536
FXUS65 KPSR 120508
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
1008 PM MST SUN APR 11 2021
UPDATE
UPDATED AVIATION DISCUSSION.
SYNOPSIS
WITH HIGH PRESSURE SLOWLY BEING REPLACED BY THE INFLUENCE OF A
WEATHER DISTURBANCE NORTH OF THE AREA, TEMPERATURES WILL STEADILY
COOL BACK NEAR THE SEASONAL NORMAL BY THE MIDDLE OF THE WEEK.
THIS PATTERN WILL ENSURE DRY WEATHER CONTINUES WITH LOCALLY BREEZY
CONDITIONS DURING THE MIDDLE OF THE WEEK. TEMPERATURES SHOULD
GRADUALLY MODERATE SOMEWHAT WARMER HEADING INTO NEXT WEEKEND.
DISCUSSION
OBJECTIVE ANALYSIS THIS AFTERNOON SHOWS A WEAK SYNOPTIC FLOW
PATTERN OVER THE REGION WITH A WEAK LOW AMPLITUDE SHORTWAVE TROUGH
ALONG THE WESTERN COASTLINE. SCATTERED TO BROKEN CIRRUS ARE SEEN
SPREADING EASTWARD OVER THE AREA DOWNSTREAM OF THIS SHORTWAVE.
FORECAST SOUNDINGS INDICATE THE HIGH CLOUDS MAY STILL BECOME A
LITTLE THICKER THROUGH THE REST OF THE AFTERNOON, BUT IT DOES NOT
APPEAR THEY WILL HAVE TOO MUCH INFLUENCE ON THE MAX TEMPERATURES
EXPECTED IN THE LOW 90S AS NBM MAINTAINS ONLY A 2-3 DEGREE
SPREAD.
BY SUNRISE MONDAY MORNING THE SHORTWAVE SHOULD MOSTLY BE EAST OF
THE AREA WITH SKIES CLEARING UP IN ITS WAKE. HOWEVER, A GENERAL
CYCLONIC FLOW SHOULD PERSIST ACROSS THE REGION AS A BROAD TROUGH
PATTERN IS ESTABLISHED ACROSS THE WESTERN CONUS. WITHIN THIS BROAD
TROUGH PATTERN, A SHORTWAVE TROUGH ON THE WESTERN FLANK IS
EXPECTED TO DIG INTO THE PACIFIC NORTHWEST BY THE END OF MONDAY.
THIS SHORTWAVE WILL EVENTUALLY BECOME CUT OFF TUESDAY INTO
WEDNESDAY AS A SIGNIFICANT BLOCKING PATTERN SETS UP ACROSS THE
EASTERN PACIFIC AND THE ENTIRE CONUS. ALTHOUGH THE DEVELOPING CUT-
OFF LOW WILL LARGELY REMAIN WELL TO OUR NORTH, IT WILL LEAD TO
INCREASING WESTERLY FLOW TUESDAY INTO WEDNESDAY AND BREEZY TO
LOCALLY WINDY DAYTIME CONDITIONS. WIND GUSTS BOTH DAYS OF 20-30
MPH ARE LIKELY FOR THE BULK OF THE AREA WITH NEAR ADVISORY LEVEL
WINDS POSSIBLE ACROSS SOUTHEAST CALIFORNIA. THE INCREASED WINDS
AND LOW DAYTIME RHS SHOULD AGAIN BRING ANOTHER PERIOD OF ELEVATED
FIRE WEATHER CONCERNS. TEMPERATURES WILL SLOWLY RETREAT STARTING
TUESDAY AS UPPER LEVEL HEIGHTS GET SUPPRESSED FROM THE LOW TO OUR
NORTH. BY WEDNESDAY, HIGH TEMPERATURES ARE FORECAST TO FALL BACK
TO NEAR NORMAL READINGS, THE FIRST TIME IN OVER TWO WEEKS.
