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Area Forecast Discussion
Issued by NWS Pendleton, OR
Issued by NWS Pendleton, OR
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737 FXUS66 KPDT 142125 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 225 PM PDT Sun Jul 14 2024 .SHORT TERM...Today through Tuesday...Little relief in store for the forecast area as far as fire weather conditions are concerned. Above- normal heat is expected to continue, keeping the atmosphere very dry. This, combined with a series of upper-level waves passing through the region, will make for a myriad of impacts that will only exacerbate ongoing wildfires in the area, not to mention the risk for new fire starts. Today, breezy winds have picked up through the Cascade Gaps and into the Basin as a result of a mid-level shortwave trekking through the PacNW, resulting in a Red Flag Warning. This wave has also oriented the winds aloft more SW, leading to some moisture advection across southern and eastern Oregon. Cloud cover is evident, however the bulk of shower and thunderstorm activity has remained to our south. Current thinking is that cloud cover will put a bit of a cap on instability across the southernmost portion of the CWA, however this shortwave will still promote extreme fire behavior via a very dry air mass combined with instability. Red Flag Warning remains in effect for OR642 as a result. Things quiet down a bit heading into Monday on the back end of today`s shortwave, however heat will persist and breezy winds will continue through the Cascade Gaps. Next concern comes in the form of an upper-level low that looks to pass through from the SW overnight Tuesday into Wednesday. These types of systems this time of year always raise a concern for thunderstorms and elevated winds. As of now, confidence is low on the exact extent and magnitude of the thunderstorm threat, given how dry models depict the mid-levels of the atmosphere, however the synoptic pattern is still suitable for at least some isolated storm activity across the region. And given how dry the boundary layer has been over the last week or so, thunderstorms are almost certain to be dry. This feature will be the focal point of our forecast concerns over the next few days. Evans/74 .LONG TERM...Wednesday through Sunday... Bottom Line Up Front 1. Thunderstorms across the crests and east slopes of the WA Cascades Wednesday 2. Elevated winds Wednesday especially through the Cascade Gaps 3. Continued very hot temperatures Models remain in firm agreement with the mundane synoptic set up. The region will continue to sit wedged between the Four Corners high with the upper level low off the coast. An upper level shortwave will wiggle its way around the top of the ridge and will assist with the chances of thunderstorms as well as a change in winds. This will keep the region under a dry southwesterly flow through much of the term. This set up can be privy to orographically lifted thunderstorms with the highest chances for them are at the very beginning of the period along the Cascade Crests of WA and through the Columbia Basin of WA. However, with the lack of mid level moisture to assist with the accent, thunderstorm probabilities are low (less than 10%). Keep in mind with the hot and dry conditions st the surface, any fire start will exhibit some extreme fire behaviors. Although the flow remains southwest through the period, there is a weak shortwave that makes its way up and over the top of the ridge. Surface guidance shows a tightening of the pressure gradient at the surface which will cause and increase in the winds along the Columbia River Gorge, foothills of the southern Blues and the Kittitas Valley. The signal is strongest through the Gorge and along the foothills of the southern Blue Mountains. Over 60% of the raw ensembles are in agreement the aforementioned with probabilities of 15% through the Kittitas Valley of sustained winds near 20 mph and gusts to 30 mph. Again, this is nothing new but with the fire on the landscape and any new fire, the winds coupled with the dry vegetation, any new fire start will flow with the winds. Lastly, the EFI continues to have much of region above climatologically normal temperatures through the long term. NBM shows central OR, foothills of the Cascades and Blue Mountains as well as Wallow Valley to be in the mid to upper 90s while the remainder of the lower elevations will be in the 100s. NBM shows very little variance with the temperatures through the long term with maybe only a few degrees less each day. Looking at the raw ensembles and setting the max temperature to 95 and greater, more than 90% show the raw ensembles in agreement across the majority of the area with the exception of the highest terrains. Not looking to get any reprieve through the long term just yet. Bennese/90 && .AVIATION...18z TAFs (Previous Discussion)...VFR conditions will prevail through the forecast period. CIGs will remain mostly clear with a few scattered upper level clouds with a bit of smoke aloft across the eastern TAF sites. Breezy conditions across all sites at 10 to 15 with gusts near 25 kts before settling down and returning to diurnally driven and below 10 kts near/after 4Z. Bennese/90 && .PRELIMINARY POINT TEMPS/POPS... PDT 59 95 57 99 / 0 0 0 0 ALW 63 98 62 102 / 0 0 0 0 PSC 66 100 62 102 / 0 0 0 0 YKM 62 98 63 100 / 0 0 0 0 HRI 64 99 61 103 / 0 0 0 0 ELN 61 94 58 100 / 0 0 0 0 RDM 54 94 53 98 / 0 0 0 0 LGD 55 93 52 97 / 0 0 0 0 GCD 57 95 55 98 / 10 0 0 0 DLS 61 97 61 104 / 0 0 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...Heat Advisory until 10 PM PDT this evening for ORZ041-044-049- 503-505>508-511. Red Flag Warning until 9 PM PDT this evening for ORZ641. Red Flag Warning until 11 PM PDT this evening for ORZ642. WA...Heat Advisory until 10 PM PDT this evening for WAZ024-026>029- 521. Red Flag Warning until 9 PM PDT this evening for WAZ690-691. && $$ SHORT TERM...74 LONG TERM....90 AVIATION...90