Marine Weather and Tide Forecast for Lewiston, ID

SYNOPSIS
Today through Monday will see seasonable temperatures along with chances for showers and isolated to scattered thunderstorms.
Frosty conditions with chilly overnight temperatures expected Monday night into Tuesday morning. Warm and dry conditions return toward the middle of the week then turning unsettled again at the end of the work week into next weekend.

DISCUSSION
Today through tonight: Temperatures today reflect the recent frontal passage with highs cooling to near normal. As mostly zonal westerly flow moves through tomorrow in the wake of the front, breezy winds with gusts up to 25 mph will cover much of the forecast area apart from the Okanogan Highlands and the Northern Mountains. Coverage of breezy winds will be slightly spotty in the northern Idaho Panhandle. Another impact of note today will be thunderstorm potential in the northeast and southeast portion of our forecast area. Favorable parameters for thunderstorms include 200-300 J/kg of CAPE, and the NAM favors steep low level lapse rates of 7-8 degC/km.
The current SPC outlook has the areas of Republic, Colville, Bonners Ferry, and Sandpoint in general thunderstorms for this afternoon.
However, showery precipitation from the cold front passage could bring thunderstorms as far south as Coeur d'Alene. Additionally, the Northeast Blue Mountains have a chance for thunderstorms as well.
Main threats with these thunderstorms include: gusty winds near 40 mph, small hail, and dangerous cloud to ground lightning.

Monday through Monday night: On Monday, a shortwave trough moves through northern Washington, continuing the chances of thunderstorms into tomorrow and tomorrow afternoon. CAPE values are very similar to today, and will be situated over similar areas.
While the afternoon will be breezy, winds will be calm going into the evening. This combined with minimal cloud cover will lead to a chilly Monday night/Tuesday morning, with NBM percentages showing a 10-20 percent chance of lowland areas reaching 32 degrees as a low.
As such, a Freeze Watch has been issued for the Moses Lake, Lower Garfield and Asotin Counties, Lewiston, and Wenatchee areas from midnight to 9am Tuesday. Main impacts with these low temperatures include damage to vegetation.

Tuesday through Thursday: Once the shortwave makes its way eastward and out of the area, a weak ridge will begin forming.
High temperatures will rebound back up to 6-8 degrees above normal, and dry conditions will mostly prevail through Thursday afternoon.

Thursday through Sunday: By Thursday, around half the clusters support a low pressure system off the coast of the Pacific Northwest, which will bring chances of unsettled weather back to the region. This will bring widespread precipitation to the area, mostly composed of rain apart from the highest elevations in the Cascades.
Precipitation amounts right now look light, with long range models anticipating 0.25-0.5 inches of rain in total, with much of it falling through Friday evening. Winds will be elevated through the Okanogan Valley, Waterville Plateau, and the Columbia basin on Thursday, Friday, and Saturday afternoon and evening. Will keep an eye on this low pressure system as the week presses on to monitor precipitation and wind potential, as CPC's 6-10 and 8-14 Day Outlooks both support precipitation chances trending above normal for the extended period.

AVIATION
00Z TAFS: All TAF sites currently at VFR. A shortwave disturbance moving into the area will bring afternoon showers, thunderstorms, and breezy winds. KGEG-KSFF-KCOE are currently experiencing showers, with the showers projected to end around 03-04Z. KCOE will experience intermittent rain from 15-19Z and again chances of rain near the end of the TAF period, at 22Z.
KCOE's ceilings could also drop to MVFR around 15Z. KPUW isn't experiencing any showers, but will through the middle of the TAF period, starting at ~09Z and lasting through ~17Z. Gusty winds will prevail through the evening for all TAF sites but KLWS, with gusts near 20-25kts, and will end around 03-04Z. KEAT could see gusty winds at 21Z, near the end of the period.

These widely scattered showers will result in potential for thunderstorm formation in the northern parts of the forecast area, particularly from Omak to Sandpoint, but cannot rule out thunderstorms for KCOE-KMWH-KPUW-KLWS. Any thunderstorms that do develop will be capable of gusty outflow winds, small hail, and brief heavy downpours. Convection will continue into the evening with potential for thunderstorms waning overnight.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: Continued high confidence in VFR conditions across central WA, and the Lewiston area through Sunday evening. Low to moderate confidence in thunderstorms today with best chances between Omak and Sandpoint at a 20-30%. Low to moderate confidence of rain in KCOE near the end of the TAF period and gusty winds in KEAT near the end of the TAF period. /AS

Preliminary Point Temps/PoPs
Spokane 36 55 31 59 35 64 / 30 10 0 0 0 0 Coeur d'Alene 34 53 31 57 32 62 / 50 40 10 0 0 0 Pullman 37 51 32 55 33 60 / 40 30 0 0 0 0 Lewiston 42 60 36 61 38 65 / 40 20 0 0 0 0 Colville 31 56 31 60 33 64 / 60 20 20 0 0 0 Sandpoint 36 53 32 55 32 60 / 70 60 40 10 10 10 Kellogg 37 49 32 53 35 58 / 70 70 20 10 10 10 Moses Lake 37 61 33 63 36 67 / 10 0 0 0 0 0 Wenatchee 39 60 37 62 39 66 / 10 0 0 0 0 0 Omak 35 60 34 63 35 67 / 10 0 0 0 0 0

OTX WATCHES/WARNINGS/ADVISORIES
WA...None.
ID...None.