textproduct: Pendleton

KEY MESSAGES

1. Continued rainfall through Wednesday evening

2. Breezy to windy conditions Wednesday

3. Pattern shift will bring drier and below average temperatures.

DISCUSSION

Current radar shows some moderate returns over the Basin with ground observations showing 0.12-0.16 inches of rainfall has fallen between Pasco and Walla Walla in the last hour. Elsewhere, radar shows lighter returns with 0.03-0.07 inches of rainfall in the last hour with higher amounts through Meacham. Rainfall is expected to continue through the day today.

Models show the closed low to be off the coast of northern California with the leading edge spinning directly across the region. Southeast flow is bringing widespread rain across the region currently and models show precipitation to continue through much of the day. Rainfall amounts will vary across the region with heaviest amounts focused across the Blues and portions of the eastern mountains decreasing lightly as we move westward. Lightest amounts will be found through central and north central OR up to the western portion of the Gorge. NBM QPF shows plenty of precipitation available with 60-90% of the NBM raw ensembles showing rainfall totals nearing 1-1.5 inches over the next 24 hours along the crests of the Northern Blues. The foothills show 40-60% probabilities of near an inch of rainfall while the eastern portion of the Columbia Basin sees 40-60% for 0.80-1 inch while the western portion of the Columbia Basin of WA has 40-60% probabilities of seeing near 0.50 inches of total rainfall. Moving to the Simcoe Highlands of Klickitat and Yakima Kittitas Valleys, 40-60% probabilities these areas will see up to 0.40 inches of rainfall. As for central and north central OR, 60-80% chances of 0.01-0.02 inches. A quick note, snow levels have begun to decrease to around 4500 feet and precipitation above that will likely fall as wet snow. A winter weather advisory is in effect for the Northern and southern Blues for 7 to 12 inches and 4 to 8 inches respectively through 8 PM.

A wind advisory is in effect for the Kittitas/Yakima Valleys, Blue Mountain foothills, Columbia Gorge and Basin, North central OR and the Simcoe Highlands of Klickitat County. sustained winds of 25 to 35 mph with gusts of 40 to 55 mph expected. In house models guidance shows a 12-14 mb pressure gradient change over the region will lead in increased winds, especially through the wind prone mountain gaps and foothills. NBM raw ensembles show 70-80% probabilities of the winds occurring with ground observations already showing Kittitas Valley having winds in the 25-30 mph sustained winds and gusts that have already reached 43-45 mph. Winds are expected to remain elevated through 11 PM Wednesday night.

As we move into Wednesday night and Thursday morning the upper level low begins to move inland and over the region. With the low off now to the east and the semi formed Rex block to the west, northerly flow will begin to dominate over the region. Models show much of the precipitation to be tapering off with only a few lingering showers over the Cascades and eastern mountains. As we move into Thursday, drier conditions will begin to dominate and the north flow aloft will usher in colder air. In could calculations show that temperatures will be anywhere from 10-20 degrees below seasonal average with EFI in agreement. Temperatures Thursday and through the weekend will be in the low to mid 50s across a vast majority of the region with 70-80% probabilities and isolated 60s in the Basin. Models show this pattern to persist through Sunday night ahead of another pattern shift. 90

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Conditions range from VFR (most areas) to MVFR and even some IFR across the region as low pressure and rain impact the area. If rain is heavy or steady or enough, then lowered CIGS and/or VSBYS have been the result.

Expect these conditions to remain through the day before improvement to VFR occurs everywhere this evening.

The other story is the gusty winds, mainly from the southwest to northwest across the TAF sites. These winds have beens as high as 40 to 45 kts across the region. Winds will remain gusty through the afternoon and evening hours before decreasing somewhat overnight. However, winds in the 15 to 25 kt range will be prevalent through the overnight hours.

HYDROLOGY

Aerial flood watches are in effect for the northern and southern Blue Mountains and the norther and southern Blue Mountain foothills through Thursday morning. Umatilla at Pendleton and Gibbon is expected to reach minor flood stage Thursday, John Day at Service Creek, Walla Wall near Touchet, Naches near Cliffdell and Naches are all expected to reach bankfull by Thursday as well. Moderate to heavy rains through the area through Wednesday will cause these rivers to rise. 90

Preliminary Point Temps/PoPs

PDT 50 39 59 38 / 100 40 20 20 ALW 50 42 59 39 / 100 50 40 30 PSC 61 42 66 40 / 100 20 20 10 YKM 63 39 67 40 / 80 0 0 10 HRI 55 40 64 39 / 100 20 10 10 ELN 56 39 60 35 / 80 0 0 10 RDM 51 26 62 29 / 60 10 0 0 LGD 45 36 54 35 / 100 90 30 50 GCD 45 31 56 32 / 100 80 0 10 DLS 57 41 66 42 / 80 10 0 0

PDT WATCHES/WARNINGS/ADVISORIES

WA...Wind Advisory until 11 PM PDT this evening for WAZ024-026>029- 521. Flood Watch through Thursday evening for WAZ029. Winter Weather Advisory until 8 PM PDT this evening for WAZ030. OR...Wind Advisory until 11 PM PDT this evening for ORZ041-044-507- 508-510. Flood Watch through Thursday evening for ORZ502-507-508. Winter Weather Advisory until 8 PM PDT this evening for ORZ502- 503.