Sunday, August 2, 2015

Cooling Ahead and Supersmoke

Although the temperatures earlier today were suppressed a bit by high level convection that moved through, that air above us is equally warm and many should get near 90F.   But today should be the last really hot day for a while, since the circulation over the eastern Pacific will be be changing substantially.   Tomorrow (Monday) should slide down into the lower 80s and for the rest of the week the upper 70s looks like a good forecast.

But little precipitation the next few days, particularly west of the Cascade crest.

The best way to get a quick look at the weather situation is to examine the upper level charts and for meteorologists, the 500 hPa pressure level--roughly 18,000 feet up-- is a favorite.  This level is about half-way up in the lower layer of the atmosphere where most weather occurs:  the troposphere.  The plots below show the heights at this level (solid lines)...think of them as pressure.

This morning (5 AM) a broad ridge of high pressure (high heights) is found over the western U.S.   That is why we are warm.


  But by 5 AM Monday, things have changed!  The ridge has pushed inland and a trough of low pressure is along our coast.  Marine air will start invading of region.


By Thursday morning, the trough has moved into BC and a very weak ridge is just offshore.   Slight warming, but no 90s.

But by next weekend (5 AM Sunday is shown) a deep trough is over the West Coast.   That would bring clouds, showers, and much cooler temperatures.


Cooling temperatures and high humidities should add wildfire suppression, as will the relativity littel lightning expected during the next several days.  This is now  the climatologically warmest time of the year, but nights are starting to get longer and temperatures will inevitably start to decline later this month.

Another interesting issue is the HUGE amount of smoke coming off the Wolverine fire near Lake Chelan.   This fire has quadrupled in size during the past few days, with the smoke plume even visible from Seattle.

Here is the MODIS satellite image on Saturday afternoon.  Seattle is on the left side of the picture.  Smoke from the fire has filled much of eastern WA, with a particularly dense plume heading due eastward.


Take a look at the visible satellite image around 5 PM Saturday...the plume is amazing.  If you look closely you can see smoke from the Olympic Park fire...that has revved up as well with the warm weather.


One final thing..some weak showers are now moving northward over western Oregon into SW Washington...nothing serious, but key your eyes on them (see radar). Raining in Portland right now, with a few lighning strikes to the south.  Not much discussion of this feature in the forecasts.


Not a good day for Portland forecasts on Sunday.  Their forecast the evening before for Portland and vicinity was:

 ORZ006-WAZ039-021115-
 GREATER PORTLAND METRO AREA-GREATER VANCOUVER AREA-
 INCLUDING THE CITIES OF...HILLSBORO...PORTLAND...WILSONVILLE...
 OREGON CITY...GRESHAM...TROUTDALE...VANCOUVER...BATTLE GROUND...
 RIDGEFIELD...WASHOUGAL...YACOLT...AMBOY
 829 PM PDT SAT AUG 1 2015
 
 ...HEAT ADVISORY IN EFFECT UNTIL 9 PM PDT SUNDAY...
 
 .TONIGHT...PARTLY CLOUDY. LOWS 60 TO 65...EXCEPT AROUND 55 IN
 OUTLYING AREAS. NORTHWEST WIND 5 TO 10 MPH. 
 .SUNDAY...MOSTLY SUNNY IN THE MORNING...THEN PARTLY CLOUDY. HIGHS
 90 TO 95. NORTHWEST WIND 5 TO 10 MPH. 
 .SUNDAY NIGHT...PARTLY CLOUDY. A 20 PERCENT CHANCE OF SHOWERS AND
 THUNDERSTORMS AFTER MIDNIGHT. LOWS AROUND 60. NORTHWEST WIND 5 TO
 15 MPH.

They were going 90-95.   Instead it was mostly clouds with highs around 80F.  
Virtually every modeling system missed the mid-level convection that was the origin
of this  forecast failure.


Announcement

     I have am giving two public lectures on the San Juan Islands this month:

First, Lopez Island at 7 PM, August 19th on "The Future of Weather Prediction"  Details here.

And on Orcas Island at 5:30 PM August 20th at the Orcas Community Church in Eastsound on "Why is the Northwest so Warm?"

3 comments:

Greg Metcalfe said...

So what is the mechanism that drives whatever might have been learned after a forecast miss into the models?

Jeff Glanzrock said...

Cliff, any suggestions for the best viewing areas sans smoke for the Perseid meteor shower Aug 12 - 14?

Thanks,
Jeff

Anonymous said...

Thank you for such an interesting and informative blog. I have a question that might make an interesting future topic. The NDBC reports very useful information for mariners. Unfortunately, this data is delayed by at least an hour by the time it gets to the website. For example, the conditions at West Point (off discovery park) are reported here: http://www.ndbc.noaa.gov/station_page.php?station=wpow1

How quickly do the conditions tend to change? Would those using the sound for work and/or pleasure benefit from true real-time reporting from these buoys?

When rigging a boat in Shilshole, sheltered from the wind, I would be likely to use the NDBC data to set up my boat, as it seems like that would be much more accurate than the forecast, or at least reveal the deviation from forecasted conditions.