949
FXUS66 KPDT 220956
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
ISSUED BY NATIONAL WEATHER SERVICE SPOKANE WA
256 AM PDT TUE APR 22 2025
SHORT TERM...TODAY THROUGH THURSDAY
KEY POINTS
1. FREEZE WARNING THIS MORNING
2. DRY AND WARM CONDITIONS WITH MOUNTAIN PRECIPITATION RETURNING
THURSDAY.
CURRENT NIGHTTIME SATELLITE SHOWS MOSTLY CLEAR SKIES OVER
THE REGION WITH A FEW POCKETS OF HIGH CIRRUS CLOUDS COMING OFF
THE SOUTHERN AND NORTHERN BLUES.
MODELS SHOW THAT WITH THE CLEAR SKIES OVERNIGHT, BELOW FREEZING
TEMPERATURES (60-80% PROBABILITIES) WILL PLAGUE MUCH OF THE REGION
WITH THE EXCEPTION OF THE BASIN, GORGE AND THE FOOTHILLS OF THE
BLUES. DUE TO THE TIME OF YEAR AND THE CONFIDENCE IN THE SUB
FREEZING TEMPERATURES, A FREEZE WARNING HAS BEEN PUT OUT FOR THIS
MORNING THROUGH 9 AM FOR KITTITAS/YAKIMA VALLEY AS WELL AS THE
FOOTHILLS OF THE BLUES THROUGH 9 AM.
MODELS SHOW THE REGION TO BE UNDER A SLIGHT NORTHWEST FLOW AS AN
UPPER LEVEL WEAK TROUGH MOVES ACROSS THE REGION. THERE IS NO
PRECIPITATION IS EXPECTED WITH THIS TROUGH. 60-80% OF THE RAW
ENSEMBLES SHOW ONLY THE BASIN, GORGE AND AN ISOLATED AREA ALONG
THE FOOTHILLS OF THE NORTHERN BLUES WILL SEE TEMPERATURES ABOVE 60
DEGREES TODAY. MODELS THEN SHOW THE WEAK TROUGH TO SINK FARTHER
TO THE SOUTH WITH SLIGHT RIDGING MOVING BACK OVERHEAD AND
INCREASING THE SURFACE TEMPERATURES BELOW. 60-80% OF THE RAW
ENSEMBLES SHOW THE AFOREMENTIONED AREAS WILL SEE TEMPERATURES IN
THE MID TO UPPER 60S WEDNESDAY WITH SOME ISOLATED LOW 70S IN THE
BASIN. THURSDAY 60-80% OF THE ENSEMBLES SHOW THE BASIN, GORGE,
YAKIMA/KITTITAS VALLEYS AND THE FOOTHILLS WILL SEE TEMPERATURES IN
THE LOW TO MID 70S, WHILE CENTRAL/NORTH CENTRAL OR HAVE A 20-40%
PROBABILITY OF SEEING LOW 70S. LATE THURSDAY EVENING, MODELS SHOW
A SHORTWAVE TO MAKE ITS WAY INTO THE CASCADES BRINGING 20-40%
PROBABILITIES OF 0.05 INCHES OF RAIN TO THE CRESTS OF THE
CASCADES OF OR. WITH THE NBM SHOWING SNOW LEVELS TO BE ABOVE 5600
FEET OVERNIGHT, MUCH OF THE PRECIPITATION WILL FALL AS RAIN BELOW
5600 FEET WITH 0.1 TO 0.5 INCHES (60-80%) ALONG THE HIGHER
ELEVATIONS.
