textproduct: Pendleton

KEY MESSAGES

- Last day of dry conditions before a cold front passage brings unsettled weather through the region.

- Thunderstorm development possible (10-25% chances) Tuesday and, to a lesser extent, through Wednesday morning.

- Breezy to locally windy conditions developing with the pattern change.

DISCUSSION

RIGHT NOW THROUGH TUESDAY MORNING: Synoptic wise, upper level ridging will continue to dominantly influence the pattern in the short term. High clouds are currently in the region with no/very little precipitation reaching the ground. Monday will see the warmest day in the immediate future before a cold front passes on Tuesday (more on that later on). Today, we'll see high temperatures in the high 70s to low 80s in most of the populated regions (>90% chance) with light to variable winds.

TUESDAY MORNING TO WEDNESDAY NIGHT: Overall guidance shows good chances of thunderstorm coverage, but to what extent is a bit less clear. LREF clusters aren't in great agreement with the amount of CAPE that will develop, which in turn means the extent of thunderstorm develop isn't clear. Out of the clusters, 78% of clusters likes to develop 400-700 J/kg of CAPE with a second maxima spot in the Kittitas Valley with similar amounts of CAPE. The other 22% only bring the CAPE values up to 200 J/kg, with limited CAPE values in the Kittitas Valley.

Chances of wetting rain remain high (70-90% chance) late Tuesday afternoon through the overnight hours into Wednesday. A portion of the Blue Mountains will see a total of up to 2.5" through Wednesday (60-80% chance) with areas of the Columbia Basin reaching up to 1" (50-70%). Breezy to locally windy conditions will develop as tight pressure gradients develop from the low pressure system bringing at least 30-40 mph gusts across the region (50-70%). Wind advisory highlights are possible with the NBM hinting that probabilities of 45 mph+ gusts to the Foothills of the Blues at 60-80% with parts of the Basin reaching 40-60%.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

VFR conditions are expected through the TAF period. Winds will generally be 10 kts or less, except at BDN and RDM, which will see gusts to around 20 kts this afternoon and early evening before decreasing once again.

By the end of the forecast period, rain chances will be creeping up at DLS, BDN and RDM, but will still be too low to warrant a mention in the individual forecasts. in later TAF issuances rain chances will need to be introduced, and possibly thunder as well.

Preliminary Point Temps/PoPs

PDT 75 48 71 44 / 0 0 40 80 ALW 76 52 73 46 / 0 0 20 80 PSC 80 49 78 49 / 0 10 10 70 YKM 79 50 76 50 / 0 10 20 40 HRI 78 49 74 46 / 0 10 20 70 ELN 75 48 69 45 / 0 10 30 40 RDM 75 43 61 36 / 10 20 50 50 LGD 75 44 73 42 / 0 0 40 90 GCD 77 44 69 39 / 0 10 70 90 DLS 78 52 67 48 / 10 20 40 40

PDT WATCHES/WARNINGS/ADVISORIES

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