![National Oceanic and Atmospheric Administration](/build/images/header/noaa.d87e0251.png)
![National Weather Service](/build/images/header/nws.4e6585d8.png)
![United States Department of Commerce](/build/images/header/doc.b38ba91a.png)
Area Forecast Discussion
Issued by NWS Pendleton, OR
Issued by NWS Pendleton, OR
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
434 FXUS66 KPDT 151742 AAA AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 1042 AM PDT Mon Jul 15 2024 .Updated aviation discussion .SHORT TERM...Today through Wednesday...A large scale ridge of high pressure continues over the western USA with a dry westerly flow across much of the Pacific Northwest. One exception is some monsoon moisture being pulled up into southern and southeast Oregon by the combined circulation of the high and a small upper level low off the central California coast. This will lead to a slight chance of thunderstorms this afternoon and evening mainly from Burns Oregon southward. This will keep convection just outside of the forecast area for today. Otherwise, the forecast area will remain mostly clear with slightly cooler temperatures as the result of some cooler marine air that spilled over the Cascades Sunday afternoon and evening instigating the breezy conditions. On Tuesday the upper level ridge begins to expand further northward while the small upper level low off the central California coast begins to lift northward towards the SW coast of Oregon. This begins to increase the southerly flow into central Oregon in the afternoon lifting some of the monsoon moisture back into the forecast area. Combine this with the increased instability provided by the approaching system and it will produce some isolated thunderstorms in the late afternoon and evening across central Oregon. The small low begins moving into western Oregon Tuesday night and then continues moving across eastern Washington on Wednesday. The forcing and elevated instability should be enough to generate a few nocturnal thunderstorms overnight and into Wednesday morning pushing northward across the forecast area. By midday Wednesday there could be some lingering thunderstorm activity over the far northern portion of the forecast area and the eastern mountains which all comes to an ending by late afternoon as the system exits to the north. The high pressure ridge building northward will begin to increase temperatures again Tuesday and Wednesday. This will keep the Heatrisk in the moderate range but the Lower Columbia Basin begins seeing some Major Heatrisk Tuesday and Wednesday with the possible need of advisories. .LONG TERM...Thursday through Monday...Ensemble NWP is in excellent agreement that an upper-level ridge will remain in place over the West through at least Sunday, albeit with a shortwave passing to the northwest on Thursday. Subsequently, ensemble agreement in the 500- mb pattern loosens by Monday, primarily with regard to a Pacific low and if/when it tracks onshore into the PacNW. In ensemble cluster space, ~35% of members support the trough moving onshore while the remainder keep the ridge in place with the trough deflecting into British Columbia. In terms of tangible weather, the region will see continued hot and dry conditions area-wide coupled with breezy to locally windy westerly gap winds on Thursday and Monday. Winds will be strongest if the "troughier" solutions materializes. Heat is forecast to peak over the weekend with near-ubiquitous Moderate HeatRisk and widespread Major HeatRisk. In terms of temperatures, NBM probabilities of afternoon highs reaching or exceeding 90 degrees for our main population centers remain very high (>90%) through Sunday, only dropping (55-85% chance) on Monday given the aforementioned uncertainty in the longwave pattern. Increasing the threshold to 100 degrees, probabilities drop and highest confidence (40-85% chance) is over the weekend. Plunkett/86 && .AVIATION...18Z TAFs...VFR conditions are expected to prevail at all TAF sites with just FEW-SCT clouds at or above 18K feet AGL. However, smoke from area wildfires reduced VSBYs along the Blue Mountain Foothills earlier this morning from 9S9 to PDT and ALW though increasing winds and breaking surface inversions have improved VSBYs in the last couple of hours. Tonight will see potential once again for FU to reduce overnight and early morning VSBYs along the Blue Mountain Foothills. Due to the uncertainty of smoke concentrations, have limited mention of 6SM FU to PDT from 13Z- 18Z tomorrow morning. Westerly to northwesterly winds of 10 to 20 kts with gusts to 25 kts is expected at DLS, PDT and ALW through 03Z this afternoon and at RDM and BDN from 22Z-03Z. Otherwise, winds will remain below 12 kts for the next 24 hours. Perry/83 && .FIRE WEATHER...Fire weather concerns will continue to be elevated due to the hot and dry conditions. Haines levels will generally be a 5 which is still sufficient to promote plume dominated fires. There will continue to be some westerly winds of 5 to 15 mph today especially during the afternoon through evening hours. There will be some localized 10 to 20 mph winds along the eat slopes of the Cascades primarily through the Columbia Gorge and Kittitas Valley. Isolated thunderstorm potential returns to central Oregon late Tuesday and then spreads north across the forecast overnight through Wednesday. At this point LAL of 2 is expected with coverage remaining isolated. && .PRELIMINARY POINT TEMPS/POPS... PDT 95 58 99 63 / 0 0 0 10 ALW 98 63 101 66 / 0 0 0 10 PSC 100 63 102 68 / 0 0 0 0 YKM 98 63 100 70 / 0 0 0 10 HRI 99 61 102 67 / 0 0 0 10 ELN 96 60 100 66 / 0 0 0 10 RDM 94 55 98 59 / 0 0 0 20 LGD 94 56 97 60 / 0 0 0 10 GCD 95 57 99 63 / 0 0 0 20 DLS 97 61 105 69 / 0 0 0 20 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. && $$ SHORT TERM...91 LONG TERM....86 AVIATION...83 FIRE WEATHER...91