Hurricane Florence: The Old Versus the New U.S. Global Weather Forecasting Model

Early next year, the U.S. will move to new global model.   The new model (FV-3) was developed at the NOAA Geophysical Fluid Dynamical Lab (GFDL) in Princeton and will replace the old Global Forecast System (GFS) model that has been around forever.

The new model is being run in parallel right now and fascinatingly, it is providing very different forecasts than the current system for Hurricane Florence, which is now approaching the SE U.S..

 Which will be right?  You will know in a week.   But first, let me show you the amazing differences.  Here is the forecast for 5 AM PDT September 14th of sea level pressure.  Both have Hurricane Florence on the Carolina coast, by the differences in central pressure is HUGE!:   913 hPa for the old GFS, 979 hPa for the new FV-3.

And  the forecast two days later are stunningly difference.  The GFS has a very deep low (913 hPa) hanging around on the coast, but the FV-3 has weakened and moved inland.

The track forecasts (see below--AVNO is the GFS, FV3G is the new model)) are initially similar, but near the coast, FV-3 swings farther south (bottom left) and the intensity forecasts are hugely different, with FV3 having weaker winds.

Considering more general verification, here is a representative upper level (500 hPa, about 18,000 ft) for the five-day forecast (see below).  The field below is anomaly correlation (1 is a perfect forecast) and you are looking at the verification of 500 hPa heights for the five day forecast.  The European Center (ECM) is the best, but new model is tied for second place  with the UKMET office.   This is improved performance.

FV3  (red line) appeared to perform better that the GFS (blue line) for the recent Hurricane Lane near Hawaii, with much lower track errors (see below)

Hurricanes are a big concern and the National Weather Service decided to replace the GFS after problems for Hurricane Sandy in 2012.  Thus, a lot of eyes will be watching the performance for Florence. The implications of the differing forecasts for Florence are huge---the next few days should be interesting.

The Fall Transition

Summer is over west of the Cascade crest.  Heat waves are done.  Dense smoke in western Washington is finished. 

Take out your sweaters and rain gear.   You will need them.   A reason to be thankful we are living in the Northwest rather than central and southern California, which the threats of fires and smoke will continue for several months more.

Let's take a look at the latest ensemble prediction of the NOAA/NWS GFS model for surface air temperature at Sea-Tac Airport (remember an ensemble is when we run the model many times using different initial conditions or model physics).  The black line is the mean of the ensemble (generally a very good forecast) and you can see the prediction of the various ensemble members. The forecasts go through September 16th.

No heat waves..in fact, we expect cooler temperatures, with Monday and Tuesday barely getting into the 60s!    Then a very modest warm up with highs in the 60s.

And with the cooling temperatures, there will be multiple opportunities for light rain (see ensemble predictions for 3-h precipitation).  

Why all the changes?  Because of a major reconfiguration of the atmosphere with the development of a persistent upper level trough over the northeast Pacific.  

To illustrate, here is the upper-level map (500 hPa, about 18,000 ft ASL), showing a major trough right off our shore.

Wednesday at 8 AM...wow... BIG trough over the northwest.  A very cool pattern for us.

 The problem for heat wave lovers among you is the rapid weakening of the sun, which has a big impact no matter what the meteorology is doing.  

We are running out of sun (and time) for warm weather.   To give you an idea, here is the climatological temperatures for Sea Tac Airport, with the yellow line showing the daily max temps.  The vertical green line shows today.  Temperatures have NEVER gotten above the low 90sF for the rest of the month and soon never above 90F. 

The super-extended forecasts (e.g., the NAEFS US/Canada ensemble) show no hint of getting back into the 80s.  The cooler weather should be putting a damper on fire growth west of the Cascade crest, and increasing westerly flow will keep east WA and Canadian smoke away from us.  For me, I suspect the calls about "smokestorms" will be over.   

Light Smoke Reaches Western Washington But Won't Last

The sunrise this morning had a reddish twinge to it and the Seattle Space Needle cam clearly showed a haze layer on the eastern horizon (see below)

A thin veil of smoke has extended over western Washington, with far higher values east of the Cascade crest.   The excellent http://wasmoke.blogspot.com/ web site shows the air quality situation at 7 AM (see below), indicating moderate air quality in most of eastern Washington, extending into Puget Sound and Northwest Washington.    Fine on the coast.

