textproduct: Pendleton

KEY MESSAGES

1. Dry and warm conditions today ahead of a cold front

2. Breezy to windy through the gaps Monday *Wind Advisory in effect*

3. Increased chances of showers Monday onward

4. Increase chances of thunderstorms Monday afternoon and again Thursday afternoon

DISCUSSION

Current satellite shows mostly clear skies with some high cloud lingering over the region. Temperatures today will remain warm with 80-90% probabilities of low to mid 80s across the Gorge, Basin, adjacent valleys, central OR and the foothills. Elsewhere will be in the mid to upper 70s.

Satellite shows the upper level low has formed off the coast of Canada and steadily moving to the south. Models show ahead of the low, a cold front will pass the area by Monday afternoon. This will bringing increased chances of breezy to windy conditions . A Wind Advisory has been issued for central and north central OR, the Simcoe Highlands of Klickitat County and the Yakima Valley fro sustained winds of 20-30 mph with gusts to 55 mph possible. 70-90% of the NBM ensembles are in agreement. This advisory begins at !! AM Monday through 11 PM Monday. Winds elsewhere will be breezy with sustained winds of 10-15 with gusts to 35 possible, especially along the foothills of southern and northern Blues and through the Kittitas Valley.

The cold front an associated low will also bring with it increased chances of precipitation beginning in the mountains Monday afternoon before becoming widespread in the evening. There is a 30-50% probability of seeing between 0.01-0.03 along the crests of the Cascades and 0.03-0.06 over the Blues through the evening hours Monday. As we move into Tuesday, the area where most precipitation is expected to fall will be along the OR Cascades with up to 0.06- 0.09 inches with 60-80% of the NBM raw ensembles in agreement. The Northern Blues also will see higher amounts of precipitation between 0.05-0.10 inches of rain with also 60-80% probabilities. As we move into Wednesday, models become a bit more spread in their agreement, however, 0.02-0.06 inches of rainfall accumulations are still expected for Wednesday across the Blues. Thursday is expected to be the most active day in the period with highest rainfall amounts over the vast majority of the region. Much of the rainfall is expected through central OR and along the eastern mountains and through Wallowa Valley although models are still a bit spread on rainfall amounts with only 30-50% chances of 0.05-0.09 inches of rain.

Lastly, models show that ahead of the incoming cold front, instability over the area is increasing. Monday afternoon, CAMs forecast soundings show 100-300 J/kg of CAPE intruding into the area over the Cascades. This coupled with orographic lifting could lead to some isolated thunderstorms over the eastern mountains and the Blues after 5 PM Monday night with 15-20% probabilities. Models than show the upper level low dive to the south through Wednesday before traversing back up towards the region causing some wrap around. Models are also showing an increase in instability due to the wrap around of the low with forecast soundings showing CAPE values of 250- 450 J/kg, lapse rates of 7.2 C/km and lifted indices of -4. This coupled with the orographic lift along the mountains could allow for isolated thunderstorms across central OR and the slopes of the Cascades Thursday with 15-20% probabilities.

AVIATION /06Z TAFS THROUGH 06Z TUESDAY/

VFR conditions are expected through the TAF period. The main concern will be gusty winds once again on Monday, with the passage of a cold front. Winds could gust to around 30 kts. CIGS will lower during the day and should be around BKN050 by evening.

FIRE WEATHER

Highest day of concern is Monday when RHs are in the low to mid 20s and winds are sustained at 20-30 mph with gusts to 55 mph. This puts the Basin, isolated locations in central OR around Prineville and Kittitas Valley in elevated fire danger for tomorrow with 5-19% probabilities.

Preliminary Point Temps/PoPs

PDT 51 82 43 62 / 0 0 80 30 ALW 56 84 47 62 / 0 0 60 30 PSC 54 86 45 68 / 0 0 60 0 YKM 52 78 44 69 / 0 0 20 0 HRI 53 83 44 66 / 0 10 70 10 ELN 47 73 40 62 / 0 0 30 10 RDM 45 80 34 59 / 0 0 20 30 LGD 47 86 41 55 / 0 10 60 70 GCD 46 87 39 56 / 0 0 80 70 DLS 54 76 46 69 / 0 0 20 10

PDT WATCHES/WARNINGS/ADVISORIES

WA...Wind Advisory from 11 AM to 11 PM PDT Monday for WAZ027-521. OR...Wind Advisory from 11 AM to 11 PM PDT Monday for ORZ510-511.