Area Forecast Discussion
Issued by NWS Pendleton, OR
Issued by NWS Pendleton, OR
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193 FXUS66 KPDT 221727 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 1030 AM PDT Sun Sep 22 2024 .SHORT TERM...Today through Tuesday...The short term should be an overall benign period in terms of significant weather concerns, with a trough bringing the smallest of chances for some Central Washington Cascade rain and breezy winds through the gaps, with high pressure then overtaking and causing a warming trend lasting through the end of the forecast period. As mentioned for today, an upper level shortwave passes across the region, but the majority of the energy from this system remains over Canada. Because of this, we`ll see little in the way of significant effects from it. Perhaps an isolated shower makes its way into the Central WA Cascades, but the NBM only paints <25% chance at a hundredth of an inch for Snoqualmie Pass, barely worth mentioning. The pressure gradients will briefly tighten though, and we should get some breezy winds through the Cascade Gaps. The NBM shows a 30-60% probability of maximum wind gusts 30+ mph today in the Columbia Gorge and Kittitas Valley, but this seems a bit low. Winds at 850 mb are are around 35-40 knots during the peak windy period, and models indicate a 5-7 mb difference in the pressure gradient from Seattle to Vantage. Because of this and the fact that Ellensburg tends to run a little higher than the NBM performs in terms of gusts, have upped the max gusts this afternoon to show around 35 mph as the peak in the Kittitas Valley. Minimum RH values will be lowest further south in Central and eastern Oregon, which should help to preclude any sort of fire weather headlines for the day (it also helps that the Autumnal Equinox is today and generating extreme fire behavior will get more and more difficult each day!). After today an upper level high will take over and shift across our region through Tuesday, centering over the Four Corners area by early Wednesday. This will allow for a steady warming trend, bringing our highs notably above normal. Temperatures today start in the upper 70`s to mid 80`s across our population centers, with a slight increase on Monday, and by Tuesday will be around 5 to 10 degrees warmer, in the upper 80`s to low 90`s - around 10-18 degrees above normal for this time of year. Central Oregon will be the warmest region with highs in the lower 90`s at a 30-70% probability of occurring. Daily record highs are around the mid 90`s, so hopefully we shouldn`t see any broken, but we could come close. If you like warmer temperatures, enjoy this brief little return to summer before we cool back off in the long term. Goatley/87 .LONG TERM...Wednesday through Sunday...Ensemble runs continue to support a pattern change beginning Wednesday with a couple of shortwave troughs impacting the forecast area through the extended period and returning us to cooler Autumn conditions. The upper level ridge of high pressure over the western USA through the first of the week will be pushed into the central USA midweek as an upper level trough in the Gulf of Alaska moves towards the Pacific Northwest. The trough will move inland on Wednesday pushing a cold front across the forecast area ushering in breezy to windy conditions and providing a chance of precipitation mainly over the mountainous areas. This system quickly moves east and exits the region overnight before another system sweeps across the forecast area Thursday night and Friday. This system will also produce a chance of precipitation and provide breezy conditions as a cold front moves through the forecast area. Ensemble runs are showing this trough exiting and being followed by a westerly flow with relative dry conditions for next weekend. However, there are some variations in the deterministic models that range from another trough passage in the ECMWF to a southwest flow under a ridge pattern in the GFS. For now the forecast leans towards the dry westerly flow scenario on the ensemble but with moderate to low confidence. && .AVIATION...18z TAFs...VFR conditions to prevail through the period with increasing high level clouds sct-bkn200-250 late today and overnight. Winds will be light through the morning then will see westerly 5-15 kts and in the afternoon through evening. DLs will see the strongest winds at around 15kts with gusts to 25kts. && .PRELIMINARY POINT TEMPS/POPS... PDT 78 51 79 51 / 0 0 0 0 ALW 81 54 81 54 / 0 0 0 0 PSC 82 56 83 56 / 0 0 0 0 YKM 81 52 83 53 / 10 10 0 0 HRI 82 54 83 54 / 0 0 0 0 ELN 80 56 82 54 / 10 10 0 0 RDM 80 46 80 48 / 0 0 0 0 LGD 78 47 78 48 / 0 0 0 0 GCD 78 46 79 49 / 0 0 0 0 DLS 84 57 86 58 / 10 10 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. && $$ SHORT TERM...87 LONG TERM....91 AVIATION...85