Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 310957
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
255 AM PDT TUE MAY 31 2016

.SHORT TERM...Today through Thursday night...An upper level ridge is
building over the area with only scattered cirrus rotating through
early this morning. This trend will continue with skies remaining
mainly clear through the day areawide. Temperatures will be above
average with highs reaching into the 80s in the lower
elevations...or about 5-10 degrees warmer than Monday. Winds will
remain light through the day...generally less than 15 MPH. The upper
ridge remains in place tonight with mainly clear skies and
seasonable overnight lows. The ridge then begins to flatten out on
Wednesday as a weak disturbance moves by in the westerly flow.
Models are indicating marginal instability over the eastern
mountains Wednesday afternoon and evening...therefore continued with
a slight chance of showers and thunderstorms here. Temperatures will
warm several degrees Wednesday with highs reaching the mid-80s to
lower 90s in the valleys/basins. West to northwest winds will also
increase on Wednesday...becoming breezy at 15-25 MPH in the
afternoon. A zonal flow with another weak shortwave is progged to
move through once again Wednesday night into Thursday morning. This
system is forecast to have higher amounts of mid-level moisture and
could initiate some showers along the East Slopes of the Washington
Cascades and possibly even the northern Blue Mountains due to a
westerly upslope flow. On the other hand the strong westerly flow
will keep conditions dry elsewhere due to downsloping(including the
Yakima, Kittitas Valleys & Lower Columbia Basin). Cloud cover was
bumped up to partly to mostly cloudy on Thursday and temperatures
will fall back several degrees compared to Wednesday. It will likely
be breezy again on Thursday...especially in the afternoon. Heading
into Thursday night another upper level ridge begins to quickly
build over the area. This should allow skies to become mostly clear.
This ridge will be responsible for increasing heat into the extended
period. 77

.LONG TERM...Friday through Tuesday...The region will be entrenched
at the northern periphery of s very strong upper level ridge through
the upcoming weekend. The flow at the mid levels will gradually back
from the west on Friday to the S/SW by Sunday which will result in a
slow increase in layer moisture. However...with a strong cap
remaining in place at least through Saturday...will keep all areas
dry through the first half of the weekend. A few high-based tstms
producing limited rainfall may be possible Sunday aftn...will keep
slight chance PoPs for the higher elevations Sunday aftn/evening.
This will leave the main forecast concern the heat. Models are
beginning to get in better agreement...with the first summer-type
heat event becoming likely. Highs Friday will be 10-15 degrees above
normal with the lower elevations mainly around 90. The heat will
intensity Saturday/Sunday as the ridge axis moves overhead...with
temperatures at 850 mb rising to 21-23C Saturday and to 23-26C
Sunday. The result will be the hottest temperatures of the season
thus far...with record highs likely both days. Columbia basin and
Blue Mtn foothills high temperatures will rise to 95-100
Saturday...and to 100-105 Sunday. The higher elevations will not be
spared from the heat...with 85-95 for most locations. Record highs
for Saturday through Monday are listed below...

              Saturday 6/4       Sunday 6/5        Monday 6/6

PDT           98 (1969)          95 (1957)         94 (1972)
ALW           98 (1969)          96 (1973)         94 (1972)
YKM           95 (1978)          98 (1949)        100 (1949)
PSC          100 (1969)          98 (1949)         99 (1949)
RDM           95 (1969)          92 (1973)         92 (1949)
JDAY          97 (1970)          96 (2000)         99 (1970)

For Monday/Tuesday...The ridge will nudge to the east...with a
little more moist SW flow across the region. With some residual cap
remaining...do not expect a significant coverage of showers and
storms...with mainly aftn/early evening activity in the mtns. Will
keep PoPs slight chance to low end chance. Hot temperatures will
persist Monday with another day of around 100 for the
basin/foothills. 90s will prevail for the lower elevations on
Tuesday.

&&

.AVIATION...12Z TAFS...VFR conditions will prevail for the next 24
hours. Winds will generally remain below 10 KT.

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  82  50  86  57 /   0   0  10  10
ALW  82  55  86  60 /   0   0  10  10
PSC  86  52  91  61 /   0   0   0   0
YKM  85  52  88  58 /   0   0   0   0
HRI  85  50  90  59 /   0   0   0   0
ELN  84  50  84  57 /   0   0   0  10
RDM  84  47  85  50 /   0   0  10  10
LGD  77  45  82  53 /   0   0  20  10
GCD  82  47  87  51 /   0   0  20  10
DLS  90  56  87  60 /   0   0   0  10

&&

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

$$

77/80/80



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