textproduct: Pendleton

KEY MESSAGES

1. Thunderstorms chances this afternoon

2. Dry and above normal temperatures through the week

3. Pattern change next weekend will bring precipitation back to the region

DISCUSSION

Current satellite shows mostly clear skies over the forecast area. Some cumulus are beginning to pop up over the ridgelines of the eastern mountains and central OR. The upper level low has moves south of the region but is still slightly influencing the southern portion of the region. Radar shows a few returns with a cell that has embedded lightning flashes within. Otherwise, clear skies and dry conditions will persist through the day today.

Models show the upper level low to be to the south of the region with some upper level flow influencing portions of central OR. CAMs models show there to be increased probabilities of 10-20% for thunderstorms through central OR and portions of the eastern mountains today beginning after 2 PM and persisting through 9 PM. An unstable atmosphere coupled with forecast model soundings showing MUCAPE values between 800-1200 J/kg, lifted indices between -3-(- 5), lapse rates of 8.5-9.5 C/km with effective bulk shear of 10-20 kts, thunderstorms cannot be ruled out.

Deterministic models show the upper level low to continue to move east lessening its influence of the region each day. Models also show an upper level ridge moving into the region as well. This will keep the region under dry and warming conditions. Yesterday saw a temperature record broken at Pasco and based on persistance and ensembles, chances of seeing the record break again to day with a high of 91 in Pasco is 20-40%. As for the remaining areas, in house calculations show much of the region to be 15-20 degrees above seasonal normal with some areas seeing s high as 25 degrees above normal. Temperatures today will be in the upper 80s to low 90s through the Basin, Gorge, Yakima/Kittitas Valleys and along the foothills of the Blues with 80-90% of the raw ensembles in agreement. The remainder of the region will see low to mid 80s with mid 70s along some of the higher terrains. These conditions will persist through the week with high confidence (70-90%).

Models are in some agreement with a pattern change expected to arrive Friday. Clusters show that the main area of disagreement is with the position and timing of the system. Models show there to be increased chance of precipitation along the Cascades and an increase in winds as the system moves across the region. Confidence in the pattern change is moderate (60-70%) with confidence in the precipitation and the increased winds being low/moderate (40-60%). NBM also shows the system will bring temperatures down a bit with in house calculations showing temperatures to be 5-7 degrees above seasonal normal.

AVIATION /00Z TAFS THROUGH 00Z TUESDAY/

VFR conditions will persist through the forecast period. CIGs will be SKC for many sites with BDN/RDM seeing mid level clouds as the Cu field builds. Winds will be light and below 10 kts except around thunderstorms. KRDM/KBDN are experiencing breezy winds between 10-12kts with gusts 15-20 kts. BDN/RDM will see a slight chance (10-20%) of isolated thunderstorms developing and persisting through 9 PM. 90

Preliminary Point Temps/PoPs

PDT 52 83 52 79 / 0 0 0 0 ALW 56 83 54 79 / 0 0 0 0 PSC 53 89 53 85 / 0 0 0 0 YKM 55 88 55 85 / 0 0 0 0 HRI 52 87 53 84 / 0 0 0 0 ELN 51 83 51 79 / 0 0 0 0 RDM 43 81 44 78 / 20 0 0 0 LGD 48 78 49 75 / 10 0 0 0 GCD 45 78 47 76 / 20 0 0 0 DLS 58 85 56 83 / 0 0 0 0

PDT WATCHES/WARNINGS/ADVISORIES

WA...None. OR...None.