Area Forecast Discussion
Issued by NWS Pendleton, OR
Issued by NWS Pendleton, OR
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192 FXUS66 KPDT 170502 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 1002 PM PDT Tue Jul 16 2024 Updated Aviation Discussion .AVIATION...06Z TAFs...VFR conditions prevail with light winds for the remaining TAF period. Mid to high clouds will stick around for all sites. Showers continue for KRDM/KBDN tonight with occasional wind gusts to 20-25kts until Wednesday morning. KDLS/KPDT/KYKM/KALW might have showers around Wednesday morning also, but confidence is low (30-40%) with lower confidence (10-15%) for thunderstorms impacting sites as well. Area haze and smoke will stick around in the horizon but surface VSBYs will remain unaffected. Feaster/97 && PREV DISCUSSION... /issued 244 PM PDT Tue Jul 16 2024/ .SHORT TERM...Today through Thursday... Bottom Line Up Front 1. Thunderstorms through much of the WA region and along the OR and WA Cascades tonight through Wednesday. 2. Hot and dry conditions persist through the period with hear advisories and warnings in effect. The models are in firm agreement with the upper level high still parked over the Four Corners with the upper level low beginning to make its way along the top of the ridge. This will continue to keep the region under southwesterly flow aloft and ushering in some mid level moisture. This will also bring elevated fire weather concerns to the area triggering RFW across a large portion of the area. Short term model ensembles are showing decent reflectivity across the OR Cascades beginning now and lasting through this evening and overnight. A RFW has been issued for the OR Cascade crest and east slopes from now until 9 AM tomorrow for thunderstorms, outflow winds and instability. Confidence in the thunderstorm activity is 50-60% along the Cascade crests and east slopes of OR. Short term model ensembles also show reflectivity returns continuing to make their way north and north east along the east slopes of the WA Cascades as well as through the lower Columbia Basin and foothills of the southern Blues with a RFW in effect from 11 PM this evening through 5 PM Wednesday. This is for thunderstorms, winds and RHs. Any fires that start under these conditions will exhibit extreme fire behavior. Lastly, a RFW is in effect from now until 11 PM this evening for the Souther Blues and Strawberry Mountains for dry and unstable conditions. The fire on the landscape (Falls Fire) is already exhibiting extreme fire behavior per the IMET on site and will continue through the evening. Temperatures are not expected to provide any reprieve through the forecast period as the upper level high continues to remain parked over the Four Corners. This will continue to keep the warm conditions over the area with very little overnight reprieve as well. EFI continues to show the region with above average seasonal temperatures for the daytime highs as well as above seasonal averages for the overnight lows. NBM shows the majority of the area to stay in the 100-104 degree range through the Basins, Gorge, Kittitas/Yakima Valleys as well as portions of Central OR. 92% of the raw ensembles have temperatures across the region in the mid to upper 90s with 67% showing the Gorge, foothills of the Blues, John- Day Basin and portions of Central OR above 100 degrees. roughly 50% of the raw ensembles have the majority of the region seeing overnight temperatures remaining in the upper 60s to low 70s. With this we have issues an Excessive heat warning the Kittitas and Yakima Valleys as well as heat advisories for the Simcoe Highlands, Gorge, John-Day Basin, foothills of the Southern and Northern Blues as well as through the Columbia Basin due to high daytime temperatures and little to no overnight cool temperatures. This will greatly impact the vulnerable within the community. Please check on elderly or sick neighbors and keep and eye on children and pets. More information on heat safety can be found at weather.gov/heat. Bennese/90 .LONG TERM...Friday through Tuesday...Models continue to be in excellent agreement through the majority of the long term period before some differences develop Monday and Tuesday. Overall, a continuation of the hot and dry weather pattern is expected to continue into early next week until cooler but still above normal temperatures are anticipated on Tuesday. The Extreme Forecast Index highlights temperatures, especially Saturday through Monday with values of 0.90 to 0.98. Sunday will be the hottest day of the long term period. On Friday, model clusters are in excellent agreement in having a strong ridge centered over eastern Idaho, a large trough several hundred miles offshore and a southwesterly flow over our area. Deterministic runs show a weak wave passing through the trough offshore with only minor impacts over our area aside from west to northwest winds of 10 to 20 mph through the Cascade gaps and temperatures a few degrees cooler than Thursday. Highs will be in the mid 90s to lower 100s in the lower elevations and in the mid 80s to