textproduct: Pendleton

KEY MESSAGES

- Hot and dry conditions continue through the next week.

- Chance of widespread moderate HeatRisk and slight chance of major HeatRisk going into mid next-week possible.

- Slight chances (10-20%) of isolated thunderstorms possible through the Blue Mountains Monday to Wednesday.

DISCUSSION

Satellite and radar continue to show our expected dry weather conditions continue through the afternoon hours through tonight. The synoptic pattern will continue to be influenced with southwest flow aloft with a trough and low pressure system situated over British Columbia. This will allow to keep our temperatures steady over the weekend to near normal values in the mid 80s to low 90s through most of the lower elevated areas. Tight pressure gradient development from the oncoming trough will bring breezy winds through the Columbia Basin and Kittitas/Ellensburg region (40-70% chance) through the next several days, bringing elevated fire weather concerns across the area. Guidance is in good agreement that the trough just off the coast will retract into British Columbia by Sunday afternoon to early evening, allowing winds to not be as breezy as it will be previously (70-80% chance).

After the trough retracts, a ridge will be situated over much of the Great Plains through the four corners, allowing the ridge to influence the pattern more. This will actually allow mid-level monsoonal moisture from Mexico to wrap around into the region by late Monday through Wednesday, allowing 10-20% chances of an isolated thunderstorm possible through the Blue Mountains and Eastern Mountains. The synoptic pattern becomes a bit more unclear going through mid next-week, with models struggling to determine the strength/location of the ridge encompassing most of the lower-48 and a shortwave still situated off the coast still bringing mostly southern wind flow aloft. A stronger/closer ridge dominated set-up will allow temperatures to climb above 100 degrees in places of the Columbia Basin (10-30% chance) while a more trough influenced pattern would allow a more 'cooler' set-up. Regardless, meteograms for both the ECMWF and GFS are in great agreement that at least a warming trend will initiate through next week, tho to the extent is still uncertain as mentioned earlier. Notably, widespread chances of moderate HeatRisk with a >60% chance develop Tuesday through Thursday, with widespread 30-50% chances on Friday. Major HeatRisk chances go up to 35% in most places by Wednesday and Thursday, with isolated areas reaching 45% chances of development. Will be a set-up to pay attention to see if HeatRisk will play an issue next week, but the likely scenario at this point is that moderate HeatRisk will develop Tuesday through Thursday and possibly Friday.

AVIATION /00Z TAFS THROUGH 00Z SATURDAY/

00Z TAFS...VFR conditions are expected through the TAF period. At DLS, PDT, RDM, BDN winds will gust 20-25 kts this afternoon evening before decreasing to 10 kts or less overnight. Winds will will increase again to around 20 kts at PDT, RDM and BDN on Saturday afternoon and 20 to 25 kts at DLS. All other sites will be 10 kts or less throughout the period.

Preliminary Point Temps/PoPs

PDT 56 87 57 85 / 0 0 0 0 ALW 62 90 62 87 / 0 0 0 0 PSC 60 92 61 89 / 0 0 0 0 YKM 57 90 58 89 / 0 0 0 0 HRI 60 90 60 88 / 0 0 0 0 ELN 54 83 52 82 / 0 0 0 0 RDM 47 88 52 88 / 0 0 0 0 LGD 55 95 57 89 / 0 0 0 0 GCD 54 97 56 92 / 0 0 0 0 DLS 59 85 60 88 / 0 0 0 0

PDT WATCHES/WARNINGS/ADVISORIES

WA...None. OR...Heat Advisory until 7 PM PDT Sunday for ORZ050.