017
FXUS65 KPSR 212322
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
422 PM MST SAT DEC 21 2024
UPDATE
00Z AVIATION DISCUSSION.
SYNOPSIS
WELL ABOVE NORMAL TEMPERATURES WILL CONTINUE, AHEAD OF COOLING
TEMPERATURES AND INCREASED BREEZINESS THROUGH THE MIDDLE PORTIONS
OF NEXT WEEK. WHILE THE WEATHER PATTERN WILL BECOME MORE ACTIVE,
RAIN POTENTIAL WILL CONTINUE TO REMAIN LOW TO VERY LOW ACROSS THE
REGION THROUGH THE MIDDLE OF THE WEEK, WITH HIGH PRESSURE BUILDING
INTO THE REGION BY NEXT WEEKEND.
DISCUSSION
HIGH AMPLITUDE RIDGING CONTINUES TO PERSIST ACROSS WESTERN CONUS
THIS AFTERNOON, WITH ONLY RESIDUAL HIGH CLOUDS IN ASSOCIATION
WITH A WEATHER SYSTEM MOVING THROUGH THE PACIFIC NORTHWEST. NEAR
RECORD TO RECORD HIGH TEMPERATURES WILL CONTINUE TODAY BEFORE
SLIGHT COOLING WILL BRING LOWER DESERT HIGH TEMPERATURES DOWN MORE
TOWARDS THE MIDDLE 70S GOING THROUGH EARLY NEXT WEEK.
THE MID-LEVEL PATTERN WILL TRANSITION FROM HIGH AMPLITUDE RIDGING
TO MORE FLAT RIDGING DUE TO THIS TROUGHING FEATURE TRAVERSING
ACROSS THE INTERMOUNTAIN WEST THROUGH TOMORROW, WITH SOME SLIGHT
BUILDING OF MID-LEVEL HEIGHTS INTO EARLY NEXT WEEK BEHIND THIS
TROUGH. A STRONGER TROUGHING FEATURE WILL ROTATE AROUND THE
ANOMALOUSLY STRONG LOW CENTERED OVER THE GULF OF ALASKA INTO THE
NORTHERN PACIFIC EARLY NEXT WEEK, BEFORE MOVING ONSHORE OF THE
WEST COAST GOING INTO TUESDAY. THIS TROUGH WILL BE MUCH MORE
POTENT THAN PREVIOUS SHORTWAVES, WITH NEGATIVE HEIGHT ANOMALIES
DIGGING INTO NORTHERN ARIZONA BY THE MIDDLE OF NEXT WEEK.
THIS STRONG TROUGH WILL BRING MUCH COOLER TEMPERATURES TO THE
REGION, AS A FRONTAL SYSTEM MAY BRING THE BEST SHOT FOR
RAIN/PRECIPITATION INTO CENTRAL TO EASTERN ARIZONA OVER THE NEXT
SEVEN DAYS. HOWEVER, TEMPERATURES WILL CONTINUE TO RUN ABOVE
NORMAL GOING THROUGH THE MIDDLE OF NEXT WEEK. ENSEMBLES AREN'T
VERY EXCITED WITH MOISTURE LEVELS, AS MEAN PWAT'S TOP OUT AROUND
0.50", THUS CURRENT NBM POP'S AT THIS POINT ARE AROUND 10-20%,
WITH HIGHER CHANCES FAVORING THE USUAL HIGHER TERRAIN AREAS IN
SOUTH-CENTRAL ARIZONA. HOWEVER, THESE POP'S CONTINUE TO RUN HIGH
BASED ON THE SHORTWAVE TROUGH TRAJECTORY AND LACK OF MOISTURE,
THUS POP'S WERE LOWERED AS HAS BEEN DONE IN PREVIOUS FORECASTS.
