Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 240522 AAA
AFDPDT

Area Forecast Discussion...Updated
National Weather Service Pendleton OR
922 PM PST Thu Nov 23 2017

Updated Aviation Discussion

.SHORT TERM...Slow moving cold front extends from the Blues to the
John Day highlands this evening. Southwest flow aloft along the
boundary continuing to produce some light rain. Behind the front
satellite shows clearing skies. Occasional light rain will continue
for the remainder of the evening over the eastern portion of the
forecast area. Overnight the front should move east into Idaho. A
weak ridge with drier westerly flow on Friday will bring partly
sunny skies. The airmass is much cooler aloft and highs will be
in the 50s. A surface low pressure system offshore will push a
warm front through the region Saturday with increasing clouds and
a chance of rain. 94

.AVIATION...06Z TAFs...Generally VFR conditions with light winds are
expected through the next 24 hours as transitory ridging builds into
the region Friday. Patchy fog will be possible early Friday morning
in protected valleys and other low spots where cooler air can pool,
but at this time confidence is too low to include any visibility
reductions for any terminals. 74


&&

.PREV DISCUSSION... /issued 400 PM PST Thu Nov 23 2017/

SHORT TERM...Tonight through Sunday night...At 2 PM, the cold front
stretched from near Yakima to The Dalles and should move east of a
line from Joseph to John Day by midnight. Brief showers and breezy
to locally windy conditions will precede and accompany the front
this evening, though rain showers may linger longer in the upslope
areas of west facing Blue Mountains. After the frontal passage,
rainfall should decrease and melting levels lower along the
Washington Cascades, so ending the Flood Watch this evening still
looks on track. For later tonight into early Saturday the area will
be protected from precipitation by a ridge of high pressure. By
midday Saturday, models consistent in showing another surge of
moisture from the southwest. Snow levels to remain generally above
4000 feet during the precipitation, so impacts minimal. Sequence
similar to the past couple days, with mild temperatures and off and
on rain to prevail through Sunday night.

LONG TERM...Monday through Thursday...latest 12Z and 18Z GFS
runs indicate a mid/upper level trough tracking in a more SE
direction into northern California, which is what the ECMWF model
has been indicating since yesterday`s ECMWF runs. As such
precipitation on Monday is going to be mainly a chance of
rain/snow showers in the eastern Oregon mountains with dry
conditions expected across the Lower Columbia basin through Monday
afternoon. A rapidly amplifying mid/upper level ridge of high
pressure then builds over the interior Pacific Northwest Monday
night through Tuesday night for dry conditions.

A rather weak Pacific system moves across the region Tuesday night
and Wednesday and brings mostly cloudy skies, but only a few
sprinkles in the highest mountains. Thursday another mid/upper level
ridge of high pressure moves inland and over the forecast area for
dry conditions.  Polan

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  39  56  34  51 /  70   0   0  30
ALW  41  57  37  53 /  70   0   0  20
PSC  41  58  34  47 /  20   0   0  30
YKM  36  54  32  45 /  20  10  10  40
HRI  38  58  33  48 /  30   0   0  30
ELN  33  51  30  43 /  20  10  10  40
RDM  32  53  30  52 /  60  10   0  40
LGD  38  51  32  48 /  60  10   0  30
GCD  38  51  33  51 /  70  10   0  30
DLS  41  57  35  48 /  30  20   0  50

&&

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

$$

94/74


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