As shown by the small particle concentrations at the Seattle Duwamish site (see below), values have increased to around 30 micrograms per cubic meter--enough to produce a light haze that obscures the Cascades and Mount Rainier.

But some perspective is needed....this is spare change compared to what we experienced a few weeks ago (see plot since August 19th below).    Based on forecast models and the latest wind observations, I don't expect the values to get much higher in Seattle.

Why did we get some smoke?    Because the winds turned easterly (from the east) aloft and some of the smoke from the fires over NE Washington headed our way.  This is evident from the time-height cross section at Sea-Tac, which shows winds and temperatures with height over time (time increases to the left). The y-axis is height in pressure--850 is about 5000 ft, and the wind barbs are in blue.

The latest visible satellite image shows some light smoke over western WA (you can see some from the Maple Fire on the Olympic Peninsula), but huge plumes of smoke are heading northeastward over Oregon, heading towards southeast WA.

And the 10:45 AM image from GOES-16 shows smoke coming from the Maple Fire on the Olympic Peninsula and a new fire north of Mt. Rainier.  You can see the low-level haze around Puget Sound if you look closely.

Let's check out the NOAA HRRRsmoke model to see what is happening and will happen.  Below I will show integrated smoke...the total smoke in the vertical column....not smoke at the surface.

At 6 AM today , low levels of smoke are found over Puget Sound (blue), with serious smoke near the NE WA fires and in a dense plume originating out of the fires of SW Oregon and northern CA.

Similar situation at 2 PM today.

But tonight (11 PM) the onshore flow over the region will increase as an upper-level disturbance approaches and the smoke will be pushed out of western Oregon and Washington.

 And by tomorrow at 10 AM, most of WA state will be able to breathe freely, except for folks immediately downstream of the NE WA fires and the far SE corner of the state.

Clean air is expect for the weekend.

What kind of weather pattern produces lots of smoke in Puget Sound?

Even with all the talk about smoke here in Puget Sound, little real research has clarified the weather patterns associated with our smoky days.

OK....let's address this deficiency!

I will do this by using a technique called compositing--- finding a series of times of big, recent smoke events and then averaging weather maps for these times.  Common features should reinforce themselves, showing us the essential circulation patterns accompanying smoke.

The times I will composite are the most smoky times during the past three years:

8/21/2018    1500 UTC , 8/15/2018   0300 UTC , 8/4/2017 1200 UTC

8/9/2017 1200 UTC, 9/7/2017 0000 UTC, 8/23/2015 2100 UTC

First, let's composite a representative mid-level parameter-- 500 hPa heights (think of it like pressure around 18,000 ft)--see below.

Mama mia, there is quite a signal!  Big ridge of high pressure over the West Coast, with troughs (low pressure or height) over the eastern Pacific and the eastern U.S.

If you really want to see the wave-like anomalous upper circulation, here is the same map with the mean values for the period taken out (these are called anomalies from climatology).

Amazing. When we have smoky periods, anomalous high pressure is found over southeastern BC. Such high pressure is associated with warm, sinking air aloft. In contrast, the eastern U.S. has a cool trough when we get smoky.

What about at the surface? There we tend to get lower heights (or pressure) over western Washington due to the warm air aloft (see below). We call that feature a thermal trough. In such a pattern, the normal east Pacific high pressure area is pushed offshore, other high pressure builds inland, and the onshore flow of clean ocean air is interrupted. In fact, with high pressure inland, we tend to get offshore (easterly flow), which pushes inland smoke over Puget Sound.

This pattern--high pressure aloft centered over southeastern BC, thermal trough over western WA, lack of onshore flow, and modest offshore flow-- is very good for pushing  smoke over western WA. And it brings warm temperatures and dry conditions across the region...good for fires.
   

But the question you are asking is whether this pattern has become more frequent in time and whether global warming could be the cause.  A very good question.

To help answer your question, I have plotted for over many years the values of the 500 hPa heights (think pressure at roughly 18,000 ft) over exactly the region associated with our heat waves-- the area centered on SE British Columbia-- for July and August (see below).  Higher heights (or pressure) is associated with our smokiest periods. (see below).  This figures does not provide insight into what happened during height of the smoke, but the general environment of the surrounding months.

No wonder this was the big year for smoke!  This year had the highest heights/pressures aloft since the late 1940s.  Heights appear to have risen over the past decades, which is expected as the region (and the planet) have slowly warmed.  Warming causes air to expand, which increases the heights aloft.  This year's spike up seem anomalous and unprecedented, and this is why is would be unexpected to have a repeat next year.

