719 FXUS66 KPDT 300343 CCA AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 820 PM PDT Sat Jun 29 2019 corrected for wording .UPDATE...Thunderstorms fired up mostly over central oregon this aftn/evening and some became strong producing half inch size hail. However the tsra were weakening into showers that are forecast to push north along the cascades tonight and the forecast was updated to reflect this. Meanwhile a stationary low pressure system over the pacnw was pumping moisture into the region and combining this with daytime heating created the thunderstorms. A weak disturbance ahead of the low pressure will spin across the region and showers were developing over north central oregon and this extended northeast into the northern blue mountains and the forecast was updated for this too. Most of the showers should begin to lessen with the loss of daytime heating but may linger overnight over portions of the area. Temperatures are forecast to fall into the 50s with 40s across the higher elevations. && .PREV DISCUSSION... /issued 233 PM PDT Sat Jun 29 2019/ SHORT TERM...Tonight through Monday night...A large scale upper level trough with the upper low offshore will maintain the unstable conditions east of the Cascades. Any weak embedded disturbance in the southwest flow aloft will bring a chance of showers and thunderstorms over the forecast area. Currently, scattered thunderstorms have developed along the Oregon Cascades as well as the Grande Ronde Valley. Towering cumulus have developed throughout central and northeast Oregon where there is at least a slight chance of showers and thunderstorms this evening. Most of the lightning will occur along the east slopes of the Oregon Cascades. Other storms should only bring occasional lightning, not expected to meet red flag warning criteria. The 0-6km bulk shear is around 55 knots but it is mostly channeled vorticity lacking support for organized convection. The synoptic pattern on Sunday is similar to today, and it will be a primarily persistent forecast. Once again, the forecast area will be under a cyclonic flow aloft and unstable air mass with a slight chance to chance of showers and thunderstorms. Lightning activity will be limited and not enough to warrant red flag warnings. The WA/OR Cascades will have the best potential for thunderstorms with isolated elsewhere. On Monday, the upper low will deepen into a closed low in response to the upper level jet approaching the Pacific NW. The dynamics and upper level support will be stronger for more numerous showers and thunderstorms. Some storms could be strong with heavy rain and hail. Despite the frequent lightning strikes, storms bringing 0.25-0.5 inch of rain will limit the potential for rapid fire spread. Issuing a fire weather watch could be overkill, but there is a possibility of new starts from lightning. For now, will headline the fire weather forecast to alert agencies of the frequent lightning potential (LAL of 4). Wister LONG TERM...Tuesday through Saturday...The upper level trough that has been situated along the Oregon/Washington coast for the last several days will slowly shift east and be located over the forecast area by Wednesday. Moisture and instability will be limited, bringing only slight chances for showers & a few thunderstorms each afternoon primarily over the southern Blue/Wallowa Mountains. By Thursday the upper level low moves east of the area with dry conditions expected for most, although an isolated shower/thunderstorm cannot be ruled out over far eastern portions of Wallowa County. Zonal flow arrives for Friday and Saturday bringing dry conditions as well as a warming trend. Temperatures Tuesday through Thursday will be in the lower to mid 80s with 60s/70s for the mountains. By Friday and Saturday temperatures climb into the lower to middle 90s with 70s/80s expected for the mountains. Richards AVIATION...00Z TAFS...VFR conditions will continue at all TAF sites for the next 24 hours. Ongoing showers and weak thunderstorms will continue over the mountains this evening through 06Z, possibly affecting KRDM and KBDN. A few showers may affect KDLS. Elsewhere generally scattered skies above 070 are expected becoming mostly clear early Sunday morning. Winds are expected to generally remain below 10 kts for the next 24 hours. Richards && .PRELIMINARY POINT TEMPS/POPS... PDT 55 86 58 86 / 20 0 0 10 ALW 57 89 60 89 / 20 0 0 10 PSC 59 91 61 91 / 20 0 0 10 YKM 56 85 59 85 / 10 10 10 20 HRI 58 90 60 89 / 20 0 0 10 ELN 53 80 55 80 / 10 10 10 20 RDM 46 82 49 79 / 20 10 10 40 LGD 51 83 52 84 / 20 10 10 10 GCD 50 82 53 83 / 20 10 10 20 DLS 60 86 62 81 / 20 10 10 20 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. && $$ 97/