Area Forecast Discussion

KEY MESSAGES

- Warmer temperatures continue through Tuesday, with cooler temperatures to follow by a cold frontal passage in the midweek.

- Widespread 10-25% chances of thunderstorms with isolated to scattered development Tuesday, with much less coverage through the early Wednesday morning hours.

- Breezy to locally windy conditions possible going into Wednesday as the cold frontal system passes through the region.

DISCUSSION

NOW THROUGH TUESDAY MORNING: An overhead ridge is promoting dry and mostly clear conditions through the next 48 hours. Temperatures will continue to trend warmer through Monday with areas in the Columbia Basin reaching the low to mid 80s and mid to high 70s in some of the higher elevated population centers (>90% chances in both scenarios). Winds will remain light and variable for the most part, with a brief 10-20 mph gust possible late Monday into Tuesday morning (40-60% chance).

TUESDAY MORNING THROUGH WEDNESDAY: Model guidance is in very good agreement that the ridge will quickly lose influence by Tuesday morning with a low pressure system embedded with a cold front will push onshore and bring unsettled weather into the region. Sufficient moisture transportation from the south and daytime heating build-up will aid in the development of unstable atmospheric conditions, which includes CAPE values of 150-400 J/kg. NBM is bringing 10-25% chances of thunderstorm development across much of the area Tuesday morning through Tuesday night, with some lingering storms in the Washington Columbia Basin in the early Wednesday morning hours.

After the cold front passes through the area Tuesday morning, tight pressure gradients from the system will stir chances of 30-40 mph wind gusts across the area Wednesday morning into the early evening hours. NBM probabilities currently don't anticipate any decent coverage probabilities of greater than 45 mph gusts on Wednesday. Dropping the threshold to 30 mph or greater yields 20-50% chances across the region. Not super confident in wind advisories criteria yet, but will see how trends continue in the next 48-hours. On the rain side, chances of wetting rain are decent with the greatest 6-hour rainfall amount according to the latest guidance is the early to late morning hours of Wednesday. Wetting rain chances are highest in this period with 50-70% chances across the Northern Blue Mountains & 40-60% chances across the Foothills of the Blues and large portions of the Columbia Basin.

AVIATION /18Z TAFS THROUGH 18Z MONDAY/

VFR conditions are expected through Monday. Winds will mainly be 10 kts or less through the period, though some afternoon breezes could reach the 10 to 15 kt range at times.

Preliminary Point Temps/PoPs

PDT 73 44 77 48 / 0 0 0 10 ALW 73 49 77 52 / 0 0 0 10 PSC 77 45 81 50 / 0 0 0 10 YKM 75 47 79 50 / 0 0 0 10 HRI 75 45 80 49 / 0 0 0 10 ELN 70 45 75 47 / 0 0 0 10 RDM 74 41 75 42 / 0 0 10 10 LGD 68 42 75 44 / 0 0 0 10 GCD 72 44 77 44 / 0 0 10 10 DLS 75 52 79 52 / 0 0 10 10

PDT WATCHES / WARNINGS / ADVISORIES

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