THE BLOCKING PATTERN SHOULD LAST THROUGH LATE WEEK KEEPING MOSTLY
ZONAL DRY WESTERLY FLOW OVER OUR REGION. THE LOW TO OUR NORTH WILL
GRADUALLY WEAKEN BEFORE LIKELY BECOMING AN OPEN WAVE BY THURSDAY OR
FRIDAY ALLOWING HEIGHTS ALOFT TO SLOWLY RISE OVER OUR REGION. THIS
SHOULD MARK THE BEGINNING OF A SLOW UPWARD CLIMB IN TEMPERATURES,
BUT SUB 90 DEGREE READINGS ARE LIKELY TO STAY THROUGH AT LEAST
FRIDAY AND NEAR 90 BY SATURDAY. MODEL ENSEMBLES SHOW OBVIOUS
DISAGREEMENT AND LARGER SPREAD IN A TRANSITION PERIOD FOR NEXT
WEEKEND, BUT A BUILDING RIDGE TO OUR WEST AND A SLOW WARMING TREND
LOOKS TO BE SLIGHTLY FAVORED. HOWEVER, LATEST ENSEMBLE CLUSTERS
SHOW AROUND 60% OF GLOBAL MEMBERS SUPPORT A TRAILING SHORTWAVE
INTO THE WEEKEND, BUT THIS MAY JUST LIMIT HOW QUICKLY TEMPERATURES
WARM BACK UP.
AVIATION
UPDATED AT 0510Z.
SOUTH-CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
A WEAK UPPER LEVEL LOW PRESSURE SYSTEM WILL MOVE THROUGH THE
DESERT SOUTHWEST OVERNIGHT. MID AND HIGH CLOUDS ASSOCIATED WITH
THIS SYSTEM WILL PERSIST TONIGHT, BEFORE CLEARING OUT MONDAY
MORNING. OTHERWISE, WINDS WILL GENERALLY REMAIN DIURNAL AT ALL
TAF SITES. THERE WILL LIKELY BE A PERIOD OF SOUTHERLY CROSSWINDS
AT KPHX EARLY MONDAY AFTERNOON, THOUGH SPEEDS WILL GENERALLY
REMAIN BELOW 12 KT.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO AVIATION WEATHER IMPACTS ANTICIPATED. MID AND HIGH CLOUDS
ASSOCIATED WITH A WEAK UPPER LEVEL LOW PRESSURE SYSTEM WILL
PERSIST EARLY TONIGHT, BEFORE CLEARING OUT EARLY MONDAY MORNING.
OCCASIONAL BREEZINESS IS LIKELY MONDAY AFTERNOON, PARTICULARLY AT
KBLH WHERE SOUTHERLY WINDS WILL LIKELY REACH 12 KT.
FIRE WEATHER
WEDNESDAY THROUGH SUNDAY:
NEAR NORMAL TEMPERATURES ARE EXPECTED DURING THE MIDDLE OF THE
WEEK, BUT SHOULD GRADUALLY WARM BACK UP DURING THE WEEKEND, WITH
HIGHS RETURNING TO THE LOW 90S AREA WIDE BY SUNDAY. AFTERNOON
BREEZINESS WILL BE COMMON WITH THE TYPICAL UPSLOPE FAVORED AREAS
EXPERIENCING THE STRONGEST GUSTS. STRONGER WINDS WILL BE LIKELY
DURING THE MIDDLE OF THE WEEK YIELDING A PERIOD OF ELEVATED FIRE
DANGER, PRIMARILY WEDNESDAY. DRY CONDITIONS WILL ALSO PREVAIL
THROUGH THE WEEK WITH AFTERNOON MINIMUM HUMIDITY VALUES FALLING TO
NEAR 10% WHILE OVERNIGHT RECOVERY WILL BE POOR ONLY BOUNCING BACK
TO A 25-40% RANGE. THE WEATHER CONDITIONS MUCH OF NEXT WEEK WILL
PROVIDE AN EXCELLENT OPPORTUNITY FOR PRESCRIBED BURNING OPERATIONS
DURING THE MORNING AND EARLY AFTERNOON HOURS.
SPOTTER INFORMATION STATEMENT
SPOTTERS SHOULD FOLLOW STANDARD REPORTING PROCEDURES.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...NONE.
DISCUSSION...BENEDICT/KUHLMAN
AVIATION...HIRSCH
FIRE WEATHER...BENEDICT/MO/KUHLMAN
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