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Area Forecast Discussion (AFD)

Issued by Pendleton, OR (PDT)

                            
000
FXUS66 KPDT 230627 AAA
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
1010 PM PST Fri Feb 22 2019

updated the aviation discussion

.UPDATE...The latest radar was showing a band of precipitation 
over the blue mountains and its foothills. In the blue mountains
light snow was accumulating and this will continue tonight and a
winter storm warning remains in effect in this area for the next
several days. Elsewhere and along the foothills of the blue
mountains rain may mix with the snow at times. The snow will 
expand into the grande ronde valley and the wallowa region 
overnight. The greatest chances of pcpn will occur in the 
mountains that also includes the wa/or cascades. The bulk of the 
pcpn drifts south and into the ochoco mountains and john day 
valley later tonight. Although there may be a brief break in the 
pcpn tomorrow...light snow will persist and increase in intensity
and coverage Saturday afternoon and night when additional winter 
weather warnings go into effect. Some changes were done to wx and 
pops along with sky and qpf tonight and temps are expected to fall
into the 20s with teens in the mountains.

.AVIATION...lcl mvfr conditions with lowering ceilings and vsby 
can be expected especially in showers that will increase in coverage 
and intensity after 15z in krdm and kbdn and then the remainder of 
the taf sites after 18z.

&&

.PREV DISCUSSION... /issued 213 PM PST Fri Feb 22 2019/ 

SHORT TERM...Tonight through Monday...Initial wave of 
precipitation associated with approaching cold front has arrived 
in the Cascades this afternoon. Through midnight tonight 
accumulations above 1 inch will be limited to the immediate 
Cascade crest and eastern mountains where 4 to 10 inches will be 
possible, with the highest amounts in the northern Blues between 
Tollgate and Ski Bluewood. Precipitation shadowing will limit any 
accumulation potential in the Columbia Basin to a trace. The cold 
front will continue to sag south overnight and into Saturday 
morning and will be the major focus for significant snowfall 
Sunday into early next week as it drifts back to the north. 
Moisture streaming over this boundary will create conditions 
favorable for near continuous, relatively light snow with an 
increase in intensity expected during the day Sunday and again 
early Monday morning as a more substantial plume of moisture 
arrives. This heavier precipitation will primarily impact the 
Cascades, north central/central Oregon, the Columbia River Gorge 
and Simcoe highlands. Models have converged enough on this 
solution to issue long duration Winter Storm Warnings for the 
Cascades, central/north central Oregon, the Columbia River Gorge, 
Simcoe Highlands, Blue Mountains and Wallowa County valid through 
early Wednesday morning. While surface temperatures may be 
marginal for accumulating snow especially during the afternoons we
are expecting storm total snow amounts in these areas of 10 to 20
inches. The warning for the northern Blues will go into effect 
tonight where low end warning amounts with the aforementioned 
front will occur in additional to the long duration snow Saturday 
night through Wednesday morning. Will leave current watches in 
effect or issue new watches for the remainder of the area where 
confidence in significant travel impacts with a long duration snow
event are lower. Peck

LONG TERM...Monday night through Friday...Active weather pattern 
will persist through mid week as a frontal boundary meanders north 
and south across the forecast area. Used an ensemble approach for 
much of the forecast due to the uncertainty and spread exhibited in 
the deterministic models. Monday night and Tuesday a warm front will 
be lifting north across Oregon into southern Washington with 
moderate to locally heavy snow along and north of the boundary. 
Accumulations could be significant especially in the mountains. 
Lower elevation accumulations could be tempered a bit by marginal 
temperatures...but could still accumulate in the colder areas and 
under the heavier snow bands. Wednesday the front will begin to sag 
sewd as a cold front with the heaviest snow over the eastern 
mountains. By Thursday most of the precipitation will have ended. 
Friday looks mostly dry and cold with much below normal 
temperatures. 78

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  27  35  25  31 /  50  10  60  80 
ALW  28  36  25  33 /  80  20  30  50 
PSC  23  34  25  32 /  20   0  30  40 
YKM  17  33  23  32 /  10  20  40  50 
HRI  28  37  26  33 /  20  10  40  70 
ELN  18  32  19  31 /  20  30  50  40 
RDM  27  40  30  40 /  30  40  70  70 
LGD  25  35  26  37 /  80  60  70  80 
GCD  27  36  30  39 /  70  60  80  90 
DLS  29  40  30  35 /  50  30  70  80 

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Winter Storm Warning from 4 PM Saturday to 4 AM PST Wednesday 
     for ORZ503-508>511.

     Winter Storm Watch from Saturday afternoon through late Tuesday 
     night for ORZ044-505>507.

     Winter Storm Warning from 10 PM Saturday to 4 AM PST Wednesday 
     for ORZ041-050.

     Winter Storm Warning until 4 AM PST Wednesday for ORZ502.

     Winter Storm Watch from Saturday evening through late Tuesday 
     night for ORZ049.

WA...Winter Storm Warning from 10 PM Saturday to 4 AM PST Wednesday 
     for WAZ024-520-521.

     Winter Storm Warning until 4 AM PST Wednesday for WAZ030.

     Winter Storm Watch from Saturday evening through late Tuesday 
     night for WAZ026>029.

&&

$$

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