413
FXUS65 KPSR 180913
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
213 AM MST TUE FEB 18 2025
SYNOPSIS
DRY AND GENERALLY TRANQUIL CONDITIONS WILL BE COMMON OVER THE NEXT
SEVERAL DAYS, WITH TEMPERATURES REMAINING ABOVE NORMAL ACROSS THE
REGION. LOCALLY BREEZY CONDITIONS WILL ACCOMPANY A FEW WEAK
SYSTEMS PASSING OVER NORTHERN ARIZONA THROUGH THE REMAINDER OF THE
WORKWEEK. STRONG HIGH PRESSURE WILL BUILD OVER THE WEEKEND,
PUSHING DAILY HIGH TEMPERATURES TOWARD RECORD TERRITORY BY EARLY
NEXT WEEK.
DISCUSSION
EARLY MORNING UPPER-AIR ANALYSIS REVEALS QUASI-ZONAL FLOW STRETCHED
OUT OVER THE DESERT SOUTHWEST AS A LOW-AMPLITUDE SHORTWAVE TROUGH
MOVES THROUGH THE GREAT BASIN AND INTERMOUNTAIN WEST. THIS SYSTEM
WILL CONTINUE ITS EASTWARD MIGRATION THROUGH THE REMAINDER OF TODAY,
BRUSHING PAST NORTHERN ARIZONA AS IT PROGRESSES. DUE TO THE
CONTINENTAL TRAJECTORY AND WEAK PROFILE OF THIS DISTURBANCE,
MINIMAL CHANGES IN DAY-TO-DAY CONDITIONS ARE EXPECTED FOR MUCH OF
OUR FORECAST AREA. THE ONE EXCEPTION TO THIS WILL BE SEEN OUT
TOWARD THE LOWER COLORADO RIVER VALLEY (LCRV) AND AROUND ENHANCED
TERRAIN FEATURES IN RIVERSIDE AND IMPERIAL COUNTIES, WHERE A
TIGHTENING OF THE PRESSURE GRADIENT WILL HELP TO GENERATE SOME
MARGINALLY GUSTY WINDS (GUSTS 25-30 MPH). HIGHS THIS AFTERNOON
ACROSS LOWER DESERT AREAS WILL CONTINUE TO RUN 5 OR SO DEGREES
ABOVE NORMAL, EVEN WITH LOWERING HEIGHTS ALOFT ASSOCIATED WITH THE
AFOREMENTIONED SHORTWAVE, WITH READINGS RANGING FROM THE MIDDLE
70S IN SOUTH-CENTRAL ARIZONA, TO NEAR 80 FOR SW AZ AND SE CA.
AFTER THE PREVIOUSLY-MENTIONED SHORTWAVE EXITS TOWARDS THE GREAT
PLAINS, HIGH PRESSURE WILL BUILD IN ITS WAKE, KEEPING THE STREAK
OF DRY, WARM, AND MOSTLY QUIET CONDITIONS GOING THROUGH THE MIDDLE
OF THE WEEK. IN RESPONSE TO BUILDING HEIGHTS ALOFT, A SLIGHT
WARMING TREND WILL TAKE PLACE WITH READINGS MORE IN THE UPPER 70S
AND LOWER 80S ACROSS THE LOWER DESERTS ON WEDNESDAY AND THURSDAY.
WHILE THE DESERT SOUTHWEST WILL BE INFLUENCED BY THIS RIDGING
PATTERN, ANOTHER WEAK AREA OF LOW PRESSURE IS EXPECTED TO TRAVERSE
THE GREAT BASIN AND INTERMOUNTAIN WEST, BRINGING SOME SLIGHT
CHANGES TO CONDITIONS TO PARTS OF THE REGION FOR THE LATTER
PORTION OF THE WEEK.
THIS SUBSEQUENT TROUGH, MUCH LIKE THE INITIAL SYSTEM, IS PROJECTED
TO REMAIN OFF TO THE NORTH OF OUR FORECAST AREA, RESULTING IN
MINIMAL IMPACTS FOR THE REGION. HOWEVER, WITH A SIMILAR FORECAST
TRACK COMPARED WITH ITS PREDECESSOR, THIS LOW WILL, ONCE AGAIN,
YIELD LOCALLY BREEZY CONDITIONS ACROSS PORTIONS OF SE CA AND THE
LCRV THANKS TO THE ENHANCEMENT OF THE THERMAL AND PRESSURE
GRADIENTS. SOME MARGINAL GUSTINESS IS SHOWN FOR THURSDAY, BUT
FRIDAY LOOKS TO CONTAIN THE STRONGEST WINDS WITH GUSTS NEAR 30-35
MPH. ENHANCED GUSTS, COMBINED WITH LOW RELATIVE HUMIDITY, AND VERY
DRY FUELS, MAY LEAD TO LOCALLY ELEVATED FIRE WEATHER CONDITIONS
FOR AREAS ALONG THE THE LCRV. DURING THIS TIMEFRAME, TEMPERATURES
ARE NOT EXPECTED TO CHANGE MUCH COMPARED TO THE REST OF THE WEEK,
WITH READINGS GENERALLY REMAINING THE MIDDLE 70S TO AROUND 80
DEGREES.
