Area Forecast Discussion
Issued by NWS Pendleton, OR
Issued by NWS Pendleton, OR
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104 FXUS66 KPDT 080537 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 1037 PM PDT Tue May 7 2024 Updated Aviation Discussion .AVIATION...06Z TAFs...VFR conditions to prevail through the period. While skies will be mostly clear through tonight, CIGS AOA 15kft AGL will periodically impact sites tomorrow afternoon. Breezy winds of 12-17kts with gusts up to 25kts will continue to impact sites DLS/PDT/YKM through 7Z-8Z, then becoming less than 12kts overnight. While winds will be less than 12kts through the period at most sites, northwest winds increasing to 12-15kts and gusts around 20kts will impact site DLS between 17Z-2Z. Lawhorn/82 && .PREV DISCUSSION... /issued 436 PM PDT Tue May 7 2024/ SHORT TERM...Tonight through Thursday Night...The main weather concerns will occur during the next 24 hours as a longwave trough over much of the CONUS shifts east as an upper ridge strengthens out in the eastern Pacific. Currently we have a northwest flow over the area and that is promoting an upslope flow into the Cascade crest and the eastern Oregon mountains where some lingering showers continue. Temperatures have warmed, so snow has turned over to rain and have let the Winter Weather Advisory for the East Slopes of the Oregon Cascades and Northern Blue Mountains expire a few hours ago. The northwest flow will continue this evening with just light precipitation amounts and as the flow turns more northerly and drier overnight, precipitation will end. Pressure gradients remain tight though the Kittitas Valley and models show the pressure differences between Seattle and the Tri-Cities beginning to relax in the evening. The current Wind Advisory in the Kittitas Valley will remain in effect through 11 PM this evening and winds there will continue at around 20 mph overnight while the rest of the Columbia Basin will see breezy winds through this evening dropping off to 5 to 10 mph overnight. Another concern is that skies will clear over much of the area overnight. radiative cooling will allow temperatures to cool several degrees from last night with lows in the mid 30s to around 40 in the Columbia Basin and in the mid 20s to lower 30s elsewhere. Have some concerns about temperatures dropping to around freezing in pockets in the Columbia Basin, Yakima Valley and Blue Mountain Foothills. The forecast low temperatures at Yakima, Pendleton and Connell are around 34-35 degrees, but probabilistic guidance shows a less than a 10 percent chance of freezing temperatures in Yakima and Pendleton and only about a 25-35 percent chance around Connell and in isolated rural areas around Pendleton and Yakima. Other locations in the Columbia Basin and Gorge are warmer, so will not issue a freeze warning for zones eligible for one. Tomorrow will see the offshore ridge strengthen and move closer to the coast and the flow will turn to the northeast in the afternoon. The northeast flow will allow for a slight chance of light rain and snow showers in far eastern Wallowa county but further west impacts will be just partly to mostly cloudy skies. With the ridge having more influence, temperatures will warm 6 to 10 degrees from today with highs in the 60s and lower 70s in the lower elevations and in the 50s in the mountains. As we get into Wednesday night through Thursday night, the trough to our east will split with a lobe of low pressure retrograding westward into southern California and Nevada while the main energy of the trough will move eastward into the Midwest. This will tilt the ridge along our coast, but will not have a significant impact on our weather. A period of dry and sunny weather is expected with temperatures warming another 10 degrees or so on Thursday. Highs will be in the 70s and lower 80s and in the 60s in the mountains, roughly 10 degrees above normal. The pressure differences between the ridge and the low to the south will generate some breezy 10 to 20 mph northeast winds Thursday afternoon but do not expect any wind highlights will be needed. Perry/83 LONG TERM...Friday through Tuesday...High pressure remains the prevailing weather feature during on the onset of the forecast period. Dry and warming conditions will be present through at least Sunday under the influence of this pattern. The warmest locations anticipated to be across the Columbia Basin and into the Kittitas Valley on Friday, where guidance indicates an 80 to 100% chance for temperatures to reach or exceed 80 degrees. The warm air will spread to include more of the lower elevation locations on Saturday with numerous locations indicating a high chance (80-100%) for temperatures of 80 degrees. Additionally, on Saturday, portions of south-central Washington, including the Tri-Cities area will see a 70-80% chance for high temperatures of 90 degrees. Saturday will be the warmest day of the forecast period as the area of high pressure flattens and progresses eastward on Sunday. During the warmest periods, temperatures will be between 15 and 20 degrees above normal. As the ridge flattens on Sunday, temperatures will be able to cool slightly, though a wide swath of south-central Washington remains in a high chance (80-95%) of seeing daytime temperatures of 80 degrees. Lower elevations in northern and central Oregon will see values between 70 degrees and 80 degrees, though guidance indicates a moderate (40-60%) chance for temperatures to reach 80 degrees. Dry conditions will still prevail through the remainder of the weekend. Conditions will continue to cool for the beginning part of next week. By Monday morning, guidance indicates a low chance (10-20%) for showers to develop over the Washington Cascades, with the remainder of the area remaining dry. QPF related clusters indicate additional disagreement on the development of showers, helping to keep those probabilities low. Even with the cooling, temperatures at the warmest locations will still be around 5 degrees above normal. Through the forecast period, the pattern related Cluster Analysis indicates decent agreement. There is some variation on intensity of the high pressure, which will impact the level of warmth across the area, but placement is generally similar. Branham/76 && .PRELIMINARY POINT TEMPS/POPS... PDT 35 62 40 73 / 0 0 0 0 ALW 38 64 42 77 / 0 0 0 0 PSC 40 71 45 81 / 0 0 0 0 YKM 35 73 42 81 / 0 0 0 0 HRI 37 69 42 79 / 0 0 0 0 ELN 37 69 42 80 / 0 0 0 0 RDM 27 60 34 71 / 0 0 0 0 LGD 32 57 37 71 / 0 10 0 0 GCD 31 57 32 72 / 10 0 0 0 DLS 40 71 46 80 / 0 0 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...None. WA...Wind Advisory until 11 PM PDT this evening for WAZ026. && $$ SHORT TERM...83 LONG TERM....76 AVIATION...82