 Why do I say that?  Because I have done extensive research (with graduate Matt Brewer) on exactly this issue.   Heights aloft are controlled by the mean conditions (which are slowly rising with the warming earth) and transient high pressure areas, like the one over southeast BC that was associated with the smoke.    Our research (based on past trends and climate models for the next century) suggests that transient high pressure areas should be attenuated under global warming--which would work against the fires and smoke.   On the other hand, global warming would  warm temperatures and thus help reduce relative humidities,  which thus encourage fire and smoke.

So the bottom line is this.  The anomalous patterns (big ridge of high pressure along our coast), which was the proximate cause of our warmth/dry conditions/fires/smoke this year, were probably not the result of global warming.  Thus, they are probably due to the chaotic, random nature of the atmosphere.   The small background warming we have experienced in our region (1-2F) helped the fires/smoke slightly but weren't dominant factors.

But by the end of the century, as global warming really hits, the potential for Northwest fires will substantially increase, everything else being equal.

Weather Radar, Birds, and Smoke

Taking a nice walk in Seattle's Magnuson park tonight, I saw and heard a lot of geese in the air, and, of course, I thought about bird migration.   So I wanted to check the Doppler weather radar when I got home to see which way the birds were moving aloft.

The  (9:08 PM) Doppler weather radar from Langley Hill on the the WA coast was fairly dramatic, showing strong southward motion for our feathered friends.  How can I tell?   The colors tell the speed of the air towards (green or blue) or away (yellow or red) from the radar.  The couplet of green to the NW and red to the SE tell us that the birds of flying south/southeast.  The don't like flying offshore.

Compare this to the pattern in May....just the opposite, birds flying north.

Then I started to muse about smoke and birds, and took a look at the Doppler velocity imagery during the period of greatest smoke (roughly August 21-22) at 9:09 PM--and I was surprised what I saw (see below).   It appears that the radar was picking up the smoke offshore (all the gray colors, little velocity), in contrast to the birds over land, who were heading to the south.

A few days later when the smoke was much less (August 25th), the offshore radar returns were gone.

The birds kept flying to the smoky periods, perhaps they were high enough to be above the worst of it.  I did notice less birds singing in my backyard during the worst of the smoke. 

Finally, today I learned about another impact of the wildfire smoke---regional stores were stripped of the better quality furnace filters.  Absolutely none in the local Fred Meyer store.  This may be a big business opportunity for someone-- imagine starting an Air Quality Store.  Imagine-- a wide selection of filter masks,,home air quality filtration systems, particle sensors, and yes, even furnace filters.  Could even run tours to places with clean air.

A Dry Summer

Western Washington's summers are nearly always quite dry, but this summer is unusually so.  

At SeaTac Airport, we are down about 2 inches from normal for the last 12 weeks (see below)

 And looking at the precipitation anomaly (difference from normal) over the past 90 days for WA state shows near normal precipitation over the Columbia Basin, but a dry western Washington, with the windward slopes of the Cascades being roughly 3-5 inches below normal.

To get some historical perspective, here is the May to July precipitation for Washington State since 1930.  This year was not a record low, but was one of the driest years during that period.  Overall, there has not been much a long-term trend in early summer precipitation, but we have had a drier than normal spell the last few years.

The good news is that the models are showing the return of light rain to our area.

For example, here is the forecast cumulative precipitation through next Friday using the UW WRF model.  Decent rain in British Columbia, which is very good--can help dampen down the fires.  And western Washington gets moistened, particularly the western side of the Cascades.

Regarding the holiday weekend, it should be dry through Sunday night, but then a upper level trough moves in.  So expect some light showers Monday AM that will be over by noon.

And then on Thursday a potent upper trough approaches (see below)...expect substantial cloudiness and some rain later on Thursday into Friday.  In short, normal conditions are back.  Heat waves and smoke are in our rear-view mirror.

The Smoke Outlook for the Next Week

Air quality today is far better over the region today that last week, but some smoke is present and will stay present.

Here is the latest surface particulate map from the wonderful  Washington State smoke website : http://wasmoke.blogspot.com/.  Most of the sites are green (good air quality)....but there are problem spots.   Because of the Maple Fire on the Olympic Peninsula and persistent wildfires on northern Vancouver Island, some smoke is getting into western Washington.  That is why a few central Puget Sound sites are reporting moderate levels (but on the low level of moderate).  And the persistent fires on the northeast slopes of the Cascades are producing moderate to unhealthy values there.

