Area Forecast Discussion
Issued by NWS Spokane, WA
Issued by NWS Spokane, WA
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518 FXUS66 KOTX 112219 AFDOTX Area Forecast Discussion National Weather Service Spokane WA 319 PM PDT Tue Jun 11 2024 .SYNOPSIS... This afternoon and evening will be windy raising concerns of isolated power outages, rough water on area lakes, and the heightened potential for grass fires. Another cold front is expected to bring more breezy conditions Friday and Saturday. The weekend will be cooler along with the chance of mainly mountain showers. && .DISCUSSION... Rest of today through Thursday afternoon: Warm, dry, and windy conditions will continue through the rest of the afternoon and into the evening hours, raising concerns of rapid spread of new fire ignitions. Dry grasses and brush in places that haven`t gotten rain recently like Grant, Chelan, and Douglas counties will be of particular concern today. GOES low level water vapor imagery shows very dry air aloft and mountain waves - a sign of the dry and windy conditions out there. Vigorous showers have mostly stayed in Canada as dry air entrainment has mostly kept terrain based cumulus under control. The mid level speed max will stay in our area this evening, keeping breezy conditions around in the higher peaks overnight. Still, an isolated lightning strike cannot be ruled out in northeastern Washington. Fair to poor RH recoveries are forecasted given little decoupling of the boundary layer tonight. Sheltered valleys (Deer Park and Priest lake areas) have the best shot at some decent humidity recoveries tonight. Tomorrow`s temperatures will be much closer to normal (in the 70s and low 80s) following the frontal passage. PWATS will drop to 40 to 60% of normal as well. Tomorrow will be even drier but far less windy. Overall expecting a gorgeous day. My concern for frost in the sheltered valleys of northeastern Washington tomorrow night is increasing given very dry air and calm winds forecasted. Some guidance is explicitly forecasting a low of 32 degrees for Deer Park (MOS guidance, which handles these situations well usually). Will hold off on frost products for now but definitely something to watch. Temperatures rebound into the lower 80s Thursday as a shortwave ridge builds in the interior Northwest. Light winds forecasted will pose a minor HeatRisk - a level of heat that impacts extremely sensitive populations when outdoors without effective cooling and/or adequate hydration. /Butler Thursday night to Tuesday: The next system starts to move in with cooler temperatures, breezy to windy conditions and, for some, a chance of showers and thunderstorms and even be some high terrain snow. Patchy frost is also possible in some of the sheltered northern valleys in the morning early next week. First Thursday night into Saturday a couple shortwave disturbances pivot around the approaching low and cross the region, thickening clouds and another increase in winds. Winds start increasing overnight into Friday morning near the Cascades and increase throughout the region heading through the day, peaking once in the evening, subsiding some overnight and then increasing again through Saturday afternoon. Speeds of 15-30 mph, with gusts of 30 to 40 mph will be possible, strongest around the lee of the Cascades through the Waterville Plateau and Upper Columbia Basin. In terms of fire weather concerns, afternoon RH values will hover near critical values, similar to today (Tuesday), especially Friday so this will be monitored. Wind gradually decline late Saturday night into Sunday morning. Precipitation-wise, the main precipitation chances lay near the Cascade crest Friday and perhaps skimming near the Canadian border. By Saturday the atmosphere moistens up some and the threats of showers expands over most of the Cascades and northern mountains and central Panhandle mountains, with a risk for snow in the higher terrain. Some snow may be found near Washington Pass and a rain/snow mix could even be seen near Stevens and Sherman Pass. Shower chances were expanded to include the northern Basin into the Spokane/C`dA area and the northern Palouse. Thunderstorms are possible around the NE WA and ID Saturday afternoon too. Some could be locally stronger and could enhance the synoptic scale winds. All of this combined will be another fire weather concern. Sunday to Tuesday the area remains in a troughy pattern, but models still do not have a good handle on the details. Overall it continues to favor shower chances around the mountain zones and at least a slight chance around the eastern third of WA and lower ID, especially late Sunday to Tuesday. As the models start to settle on a solution confidence in who will have the higher risk will start to come into focus. A limited risk for t-storms will linger over the northern mountains too each afternoon. Wind will still remain a bit breezy, but not as much as previous days with gusts near 10-20 mph strongest near the Cascades to Waterville Plateau. Afternoon RH values will be a bit higher than earlier in this period. As for temperatures they begin to drop heading into Friday and especially Saturday into Sunday. Highs on Friday are forecast in the 70s to near 80, then 60s to mid-70s for the weekend, warming a couple degrees Monday and Tuesday. Lows are forecast to be in the 40s and 50s Friday morning, 40s Saturday morning, 30s to mid-40s Sunday morning, moderating slightly Monday morning. These latter temperatures could bring some frost to the sheltered valleys near the Cascades and Canadian border counties. Overnight Saturday into Sunday has the highest risk. As we get closer we will have more confidence, but could impact anyone with sensitive plants or crops. /Solveig && .AVIATION... 00Z TAFS: Sustained 15 to 25 kts winds with gusts to 35kts will be common for our TAF sites including Wenatchee, Moses Lake, Spokane, Coeur d`Alene and Pullman. Peak gusts will likely occur between 00-04z. Winds tomorrow will be much lighter with VFR conditions. FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: There is a low chance of visibility reductions due to blowing dust at Moses Lake and Spokane International as winds peak late in the afternoon. ----------------------- 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 44 74 46 80 53 75 / 0 0 0 0 0 0 Coeur d`Alene 43 71 45 78 51 74 / 0 0 0 0 0 0 Pullman 42 69 43 78 51 70 / 0 0 0 0 0 0 Lewiston 51 78 51 86 58 82 / 0 0 0 0 0 0 Colville 38 74 41 78 46 77 / 0 0 0 0 0 0 Sandpoint 42 70 42 77 48 74 / 0 0 0 0 0 0 Kellogg 46 68 48 78 55 70 / 0 0 0 0 0 0 Moses Lake 45 79 46 84 51 80 / 0 0 0 0 0 0 Wenatchee 48 78 49 82 54 75 / 0 0 0 0 0 0 Omak 45 79 47 83 51 80 / 0 0 0 0 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...Wind Advisory until 8 PM PDT this evening for Coeur d`Alene Area- Northern Panhandle. WA...Wind Advisory until 8 PM PDT this evening for Moses Lake Area- Northeast Mountains-Okanogan Highlands-Spokane Area-Upper Columbia Basin-Waterville Plateau-Wenatchee Area. && $$