HEADING INTO TO THE WEEKEND, ENSEMBLES REMAIN IN EXCELLENT
AGREEMENT REGARDING AN UNSEASONABLY STRONG RIDGE BUILDING OVER THE
WESTERN CONUS, KEEPING DRY AND QUIET CONDITIONS IN THE FORECAST
THROUGH THE EXTENDED OUTLOOK. CONFIDENCE REMAINS STRONG EVEN INTO
THE FOLLOWING WEEK THAT THIS HIGH PRESSURE REGIME WILL REMAIN
OVERHEAD, ALLOWING FOR REGIONAL TEMPERATURES TO RISE TO
ANOMALOUSLY HIGH LEVELS, EVEN PUSHING TOWARD RECORD TERRITORY. THE
NBM IS CURRENTLY ADVERTISING LOWER DESERT TEMPS RISING INTO THE
MIDDLE, AND FOR SOME LOCATIONS, UPPER 80S BY MONDAY, A GOOD 10-15
DEGREES ABOVE NORMAL FOR THE TIME OF YEAR. IT IS NOT OUT OF THE
QUESTION THAT SOME LOCATIONS EVEN REACH THE 90 DEGREE MARK FOR THE
FIRST TIME THIS YEAR. FOR PHOENIX, TUESDAY AND WEDNESDAY APPEAR TO
HAVE THE BEST CHANCES OF REACHING THAT VALUE, WITH THE NBM
INDICATING PROBABILITIES OF 40-60%. IF READINGS THAT HIGH COME TO
FRUITION, IT WOULD BE WELL AHEAD OF EARLIEST AVERAGE 90 DEGREE
DAY FOR PHOENIX WHICH IS APRIL 3RD. THANKFULLY, THE EARLIEST 90
DEGREE DAY EVER AT PHX WAS FEBRUARY 17TH OF 2016, SO IT IS SAFE TO
SAY THAT WE WILL NOT BE BREAKING THAT RECORD, AT NOT LEAST THIS
YEAR.
AVIATION
UPDATED AT 0528Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT; AND
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO AVIATION WEATHER CONCERNS ARE EXPECTED THROUGH THE TAF PERIOD
UNDER PASSING HIGH CIRRUS DECKS. WINDS WILL FOLLOW LIGHT, DIURNAL
TENDENCIES, WITH SPEEDS MOSTLY BELOW 10 KTS, WHILE EXTENDED
PERIODS OF CALM OR VARIABLE CONDITIONS MAY OCCUR DURING THE
DIURNAL TRANSITION PERIODS. SOME BREEZY NORTHERLY WINDS WILL BE
POSSIBLE AT KBLH STARTING AROUND 17-18Z WITH A FEW GUSTS UPWARDS
OF 15-20 KTS THROUGH THE AFTERNOON.
FIRE WEATHER
DRY CONDITIONS, WITH MINRH VALUES GENERALLY IN THE MIDDLE TO UPPER
TEENS, WILL PERSIST THROUGH THE END OF THE WORKWEEK. WINDS ACROSS
MOST OF THE DISTRICTS WILL FOLLOW LIGHT AND DIURNAL TRENDS OVER
THE NEXT FEW DAYS, WITH THE ONE EXCEPTION BEING THIS AFTERNOON
ACROSS PARTS OF THE WESTERN DISTRICTS WHERE MARGINAL BREEZINESS
(25-30 MPH) WILL DEVELOP. MORE ROUNDS OF LOCALLY BREEZY
CONDITIONS SHOULD BE ANTICIPATED FOR THESE SAME AREAS DURING THE
LATTER PORTION OF THE WEEK. TEMPERATURES WILL REMAIN 5-10 DEGREES
ABOVE-NORMAL INTO THIS WEEKEND.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...NONE.
DISCUSSION...RW
AVIATION...SMITH
FIRE WEATHER...RW
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