textproduct: Pendleton

DISCUSSION

Current nighttime satellite shows some mid level clouds lingering over the region. Radar shows a few returns along the eastern slopes of the Cascades but no thunderstorms within the cells. Overnight temperatures will be in mostly in the 50s with isolated areas in the Basin seeing low 60s.

Southwest flow aloft will continue over the region with a trough just off the coast. Models show a shortwave will make its way into the region bringing with it increased moisture form the southwest. T his will lead to increased chances of thunderstorms and showers over the Cascades as well as the eastern mountains again today. Looking at forecasted NAM soundings, there are MUCAPE values between 250-750 J/kg with isolated pockets of near 1000 J/kg, LIs of -3 to -4, lapse rates between 1-10 C/km and effective bulk shear of 18-22 kts. HREF lightning density paintball shows much of the lightning forming along the crest and east slopes of the Cascades as well as across the eastern mountains beginning with highest density being after 1 PM. NBM raw ensembles show 30-40% chances of thunderstorms occurring in those same region. Even with the increased chances of showers accompanying these storms, there is moderate confidence (60-70%) of elevated fire weather conditions developing due to lightning potential outside of rain cores and gusty outflow winds. Therefore a Red Flag Warning has been issued for these areas through 9 PM tonight.

Sunday through Monday models show an upper level low off the coast moving towards the south and deepening the southwest flow across the region. Models do show some moisture being swept up into the region leaving slight chances (10-20%) of showers and thunderstorms occurring Sunday afternoon, especially along the Wallowa Mountains. There are also chances (10-15%) of thunderstorms in central OR as well as the WA Cascades. Monday also shows slight chances (10-15%) of thunderstorms along the same areas.

Tuesday models show a bit of split flow across the region as an upper level shortwave moves south out of B.C. bringing northwest flow aloft across the northern portion of the CWA while the trough remains just off shore and is pushing southwest flow into the southern portion of the CWA. The northwest flow aloft will allow for breezy gap winds to form Tuesday with NBM raw ensembles showing sustained winds speeds between 15-20 mph with 50-70% of the ensembles in agreement.

AVIATION /12Z TAFS THROUGH 12Z SUNDAY/

VFR conditions will persist through the forecast period as smoke is lingering but mostly stating aloft and not affecting VIS at the ground.

Predominately light winds across all TAF sites with only DLS seeing breezy winds above 12 kts and gusting to 20-25 this afternoon. Any showers and thunderstorms that pass over or in the vicinity of TAF sites will be capable of producing gusty outflow winds; best chances are at PDT/ALW in the afternoon.

FIRE WEATHER

Continued monsoonal moisture will bring thunderstorm chances across the region again today with 30-40% chances for the Blues Mountains and Wallow Mountains. Eastern slopes of the WA Cascades will see 10-15% chances for thunderstorms today as well. Sunday and Monday will also continue to see 10-15% chances of thunderstorms for the eastern mountains s well as the WA Cascades. A slight pattern shift Monday night into Tuesday will bring breezy gap winds of 15-20 mph sustained.

Preliminary Point Temps/PoPs

PDT 87 56 89 60 / 20 0 0 0 ALW 90 62 91 65 / 30 10 0 0 PSC 92 59 93 60 / 20 0 0 0 YKM 89 61 92 61 / 20 10 0 0 HRI 90 61 92 63 / 20 0 0 0 ELN 85 59 87 59 / 20 10 0 0 RDM 85 50 87 52 / 20 10 0 0 LGD 86 54 89 56 / 70 20 10 0 GCD 88 54 91 56 / 40 0 0 0 DLS 90 64 92 63 / 20 0 0 0

PDT WATCHES/WARNINGS/ADVISORIES

WA...Air Quality Alert until noon PDT Monday for WAZ026-522-523. Red Flag Warning from noon today to 9 PM PDT this evening for WAZ692-693. Air Quality Alert until noon PDT today for WAZ027-521. OR...Air Quality Alert until noon PDT Monday for ORZ041-503-505-506- 508>511. Red Flag Warning from noon today to 9 PM PDT this evening for ORZ692>695-699.