCENT
CHANCE WEDNESDAY, WHICH IS STILL WELL BELOW THE DAILY RECORDS THAT
ARE NEAR 90 DEGREES.
BY MIDWEEK, FOCUS WILL SHIFT TO A PACIFIC LOW PRESSURE SYSTEM AND
THE POTENTIAL FOR RAINFALL ACROSS THE DESERT SOUTHWEST. ENSEMBLE
SYSTEMS HAVE GENERALLY COME INTO BETTER AGREEMENT AND THIS IS
REFLECTED IN THE POPS, WHICH CONTINUE TO INCREASE. THE 12Z NBM IS
NOW SHOWING A 75% PROBABILITY OF 24-HR QPF GREATER THAN 0.01"
ACROSS CENTRAL PORTIONS OF AZ. MAIN SOURCE OF UNCERTAINTY SEEMS TO
BE WITH THE AMPLITUDE OF THE WAVE. THE TRACK HAS TRENDED A LITTLE
FURTHER NORTHWEST, BUT EPS AND NAEFS STILL SUPPORT A MODERATE IVT
PLUME INTO AZ. RIGHT NOW, BEST CHANCE FOR RAIN APPEARS TO BE
WEDNESDAY NIGHT INTO THURSDAY MORNING, THOUGH SOME GEFS MEMBERS
SUGGEST SHOWERS COULD DEVELOP AS EARLY AS WEDNESDAY AFTERNOON.
GREATEST QPF WILL FAVOR THE HIGHER TERRAIN NORTH AND EAST OF
PHOENIX.
NCEP CLUSTER ANALYSIS REVEALS THAT NEARLY THREE QUARTERS OF THE
MEMBERS RESULT IN A SCENARIO THAT WOULD PRODUCE A WIDESPREAD TENTH
OF AN INCH OF PRECIPITATION FROM MARICOPA COUNTY NORTH AND
EASTWARD AND EVEN UP TO A QUARTER OF AN INCH CLOSER TO THE
MOGOLLON RIM. A FEW GEFS AND A COUPLE EPS MEMBERS EVEN SUGGEST
RAINFALL AMOUNTS NEAR HALF AN INCH IN PHOENIX, THOUGH THE
PROBABILITY OF THIS OCCURRING IS LESS THAN 5 PERCENT. THE WPC
FORECAST HAS GENERALLY BEEN IN LINE WITH MOST ENSEMBLE MEANS WITH
AROUND 0.1" IN THE PHOENIX AREA TO UP TO 0.25"-0.50" TO THE NORTH
AND EAST.
IN THE WAKE OF THE LOW PRESSURE SYSTEM, LATEST GEFS/EPS MEANS
INDICATE AN ANOMALOUSLY STRONG RIDGE WILL BUILD ACROSS THE
INTERMOUNTAIN WEST. PROBABILITIES ARE HIGH THAT WE WILL SEE THE
WARMEST CONDITIONS OF THE YEAR SO FAR BY NEXT WEEKEND. HIGH
TEMPERATURES IN PHOENIX WILL LIKELY REACH THE LOWER 80S BY FRIDAY
AND PERHAPS EVEN THE MID 80S BY SATURDAY.
AVIATION
UPDATED AT 1650Z.
SOUTH-CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
WINDS WILL CONTINUE TO BE THE MAIN WEATHER CONCERN THROUGH EARLY
EVENING UNDER MOSTLY CLEAR SKIES. NORTHWESTERLY WINDS WILL REMAIN
GUSTY TO AROUND 25 KTS THROUGH MUCH OF THE AFTERNOON. A GUSTY NNW
HEADING MAY BE ENOUGH OF A CROSS RUNWAY COMPONENT TO IMPACT
ARRIVAL RATES. GUSTS SHOULD QUICKLY DIMINISH WITH SUNSET WHILE
DIRECTIONS WILL TREND MORE TOWARDS A NE DIRECTION PROGRESSING
THROUGH TONIGHT. WINDS SHOULD EVENTUALLY SHIFT DIRECTLY OUT OF THE
EAST FOR AT LEAST KPHX AND KIWA AFTER SUNRISE MONDAY MORNING,
LIKELY STAYING EASTERLY ALL DAY MONDAY.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
GUSTY NORTHERLY WINDS WILL CONTINUE FOR MUCH OF TODAY UNDER CLEAR
SKIES. GUSTY WINDS TO AROUND 30KTS ARE EXPECTED FOR KBLH THROUGH
THIS AFTERNOON. WINDS WILL EVENTUALLY DIMINISH, BUT STAY OUT OF
THE NORTH THROUGH MONDAY MORNING. FOR KIPL, LOOK FOR NORTHERLY
WINDS TO BE GUSTY AT TIMES THROUGH THIS AFTERNOON WITH SPEEDS TO
AROUND 20 KTS. WINDS WILL EVENTUALLY RELAX AND TURN MORE OF THE
THE WEST THIS EVENING, LASTING THROUGH THE REST OF THE PERIOD.
FIRE WEATHER
TUESDAY THROUGH SATURDAY:
RELATIVELY WARM AND DRY CONDITIONS ARE LIKELY TUESDAY. BREEZY
CONDITIONS ARE THEN EXPECTED TO DEVELOP AHEAD OF A PACIFIC LOW
PRESSURE SYSTEM WEDNESDAY. THIS SYSTEM WILL ALSO BRING A CHANCE OF
RAIN TO THE DESERT SOUTHWEST WEDNESDAY NIGHT. HIGHEST RAIN TOTALS
ARE LIKELY IN THE HIGHER TERRAIN NORTH AND EAST OF PHOENIX,
HOWEVER WETTING RAINS WILL STILL BE POSSIBLE ACROSS THE LOWER
DESERTS. IN THE WAKE OF THE LOW PRESSURE SYSTEM, A WARMING TREND
IS ANTICIPATED ALONG WITH A RETURN TO ABOVE NORMAL TEMPERATURES
AND SEASONABLY DRY CONDITIONS BY FRIDAY.
SPOTTER INFORMATION STATEMENT
SPOTTERS SHOULD FOLLOW STANDARD REPORTING PROCEDURES.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...FREEZE WARNING FROM 2 AM TO 9 AM MST MONDAY FOR AZZ553.
WIND ADVISORY UNTIL 4 PM MST THIS AFTERNOON FOR AZZ530>533-535-
536.
CA...WIND ADVISORY UNTIL 3 PM PST THIS AFTERNOON FOR CAZ560-564-565-
568>570.
DISCUSSION...BENEDICT/HIRSCH
AVIATION...KUHLMAN
FIRE WEATHER...HIRSCH
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