BREEZY TO WINDY CONDITIONS WILL DEVELOP AS WELL, WITH THE MOST
NOTEWORTHY AREAS BEING THE HIGHER TERRAIN OF SOUTHWESTERN IMPERIAL
COUNTY. NBM PROBABILITIES INDICATE ADVISORY LEVEL WINDS OF 40+
MPH WIND GUSTS ARE LIKELY (70-90%), BUT LOWER DESERT AREAS OF
IMPERIAL COUNTY ARE ONLY AROUND 10-20% OF HAVING 40+ MPH GUSTS
TUESDAY NIGHT.
PREVIOUS DISCUSSION
THE ONGOING WINTER (AND VERY LA NINA-LIKE) PATTERN OF SHORTWAVES
DIGGING AND INTENSIFYING WELL EAST OF THE FORECAST AREA SHOULD
CONTINUE DURING THE LATTER HALF OF NEXT WEEK AS ANOTHER PACIFIC
SHORTWAVE PROGRESSES THROUGH THE FOUR CORNERS AREA. ENSEMBLE
SPREAD GROWS WITH RESPECT TO THE TRAJECTORY OF THIS WAVE WITH SOME
OUTPUT CLIPPING HIGHER TERRAIN OF EASTERN AZ WITH FORCED, MOIST
ASCENT. HOWEVER, THE PREPONDERANCE OF ENSEMBLE SOLUTIONS SUGGEST
THIS WAVE SHEARING EAST INTO A MIDLEVEL HEIGHT WEAKNESS OVER THE
PLAINS WHILE STRONG HEIGHT RISES AND RESUMPTION OF STRONG RIDGING
BUILDS BACK INTO THE SW CONUS. WHILE UNCERTAINTY IS NATURALLY
HIGHER IN A DAY 6- 10 FORECAST LIKELY RESTRICTING THE HASTE AND
MAGNITUDE OF WARMING VIA NBM OUTPUT, CONFIDENCE IS GROWING THAT
ANOMALOUS WARMTH AND NEAR RECORD TEMPERATURES COULD RETURN TO THE
REGION NEXT WEEKEND TO CLOSE OUT 2024.
AVIATION
UPDATED AT 2320Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT; AND
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO AVIATION CONCERNS ARE EXPECTED THROUGH THE FORECAST PERIOD.
WINDS WILL REMAIN LIGHT OUT OF THE WSW AT THE METRO TERMINALS
THIS EVENING ALONG WITH PERIODS OF CALM AND VRB. WINDS WILL RETURN
TO THE E-SE AT KIWA AND KPHX BETWEEN 03Z-05Z. WINDS SHOULD
PRIMARILY REMAIN LIGHT OUT OF THE W-NW AT THE SE CALIFORNIA
TERMINALS THROUGH TONIGHT. SCT HIGH CIRRUS WILL PASS OVERHEAD
BEFORE DIMINISHING IN COVERAGE LATE TONIGHT.
FIRE WEATHER
DRY WEATHER WITH ABOVE NORMAL TEMPERATURES WILL CONTINUE ACROSS THE
REGION THROUGH NEXT WEEK, THOUGH A COUPLE WEATHER SYSTEMS WILL
CREATE AN ENVIRONMENT OF MARGINALLY INCREASING HUMIDITIES. THROUGH
EARLY NEXT WEEK, MINIMUM AFTERNOON RH VALUES IN THE TEENS WILL BE
COMMON FOLLOWING POOR TO FAIR OVERNIGHT RECOVERY OF 20-50%. BY THE
MIDDLE OF NEXT WEEK, MINIMUM VALUES SHOULD INCREASE CLOSER TO 20-
30% WITH OVERNIGHT RECOVERY IN A 40-60% RANGE. WHILE SOME LOCALIZED
ENHANCED BREEZINESS WILL BE POSSIBLE NEXT WEEK ALONG A WEAK COLD
FRONTAL PASSAGE, VERY LIGHT WINDS WILL BE MORE TYPICAL ACROSS THE
DISTRICTS.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...NONE.
DISCUSSION...YOUNG
PREVIOUS DISCUSSION...18
AVIATION... SALERNO
FIRE WEATHER...18
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