This pattern is going to stay in place for the next week, based on on the latest model runs.  Forecasts are for the maintenance of a ridge of high pressure offshore and generally northwesterly flow--no heat wave--but the Vancouver Island smoke can waft into western Washington.  To illustrate, here is the forecast map for upper level (500 hPa) flow at 5 PM Saturday.  No heat wave.  Generally onshore flow.

The entrance of clouds into our region has revealed a problem with the NOAA/NWS HRRR smoke model I have shown in previous blogs.   It bases its fire location on satellite data (like VIRS) and when clouds occur, the fires are not well defined.  The Canadian smoke model seems to do better.

I suspect that we have seen the worst of the smoke for this season here in western Washington, so it is useful to view a trace of air quality at Seattle to get some perspective (see below for June 28th through today).   Particulate levels (PM2.5) were relatively low through approximately August 10th (although there was a small spike on July 4th).    We had two weeks of smoke, with some peaking into the very unhealthy range (above roughly 120).  Now we have settled down into low-moderate level (roughly 15-20)-- some smoke, but far down from the previous peaks.

It is interesting to compare this against recent years.   For 2017, there was a two week period in early August, that was bad, but not quite as bad as this year.

And 2015, a much warmer year that this one-- a summer similar to what we expect during the 2070s, had far less smoke that this year.

Clearly, there are subtleties to the connection between smoke and weather, something I will explore in a future blog.

Finally, for those living in Seattle, a new smoke measurement site has been put on top of my building at the UW, thanks to the US Forest Service (and particularly thanks to Susan O'Neil of the FS that supervised its installation).  This link will get you there (see graph at 8 AM Wednesday below)

The Field Trip to the Wine Country Fires

Over the weekend, I flew down to California with graduate student Brandon McClung, to view the recovery from the catastrophic wine country wildfires of October 8-9, 2017.  I have become very interested in West Coast wildfires and have completed a paper on the meteorology of the Wine Country fires and the winds that initiated them:  the Diablo winds.

I found the trip both scary and highly informative.

As many of you remember, the Wine Country fires occurred on October 8-9, 2017, with most of the damage associated with four major fires (see map below) north of San Francisco.

 44 people died, thousands of homes were destroyed, and insured damage was around 10 billion dollars.  Total loss was probably 50-100 billion.

The wine industry only experienced minor losses and our travels through much of the fire territory showed lush fields of grapes and crowded wineries and support businesses.

But then we entered the fire zones, where there were a lot of surprises.  One surprise was that the trees were really not consumed, but blackened.  There would be yellow/dead leaves but many of the trees were still alive, with some green leaves at the top.  A thick growth of grass had clearly grown during the spring, and small plants/bushes were evident.

In some places flowers were coming up, even among the charred trees.

Clearly, the chaparral vegetation is highly robust to fire and was coming back quickly.  I bet that in five years it will be hard to tell that the fires even occurred.

But then we entered some of the burned out neighborhoods of Santa Rosa, and the scene was apocalyptic and disturbing.  Hundreds of burned out lots, with nearly all the fire debris removed.  The remains of swimming pools and brick patios, but no houses to go with them. Desolation as far as the eye could see.  I really felt bad for the people that lived there before--it was like a war zone.

But then another surprise...some houses did survive.  They tended to be ones with tile or ceramic roofs, stucco walls,  and no eves.  So it was possible to build homes that could withstand the fiery onslaught. An example:

Such neighborhoods are an example of the wildland/urban interface that might not be appropriate for building.  But if you are going to live there, you need to have a house and surrounding designed to handle such fires.   We did see some new houses going up, and they looked like traditional construction.  Not good.

We also hiked above Berkeley, California in the hills that have produced huge, destructive fires, like the Tunnel Fire of 1991.   Terribly overgrown with non-native and flammable Eucalypus trees and dry grass everywhere (see picture).  There will be more fires there someday.

Above  University of California, Berkeley

My take away from all this is that the chaparral vegetation of the region appears highly robust to fires, and that there is a huge population living too close to fire-prone hills.   My research deals with predicting the winds that produce the big fires of the region...that could help save lives, but too many folks are living in locations that have burned for millennia and will burn again--even under the "old normal."