Sunrise 4:59 AM   Sunset 8:27 PM Moonrise 6:56 PM   Moonset 3:49 AM

  Print   HELP   Reset   Save   Recall  New

FXUS66 KOTX 211153 AFDOTX

Area Forecast Discussion National Weather Service Spokane WA 453 AM PDT Tue May 21 2024

SYNOPSIS
A wet low pressure system is expected to move in the latter half of today into Wednesday, and linger into Thursday. Another weather system will move in on Friday and Saturday bringing more unsettled weather into the Memorial Day weekend. Monday will be the warmest day of the holiday weekend.

DISCUSSION
Today through Wednesday: A low will be dropping into the Pacific Northwest from BC. It will bring widespread precip for the next couple of days. The Low will push a warm front through the Inland Northwest today with a cold front following on Wednesday.

For Tuesday, precip will start in the Cascades around midday and shift East through the rest of the day. It will bring widespread rain as the snow levels are still remaining above 6000 ft. Amounts range from a few hundreths for the Okanogan Valley and valleys along the Cascades to near 0.4" for the Idaho Panhandle. Highs for the day will hindered by the increasing clouds. Most areas will reach into the 60s with some into the upper 50s. Overnight lows will be in the 40s.

The cold front will pass early Wednesday. It will drop snow levels to around 4000 feet. It will bring another round of rain to the lower elevations and mountain snow. Depending on the timing, light snow could impact travel over the passes. Ensembles are showing the potential for a 2 to 3 inches of snow falling in these areas. But surface temperatures remain above freezing and snow mixing with rain will affect any accumulations. Rain will be heaviest across Northern Washington and Idaho Panhandle. An additional 0.3" is expected. The precip for the rest of the region ranges from a few hundreths to near 0.2". Dynamics along the cold front could spawn an isolated thunderstorm as moves through the Inland Northwest. Highs for day will be in the 50s to low 60s. Overnight lows will be in the upper 30s and 40s.

Thursday: The Inland Northwest will be between systems Thursday as the trough exits into Wyoming and the next trough begins to approach the northern BC coast. Showers will remain in the forecast for northern WA, extreme eastern WA and the ID Panhandle with a 20-30% chance of thunderstorms in the afternoon across the northern counties. Temperatures will rebound from Wednesday's cool temps, but we will still remain several degrees below average. Central WA will be 3 to 5 degrees below average with highs in the low 70s. Eastern WA and the ID Panhandle will be 5 to 10 degrees below average with highs in the upper 50s to low 60s.

Friday and Saturday: The trough moves toward the region Friday.
The timing seems to have slowed down a bit. We will still see an increase in showers throughout the day, which continues through the night. The low moves into Washington early Saturday for you guessed it, more rain for the region. Friday and Saturday will be the two wetter days of the Memorial Holiday weekend. Temperatures will continue to be below average. 850mb temps cool enough for some snow possible in the mountains, and a 20-25% chance of an inch of snow at Lookout and Sherman Passes. Both days will see afternoon thunderstorms develop, but right now only have about 20% chance in the forecast.

Sunday and Monday: Sunday the trough exits the region with a 20-30% chance of rain showers across NE WA and the ID Panhandle under the northwest flow aloft. Sunday morning lows will be our coolest of the week given the exiting trough and thinning clouds.
Some of the northern valleys could once again see frost. Our daytime temperatures will start to rebound into the 60s Sunday and even further on Monday - into the 70s, which will be at or a couple degrees above average, as 55% of the model ensembles suggest a south to southwest flow from a more amplified ridge either directly over us or just to our east. Monday looks to be the driest day of the Memorial Weekend.

Tuesday: Ensembles agree on the ridge somewhere across the west or intermountain west. Placement is still uncertain. 30% of ensembles have the ridge axis further east into eastern MT with a trough approaching the Pac NW coast. This would result in cooler temps and a chance of precip. For now, forecast is dry except along the crest and temperatures are above average, which is supported by 70% of the ensembles. /Nisbet

AVIATION
12Z TAFS: Patchy valley fog is expected over the mountain valleys of NE Washington and North Idaho through 15z and is not likely for the Spokane and Coeur d'Alene areas with RH 20-30% lower compared to 24 hours ago. A low pressure system will spread across Eastern Washington late Tuesday afternoon and evening bringing lowering CIGS to MVFR over most of Eastern Washington and North Idaho. Downslope off the Cascades should keep conditions VFR for most of the Central WA airports through 06z Wed including Omak, Wenatchee, Chelan, Winthrop, and Moses Lake.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: There is high confidence in CIGS lowering to MVFR between 02-06z Wednesday over Eastern Washington and North Idaho as rain spreads in. HRRR shows at least a 70% chance of CIGS lowering to MVFR for KGEG/KSFF/KCOE/KPUW. For Wenatchee there is a 80-90% chance of conditions remaining VFR through the TAF period. Low confidence or IFR conditions with the incoming showers.

-----------------------

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 64 45 56 42 63 45 / 20 90 90 30 30 20 Coeur d'Alene 62 46 53 41 60 44 / 10 100 90 50 50 30 Pullman 62 43 52 40 57 40 / 10 90 90 50 30 10 Lewiston 70 51 60 45 64 45 / 10 90 90 50 30 0 Colville 65 41 55 37 65 40 / 30 100 100 50 60 50 Sandpoint 61 44 52 40 58 45 / 20 90 100 70 60 50 Kellogg 60 46 49 43 57 43 / 10 90 100 80 60 30 Moses Lake 69 45 61 44 71 44 / 40 60 60 10 0 0 Wenatchee 65 46 58 46 71 48 / 50 50 50 10 0 0 Omak 67 45 59 43 71 46 / 60 60 80 20 20 10

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

Full Color Weather Map

Link to Loop


Other links: GEOS-West     Contential US     Full GOES-East

Spokane, WA,