Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 281111 AAA
AFDPDT

Area Forecast Discussion...Update
National Weather Service Pendleton OR
410 AM PDT SAT MAY 28 2016

Update Aviation Discussion

.SHORT TERM...Today through Monday...A northwest flow is setting up
over the CWA behind a departing broad upper trough. This is
resulting in cool and breezy but dry conditions. The only moisture
there is is over the east slopes of the Washington Cascades.
Elsewhere it is dry. This scenario will continue through tonight
except the pressure gradient will weaken and the winds will become
light today. The flow will then become southwest on Sunday as
another upper trough moves across the region. This next upper trough
is fairly week. However...it will bring in some moisture and
instability by Sunday afternoon for a chance of showers and a slight
chance of afternoon thunderstorms on Sunday over the northeast
mountains. There will also be a continued chance of showers over the
Washington Cascade east slopes. Any thunderstorms that develop are
expected to be week...though some could become strong but not
severe. Thunderstorm activity will decrease by late evening Sunday.
It will become breezy to windy again on Sunday as well. On Monday an
upper ridge will build over the region for the beginning of an
extended dry period with a warming trend that will continue in the
extended forecast period. Winds on Monday will be light. 88

.LONG TERM...Monday night through Saturday night...An upper level
ridge will be building over the forecast area Monday night and
Tuesday with rising heights, temperatures and dry weather. On
Wednesday the upper ridge axis is progged to be centered right over
our CWA with 500mb heights topping 580dam. The southerly flow
increases across the area by Wednesday afternoon...and this combined
with increasing mid-level moisture will mean a slight chance of PM
thunderstorms over southern Deschutes county. The remainder of the
CWA should stay dry. Heading into Thursday moisture and atmospheric
instability increase further with a continued southerly flow. Added
a slight chance for afternoon/evening thunderstorms...mainly in the
mountains. Will need to watch this carefully as we draw closer as
some storms may try to move through the Foothills and Basin in the
forecast deep southerly flow. At this time Thursday looks to be the
hottest day next week...with highs reaching 90 to 95 in the lower
elevations with 80s in the mountains. This is about 10-15 degrees
above average. For Friday into Saturday there remains a good deal of
model uncertainty...with the GFS/CMC forecasting a gradual break
down of the upper ridge as a large upper level low approaches from
the North-Pacific. Under this scenario temperatures would gradually
cool each day (but still above average) with continued chances for
afternoon showers and thunderstorms. Meanwhile The Latest ECMWF
(which was treated as an outlier for this forecast package) showed
another upper ridge building over the CWA with temperatures turning
hot once again. Leaned the forecast heavily toward the GFS/CMC
solution as this showed more run to run consistency. 77

&&

.AVIATION...12Z TAFS..VFR conditions will persist at all TAF sites
for the next 24 hours. SCT to BKN high clouds mainly around 20-25K
FT AGL will continue to stream across the area in the northwest flow
pattern through the day on Saturday. There could also be some SCT
mid-level clouds near 7-10K FT AGL at times...especially in the
afternoon. Winds will remain relatively light...AOB 12 KTs through
period at all terminals...except at KDLS where gusts up to 20 KTs
will be possible mainly from 28/20z - 29/04z. 77

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  71  47  73  46 /  10   0  10   0
ALW  71  50  73  51 /  10   0  10  10
PSC  75  50  79  47 /  10   0  10   0
YKM  74  47  76  45 /  10  10  10   0
HRI  75  48  78  46 /  10   0  10   0
ELN  70  48  69  46 /  20  10  20  10
RDM  70  39  73  37 /  10  10  10   0
LGD  66  42  70  44 /  10  10  30  20
GCD  69  41  73  41 /  10  10  10  10
DLS  74  53  74  50 /  10  10  10  10

&&

.PDT Watches/Warnings/Advisories...
OR...None.
WA...None.
&&

$$

88/77/77



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