Area Forecast Discussion
Issued by NWS Pendleton, OR

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS66 KPDT 180526
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
1026 PM PDT Sun Mar 17 2024

Updated Aviation Discussion

.EVENING UPDATE...The axis of an upper level ridge of high
pressure has settled over the region today. With the ridge
overhead, temperatures at the surface were able to warm into the
lower to mid 70s across portions of the Columbia Basin/Gorge,
central OR, and the John Day Basin. Temperatures were also able to
warm into the 60s across the rest of the lower-mid elevation zones
as well as in mountain valleys. Expect afternoon temperatures
tomorrow to warm another 2 to 4 degrees area-wide, with mostly
clear skies and light winds. Lawhorn/82

.AVIATION...06Z TAFS...VFR conditions to prevail through the
period with mostly clear skies and a few decks of cirrus AOA 25kft
AGL. Winds will be light, less than 12kts, and diurnally driven
through the period. Lawhorn/82

PREV DISCUSSION... /issued 418 PM PDT Sun Mar 17 2024/

.SHORT TERM...Today through Tuesday...The warmest temps of this
ongoing high pressure event are upon us as the ridge axis starts
to settle in right overhead of the forecast area today. Looking at
obs across the CWA this morning, rapid warming can be observed,
with the expectation that the lower Basin will start to see
readings climb up into the 70s later this afternoon. High temp
records are generally not a concern today, however by Tuesday,
that could change as temps start to climb closer to the mid and
even upper 70s.

Confidence in near-record highs by Tuesday is in the moderate to
high range (50-60%), stemming primarily in model underperformance
across the board over the last few days. Opted to blend high temps
with the NBM and NBM 75th percentile to capture slightly warmer
temps, while allowing for somewhat of a hedge given the time of
year. Still, the forecast through the period shows clear skies,
light winds, and overall pleasant weather indicative more of early
May rather than mid-March. Wednesday looks to be the start of a
pattern change as the ridge flattens out due to an oncoming
shortwave. Evans/74

.LONG TERM...Wednesday through Friday...As a upper-level ridge
continues passing over PacNW Wednesday morning, a closed low moves
southwest from the British Columbia coastline Wednesday night
over the Oregon coast by Thursday night. By Friday morning, that
closed low is centered near the Oregon coastline as precipitation
moves across the forecast area. Breezy conditions may develop for
Wednesday late morning into Wednesday night in the forecast area
with a slight chance of windy conditions up to around 40mph
within the Simcoe Highlands (55% confidence). The ensemble means
and deterministic models seem to be in better agreement with the
evolution and direction of the trough (75% confidence).

However, the ECWMF shows wetter conditions sooner Wednesday into
Friday morning whereas GFS favors mainly dry conditions.
Therefore, confidence lowers due to difference in timing with
precipitation (45%). Temperatures remain above normal with high
EFI of 0.7-0.95, showing an anomalous event for maximum
temperatures within the forecast area on Wednesday. Snow levels
will be upwards to 4500-7500ft by Wednesday morning but decreases
to 3500-6000ft Thursday into Friday morning while the closed low
moves near PacNW. Feaster/97

Friday through Sunday...Ensemble and deterministic
models are suggesting a return to an active pattern (75% chance
Friday, 95-100% chance Saturday and Sunday). Greatest precipitation
chances will be in the mountains (70-95%) and along the adjacent
foothills (50-75%) Saturday and Sunday. While snow levels are
forecast to drop to near or below pass levels Saturday and Sunday,
advisory-level snowfall is not anticipated with the highest
probability for the Oregon Cascades (50% chance of occurrence).

Ensemble clusters reveal some differences in the forecast 500 mb
heights over the PacNW Friday (20% chance of a ridge overhead while
the remainder indicate an incoming trough from the Pacific, though
timing varies among clusters). Saturday and Sunday, ensemble members
are strongly suggesting a trough over the PacNW, but there are
notable timing differences among clusters. Of note, 40-45% of
ensemble variance is accounted for by the aforementioned timing
issues.

Regarding any climatologically unusual events, the ECMWF EFI does
not highlight any good ensemble agreement in unusual temperatures,
precipitation, or wind through the period. Plunkett/86

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  41  72  43  74 /   0   0   0   0
ALW  44  74  46  75 /   0   0   0   0
PSC  43  73  45  76 /   0   0   0   0
YKM  41  73  41  75 /   0   0   0   0
HRI  41  74  44  77 /   0   0   0   0
ELN  41  72  42  73 /   0   0   0   0
RDM  35  75  38  75 /   0   0   0   0
LGD  39  72  41  73 /   0   0   0   0
GCD  37  73  38  74 /   0   0   0   0
DLS  45  76  47  77 /   0   0   0   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
&&

$$

EVENING UPDATE...82
SHORT TERM...74
LONG TERM....86/97
AVIATION...82


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.