mid 90s in the mountains. Saturday has the models still in agreement in having the ridge amplitude strengthen considerably and the ridge axis moving westward about 100-200 miles closer to our area. Deterministic runs show another wave developing off the California coast. The ECMWF and Canadian show it dissipating as moves along the Pac NW coast in the evening while the GFS keeps it well south of us. The only noticeable impact is north to northeast 10 to 15 mph winds in the evening. With the strengthened ridge and rising 500 mb heights, temperatures will warm about 5 degrees with widespread 100-105 degree temperatures in the lower elevations and with 90s in the mountains. NBM probabilities give a 65-95 percent chance of 100 degree temperatures in the Columbia Basin and north central Oregon. Even further strengthening of the ridge is expected Sunday and temperatures warm a couple more degrees to 100-108 in the lower elevations with mid 90s to around 100 in the mountains. NBM probabilities show an 80-95 percent chance of 100 degrees and a 10- 15 percent chance of 110 degrees in the Columbia Basin. Central Oregon will have a 45-65 percent chance of 100 degrees. The delayed wave of the GFS deterministic run moves along the coast in the afternoon though like the ECMWF and Canadian, it too is weakening as it arrives. The GFS does show some showers and thunderstorms developing along the Cascades and in central Oregon but as other models are not showing this, have kept the forecast dry. On Monday, 58 percent of model ensemble members show a continued strong ridge over the area with the trough well off the coast. Other members show a weaker ridge with the trough closer to the Pac NW or British Columbia coast. The NBM cools temperatures a couple of degrees but still in the upper 90s to 105 in the lower elevations and in the lower to mid 90s in the mountains. With temperatures over 100 in the Columbia Basin Saturday through Monday and overnight lows in the upper 60s to lower 70s overing little relief, heat highlights appear probable but it`s too soon to be issuing any products. It`s less likely in north central and central Oregon as overnight lows will be around 60, offering some relief from the daytime heat. On Tuesday, model ensemble members are split. All show weakening in the ridge with half having it depressed south into California and Nevada while the trough moves ashore in southern British Columbia. The other half keeps the trough further off shore with the ridge remaining over our area. The NBM has temperatures in the lower elevations cooling back to the lower to mid 90s and mainly in the 80s in the mountains. With the trough approaching and pressure gradients tightening, the Cascade gaps will have westerly winds of 15 to 25 mph in the afternoon. Perry/83 && .AVIATION...18Z TAFs...VFR conditions continue at all TAF sites this morning and should do so through 18Z tomorrow morning. Smoke from area wildfires is apparent on visible satellite, especially along the Blue Mountain Foothills, near LGD and GCD but this morning only 9S9 has dropped below 6SM and 9S9 has improved to VFR in the latest obs. A disturbance will move through the area tonight and tomorrow morning and already see high clouds above 12K feet AGL moving into central Oregon affecting KRDM and KBDN in the next few hours. As the system moves through the area there will be some potential for thunderstorms and light rainfall but confidence is low at any terminal. Did not have the confidence to mention thunderstorms anywhere but did use VCSH to indicate the likeliest time for any showers reaching the ground or thunderstorms. Have VCSH at KRDM and KBDN from 04Z-13Z, KDLS from 09Z-15Z, KYKM after 12Z and KPDT and KALW after 14Z. Did not have enough confidence at KPSC. CIGS tonight will be BKN-OVC at around 10K feet AGL then clearing as the disturbance leaves terminal areas. Winds will be less than 12 kts for the next 24 hrs with a few higher gusts this afternoon at KDLS, KRDM and KBDN. Winds may be strong and gusty around any thunderstorms that develop. Perry/83 && .PRELIMINARY POINT TEMPS/POPS... PDT 65 100 64 98 / 0 20 0 0 ALW 66 104 68 102 / 0 20 0 0 PSC 67 104 67 104 / 0 20 0 0 YKM 68 102 64 102 / 10 20 0 0 HRI 67 105 68 103 / 10 20 0 0 ELN 66 101 66 102 / 0 20 20 0 RDM 60 96 55 95 / 20 0 0 0 LGD 61 95 60 97 / 0 20 10 0 GCD 64 98 58 99 / 10 20 0 0 DLS 71 99 67 97 / 20 20 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... OR... Heat Advisory until 10 PM PDT Wednesday for ORZ041-505-507-508- 510. Heat Advisory until 10 PM PDT Thursday for ORZ044. Red Flag Warning from 11 PM this evening to 5 PM PDT Wednesday for ORZ641. Red Flag Warning until 9 AM PDT Wednesday for ORZ610-611-639-640. Red Flag Warning until 11 PM PDT this evening for ORZ642. WA...Heat Advisory until 10 PM PDT Wednesday for WAZ024-029-521. Heat Advisory until 10 PM PDT Thursday for WAZ028. Red Flag Warning from 11 PM this evening to 5 PM PDT Wednesday for WAZ690-691-694-695. Excessive Heat Warning until 10 PM PDT Thursday for WAZ026-027. && $$ SHORT TERM...90 LONG TERM....83 AVIATION...97