A Great Month of Outreach, Education, and Radar Meteorology with DOW7

Professor Powder attempts to keep DOW7 from leaving
After more than a month in Salt Lake City, DOW7 departed the University of Utah campus and began its trip home to Boulder this morning.

It had a great run in northern Utah, despite an uncooperative Mother Nature who was quite stingy providing storms.  We exhibited the DOW for 1500 visitors at the Natural History Museum of Utah and 300 at the University of Utah.

Meteorological outreach at the Natural History Museum of Utah.  DOW in the background. 
In the DOW during sidewalk exhibit at the University of Utah

Several graduate students are now fully trained DOW operators.  Students in our cloud microphysics, synoptic meteorology, mountain meteorology and a radar special topics class were able to participate in operations either on campus or in the field.  My mountain meteorology class is presenting results this afternoon from their initial analysis of a precipitation event in the Ogden Valley.

Seven people stuffed in the DOW.  A common scene during field operations. 
Officially, we did eight "intensive observing periods", or IOPs:

IOP0- Practice IOP scanning some weak snow showers over the northern Wasatch (Location: Antelope Island Marina)

IOP1- Leeside precipitation in the Ogden Valley (Location: Huntsville)

IOP2- Frontal precipitation over the Salt Lake Valley and mountain-induced precipitation over the northern Wasatch (Location: Fielding Garr Ranch, Antelope Island)

IOP3- Exploratory effort to examine precipitation over Ben Lomond (Location: Just south of Willard Bay)

IOP4- Exploratory effort for eared grebe migration (Location: Lakepoint)

DOW near Lakepoint in the Tooele Valley scanning for eared grebes on November 25th.  National Weather Service radar imagery showed the first signs of migration last night, so the truck returned to Boulder just a little too soon. 
IOP5- Cold front with topographic interactions over Tooele Valley (Location: Stansbury Island Causeway)

IOP6- Cold front, influence of Oquirrh and Wasatch range on precipitation, small-scale precipitation structure in and around Cottonwoods (Location: South Jordan Trax Station)

DOW at the South Jordan Trax Station with frontal/orographic cloud over Wasatch
IOP7- Mountain and lake-effect precipitation (Location: Baccus Highway near 7000 South)

Mother Nature's stinginess forced us to take what we could get and do a couple of all-night operations.  IOP1 and IOP2 covered the same storm.  We just moved the DOW from Huntsville to Antelope Island as the storm slid south, changing the IOP number.  IOP6 and IOP7 were also the same storm and we just moved the radar from the South Jordan Trax Station to the Baccus Highway as the winds veered and orographic and lake-effect precipitation evolved.  Knowledge of meteorology, terrain, and potential site characteristics are a real key to making such efforts successful.  Not to mention some motivated graduate students willing to work graveyard shifts.  During such operations, we rotate crews and bring in a fresh driver for moving the DOW in the morning.

Special thanks goes to our sponsor, the National Science Foundation, and the operators of the DOW, the Center for Severe Weather Research, for making the visit possible.  The Center for Severe Weather Research extended the DOW visit a few days to let us capture our most recent storm and for that we are grateful.  I'm fairly certain that storm will make it into at least one master's thesis and maybe more.

Another Highly Predictable Windstorm/Wildfire Event: Ventura and Los Angeles Counties

It has happened again:  a major wildfire event initiated by strong offshore winds.  Again, the winds were caused by cool, high pressure moving into the intermountain west.  And again, the forecasts were stunningly good.  And I
suspect, again, problematic power lines will be involved in starting the fires.


Wildfires are burning right now in Ventura and Los Angeles counties, with the largest fire (the Thomas fire impacting Ventura, CA) starting in the hills and then descending down to town (just like the Tubbs fire that hit Santa Rosa on October 8-9).

As I write this, the Thomas Fire is out of control, having consumed more than 50,000 acres, with other fires on the southern slopes of the terrain surrounding the LA Basin (see map of its current extent).  


Over 200 buildings have lost, and more will soon join them.  The fires started abruptly as winds picked up late in the afternoon on Monday.  We went from nothing to tens of thousands of burnt acres in a few hours.   The NASA MODIS satellite tells a stunning story, with no smoke or fires yesterday and multiple large fires around noon today (see below).



The fires began around dinner-time Monday as strong, dry Santa Anna winds revved up.  Here are the maximum wind gusts for the 24h ending 7 PM Tuesday. A number of locations got about 60 mph (purple color), with several getting up into the upper 70s.  Huge variability in the winds, depending location and exposure.  These strong winds were from the northeast.


Over 200,000 customers were out of power by late Monday.  

Let me show you a sample of the wind evolution at a mountain site, Chilao, CA, located at 5490 ft in the hills north of Los Angeles.  Winds increased rapidly yesterday and around 72 mph starting around 4 PM Monday.  Now dropping but still strong.


Interestingly, temperature COOLED as the winds increased from around 50F to the lower 30sF as the winds increased.  This event is not about heat, it is about dry air and wind.


 The whole event was caused by cool, high pressure moving into the Northwest (yes, us!) and then southward into Idaho and Nevada (see map for 1 AM today, showing the pressure analysis).


 This pattern produced an offshore pressure gradient (higher inland, lower along the shore), which in turn produced offshore (easterly and northeasterly) winds over southern CA.  These winds were strengthened by their interactions with the substantial terrain of the region, producing what is known as Santa Anna winds.


 Numerical weather prediction models run by the National Weather Service and others skillfully forecast this event days before, with the predictions the day before being dead on.   For example, the Desert Research Institute (DRI) WRF model prediction initialized at 4 AM Monday showed huge sustained winds over the region later that day (forecast for 10 PM Monday is shown).


The forecast made two days before for the same time was essentially the same...and very threatening (see below).   So this event was highly predictable.


The National Weather Service High Resolution Rapid Refresh (HRRR) model initialized at 4 AM Monday predicted strong winds in the area later that day.  I could show you more forecasts, but the message is clear:  my profession has now gained the ability to skillfully forecast such downslope wind events days before.


 And the National Weather Service forecasters were providing excellent guidance, pushing the severe threat in their communications on Monday, before the fires started (see below).  Excellent messaging.



Could this have all been avoided?

Let me ask the same question I offered in my blogs on the Wine Country fires.

We had nearly perfect weather forecasts that called for very strong winds over and downwind of the regional terrain.  The fuels (grasses, bushes) were very dry. Their was a strong probability that power would be lost in large areas and that power lines could start fires, which would explosively develop.

So why not preemptively shut off the power, to all the power lines that ran in the vegetated hills?   Could we have stopped this growing disaster from ever happening?

Power companies and those in responsible positions need to rethink about how they respond to these predictable wind events.  We can radically reduce the damage toll and loss of life by taking more active measures, informed by excellent weather forecasts.