A classic early-fall east wind event has arrived this evening. This is the time of year when east winds make our temperatures jump up, drop the relative humidity, and give us crystal clear skies (assuming no fires). The view from our Skyline Camera at 1,900′ in the West Hills (recently upgraded) was stunning this afternoon. We could easily see into the west end of the Gorge…the sandy hill on Sand Island at Rooster Rock SP showed up clearly 20 miles away! That’s something we couldn’t do all summer with the haze/smoke filling our skies most of the time.
High pressure is centered well to our east, and a “thermal trough” of low pressure is right along the coast. So wind flows from east to west, over the Cascades and down into the lowlands. As a result temperatures warm quickly. In the case of tomorrow and the first part of Saturday, that wind will make it all the way to the beaches. Tomorrow will be one of those rare days at the Coast when temperatures soar into the 80s or even 90.
Today we hit 85 at PDX, a 12 degree jump from Wednesday. Models seem to show 4-5 degrees warming for tomorrow, so I forecast a 90. Then another 3-5 degrees warming on Saturday as 850mb top out around +20 to +21. That would put us in the 93-95 degree range. Saturday is going to be a windy scorcher!
In September last year and in 2012 we hit 95 degrees at PDX. 850mb temps were +23 and +21 degrees at Salem. Similar offshore flow pattern so I’m pretty confident of the 94 we have in the forecast for Saturday.
What about the big picture? Is September going to be a blowtorch month? Two thoughts on that.
1. Yes, the first half of the month looks extremely warm. The general pattern is the ridge/offshore flow through Sunday, a weakening trough giving us cooling Monday-Tuesday, then a return to ridging and offshore flow the 2nd half of next week.
2. Things could change quickly the last two weeks! We’ve seen that in the past. Flip a coin. A little bit of information can be gleaned from last night’s maps from the monthly run of the ECMWF.
They show the well above average upper-level heights through the 20th. That’s a little more than 2 weeks away. Then the following two weeks:
That last map isn’t real helpful is it?
We didn’t have measurable rain in August here in Portland (officially). Yes, yes, I fully aware some of us had showers. But many of us didn’t, just like PDX. The ECMWF shows no precipitation for the next 10 days, and it would be fair to assume it shows below normal rainfall for the next 5-10 days after that.
So keep watering…your yards/plants/trees are more stressed now than back in July/August as the soil continues to dry out.
Chief Meteorologist Mark Nelsen
Looks like PDX eeks out another 90 + degree day.
I’m guessing the thermal low has pushed just onshore @ Newport as the winds have turned onshore from the WNW, and the temps have dropped from 91 to 81 in 20 minutes.
My favorite type of heatwave going on right now! I think I got a wind burn today! Eugene almost hit 97 today, Salem 93 so far…
Wow. North Bend just dropped 25 degrees in 40 minutes! From 91 at 1:35pm to 66 at 2:15pm.
Beware the DOUBLE-DOWNSLOPE EFFECT!
NATIONAL WEATHER SERVICE PORTLAND OR
906 AM PDT FRI SEP 5 2014
WITH OFFSHORE FLOW CONTINUING MUCH IF NOT ALL OF THE DAY…850 MB TEMPS IN THE +18 TO +20 DEG C RANGE…AND DOUBLE-DOWNSLOPING OFF BOTH THE CASCADES AND COAST RANGE…WOULD NOT BE SURPRISED IF COASTAL
TEMPS WARMED UP QUICKLY TOWARD 90 DEGREES BY MIDDAY. WHILE INLAND VALLEYS ARE EXPECTED TO TOP OUT IN THE LOWER 90S…SOME COASTAL
LOCATIONS COULD BE THE WARMEST IN OUR CWA… POTENTIALLY REACHING THE MID 90S THIS AFTERNOON DUE TO THE ABOVE- MENTIONED DOUBLE-DOWNSLOPE
Make mine a double!!
Mark, do you see this dry warm pattern continuing past what would be normal, as in going into October? Just curious as it seems this pattern has been stable for a while now
Low last night in BG> 47. Low last night on Larch Mountain> 68
Winds now gusting to 44 mph at Larch (in Washington)
We are 18° warmer this morning than we were yesterday. 68° with the east wind blowing all night.
Love east winds in September! As I do in December and January as well. 🙂
9/4/2014 Oregon (All) Temperature Summary
High:94 at Brookings (US 10( 150 ft) & Brookings Airpor(459 ft) & DW5789 Eagle Poi(1463 ft)
Low: 66 at RED MOUND(1753 ft)
High:47 at HOWARD Mt Howard(8150 ft)
Low: 20 at Horse Ridge (US (4160 ft )
Largest Diurnal Change: 56 degrees
PROVOLT SEED ORC (93/37 ) (1180 ft )
Here’s the billion-dollar question: How much of the current and upcoming offshore pressure gradient would have happened, given the exact same upper-level (500mb) pattern in July instead of early September? I’m curious as to what share of the “credit” goes to the increasing hours of darkness and weaker sun.
I’m looking forward to it!!
I really like it when the yard dries out. No more grass cutting or mole hills!