Slight relief in temperatures but fire danger remains high

Weather Blog

PORTLAND, Ore. (KOIN) — Morning temps will feel cooler in the upper 50s around PDX this Thursday.

By the afternoon we shoot right back to above normal temps, but this time we’ll stop at 82 with a northwesterly breeze. Another 10-degree drop happens this weekend with a chance for very light rain Saturday and Monday.

Before we jump into fire weather. Let’s review Wednesday’s hot & windy day.

Wednesday review PDX: high 90°. No record there but that morning temp of 65° broke the highest min temp of 61° in 2009. Records were broken in eastern OR/WA in the 100’s.

The Milepost 85 Fire: The Dalles reached 98°, plus it was very windy and dry.  Fire containment at last check was 70%. Conditions were favorable overnight.  

Thunderstorms Central OR: There was an average of 90 to 110 lightning strikes in a half hour period over the course of the afternoon and evening.

Looking ahead at the Milepost 85 Fire: 

Fire Weather Watch will be in effect from 1 p.m. Thursday until Friday night. Gusty winds should peak around 4 – 6 p.m.  Temps upper 80s. Don’t be fooled. It’s very dry and will get drier. RH 10-20%. 

Heat Advisory Lower Columbia Basin

Thunderstorms: New fire starts possible with dry lightning. It’s not too often we get into the marginal category for thunderstorm risk but on this day, we do across central and eastern OR. It’s a marginal risk for severe t-storms.

What’s severe? Wind gusts up to 58 mph. Hail 1 inch in diameter. A tornado

Fire Weather Watch

East Slopes of the Northern Oregon Cascades- Lower Columbia Basin of Oregon- East Slopes of the Southern Washington Cascades-

FIRE WEATHER WATCH IN EFFECT FROM THURSDAY AFTERNOON THROUGH FRIDAY EVENING FOR WIND AND LOW RELATIVE HUMIDITY FOR FIRE WEATHER ZONES

The National Weather Service in Pendleton has issued a Fire Weather Watch for wind and low relative humidity, which is in effect from Thursday afternoon through Friday evening.

* AFFECTED AREA…Fire Weather Zones 639 East Slopes of the Northern Oregon Cascades, 639 East Slopes of the Southern Washington Cascades and 641 Lower Columbia Basin of Oregon, mainly coming out of the Columbia Gorge and into the Columbia Basin of Oregon.

* WINDS…West 15 to 30 mph with gusts up to 40 mph.

* RELATIVE HUMIDITY…10 to 20 percent.

* IMPACTS…Increased chance of rapid fire growth on new or existing fires.

A Fire Weather Watch means that critical fire weather conditions are forecast to occur. Listen for later forecasts and possible Red Flag Warnings. &&

https://forecast.weather.gov/showsigwx.php?warnzone=ORZ510&warncounty=ORC065&firewxzone=ORZ639&local_place1=8%20Miles%20SSW%20Chenoweth%20OR&product1=Fire+Weather+Watch&lat=45.5315&lon=-121.3203#.YLiZKKhKiUk

Breakdown of thunderstorm details

Oregon northeastward into western Montana…

A midlevel shortwave trough is forecast to move into the Pacific Northwest later today into tonight, which will tend to flatten the northern portion of the upper ridge with time. In conjunction with the shortwave trough, a cold front will move into portions of eastern OR, northern ID, and western MT by this evening. Isolated to widely scattered high-based thunderstorms are expected in association with the front. Steep low/midlevel lapse rates will support a threat of localized severe wind gusts and perhaps some hail with initial development across OR/ID. A small cluster may move northeastward into western MT later tonight, with a continued threat of isolated strong gusts.

https://www.spc.noaa.gov/products/outlook/day1otlk.html

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