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FXUS66 KPDT 211730 AAA

Area Forecast Discussion
National Weather Service Pendleton OR
1025 AM PDT Sun Jul 21 2019

updated the aviation discussion

.UPDATE...High pressure continues to dominate the areas weather
with dry conditions and much warmer temperatures are expected as
afternoon high temps climb into the 90s across portions of the
columbia basin. Meanwhile some moisture moves toward central
Oregon later this aftn/eve and combining with daytime heating
could produce an isold tsra over the southern Oregon cascades. 
Some additional moisture tries to move further north overnight 
that may produce some showers over Grant county that could push 
into northeast Oregon toward Monday morning. Otherwise minor 
changes were done to temps and sky and the present short term 
forecast appears on track.

.AVIATION...vfr conditions will persist at all taf sites for the 
next 24 hours. Meanwhile some mid level clouds may move into taf 
sites krdm and kbdn after 06z and then after 10z for the remaining 
taf sites. 


.PREV DISCUSSION... /issued 207 AM PDT Sun Jul 21 2019/ 

SHORT TERM...Today through Tuesday...A challenging forecast is in 
store for the beginning of the coming week. A deep southwest flow 
aloft between an upper high over the southern Rocky Mountains and an 
upper low in the Gulf of Alaska will prevail for the next few days 
keeping a southwest flow aloft over the forecast area. This will 
cause hot air to be pulled into the forecast area from the south. 
With it will be increasing instability and some moisture, especially 
in the afternoons and evenings. Today will be the exception, with 
mostly sunny and dry conditions. There may be a stray thunderstorm 
over southern Deschutes County in the late afternoon, but most of 
the forecast area will not have any. Today's high temperatures will 
be about 8-10 degrees warmer than Saturday. Tonight and Monday 
morning, there will be increasing elevated instability for a slight 
chance of thunderstorms late tonight and early Monday morning. The 
slight chance of thunderstorms will persist all day on Monday as 
instability continues to increase in the southwest flow. 
Thunderstorms will likely linger overnight as nocturnal storms again 
Monday night, into Tuesday morning. Tuesday will be the most active 
day with a slight chance of thunderstorms from morning to night in 
the mountains. The best chance of thunderstorms will be over the 
central and northeast mountains, but there also could be a few 
thunderstorms along the east slopes of the Cascades of both Oregon 
and Washington in the afternoon Tuesday. A cold front will be 
approaching from the west which will push the more moist and 
unstable air to the east heading into the extended forecast period 
(Tuesday night). Monday and Tuesday will be the hottest days with 
high temperatures in the mid to upper 90s in the lower elevations 
and 80s to near 90 in the mountains. It will also become locally 
breezy each afternoon, mainly in the eastern Columbia River Gorge. 
The winds combined with low humidity and the possibility of 
thunderstorms will increase the threat of critical fire weather 
conditions on Monday and Tuesday, mainly in the afternoons and 
evenings. 88

LONG TERM...Tuesday night through Sunday...A strong shortwave 
trough will move across northern ORE/WA Tuesday evening and night 
bringing ample large scale forcing for ascent to the region. There 
will be sufficient elevated instability for at least a few 
thunderstorms for the Columbia Basin eastward to the northeast 
mountains. Have kept POPS mostly at slight chance for now but it is 
possible that pops could be nudged up as the event gets closer. The 
high based nature of the convection and limited QPF may present a 
fire weather concern. It will also become at least breezy Tuesday 
evening and night into Wednesday morning across much of the lower 
elevations which would help spread any lightning ignited fires. Once 
the upper level system passes by...dry weather is expected for the 
rest of the extended period with flat westerly flow. There will be 
occasional breezy periods in the Cascade gaps. Otherwise expect 
temperatures within a few degrees of normal for this time of year. 78


PDT  91  61  93  62 /   0  10  10  10 
ALW  95  65  97  67 /   0  10  10  20 
PSC  94  66  98  67 /   0   0  10   0 
YKM  91  62  96  62 /   0   0  10   0 
HRI  94  64  97  65 /   0   0  10   0 
ELN  90  61  92  62 /   0   0  10   0 
RDM  90  55  91  55 /   0  10  10   0 
LGD  88  62  93  62 /   0  10  20  20 
GCD  96  60  97  59 /   0  10  20  20 
DLS  94  66  93  65 /   0   0  10   0 



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