Sunrise 5:45 AM   Sunset 7:46 PM Moonrise 4:35 PM   Moonset 4:47 AM

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FXUS66 KOTX 201216 AFDOTX

Area Forecast Discussion National Weather Service Spokane WA 516 AM PDT Sat Apr 20 2024

SYNOPSIS
Dry weather conditions will be in place through Saturday. A strong cold front arrives this evening and overnight ushering gusty westerly winds and chance for showers. Mild and dry weather returns for the start of work week with 60s and 70s by Tuesday.
The next cooling trend arrives Wednesday with small chances for mountain showers.

DISCUSSION
Today: It will be a gorgeous start to the weekend courtesy of high pressure aloft and an abnormally dry air mass. Skies are clear this morning and will remain cloud free through the afternoon delivering an abundance of sunshine! Temperatures are also starting off warmer than Friday morning as a light northeast wind continues to blow across the region. The combination of steady winds and the very dry air mass will allow temperatures to warm quickly today with readings into the 60s shortly after noon. Winds will not be as breezy as Friday but steady within the 6 to 12 mph range with direction shifting from northeast in the morning to southeast throughout the day.

This evening - overnight: A strong cold front arrives bringing strong winds and chance for showers. Latest models have sped up the timing of the front now coming across the Cascades in the evening and to the WA/ID border just prior to midnight. This is roughly 2-3 hours sooner than runs were showing last night. There is high confidence for a drastic increase in winds with the frontal passage with speeds sustained winds at least 20 mph. This comes with probabilities of 50-80% or greater. Areas of the Upper Columbia Basin along the Hwy 2 corridor from Douglas to Wilbur to Airway Heights as well as southeastern WA including the Palouse, Foothills of the Blue Mountains, and benches around the L-C Valley will likely experience a few hours of sustained winds of 25 mph or greater (30% chance). Wind gusts of 30-40 mph will be common with and behind the frontal passage with a few gusts of 45 mph possible over the aforementioned windier spots. This also includes the ridgelines and aligned valleys in the East Slopes of the Cascades and into the Idaho Panhandle. Typically, these strongest speeds only last 1-2 hours along and behind the front. With the last 48 hours being very dry ...still thinking patchy blowing dust is a possibility in the Western Basin for early Sunday. Would not rule out minor tree damage (small branches) and a few power outages. The biggest impact will be light weight objects blowing around like garbage cans, lawn furniture, and trampolines.
Saturday will tempting to sit out on the patio and BBQ...Please don't forget to secure those patio umbrellas and other loose items before heading to bed!

As for rain showers, amounts have been lowered and range between a trace to a tenth away from the Cascade Crest. Best chance for a tenth will be the higher terrain of North Idaho and Northeastern WA (70% chance) while the valleys carry less than a 20% chance for a tenth. The Cascade Crest could receive upwards of a quarter of an inch or more with amounts localized under narrow heavier bands.
Snow levels will come crashing down as well falling to 3000 feet by midnight with slushy accumulations possible over Stevens/Washington Passes.

Sunday: Breezy westerly winds will persist on Sunday with constant wind speeds of 10-20 mph and gusts up to 30 mph. Winds will be strongest early in the day and slowly come down as the day wears on. Cold air aloft tracking along the International Border will result in some cumulus buildups and a few shallow showers but little in the way of additional rainfall. NBM carries a 10% chance for a t-storm but this comes with very low confidence as 700-500mb is rapidly drying out and PWATS are crashing back near 0.25" across the Inland NW.

Monday through Friday: High pressure returns to the region early in the work-week bringing another period of warming and drying.
Temperatures for Monday morning will likely start off cool with temperatures in the upper 20s to lower 30s and potential for frost or at least freezing temperatures. Temperatures rebound into the 60s by the afternoon and continue to warm into Tuesday numerous locations across the Inland Northwest showing increasing odds for reaching 70F (50-80% chances). This will come with generally lighter winds. The next Pacific trough arrives middle to late week. A closer examination of the 100 member ensemble shows quite a bit of uncertainty with the track and strength of this wave. At this time, only 30% of the members show the INW receiving precipitation from this feature on Wednesday (mainly comprised of the GEFS members)which only increases toward 37% by Thursday and heavily weighted by the GEFS members. The precipitation is showery in nature and mainly focused over the mountains. Confidence is higher for some degree of cooling with the general pattern shift and potential for an increase in westerly winds. In a nutshell, temperatures peak Tuesday and cool into Thursday with readings not straying very far from the 30-averages. /sb

AVIATION
12z TAFS: Northeast to east winds will prevail through the morning hours. It will remain VFR with high clouds arriving by early evening. A cold front will be arriving this evening with a chance of showers by late evening especially for extreme eastern WA and north ID and a wind shift to west/southwest.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: Low confidence of showers bringing MVFR conditions.

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Confidence descriptors: Low - Less than a 30 percent chance Moderate - 30 to 70 percent chance High - Greater than a 70 percent chance

For additional probabilistic information for NWS Spokane airports, please refer to the Aviation Dashboard on our webpage: https:// www.weather.gov/otx/avndashboard

PRELIMINARY POINT TEMPS/POPS
Spokane 64 39 56 32 60 36 / 0 40 0 0 0 0 Coeur d'Alene 62 39 54 31 59 34 / 0 60 10 0 0 0 Pullman 64 39 53 33 57 36 / 0 40 0 0 0 0 Lewiston 72 46 61 38 65 40 / 0 20 0 0 0 0 Colville 63 35 57 29 62 33 / 0 60 10 0 0 0 Sandpoint 59 39 52 32 57 35 / 0 70 30 0 0 0 Kellogg 62 40 50 34 56 37 / 0 60 20 0 0 0 Moses Lake 69 40 62 34 64 40 / 0 10 0 0 0 0 Wenatchee 64 41 58 37 63 43 / 0 10 0 0 0 0 Omak 65 39 61 34 64 39 / 0 20 0 0 0 0

OTX WATCHES/WARNINGS/ADVISORIES
ID...None.
WA...None.

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