textproduct: Pendleton

KEY MESSAGES

- Chances of thunderstorms for Central Oregon Wednesday with more widespread coverage on Thursday. Hail and gusty winds are possible embedded in these storms.

- Minor heat risk for today and Thursday, with greater risk on Thursday before thunderstorm development.

- Breezy to windy conditions develop on Friday.

DISCUSSION

Overhead ridging will bring dry conditions in the short term, with the cut-off low pressure system situated over Nevada and California bringing enough lift to initiate isolated thunderstorms in Central Oregon through Wednesday. Sufficient daytime heating through Thursday will build minor heat risk across the region with values of "1" on Wednesday, with more widespread pockets of "2" on Thursday (70-90% chance). High temperatures will climb into the high 80s to low 90s by Thursday. Consequently, this will enable thunderstorm development with abundant atmospheric energy in the later afternoon hours Thursday, increasing our chances of thunderstorms across the region to 30-40%.

GFS deterministic advertises high CAPE values of up to 1200 J/kg and dew point values in the mid to high 50s, with the highest values situated across the Foothills of the Blues and going up into the Northern Blue Mountains. ECMWF backs up higher than usual CAPE values Thursdays with relative forecasts of 0.7 to 0.91 and a shift of tails of 0 to 1. Widespread low-level lapse rates of 8.8 to 9.2 degrees is present with mid-level rates between 8.2 to 8.7 degrees. Looking at soundings, there's an apparent cap at around 800 mb that is preventing the storms from tapping into the full available energy. Depending on whether storms can overcome the cap will determine if storms will be stronger than anticipated. Per SPC, the entire CWA is fully in a marginal risk Thursday with 5% chances of severe wind and/or hail embedded with these storms. Regardless, gusty outflows is likely from any strong developing storms, bringing erratic 40-60 mph gusts.

For Friday, a cold front passes through the region that will develop tight pressure gradients and bring along breezy to gusty winds across the region. Thunderstorm formation will be limited to the eastern part of the CWA near the Wallowas and parts of the Foothills of the WA Blues (15 to 25% chance) as the low moves off to the east. Conditions quickly become more dry over the weekend as the pattern becomes more zonal/slightly ridged over the PacNW and a warming trend continues.

AVIATION /12Z TAFS THROUGH 12Z THURSDAY/

VFR conditions persist through the TAF period. Dry conditions persist with the exception of BDN and RDM that have a PROB30 chance of some isolated thunderstorm development from 04Z to 07Z. Heavier showers and storms will produce temporary sub-VFR conditions with low visibility and cloud decks.

Preliminary Point Temps/PoPs

PDT 79 51 86 52 / 0 10 20 50 ALW 81 57 87 58 / 0 10 20 50 PSC 85 55 93 55 / 0 0 10 50 YKM 87 57 93 56 / 0 0 10 70 HRI 82 54 89 54 / 0 0 10 60 ELN 82 55 89 53 / 0 0 10 60 RDM 78 45 79 43 / 0 50 90 90 LGD 79 49 86 50 / 20 20 40 50 GCD 79 45 81 45 / 20 50 80 50 DLS 86 59 90 56 / 0 0 20 70

PDT WATCHES/WARNINGS/ADVISORIES

WA...None. OR...None.