textproduct: Spokane

SYNOPSIS

A cool and unsettled weather pattern will persist through Thursday with a warming and drying trend by the weekend.

DISCUSSION

Today through Thursday: The low has moved south, but we remain on the backside of the trough with additional weather disturbances moving through. Showers are again redeveloping this morning and will continue through the evening hours across northern Washington, extreme eastern WA and the ID Panhandle. As of 2am, there is an area of convergence between the two disturbances that is creating some light rain or sprinkles across the Spokane/CdA area south onto the Palouse and moving towards Shoshone county. While most of it will be rain, temps are cold enough on the Palouse for some light brief snow this morning. There is enough instability for isolated afternoon thunderstorms (15-20% chance), mainly for northern WA and the northern and central ID Panhandle. However, cannot rule out the potential for the Spokane area as well.

Thursday is looking fairly similar as the last push from the north will bring a shower and isolated thunder threat, mainly to extreme eastern WA and the ID Panhandle. With this stronger northerly push as the trough begins to exit and the ridge nudges closer to the coast, we will see an increase in winds down the Okanogan Valley. There is a 60-70% chance of sustained winds of 15 mph and a 20-30% chance of sustained speeds over 20 mph. There is a 30-40% chance of seeing gusts to 30 mph.The winds will push down the Okanogan Valley and onto the Waterville Plateau and parts of the northern Columbia Basin.

Temperatures will be at or a couple degrees below average for the beginning of April. Highs will be in the upper 40s and 50s, with lows in the upper 20s to mid 30s.

Friday through Sunday: Ensembles models are in really good agreement that the ridge builds in for Friday through the weekend brining warming temperatures and a very pleasant weekend. Daytime temps will be in the 50s Friday and by Sunday widespread 60s with around 70 for parts of the LC Valley and areas south of Moses Lake. Dry air in place and clear to mostly clear skies will allow overnight temps to remain chilly through the weekend. The EC ensemble is still showing drier precipitable water values than the GFS ensemble, which could impact low temps, as well as relative humidity values for any prescribed burns planned.

Monday and Tuesday: The ensembles are in agreement of the ridge being transient and moving east Monday, but they differ in how much influence a trough trying to approach the west coast will have. Currently about 65% of the guidance suggest precipitation moving east of the Cascades. The NBM has increased the chance of precipitation to 30-40%. Have daytime temps cooling a few degrees given the increase in cloud cover and potential for light rain. Overnight temps will be above average given the cloud cover. Snow levels start out high at 5-6k ft, and lower by about 1k ft by Tuesday morning.

Wednesday: Guidance shows a broad ridge developing over the western US. About 30% of the ensembles suggest it to be a messier ridge with continued threat of mainly mountain showers. /Nisbet

AVIATION

06Z TAFS: Light showers will drift southeast through the night clearing the Spokane and Coeur d'Alene area by 09z with little measurable rain anticipated. The light mid-level northwest flow accompanying the shortwave spawning these showers will have the potential to produce a 1000-2500ft stratus deck between Spokane and Pullman by Friday morning. GFS MOS guidance has advertised this potential off an on the last several hour. HREF probabilistic data gives Pullman a 50 percent chance of ceilings below 2000 feet between 14-17z and Coeur d'Alene a 40 percent chance. The most concentrated shower activity will occur over the Idaho Panhandle behind tonight's shortwave with PROB30 chances for showers at Coeur d'Alene and Pullman from mid afternoon into early evening. /GKoch

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: Mid-level northwest flow is less favorable for low stratus development around Spokane than recent nights, but it still can't be ruled out with a 30 percent chance on the HREF of ceilings below 2000ft. /GKoch

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

PRELIMINARY POINT TEMPS/POPS

Spokane 53 33 53 31 56 32 / 50 30 20 0 0 0 Coeur d'Alene 50 32 51 28 55 29 / 60 50 50 0 0 0 Pullman 49 31 48 30 54 31 / 30 20 30 10 0 0 Lewiston 55 36 56 34 59 34 / 20 0 20 10 0 0 Colville 52 30 53 27 57 30 / 60 50 10 0 0 0 Sandpoint 47 32 48 27 55 29 / 60 50 60 10 0 0 Kellogg 45 34 45 27 50 30 / 70 40 70 10 0 0 Moses Lake 59 34 59 32 62 34 / 0 0 0 0 0 0 Wenatchee 56 34 58 35 59 37 / 0 0 0 0 0 0 Omak 57 33 59 31 61 34 / 20 30 0 0 0 0

OTX WATCHES/WARNINGS/ADVISORIES

ID...None. WA...None.