269
FXUS65 KPSR 240507
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
1007 PM MST THU MAR 23 2023
UPDATE
UPDATED AVIATION DISCUSSION.
SYNOPSIS
DRY AND TRANQUIL WEATHER WILL PREDOMINATE THROUGH THE WEEKEND THOUGH
TEMPERATURES WILL CONTINUE TO HOVER AROUND 10 DEGREES BELOW THE
SEASONAL NORMAL. A WARMING TREND WILL TAKE HOLD EARLY NEXT WEEK
BEFORE THE NEXT WEATHER DISTURBANCE SWEEPS THROUGH THE REGION. THIS
SYSTEM WILL RESULT IN MODEST RAINFALL CHANCES AND A RETURN TO COOLER
THAN NORMAL TEMPERATURES TOWARDS THE LATTER HALF OF NEXT WEEK.
DISCUSSION
A BROAD, LOW AMPLITUDE TROUGHING PATTERN WILL BE MAINTAINED OVER THE
SW CONUS THROUGH THE WEEKEND WITH SEVERAL EMBEDDED VORTICITY CENTERS
TRAPPED IN THE FLOW ACROSS NORTHERN AZ. SUFFICIENT LINGERING LOW
LEVEL MOISTURE COMBINED WITH FAVORABLE UPSLOPE FLOW AND COOLER
TEMPERATURES ALOFT WILL BE SUPPORTIVE OF A FEW ISOLATED SHOWERS
ACROSS THE NORTHEAST CWA THROUGH TONIGHT BEFORE THE NEXT REINFORCING
SHOT OF DRIER AIR ARRIVES FRIDAY AFTERNOON. FORECAST CONFIDENCE IS
EXCELLENT THAT PERSISTENT GREAT BASIN TROUGHING WILL FORCE A QUASI-
ZONAL PATTERN OVER THE FORECAST AREA AND H5 HEIGHTS STUCK NEAR
564DM. VERY NARROW ENSEMBLE SPREADS SUGGEST AFTERNOON HIGHS
SEQUESTERED AROUND 10F BELOW THE SEASONAL NORMAL THROUGHOUT THE
WEEKEND WITH INTERMITTENT CLOUD COVER.
THERE IS VERY GOOD MODEL AGREEMENT THAT SHORTWAVE RIDGING WILL BUILD
INTO THE SOUTHWEST EARLY NEXT WEEK IN RESPONSE TO DEEPER NEGATIVE PV
ANOMALIES INTENSIFYING OFF THE CALIFORNIA COAST. NOT ONLY WILL
HEIGHTS EXPERIENCE A MODEST BUMP DURING THE MON-TUE TIME FRAME, BUT
THERMAL PROFILES WILL WARM MARKEDLY. RECENT NBM OUTPUT CONTINUES TO
HIGHLIGHT TUESDAY AS THE WARMEST DAY WITH BETTER THAN A 50% CHANCE
MOST LOWER ELEVATION COMMUNITIES BREACH THE 80F THRESHOLD. TIMING
AND DEPTH ISSUES ABOUND IN RECENT ENSEMBLE OUTPUT REGARDING THE NEXT
WEATHER DISTURBANCE ENTERING THE WESTERN CONUS NEXT WEEK. IN
GENERAL, GEFS MEMBERSHIP FAVORS A FASTER MOVING, LESS AMPLIFIED
OUTCOME, WHILE EPS MEMBERS LEAN TOWARDS A DEEPER, SLOWER MOVING
WAVE. TRENDS IN ENSEMBLES SEEM TO FAVOR THE SLOWER OUTCOME, ALBEIT
SIMILAR TO THE MOST RECENT SYSTEM WHERE ONLY THE TRAILING TROUGH
AXIS AFFECTS THE CWA. RECENT NBM POPS REMAIN VERY MEAGER WITH THIS
SYSTEM (LESS THAN 10%) THOUGH CONTINUE TO ADVERTISE TEMPERATURES
RETREATING BACK TOWARDS NEARLY 10F BELOW CLIMATOLOGY DURING THE
LATTER PART OF THE WEEK.
AVIATION
UPDATED AT 0510Z.
