Area Forecast Discussion
Issued by NWS Pendleton, OR
Issued by NWS Pendleton, OR
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092 FXUS66 KPDT 202205 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 305 PM PDT Thu Jun 20 2024 .SHORT TERM...This afternoon through Saturday night...Day Cloud Phase RGB imagery reveals some cumulus build-ups across the WA Cascade crest and Blue Mtns. Any convection that develops is still expected to remain isolated this afternoon and evening. The weak shortwave trough overhead will exit to the east overnight. Flow aloft will transition to a zonal pattern Friday, followed by continued height rises across the PacNW Saturday as an upper-level ridge amplifies over the northern Rockies. The result will be warming temperatures tomorrow and Saturday. Afternoon RH values will be low to very low. HeatRisk values will increase to Moderate across much of our population centers Friday and Saturday. Additionally, the probability of 90+ degree afternoon high temperatures is 70-95% for Saturday across non-mountain areas. Late Saturday, a mid/upper-level low will track towards the PacNW, resulting in a switch to onshore-directed surface pressure gradients and increasing gap winds. Plunkett/86 && .LONG TERM...Sunday through Thursday...A upper level ridge exits eastward Sunday as the zonal pattern moves over the region through Monday. The ridging will continue building into the PacNW late Monday through Wednesday. As the ridge exits to the east, a upper level trough will then move across the PacNW off OR coast through Thursday. Thunderstorms are possible in the eastern mountains for late Wednesday and late Thursday, given the orographic lifting from the cold front associated with a closed low off British Columbia. However, chances are on the low end with surface CAPE values below 100 J/Kg and weak instability (<15%). Confidence is low for mountain showers at the crest of WA/OR Cascades late Wednesday through Thursday from the dry cold front. Seasonable temperatures will be Sunday through Monday as the zonal pattern passes. Tuesday into late Wednesday, temperatures start warming up again due to the transient ridge before decreasing Thursday with the arrival of the upper trough off the coast. Wind gusts at 25-35 mph will begin Sunday afternoon into early night along the lower Columbia Basin, Columbia River and Kittitas Valley (>70% chance). Probability is moderate for wind gusts exceeding to 40 mph (60-80%). Due to increased northwesterly winds and dryness, fire weather remains to be a concern for Sunday around Columbia Basin. Nonetheless, winds will continue to decrease late Sunday night. Breezy conditions continue across the forecast area with wind gusts at around 20 mph or less through Wednesday (40-50% probability). Though, confidence increases for increased wind gusts in these areas Thursday from the arrival of the cold front associated with the trough. Feaster/97 && .AVIATION...18Z TAFS...VFR conditions are expected during this period with light winds, aside from afternoon gusts to around 15-20 kts. Mostly clear skies with some mid to high clouds during the next 24 hours. Feaster/97 && .PRELIMINARY POINT TEMPS/POPS... PDT 54 89 57 93 / 0 0 0 0 ALW 53 92 59 96 / 0 0 0 0 PSC 59 94 61 98 / 0 0 0 0 YKM 56 92 60 95 / 0 0 0 0 HRI 56 94 61 98 / 0 0 0 0 ELN 50 91 59 92 / 0 0 0 0 RDM 51 88 54 91 / 0 0 0 0 LGD 52 85 55 92 / 20 0 0 0 GCD 49 88 55 95 / 0 0 0 0 DLS 57 95 64 92 / 0 0 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. && $$ SHORT TERM...86 LONG TERM....97 AVIATION...97