LONG TERM
FRIDAY THROUGH TUESDAY…MODELS ARE ONCE AGAIN CONVERGING
ON A SOLUTION WITH REGARDS TO THE UPCOMING WEEKEND LOW, AFTER HAVING
FLIP-FLOPPED OVER THE LAST SEVERAL NIGHTS. GENERAL CONSENSUS, ACROSS
BOTH ENSEMBLES AND DETERMINISTIC GUIDANCE, NOW FAVORS A CUTOFF LOW
THAT CENTERS ITSELF AROUND THE GREAT BASIN OF NEVADA BEFORE
TRANSPLANTING EASTWARD. NET EFFECT OF THIS WOULD BE PRECIP FOR THE
MAJORITY OF THE FORECAST AREA, WITH SNOW LEVELS GENERALLY ABOVE 5000
FEET, HOWEVER THE MORE SOUTHERLY TRACK OF THIS LOW WOULD LEAVE MUCH
OF THE LOWER BASIN IN A DRY SLOT. ONCE THE LOW MOVES INLAND AND THE
FORECAST AREA FINDS ITSELF WITHIN ITS CENTER, THERE COULD BE ENOUGH
LIFT TO SUPPORT AN ISOLATED WEAK SHOWER IN THE LOWER BASIN, MAINLY ON
SATURDAY, BUT POPS ARE STILL <20%. THE CURRENT TRACK OF THIS LOW
FAVORS PRECIP MORE IN THE MOUNTAINS AND FOOTHILLS, WITH THE LOWER
BASIN NORTHWARD FINDING ITSELF MORE IN THE DRY SLOT OF THIS UPCOMING
SYSTEM.
COULD SEE SOME ISOLATED THUNDERSTORM ACTIVITY ACROSS THE MOUNTAINS
OF CENTRAL AND EASTERN OREGON WITH THE SW FLOW LEADING THIS LOW. THE
WARMING WE’RE EXPECTING THROUGH THE MIDWEEK WILL CERTAINLY HELP
ADD INSTABILITY, BUT AGAIN, SO LONG AS THIS SYSTEM TAKES A MORE
SOUTHERLY TRACK, WE SHOULD EXPECT TO BE SPARED FROM THE BRUNT OF
THIS SYSTEM’S IMPACTS. EVEN QPF ISN’T ALL THAT IMPRESSIVE, WITH NBM
PROBABILISTIC GUIDANCE SUGGESTING ONLY ABOUT A 30-40% CHANCE FOR
AT LEAST A QUARTER OF AN INCH EVEN IN THE HIGH MOUNTAINS. SO UNLESS
THIS SYSTEM SHIFTS IN A WAY THAT PROVIDES FOR US A MORE FAVORABLE
MOISTURE ADVECTION OR INSTABILITY SCHEME, EXPECT THIS TO MORE OR LESS
BE A TYPICAL SPRINGTIME SYSTEM, WITH BREEZY GAP WINDS AS THIS
SYSTEM TREKS THROUGH THE PACNW.
ENSEMBLES GENERALLY DEPICT A BENIGN PATTERN TO KICK OFF NEXT WORK
WEEK, WITH CLUSTERS LEANING TOWARDS A RIDGE BUILDING OVERHEAD AND
TEMPERATURES RISING BACK INTO THE 70S ACROSS THE LOWLANDS. SOME
ENSEMBLE MEMBERS DEPICT A MORE ZONAL UPPER-LEVEL PATTERN, WHICH
COULD INHIBIT WARMING, BUT NBM FOR NOW SUGGESTS A WARMING TREND
NEXT WEEK. EVANS/74
AVIATION...12Z TAFS
VFR CONDITIONS EXPECTED. OUTSIDE OF SOME
FEW LOW TO MID-LEVEL CLOUDS ALONG THE FOOTHILLS OF THE WA CASCADES
AND BLUES, EXPECT MOSTLY CLEAR SKIES AND LIGHT WINDS LESS THAN 10
KTS. WINDS WILL BE TERRAIN-DRIVEN AT NIGHT, AND FLOW MOSTLY OUT
OF THE N AND NW DURING THE DAY. EVANS/74
PRELIMINARY POINT TEMPS/POPS
PDT 62 36 66 39 / 0 0 0 0
ALW 61 39 68 41 / 0 0 0 0
PSC 66 36 71 38 / 0 0 0 0
YKM 65 36 69 40 / 0 0 0 0
HRI 66 36 70 38 / 0 0 0 0
ELN 62 36 67 38 / 0 0 0 0
RDM 61 28 65 31 / 0 0 0 0
LGD 59 32 63 33 / 0 0 0 0
GCD 60 31 65 33 / 0 0 0 0
DLS 67 40 71 42 / 0 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
OR...FREEZE WARNING UNTIL 9 AM PDT THIS MORNING FOR ORZ507.
WA...FREEZE WARNING UNTIL 9 AM PDT THIS MORNING FOR WAZ026-027-029.
SHORT TERM...90
LONG TERM....74
AVIATION...74
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