textproduct: Pendleton

KEY MESSAGES

- Dense Fog This Morning.

- Gusty Winds over the eastern mountains Today.

- Rain late Today through the overnight, redeveloping Monday.

DISCUSSION

Mesoanalysis was already indicating patchy dense fog developing over the Kittitas valley/Lower Eastern Cascades slopes of Washington just northwest of Ellensburg to Cle Elum as seen on highway cams and mesonet observations. The deterministic HRRR aggressively develops low visibility through the Kittitas valley by 0400 and removes the fog by 1100. With recent rains leaving the near surface layer cool and moist, and mid levels clouds clearing west to east, monitoring for development of fog and stratus will be an ongoing challenge through about mid to late morning. 24 hour precipitation totals indicated up to a few hundredths across the Columbia Basin of Washington west to the Kittitas valleys and the lower slopes. The Upper slopes of the WA Cascades received between a quarter inch and three quarters of an inch rainfall. Additional rainfalls are expected Tonight as a cold front is driven across these same mountains and valley zones, between about 11 pm and 2 am Tonight, as RRFS forecasts wetting rains in the the 0.10 to 0.50 range on the 6 hourly basis probability matched means. Lighter amounts under 0.10 are expected over the Blue Mountains and Blue Mountain Foothills early Sunday Morning. Breezy to windy conditions are still anticipated associated with this system. Model pressure gradients are the driver for NBM means bringing about 30 to 40 knots gusts by the early evening and remaining breezy through about 3 or 4 am Sunday morning. Beyond the weekend, the trend is for warmer 60s for afternoon highs Tuesday and onward following a relatively cool and wet Monday afternoon. Widespread pops in the 10 to 20 percent range for the Columbia Basin of WA and OR is sandwiched by higher pops across both mountain ranges heading into Monday evening.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/

VFR conditions across most sites, with the only exception being KDLS which is experiencing IFR conditions due to reduced ceilings of 900 feet. This should improve to VFR category ceilings by late morning. Winds will stay light and below 10kts for all terminals through the day, but high winds aloft will lead to shear at around 2kft for KPDT/KALW/KPSC this evening through the overnight period. An incoming system is responsible for these elevated winds, attributing to breezy conditions for KRDM/KBDN tonight as gusts of 20-30kts are expected. There is also a chance for light showers for KPDT/KALW Sunday morning. 75

Preliminary Point Temps/PoPs

PDT 65 44 57 39 / 0 0 30 20 ALW 66 48 57 42 / 0 0 50 10 PSC 59 40 61 37 / 0 10 20 10 YKM 59 40 59 35 / 0 20 0 10 HRI 61 40 60 38 / 0 0 20 20 ELN 54 34 51 27 / 0 40 10 10 RDM 68 39 54 31 / 0 10 10 0 LGD 59 43 51 37 / 0 0 20 10 GCD 67 41 55 36 / 0 0 10 10 DLS 62 44 57 41 / 0 70 10 20

PDT WATCHES/WARNINGS/ADVISORIES

WA...Dense Fog Advisory until 11 AM PST this morning for WAZ026-523. OR...Wind Advisory until 8 PM PST this evening for ORZ049.