Marine Weather and Tide Forecast for Ponderay, ID

SYNOPSIS
Hot and unstable conditions, low humidity, lightning, and gusty winds will maintain critical fire weather conditions across portions of Central and Eastern Washington through at least Thursday. Dry conditions resume this weekend.

DISCUSSION
This afternoon through Friday: An evolving risk for isolated to scattered showers and thunderstorms will be found this period, as a low pressure trough tracks up the Washington coast and eventually into British Columbia by late Friday night. This afternoon that low sits off the WA coast and it is projected to lift toward Vancouver Island by Friday morning. A deformation axis wrapping from Idaho westward toward the Cascades will edge north through that period too, then all these features will start to lift into British Columbia. The moist and unstable southerly flow ahead of and into that feature will be one of the focal points for the precipitation threat. However the general set-up will bring a risk for isolated showers/t-storms just about anywhere in hit-and-miss fashion. Analysis shows around 500-2000 J/kg of CAPE are found around the region, with the highest numbers around the central to southern Panhandle; however, there is a 25-250 J/kg CIN that may be inhibiting some of the convection from developing. The lift at this point it not all that impressive to overcome that, but as we head into the remainder of the afternoon into tonight activity is expected to expand. For the afternoon and evening Friday the risk for showers/t-storms linger near the Canadian border and around the central Panhandle, with a slot of drier air wrapping into the region reducing that threat of precipitation.

Right now the main activity around the 2 pm hour was showing up from the Palouse to the Idaho Panhandle in isolated fashion.
However, the low edging closer and deformation axis lifting north, I am expecting the showers to expand around the Cascades, north and eastern WA and the ID Panhandle through this afternoon and evening. Then heading into the overnight into Friday morning the threat starts to lift the primarily the northern mountain zones. Some of these thunderstorms will have the potential for gusty outflow winds, small hail and lightning.
The SPC still has a marginal threat of severe t-storms over the eastern third of WA and ID, so some of these produce strong outflow winds (up to 60 mph) and hail (up to 1 inch). The overall better threat of that is toward the ID/MT border eastward, but this will still be monitored.

The threat of lighting and gusty outflow winds is reason for the Red Flag Warnings that are currently in place. The cells have been moving at a pretty good clip, around 30 to 40 mph and lightning outside of the core of the storms and just given the speed suggest this would be mostly dry lightning. So the risk for fire starts remains. The other fire weather concerns will be found heading into Friday afternoon due to breezy/windy and dry conditions. Per the HRRR, the combined probability of RH <20% and winds >15 mph from the Okanogan Valley to Waterville Plateau is starts to rise after midday and peaks in the late afternoon to early evening. Thus fire weather watches remain in place for some of that area, the Okanogan and Methow Valley for Friday from noon to 9 pm. Relative humidity values bottom out around the mid-teens with winds of 10-20 mph and gusts of 25-30 mph.

Saturday through Wednesday: Ensemble show the low pressure continuing to track over British Columbia and east into Alberta, but a secondary shortwave trough track around the backside of the parent trough and into our region Saturday into Sunday, before a dirty ridge takes over. The drier air over the region means that the shortwave will not have much to work with in terms of precipitation, meaning a dry weekend. However heading toward Tuesday some monsoonal moisture edges toward again some limited shower/t-storm chances will reemerge near the southeastern CWA and eventually into most of the mountain zones toward Wednesday (into next Thursday). We will see about the lowland risk as we get closer.

Winds will be breezy/gusty on Saturday with the low still tracking by, so speeds of 10-20 mph and gusts of 20-30 mph are in the forecast. With minimum RH values in the teens and 20s, we will have some elevated fire weather conditions with possible pockets of critical fire weather conditions. High temperatures will hover in the upper 80s to mid 90s through Sunday, warming to mainly the 90s to low 100s next week but the model spread starts to introduce some uncertainty into the forecast as to the precise numbers. /Solveig

AVIATION
00Z TAFS: Low pressure off the Northwest Pacific coast will continue to promote a moist southerly flow across the region through tonight across eastern WA and north ID. Elevated instability in this airmass will promote occasional isolated to scattered showers and thunderstorms. Radar and hi-res model trends suggest a diminishing threat for thunderstorms near the TAF sites through tonight so have removed -TSRA mention with this update, but will continue to monitor as there will be a nonzero threat through tonight. Greatest chances for -TSRA this afternoon will be near KLWS/KPUW, and across northeast WA and north ID (north of KGEG/KSFF/KCOE) thereafter tonight. Further west towards the Cascades, drier weather will prevail with occasionally gusty gap winds until early Friday morning.
Otherwise, VFR weather will prevail through the 00z TAF cycle.

Breezy south to southwest winds develop east of the Cascades Friday, with gusty west-northwesterly gap winds closer to the range. Some measure of -TSRA activity may roll over across the northern mountains (mainly NE Washington/N Idaho) through 18z Friday.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence in VFR prevailing region-wide. Low confidence in timing and coverage of showers and thunderstorms through Friday morning with several sporadic waves of convection possible.
Moderate confidence in the greatest chances for convection tonight through Friday morning being across northeastern WA and north ID.

----------------------- 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 62 92 59 91 59 92 / 30 10 0 0 0 0 Coeur d'Alene 64 91 61 90 59 90 / 40 10 10 0 0 0 Pullman 54 86 53 86 52 88 / 30 10 20 0 0 0 Lewiston 66 95 63 96 62 96 / 40 10 10 0 0 0 Colville 60 93 55 91 54 94 / 20 30 0 0 0 0 Sandpoint 60 91 58 89 56 91 / 50 20 0 0 0 0 Kellogg 60 89 59 87 56 87 / 50 10 10 0 0 0 Moses Lake 62 93 59 93 58 94 / 10 10 0 0 0 0 Wenatchee 66 93 64 91 64 94 / 10 10 0 0 0 0 Omak 68 95 62 94 62 96 / 30 10 0 0 0 0

OTX WATCHES/WARNINGS/ADVISORIES
WA...Red Flag Warning until 11 AM PDT Friday for Colville Reservation (Zone 702)-Okanogan Highlands and Kettle Mountains (Zone 699)-Okanogan Valley (Zone 703)-Selkirk Mountains of Northeast Washington (Zone 700).
Heat Advisory until 9 PM PDT this evening for Lower Garfield and Asotin Counties-Moses Lake Area-Okanogan Valley- Spokane Area-Upper Columbia Basin-Washington Palouse- Waterville Plateau-Wenatchee Area.
Red Flag Warning until 11 PM PDT this evening for Eastern Columbia Basin -Palouse -Spokane Area (Zone 708)- Foothills of Northeast Washington (Zone 701)-Lower Palouse -Snake River (Zone 709).
Fire Weather Watch from Friday afternoon through Friday evening for Methow Valley (Zone 704)-Okanogan Valley (Zone 703).
Red Flag Warning until 5 AM PDT Friday for East Portion of North Cascades National Park/Lake Chelan National Recreation Area (Zone 697)-East Washington Central Cascades (Zone 696)-East Washington North Cascades (Zone 698)-Foothills of Central Washington Cascades (Zone 705)- Methow Valley (Zone 704)-Waterville Plateau (Zone 706).
ID...Red Flag Warning until 11 AM PDT Friday for Northern and Central Idaho Panhandle (Zone 101).
Heat Advisory until 9 PM PDT this evening for Coeur d'Alene Area-Idaho Palouse-Lewis and Southern Nez Perce Counties- Lewiston Area.