Marine Weather and Tide Forecast for Moses Lake, WA

SYNOPSIS
Diurnally forced showers with isolated afternoon thunderstorms will continue today Monday. Precipitation chances decrease and afternoon highs trend warmer through the workweek, climbing back into the 70s and 80s by Thursday and continuing through next weekend. Breezy winds are expected at times through the Cascade gaps and across the western Columbia Basin.

DISCUSSION
Today through Friday night: A deep longwave trough of lower pressure will remain over the CONUS for this weekend through the workweek. The axis of this longwave trough will slowly migrate over the Rockies by through Wednesday and then over the Plains by Thursday into Friday. The Inland Northwest will remain under the backside of this trough today with a conditionally unstable air mass. Lingering showers over extreme eastern Washington into the Idaho Panhandle early this morning will wane with decreasing instability at mid levels. However, diurnal heating will destabilize the lower levels of the atmosphere for the afternoon. There will be a lack of instability over the Columbia Basin today, which should result in much of the showers and thunderstorm activity confined to mainly the higher terrain today. Instability parameters will be much less compared to Sunday with upper levels trending warmer. Much less likely to see as much small hail like we've seen with this storms, but some is expected with slightly stronger thunderstorms over the mountains. Convection will also be capable of wind gusts up to around 20-25 mph and infrequent cloud to ground lightning strikes. Best potential for thunderstorms today will be over northeast Washington into the Northern Panhandle with 20-25% chance of occurring. Convection is expected to wane more quickly into the evening hours compared to Sunday.

We then see a drying trend into mid week as a ridge of higher pressure in the eastern Pacific nudes east into the Northwest.
There is a shortwave disturbance that pushes across BC on Tuesday and does bring a 20-30 percent chance for showers across the far northern mountains closer to the Canadian border, and this potential could linger into Wednesday for North Idaho as the shortwave pushes across fairly slowly. There is a 15% chance that places like Lauier, Northport, Metalline Falls, Porthill, and Eastport may also see a passing thunderstorm. Temperatures warm up above normal by Wednesday with our highs back into the 70s. The risk for morning frost will decrease as well as temperatures see a slow warm into the weekend.

Saturday through Sunday: Model ensembles remain in pretty good agreement with a shortwave trough of lower pressure to flatten the ridge. There is uncertainty with how deep this shortwave will be. About 80 percent of the ensemble members show this disturbance to be fairly weak with minimal cooling of just a few degrees Saturday into Sunday. Westerly winds will see an increase. Stronger wind gusts of up to around 30 mph will be across the Cascades and into the western basin and up to around 20-25 mph potentially into places like Spokane and the Palouse.
Winds would pick up Saturday afternoon, but could also remain fairly breezy into Sunday as well. Models continue to diverge as we head into the beginning of next week. Outliers such as the 00Z operational ECMWF and Canadian indicate a deep trough to dig in into BC and potentially as far south as the Pacific Northwest. This scenario would represent more cooling and a better potential for showers than what is in the forecast. The NBM suggests a more zonal flow pattern with the potential for progressive weaker waves that could bring light shower activity but nothing looking all that substantial. After our warm up late in the week, temperatures look to cool near normal for Sunday into the beginning of next week. /SVH

AVIATION
18Z TAFs: Antecedent boundary layer moisture and surface heating will result in developing cumulus fields 18-20Z. There is 40% chance for cells to develop showers and 10-25% for convection to grow deep enough for lightning. Greatest risk will be over the mountains of northern WA and the Idaho Panhandle though cells drifting south will pose a small risk into the upper Columbia Basin and Spokane-Cd'A area. Given the latest output from the cam models, did introduce prob30 for KGEG-KSFF-KCOE for -shra with a 10-15% chance for -tsra. Any thunderstorms will bring a threat for brief downpours of rain/small hail, lightning, and erratic outflow winds to 30 mph. Pending where rain falls, areas of valley fog will be possible overnight.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: There is a small risk for MVFR cigs mainly around KGEG-KSFF- KCOE-KPUW this morning as cumulus clouds are developing and cloud bases are slowly lifting. Main uncertainty this afternoon will be if thunderstorms survive off the higher terrain into KGEG-KSFF-KCOE as we have seen the last two afternoons. /sb

----------------------- 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 66 41 69 44 72 45 / 10 10 0 0 0 0 Coeur d'Alene 64 41 67 44 70 45 / 20 20 10 0 0 0 Pullman 62 39 65 42 68 43 / 10 0 0 0 0 0 Lewiston 67 43 71 46 73 48 / 10 0 0 0 0 0 Colville 69 36 71 40 75 41 / 20 30 10 10 0 0 Sandpoint 62 40 66 43 68 43 / 30 30 10 10 0 0 Kellogg 61 39 66 43 68 43 / 20 20 10 0 10 10 Moses Lake 73 42 75 46 78 49 / 0 0 0 0 0 0 Wenatchee 72 48 74 51 77 54 / 10 0 0 0 0 0 Omak 73 43 75 48 78 51 / 10 10 10 0 0 0

OTX WATCHES/WARNINGS/ADVISORIES
WA...Frost Advisory until 7 AM PDT this morning for Northeast Mountains-Okanogan Highlands-Spokane Area-Washington Palouse.
ID...Frost Advisory until 7 AM PDT this morning for Central Panhandle Mountains-Coeur d'Alene Area-Idaho Palouse- Northern Panhandle.