Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 272031
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
131 PM PDT Sun May 27 2018

.SHORT TERM...Tonight through Wednesday...A high pressure ridge
continues to amplify across the area this afternoon, with mainly
sunny skies prevailing. Dry/mostly clear conditions will prevail
through Monday night as the ridge axis crosses the area. Periods of
breezy/locally windy conditions can be expected across the Columbia
Gorge and the Kittitas Valley through Tuesday as surface pressure
gradients through the Cascade gaps remain somewhat tight. The ridge
will exit the region Tuesday, with the next trough approaching the
WA/OR coast and a weak surface cold front crossing the region. Not
much deep layer moisture with the surface boundary, thus will keep
all areas dry through Tuesday afternoon. A couple of weak impulses
will rotate around the trough, clipping the area Tuesday night and
Wednesday. Deep layer moisture is still limited, but with some
mid/upper level forcing, will use slight chance to low end chance
PoPs Tuesday night/Wednesday, mainly from a Blue Mountains/Deschutes
county line eastward. Instability will be negligible, thus will keep
thunderstorms out of the forecast. Warm temperatures will prevail
under the ridge through Memorial Day, with a gradual cooling trend
beginning Tuesday, with slightly below normal temperatures Wednesday.


.LONG TERM...Wednesday night through Sunday...Run to run consistency
in the operational models and their ensembles regarding evolution of
the upper trough over the western has been rather poor, reducing
the confidence levels in the extended forecast. 12Z guidance has
trended back toward a less amplified solution than the 00/06Z runs
of the GFS and the 00Z run of the ECMWF with less southwesterly and
more westerly/west-southwesterly flow in the middle of the week. The
net result will be lesser precipitation chances, along with more
limited instability for potential thunderstorms. Currently believe
that precipitation chances will be limited primarily to the
mountains on both Thursday and Friday with all areas staying dry
into the weekend. Very weak instability will be in place over
Wallowa/Grant County Thursday afternoon, but given rather strong
vertical wind profiles think it will probably be tough going for
any convective towers. I retained just a slight chance of thunder
in those areas for Thursday afternoon and removed the remaining
thunder from the forecast package with weak mid-level lapse rates
and no discernible model CAPE the remainder of the week. With
sustained west-southwesterly flow aloft and onshore flow, will see
breezy conditions each day in the Columbia Gorge/Kittitas Valley,
especially in the afternoons.

&&

.AVIATION...00Z TAFs...VFR conditions expected through the next 24
hours with mostly clearly skies. Winds will be 10-15KTs except for
higher gusts at DLS/RDM/BDN this afternoon and again on Memorial
Day.


&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  79  54  83  50 /   0   0   0   0
ALW  81  54  85  52 /   0   0   0   0
PSC  83  56  88  53 /   0   0   0   0
YKM  84  55  84  51 /   0   0   0   0
HRI  83  55  87  52 /   0   0   0   0
ELN  81  52  78  50 /   0   0   0   0
RDM  78  45  81  42 /   0   0   0   0
LGD  73  49  78  45 /   0   0   0   0
GCD  74  48  79  46 /   0   0   0   0
DLS  83  56  80  53 /   0   0   0   0

&&

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

$$

80/74



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