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 /12Z TAFS THROUGH 12Z TUESDAY/

With the upper level ridge starting to exit the region, high level clouds enter with no anticipation that they will drop lower than VFR level over the next 24-hour period. Winds will remain light to calm, with the exception of BDN and RDM developing some slightly breezy 15-25 mph gusts in the afternoon to evening hours. Rain chances in the Central Oregon TAF sites will start to increase towards the last few hours of the period, but not high enough to warrant a preliminary line of rain. For now it will be PROB30 chances as the last few hours of the 12Z period are capturing the start of an unsettled weather pattern that will prevail through the next few days.

Preliminary Point Temps/PoPs

PDT 76 48 71 44 / 0 10 30 70 ALW 76 52 73 46 / 0 10 30 80 PSC 80 49 78 49 / 0 10 10 60 YKM 79 49 75 49 / 0 10 10 30 HRI 79 49 74 46 / 0 10 10 60 ELN 75 47 68 45 / 0 10 20 30 RDM 75 42 62 36 / 10 20 30 50 LGD 75 44 72 42 / 0 10 40 90 GCD 77 44 70 39 / 0 10 60 90 DLS 78 52 67 48 / 10 20 20 30

PDT WATCHES/WARNINGS/ADVISORIES

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