Area Forecast Discussion
Issued by NWS Spokane, WA

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS66 KOTX 251009 AFDOTX Area Forecast Discussion National Weather Service Spokane WA 309 AM PDT Mon Oct 25 2021 .SYNOPSIS...
-- Changed Discussion --
The chance for more rain and mountain snow will persist through much of the week. The north Cascades will likely receive several rounds of accumulating snow in the high terrain. Tuesday and Wednesday will be windy across the Columbia Basin, Palouse, and West Plains with gusts of 30 to 40 mph. A wet and windy weather pattern is expected to continue into late week.
-- End Changed Discussion --
&& .DISCUSSION...
-- Changed Discussion --
Monday and Tuesday: A potent low pressure system continues to spin off Vancouver Island this morning however this system has reached its peak intensity on Sunday and will continue to fill and eject across southern BC over the next 24 hours. The system will continue to influence the weather over the Inland NW drawing breezy winds into its center and bringing on/off precipitation chances. A second low will track across the Eastern Pacific on Tuesday riding along a 160kt jet. This system will remain parked much further north in the Gulf of AK but the strong westerly jet on its southern periphery will nose into Washington ushering a midlevel warm front and one more band of precipitation. As of 2AM...the occluding front that ushered heavier showers across the region Sunday evening was drifting east through the Idaho Panhandle and should be exiting into Western Montana early this morning. Behind this front, a dry slot has moved into the region and is providing a break in the precipitation for much of Central and Eastern WA. A second boundary will cross into Central WA this afternoon renewing the threat for light showers. Most of the activity this afternoon will remain west of a line from Colville to Ritzville. Communities east of this line such as Sandpoint, Spokane-Cd`A, and Moscow-Pullman will experience a mix of sun and clouds and generally dry conditions. Ample surface heating in the afternoon may spark a few showers over the mountains of NE Oregon, some which could drift toward the Camas Prairie. A few hi-res models also suggest a few lightning strikes with this activity but this has little support from the SREF/HREF so opted to leave mainly a mention of showers. This boundary will track east Monday evening and night spreading showers into the remainder of Eastern WA and the Idaho Panhandle. Rainfall amounts with these showers today and tonight will generally be from 0.05-0.20". Heavier amounts, from 0.50-1.00" will impact the Cascade Crest as 700mb flow shifts from south to west. Precipitation will remain light on Tuesday but will become more widespread as a warm front lifts north to south. The front looks to lift into northern WA/ID by late Tuesday afternoon allowing for drier weather to return to the East Slopes and Columbia Basin prior to sunset. As for winds the next few days...breezy southerly winds will be in place today then south to southwest Tuesday. Wind speeds of 10-20 mph are to be expected for much of the open Basin and into the Okanogan Valley. Wind gusts will be on the order of 25-35 mph. Overnight temperatures will remain mild when compared to average with nearly all valleys expected to remain above freezing. Afternoon highs will fall close to those average numbers with highs in the 50s each day. Tuesday night and Wednesday: The Polar jet will nose into Washington state Tuesday night then migrate northward on Wednesday. This will bring the "potential" for several hours of strong winds Tuesday night/Wednesday morning. The signature showing up in the synoptic scale models does indicate the potential for mountain waves as a 50-80kt jet from 700-500mb crosses the Cascades but these are not always sure events to get strong winds to the surface and several of the ingredients in this case do not align with our typical mountain wave events. Consequently, this event comes with plenty of uncertainty but we cannot ignore the fact that several of the hi-res models are showing wind gusts near 50 mph along the ridgetops of the Cascades and possibly over the Waterville Plateau. This is something we will need to keep a close eye on in the coming days. Otherwise, Tuesday night and Wednesday will feature gusty winds west to southwest for most of our area outside the sheltered northern valleys. Sustained speeds of 15-25 mph will be accompanied by gusts of 25-35 mph. The West Plains, Palouse, and foothills of the Blue Mountains will also need to be monitored closely for potential stronger gusts as a 45kt jet develops just a few thousand feet off the ground. This more typical flow pattern will lead to a large rain shadow in the lee of the Cascades and across the Columbia Basin but numerous orographic showers are expected into the rising terrain of the Idaho Panhandle, Northeastern Mountains of WA, and Cascade Crest. Local heavier bands setting up on the Cascade Crest could lead to moderate snow accumulations for Washington Pass and possibly down to Stevens Pass at times. /sb Wednesday night through Sunday: Unsettled and occasionally breezy conditions will continue through the extended portions of the forecast. A warm front is expected to push into the Inland NW Wednesday night into Thursday. Rain and snow is anticipated, with snow levels (originally around 4000 ft or so) lifting through the day. Daytime temps Thursday and Friday look to run a bit above normal, with signs pointing to a drier and colder scenario setting up for Saturday and any All Hallows` Eve shenanigans. /KD
-- End Changed Discussion --
&& .AVIATION...
-- Changed Discussion --
06z TAFS: Widespread precipitation is pushing across eastern WA and north ID as of late evening and this will continue to impact the eastern sites (GEG SFF COE PUW and LWS) at times through 09-11z. We went with VFR cigs however it would not be surprising to see some brief MVFR cigs forming, especially for COE and PUW. Farther west at MWH there are some showers in the vicinity, but they will be moving out shortly. Once the precipitation ends later this morning, there will also be a small risk of some MVFR stratus, but most of that should be east of the forecast sites. The weather will settle down during the morning, but daytime heating and the approach of an upper level trough will result in an increased risk of showers during the afternoon over central WA shifting into eastern WA and north ID late in the day or evening. VFR conditions are generally expected. fx
-- End Changed Discussion --
&& .PRELIMINARY POINT TEMPS/POPS...
-- Changed Discussion --
Spokane 56 40 52 40 54 40 / 10 40 60 60 10 30 Coeur d`Alene 54 40 50 40 53 39 / 20 50 70 80 20 30 Pullman 54 38 51 42 51 37 / 30 40 60 70 20 30 Lewiston 59 44 58 45 60 47 / 40 40 50 70 20 30 Colville 53 37 51 34 54 31 / 30 60 70 60 10 30 Sandpoint 50 38 46 39 49 35 / 30 70 90 100 40 40 Kellogg 52 38 46 39 48 40 / 50 60 80 100 50 40 Moses Lake 57 42 55 40 58 40 / 20 20 50 20 0 30 Wenatchee 54 40 54 41 55 42 / 30 30 70 50 20 50 Omak 55 41 55 37 58 38 / 40 40 70 50 10 40
-- End Changed Discussion --
&& .OTX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
ID...None. WA...Winter Weather Advisory until 5 AM PDT early this morning for Western Okanogan County.
-- End Changed Discussion --
&& $$

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.