Area Forecast Discussion
Issued by NWS Spokane, WA
Issued by NWS Spokane, WA
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433 FXUS66 KOTX 062220 AFDOTX Area Forecast Discussion National Weather Service Spokane WA 320 PM PDT Sat Jul 6 2024 .SYNOPSIS... Weather conditions are expected to be hot and dry the next seven days. Northerly winds decrease into Saturday evening, followed by lighter winds through Tuesday. Then next increase in winds will be Wednesday, with continued very dry conditions. && .DISCUSSION... ...SIGNIFICANT HEAT WAVE FOR INLAND NORTHWEST... Tonight through Wednesday: High pressure will be amplifying over the West Coast and shifting inland through mid-week. This set-up will promote hot conditions through this period, peaking around Tuesday and Wednesday. Highs are forecast to be in the 90s to low 100s Sunday, rising to around 100-110 degrees for most places by Tuesday into Wednesday. Even in the mountains, all but the higher peaks will be in the 80s and 90s. Overnight lows will be in the upper 50s and 60s tonight and Sunday night. However these values will also see a warming trend dropping to 60s to mid-70s by Monday night and Tuesday night. Minor impulses will ride over the top of the ridge through Tuesday, then in from the west Tuesday night into Wednesday as the ridge axis shifts toward the Continental Divide. A few afternoon cumulus clouds are possible around the mountains and a few more passing clouds pass around Wednesday. However the lack of significant moisture or instability will keep the area dry, largely staying north and east of the area. The only area where models suggest some isolated showers may skirt by is around the northern Idaho mountains. That dampening of the ridge heading into Wednesday will come with increased breezy/gusty winds, particularly near the Cascades into central WA. Thursday to Saturday, the area shifts to a flatter flow as additional shortwave make their way onshore. However the lack of significant moisture over the Inland NW continues to support a dry forecast. Temperatures will "cool", relatively speaking, with highs falling to 90s with some lingering low 100s near the deeper basin and L-C Valley and lows in the upper 50s and 60s. /Solveig Fire Weather: as for fire weather concerns, afternoon RH percentages are forecast to range from the single digits in the deeper basin and lee of the Cascades and teens to lower 20s heading toward the eastern third of WA and the mountains through Monday, bottoming out in the single digits and teens throughout most of the region Tuesday and Wednesday. Overnight RH recoveries will be fair to poor in most areas, except some of the eastern valleys early in the period. There is not much improvement after Wednesday, except around the Cascades crest as the onshore flow increase. For the most part winds remain light through Tuesday, then concerns start to rise as we head into Wednesday and Thursday. The dampening of the ridge and increased onshore flow leads to an increase in winds. Models are still coming together on details, but confidence is increasing to show a potential sync up of winds and low RH around the lee of the Cascades through central WA, the Upper Columbia Basin. The current forecast indicated winds near near 15-25 mph and higher gusts. Wednesday looks like the more impactful day with the breakdown of the ridge. Breezy gap winds continues into the end of the week too. /Solveig Smoke/haze: in the short term (through Monday) models are showing smoke and haze around the Pioneer Wildfire in the Cascades, spreading over portions of Chelan through Douglas county and perhaps some spreading into Grant county tonight into early Sunday, abating some then re-expanding later Sunday into early Monday as far east as Wilbur in the Upper Columbia Basin. This will likely need additional fine-tuning and localized smoke is likely around any of the smaller wildfires near the Cascades. /Solveig && .AVIATION... 00Z TAFS: VFR conditions will prevail. Hazy conditions are forecasted for the Lake Chelan and Waterville Plateau area and onto portions of the Columbia Basin. Have mention of FEW200 for hazy skies around MWH and EAT at times. Haze will not reduce surface visibility and will remain elevated. FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence in VFR conditions. Low confidence for localized visibility reductions due to smoke. ----------------------- 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 60 96 63 100 66 103 / 0 0 0 0 0 0 Coeur d`Alene 58 92 60 96 63 100 / 0 0 0 0 0 0 Pullman 58 93 60 96 62 99 / 0 0 0 0 0 0 Lewiston 66 101 68 105 70 109 / 0 0 0 0 0 0 Colville 52 93 56 98 59 101 / 0 0 0 0 0 0 Sandpoint 54 88 56 94 57 97 / 0 0 0 0 0 0 Kellogg 62 88 66 95 68 98 / 0 0 0 0 0 0 Moses Lake 61 101 63 104 66 107 / 0 0 0 0 0 0 Wenatchee 69 101 70 103 74 106 / 0 0 0 0 0 0 Omak 64 102 66 105 69 107 / 0 0 0 0 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...Heat Advisory from noon Sunday to 10 PM PDT Friday for Central Panhandle Mountains-Northern Panhandle. Excessive Heat Warning until 10 PM PDT Friday for Coeur d`Alene Area-Idaho Palouse-Lewis and Southern Nez Perce Counties- Lewiston Area. WA...Heat Advisory from noon Sunday to 10 PM PDT Friday for Northeast Mountains-Okanogan Highlands. Excessive Heat Warning until 10 PM PDT Friday for Central Chelan County-Lower Garfield and Asotin Counties-Moses Lake Area- Northeast Blue Mountains-Okanogan Valley-Spokane Area-Upper Columbia Basin-Washington Palouse-Waterville Plateau- Wenatchee Area-Western Okanogan County. Heat Advisory until 10 PM PDT Friday for Western Chelan County. && $$