Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 050345
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
845 PM PDT Tue Aug 4 2020

.UPDATE...
Another quiet night across the Pacific Northwest. The only clouds
evident on satellite are across the Ochoco-John Day Highlands.
Only made minor tweaks to temps, as the current forecast is on
track.


&&

.AVIATION...
06Z TAFS...VFR through the period. There will be late
afternoon/evening TSRA mainly over the mountains and in central
Oregon on Wednesday. However, probabilities are fairly low, and
will most likely be east of the TAF sites so will not include in
any individual forecast. The TAF locations that would have the
best chances (however low they may be) of seeing TSRA would be
BDN, RDM and ALW. Any location that would see TSRA could see
locally reduced CIGS, VSBYS and gusty winds.

Otherwise, expect winds mainly 10 kts or less tonight. Wind will
increase during the day Thursday and become gusty at DLS, in the
25 to 30 kt range, and 15 to 20 kts at PDT, RDM and BDN.

&&

.PREV DISCUSSION... /issued 411 PM PDT Tue Aug 4 2020/

AVIATION...
00Z TAFS...VFR conditions will prevail through the period, with
one potential exception. There is a low chance of afternoon and
evening TSRA on Wednesday mainly over the mountains, but the
chance exists at RDM, BDN and can not be ruled out at PDT or ALW
even though the activity would most likely be east of those areas.
However chances are low enough to not include in the individual
TAF sites at this time. Any TSRA that do occur could bring reduced
VSBYS or CIGS for a short period of time and gusty winds. Outside
of this activity conditions will be VFR.

Winds are a bit gusty at RDM and BDN today and these should
subside this evening.  There will be gusty afternoon winds 25 to
30 kts at DLS and around 20 kts at PDT, BDN and RDM on Tuesday.
Otherwise, winds should be 10 kts or less.

PREV DISCUSSION... /issued 153 PM PDT Tue Aug 4 2020/

SHORT TERM...Tonight through Thursday night. Clear skies over the
Pacific northwest early this afternoon. Weak instability over
central Oregon associated with an upper low along the California
coast. Expect scattered cumulus development through the afternoon
into the evening. This should dissipate after sunset with mainly
clear skies overnight. The California system will move across the
region on Wednesday. Models remain consistent with a chance of
afternoon and evening thunderstorms over central and northeast
Oregon. Remainder of the forecast area will be mostly sunny and
warm with highs in the upper 80s and 90s. Westerly surface winds
will begin to increase in the afternoon along the Cascade east
slopes. A larger upper level trough moving out of the Gulf of
Alaska will then cross the region Wed night and Thursday. Partly
cloudy skies with cooler temps. A chance of showers along the
Cascades. Winds will increase becoming breezy to windy. 94

LONG TERM...Friday through Tuesday...Models in good agreement in
overall weather pattern through the period.  General upper level
zonal flow will continue through Monday with a few weak disturbances
embedded within this flow. At this time, the lower atmosphere will
remain too dry for any type of convection with these disturbances.
By Tuesday, the upper level flow turns more southwest as a trough
moves south from BC.  There are some minor spatial differences
between the models with the ECMWF a little farther north. Despite
this, there could be a few showers over the Washington Cascades
Tuesday afternoon.  Elsewhere, the weather will remain dry. Daytime
highs will begin the period below normal but will warm to near
normal Saturday and continue near normal through Tuesday.  Earle


FIRE WEATHER...Chance of thunderstorms Wednesday afternoon
through late evening from central Oregon Cascades across the John
Day highlands into the Blues and Wallowa mountains. Current
forecast is for LAL of 2/3. Increasing westerly winds late
Wednesday becoming breezy to windy on Thursday for the Columbia
basin and adjacent valleys into north central Oregon. Temperatures
will be significantly cooler with higher humidity this day
however this will still elevate fire danger.

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  59  94  60  81 /   0  10  10  10
ALW  61  96  62  84 /   0   0  10  10
PSC  57  98  63  87 /   0  10  10  10
YKM  59  95  57  82 /   0   0  10  10
HRI  60  97  63  85 /   0  10  10  10
ELN  58  90  57  74 /   0   0  10  10
RDM  51  88  48  75 /  10  20  20  10
LGD  54  92  57  79 /   0  20  30  20
GCD  54  93  55  80 /  10  20  30  10
DLS  62  88  61  77 /   0   0  10  10

&&

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

$$

77/81/77


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