SOUTH-CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
STRATOCU WILL THICKEN OVERNIGHT AS A WEAK LOW PRESSURE SYSTEM
MOVES THROUGH THE AREA. CEILINGS ARE GENERALLY EXPECTED TO REMAIN
ABOVE 7000 FT, THOUGH A BRIEF DROP TO 6000 FT IS POSSIBLE,
PARTICULARLY AT KSDL AND POSSIBLY AT KPHX (20% CHANCE). THERE IS
ALSO A 10 PERCENT CHANCE OF A SHOWER AROUND SUNRISE, WHICH WILL BE
FOLLOWED BY A RAPID CLEARING TREND.
WINDS WILL GENERALLY REMAIN WESTERLY OVERNIGHT, HOWEVER A BRIEF
SWITCH TO EASTERLY NOW LOOKS LIKELY AROUND 12Z. THE WESTERLY FLOW
WILL THEN REDEVELOP DURING THE LATE MORNING. BREEZY CONDITIONS ARE
ALSO ANTICIPATED FRIDAY AFTERNOON WITH GUSTS LIKELY REACHING 20
KT.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
WESTERLY WINDS WILL PERSIST THROUGH FRIDAY AS A WEAK LOW PRESSURE
SYSTEM PASSES BY TO THE NORTH OVERNIGHT. GUSTS WILL LIKELY REACH
30 KT AT KIPL TONIGHT FOLLOWED BY SOMEWHAT LIGHTER WINDS FRIDAY.
FIRE WEATHER
TEMPERATURES WILL REMAIN BELOW AVERAGE THROUGH THE WEEKEND, BEFORE
WARMING EARLY NEXT WEEK THEN COOLING AGAIN BY MIDWEEK. SOME LATE
AFTERNOON BREEZINESS CAN BE EXPECTED IN IMPERIAL COUNTY TODAY,
OTHERWISE LIGHT TO MODERATE DIURNAL WINDS WILL PERSIST ACROSS THE
LOWER DESERTS THROUGH THE WEEKEND. A DRYING TREND IS EXPECTED
THROUGH THE REST OF THE WEEK, WITH LITTLE TO NO WETTING RAINS
EXPECTED THROUGH THE REST OF THE FORECAST PERIOD. MAXRH'S WILL BE
NEAR 70-90% TODAY, BEFORE DECREASING TO AROUND 40-60% THROUGH THE
WEEKEND. WHILE MINRH'S IN THE 25-45% RANGE WILL DIP BACK INTO THE
LOW TO MID TEENS PERCENT BY THE END OF THIS WEEKEND.
HYDROLOGY
DOWNSTREAM IMPACTS CONTINUE ACROSS OUR EASTERN CWA FROM THE
EXCESSIVE RAINFALL EVENT OVER NORTH-CENTRAL ARIZONA THE LAST 48-60
HOURS. AS OF THIS MORNING, FLOOD WARNINGS ARE IN EFFECT FOR PORTIONS
OF THE SALT, VERDE, AND GILA RIVERS. ACCORDING TO SRP DATA, THE
WATERSHED IS 95% FULL WITH ONGOING RELEASES AT BARTLETT AND STEWART
MOUNTAIN DAMS. AT GRANITE REEF, THE LATEST RELEASE VOLUME IS 38,000
CFS. DESPITE VERY LITTLE ADDITIONAL FORECAST PRECIPITATION,
SUBSTANTIAL RUNOFF IS STILL OCCURRING WITHIN THESE BASINS. THUS,
FLOOD WARNINGS ALONG THESE RIVERS WAS EXTENDED UNTIL MARCH 31.
PLEASE CONTINUE TO AVOID RIVER BANKS AND RECREATIONAL PLANS ALONG
THESE RIVERS, AND HEED ALL PARK AND ROAD CLOSURES!!
AT TONTO CREEK, THE FLOOD WARNING WAS EXTENDED UNTIL MARCH 29 AS LOW
WATER CROSSINGS ARE STILL IMPASSIBLE. FINALLY, WE CONTINUE TO
MONITOR SMALLER RIVERS/STREAMS AROUND MARICOPA COUNTY. THE NEW RIVER
NEAR PEORIA AND PORTIONS OF THE HASSAYAMPA RIVER ARE STILL ABOVE
ALARM STAGE. THESE SMALLER STREAMS AND RIVERS WILL SLOWLY FALL OVER
THE NEXT 24-48 HOURS AS SIGNIFICANT PRECIPITATION IS NO LONGER
FALLING ACROSS THEIR RESPECTIVE BASINS.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...NONE.
DISCUSSION...18
AVIATION...HIRSCH
FIRE WEATHER...LEFFEL
HYDROLOGY...HEIL
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page