Marine Weather and Tide Forecast for Ronald, WA

FXUS66 KPDT 210943 AFDPDT

Area Forecast Discussion National Weather Service Pendleton OR 243 AM PDT Mon Apr 21 2025

SHORT TERM
Today through Wednesday...Water vapor satellite imagery tonight shows the axis of an upper level trough crossing into ID, while radar imagery shows light rain/snow showers moving across portions of the northern Blues. Nighttime satellite imagery allow shows stratus layers mainly across the Cascades and eastern mountains, though a deck of low clouds currently extends across portions of north central OR and along the northern Blue mountain foothills as well.

Shower chances across the Cascades, Blues, Strawberrys, and Wallowa county will diminish through this morning as an upper level trough continues to push further east, leaving the PacNW under a dry, cool northwest flow aloft throughout the rest of the day. Breezy winds will continue through the Cascade gaps with gusts between 30-40mph in these areas, and gusts 20-30mph in portions of the Columbia Basin and north central OR. Winds will weaken through late evening, with light winds developing at least across the Columbia Basin and Yakima valley. The dry conditions, light winds, and a cooler airmass in place over the lower elevations will result in frost developing across portions of the Columbia Basin and adjacent valleys by tomorrow morning. In addition, morning temperatures tomorrow are expected to be at or below freezing in many rural locations (including agricultural areas) with near to just below freezing temperatures in many urban areas (confidence 60-80%). At this time, a freeze watch remains in effect for the all eligible zones in the Columbia Basin and adjacent valleys/foothills for Tuesday morning.

Tuesday, a shortwave trough will swing across the forecast area, but will lack enough moisture for shower activity across the region. That said, a very light shower or two is not ruled out at least over the WA Cascade crest and the interior northern Blues Tuesday afternoon. Otherwise, winds will remain light to locally breezy Tuesday. Wednesday morning, upper level ridging in the northeast Pacific will begin to slide into the PacNW, resulting in a warming trend with dry conditions and light winds persisting across the forecast area. Lawhorn/82

LONG TERM
Thursday through Monday...Main feature in the long term continues to be the arrival of an organized low pressure system starting around Friday and lasting through much of the weekend. This system continues to confound models considerably, however, so confidence remains shaky as to the exact impacts this system poses to the forecast area in terms of precip amounts and winds.

Thursday remains quiet with high pressure overhead, with precip chances moving in by Friday morning for at least our mountain zones.
The main problem when it comes to tracking this system is that models keep shifting its approach angle and eventual trajectory.
Ensemble clustering depicts a low that is centered all the way from off the BC coast to down towards northern California. The deterministic GFS and ECMWF even start to introduce a negative tilt with the upper-level trough associated with this system, which could provide for thunderstorm chances given the warm-up expected through the midweek. However, if this system dives too far south, we'd be left in the dry slot, with precip ending up primarily in the mountains and with lighter amounts. NBM seems to favor this solution, as it has backed off on QPF amounts across the lowlands quite a bit. Only thing that is certain as of now is that we will see a low pressure system impact the region Friday through the weekend, it's just a question of where exactly this low will track, as that will ultimately determine whether we get widespread showers with isolated thunderstorms, or just light mountain showers with breezy winds across the lowlands.

This system seems a bit stubborn to leave the western CONUS based on ensemble guidance, but solutions are split between diving this low down towards the Four Corners or just having it slowly progress as an open trough eastward. Main impacts still look to occur on Friday and Saturday, with quieter weather shaping up Sunday onward, however the synoptic pattern is still very much to change this far out so long as ensembles struggle to read in on this oncoming low.
Evans/74
Show more