Area Forecast Discussion
Issued by NWS Spokane, WA
Issued by NWS Spokane, WA
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970 FXUS66 KOTX 012224 AFDOTX Area Forecast Discussion National Weather Service Spokane WA 324 PM PDT Wed May 1 2024 .SYNOPSIS... Tonight will be chilly with the majority of the Inland Northwest falling into the 30s. Scattered afternoon showers will develop over north Idaho and northeast Washington on Thursday and Friday. A slow moving low pressure system will likely bring widespread precipitation over the weekend. Next week looks cooler than average and showery. && .DISCUSSION... Tonight: As of 3 PM, spring showers were detected by radar across northeast Washington and north Idaho. The most concentrated shower activity was over the northern and central Idaho Panhandle where the best combination of low level moisture and orographic lift was present. Surface dewpoints in north Idaho were mainly in the 30s while low to mid 20s were more common across central and eastern Washington. Ongoing shower activity will dissipate early in the evening with the loss of afternoon warming and the continued advancement of dry air into north Idaho. Clearing skies, dry air, and decreasing winds overnight will allow temperatures to tumble into the 30s by morning. Some of protected valley communities like Republic, Springdale, Deer Park, and Colville may dip into the 20s. A Freeze Warning has been issued for Spokane, Coeur d`Alene, Moses Lake, and the Upper Columbia Basin including Ritzville, Wilbur, and Davenport. Climatologically, these communities are in their growing season and there will be pockets of subfreezing temperatures in these zones tonight. Thursday: Our chilly upper level trough won`t move much by tomorrow afternoon, so we can expect another day of spring showers over north Idaho and northeast Washington as well as the high terrain of north central Washington. Similar to today, a handful of lightning strikes will be possible with the strongest cells in Bonner, Boundary, Pend Oreille, Stevens and Ferry counties. Pea hail and wind gusts to 30 mph will also accompany afternoon showers Thursday. High temperatures will trend a couple degrees warmer ranging from the upper 50s in north Idaho to the mid to upper 60s along the lowlands of central Washington. Aside from outflow from afternoon showers, there will be less wind Thursday so that bump in temperatures will be noticeable. Friday: Frost on Friday morning won`t be as widespread with the majority of the Inland Northwest experiencing lows ranging from the mid 30s to the low 40s. Mostly clear skies and light winds in the morning will give way to increasing mid and high clouds in the afternoon. South winds will also increase up the Okanogan Valley and on the Waterville Plateau to 15 to 25 mph in response to an approaching cold front. Afternoon temperatures will be above average with highs in the 60s. Omak, Moses Lake, and Lewiston will flirt with 70. Rain spreading east of the Cascades overnight will be the beginning of what looks to be a wetter and cooler weekend. /GKoch Saturday through Tuesday: A deep upper-level low is on track to approach the WA/OR coast Saturday, gifting all of us here in the Inland Northwest an abundance of weekend rain. The low will move inland rather slowly, and rain will crawl in along with it through the day on Saturday. Temperatures will generally be in the 60s. By Sunday, the low will be entirely over land and rain will be in full swing across the region. Cloud cover and evaporative cooling from the rainfall will send temperatures plummeting into the 40s on Sunday for many locations, and for a few spots, highs may not even break out of the 30s. Pullman has an 80 percent chance of seeing a high temperature below 50 degrees, and a 30 percent chance of a high temperature below 40 degrees. That`s cold for early May! The chance of a high below 50 degrees in Spokane is sitting at 65%, and for Coeur d`Alene, 40%. Exactly how much rain will fall over the Saturday-Sunday timeframe will be dependent on where the deformation band to the north of the low sets up. There are still wide variations among model solutions as to where that band of heavier rainfall will be located. Southeast WA and the central ID Panhandle have a 40 to 50 percent chance of receiving at least 0.5 inches of rain, while the Spokane and Coeur d`Alene areas are looking at a 30 to 40 percent chance of the same. Despite uncertainties in precipitation amounts, confidence is high that Sunday will be at least somewhat wet for nearly all of the region. Should make for great running weather. ;) Temperatures will rebound a little on Monday and Tuesday as the low works its way east of us, but we`ll still remain under the influence of a broader trough which will keep us cool with intermittent showers. Despite the large fluctuations in daytime high temperatures, overnight lows will be consistently in the upper 30s to low 40s through the period. Winds will be breezy Saturday through Tuesday with gusts of 20 to 30 mph. Some of our windier spots including the Palouse and exposed areas of the Basin may see a few gusts to 35 or 40 mph. /Fewkes && .AVIATION... 18Z TAFS: The 500 to 1500 ft stratus that developed locally around Spokane and Coeur d`Alene shortly after sunrise will lift into scattered to broken cumulus deck over north Idaho by 20z as our temperatures warm. While the majority of central and eastern Washington will advect enough dry air through the day to inhibit convective showers, north Idaho will have a 30 to 50 percent chance of showers with the highest concentration of showers between 20z and 02z. /GKoch FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: There is a 10 to 20 percent chance of lightning over the mountainous terrain of north Idaho between 20-02z. A few of the strongest cells may produce pea hail or graupel as well. Given the limited instability and wind shear, cells that become strong enough to produce lightning or pea hail probably won`t last longer than 15 minutes before collapsing. The probability of fog or low clouds Thursday morning will be quite low...less than 10 percent for GEG, SFF, and PUW. The probability for fog/low clouds at our other TAF sites will be near zero probability. /GKoch ----------------------- 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 33 62 37 65 46 67 / 10 10 0 0 10 30 Coeur d`Alene 33 59 37 64 43 66 / 10 20 20 0 0 20 Pullman 30 58 35 63 46 64 / 0 0 10 0 10 40 Lewiston 35 65 40 71 47 68 / 0 0 0 0 10 30 Colville 30 64 34 66 41 67 / 10 20 20 10 10 30 Sandpoint 35 58 38 63 42 65 / 30 40 30 20 0 20 Kellogg 35 55 38 63 44 64 / 20 40 30 20 0 30 Moses Lake 32 67 37 71 52 67 / 0 0 0 0 20 50 Wenatchee 38 66 43 67 51 58 / 0 0 0 0 30 60 Omak 37 67 40 70 49 66 / 10 10 0 0 20 50 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...Freeze Warning from midnight tonight to 9 AM PDT Thursday for Coeur d`Alene Area. WA...Freeze Warning from midnight tonight to 9 AM PDT Thursday for Moses Lake Area-Spokane Area-Upper Columbia Basin. && $$