textproduct: Pendleton

SHORT TERM...Today through Wednesday

Heat and mountain thunderstorms will be the main story of the forecast through the midweek as the PacNW finds itself wedged between a ridge axis to the north and a cutoff low to the south, currently centered off the central California coast. This low will gradually lift up through our forecast area, making for an uptick in winds Tuesday night into Wednesday, as well as a chance for thunderstorms across the mountains of central and eastern Oregon, thus making for elevated fire weather risks.

Today will be quiet, with dry and hot conditions prevailing, before temps begin their real surge on Tuesday. A Heat Advisory is in effect on Tuesday for the lower Basin and adjacent valleys, as temperatures are expected to climb to as high as 105 degrees in some areas, namely the WA lower Basin. Temps will fall off as soon as the dry front associated with the upper low moves through Tuesday evening, but this front will also kick off convective activity across central Oregon around the same time, gradually spreading northeastward heading into Wednesday. Have upgraded the Fire Weather Watch for our central Oregon zones into a Red Flag Warning as a result, as CAMs continue to consistently pick up on the thunderstorm threat for the area. Also included OR696 in the RFW as well, since CAMs seem to be trending storm activity more and more northeastward. Lack of QPF coverage across guidance further increases confidence in dry thunderstorms.

Storm activity is not quite as widespread across the eastern mountains Tuesday night into Wednesday, so held off on any fire weather products for those zones, especially given the lack of new fire starts for the area despite the persistent storm activity there over the last week. Concern instead shifts toward the Basin, as winds will pick up as mentioned before with the frontal passage. While RHs will be bone dry on Tuesday, winds don't really start to pick up until the evening, leaving Wednesday as the main potential critical day. RHs increase with this frontal passage, but models are pretty confident in Wednesday being a blustery day, with widespread gusts up to and over 30 mph. Have issued a Fire Weather Watch for both the OR and WA Basin zones as a result. WA690 in the Kittitas Valley is borderline, but with RHs forecasted to be in the 30s up there, am less confident about fire weather headlines for the zone at this time. Evans/74

LONG TERM...Thursday through Monday

Ensemble guidance generally points toward a benign pattern after Wednesday. Once the upper-level low lifts out of the region, ensemble clusters generally waver between a light NW flow or zonal pattern, which would yield dry and gradually warming conditions through next weekend. Winds look to be relatively light outside of the Cascade Gaps, which are expected to see their usual breeziness, except for the Kittitas Valley, where a NW flow pattern could perhaps generate stronger gusts. Sensible weather threats are otherwise limited under the synoptic pattern ensemble guidance currently depicts. Evans/74

AVIATION...06Z TAFs

VFR conditions are forecast for all sites through the valid period. That said, BDN/RDM have a low chance of sub-VFR conditions associated with high-based thunderstorms Tuesday afternoon and evening. Any thunderstorms that develop may be accompanied by strong, gusty, and erratic outflow winds up to 50 kts in the afternoon and evening, so included mention of TS in PROB30 groups. Winds will increase Tuesday afternoon and evening for all sites, especially those nearest the Cascade gaps. Plunkett/86

PRELIMINARY POINT TEMPS/POPS

PDT 64 101 65 90 / 0 0 10 0 ALW 69 101 68 91 / 0 0 10 0 PSC 63 103 65 94 / 0 0 0 0 YKM 64 101 63 90 / 0 0 0 0 HRI 64 104 68 93 / 0 0 10 0 ELN 64 97 65 82 / 0 0 0 0 RDM 54 96 52 86 / 0 20 10 0 LGD 61 98 61 88 / 0 20 20 0 GCD 61 100 57 89 / 0 20 20 20 DLS 66 96 66 84 / 0 0 0 0

PDT WATCHES/WARNINGS/ADVISORIES

OR...Fire Weather Watch from Wednesday morning through Wednesday evening for ORZ691.

Heat Advisory from 11 AM to 9 PM PDT Tuesday for ORZ044-507.

Red Flag Warning from 2 PM to 11 PM PDT Tuesday for ORZ696-700- 705.

WA...Fire Weather Watch from Wednesday morning through Wednesday evening for WAZ691.

Heat Advisory from 11 AM to 9 PM PDT Tuesday for WAZ027>029.