At 9:32 AM this morning, the Napa County Office of Emergency Services issued its latest set of evacuation warnings in the face of the Glass Incident, a fire which has consumed more than 48,000 acres and continues to burn nearly uncontained in the heart of Napa County and over the mountains into Sonoma County.

These new warnings effectively say that the entire town of St. Helena (a portion of which is already under mandatory evacuation) and all businesses and residences north of Whitehall Lane are on notice that they may be asked to evacuate soon, just as the residents of Calistoga were forced to do on Monday evening.

Authorities have issued these warnings in the face of unfortunate meteorological news about increasing atmospheric pressure that will drive higher temperatures, and more concerning, wind activity on Thursday and Friday. This resulted in a Red Flag warning for the period beginning 1:00 PM Pacific on Thursday through the end of day on Friday.

As you can see from the evacuation map above, which also shows fire activity, the primary fear would be the two main areas of the fire joining together and inundating the valley floor. This could occur in a situation where high winds drive burning embers into the heart of the valley, torching homes, wineries, and other businesses in the area.

To say this would be a disaster doesn’t quite begin to describe it.

Let’s start with the evacuation itself. Currently the Silverado Trail is closed due to the fire front on the east side of the valley. Highway 29 into and through St. Helena has also been closed at various times in the last 72 hours, and it is definitely closed where it becomes Highway 128 leading out of the valley north of Calistoga.

That means that there’s only one way out of St. Helena if that mandatory evacuation order comes, and that’s south on Highway 29. Those of us used to driving that highway know that it’s a traffic shitshow on any normal day. Most of us avoid it at all costs, preferring to use the Silverado Trail or other side roads to get where we’re going whenever possible.

Granted, traffic would only be one way during an evacuation, but that doesn’t offer much consolation. Trying to get 6000 or so people out of town quickly would be a nightmare even if all routes out of town were open.

Someone I was just e-mailing said that most of the folks she knows who live in St. Helena left when the west side of town was evacuated on Sunday. I hope this is true. And anyone who is still there should consider preemptively leaving before mandatory evacuation orders arrive. Especially if they have somewhere they can go. At the very least they should have their car packed, fueled up, and pointed in the right direction so they can leave at a moment’s notice.

Of course, that’s not so easy to do if you’re a winemaker with a winery full of fermenting juice. Telling a winemaker that she has to just walk away from an entire vintage in the middle of the crush isn’t exactly an easy thing to swallow.

But that’s exactly what Cathy Corison is going to have to do if the mandatory evacuation order comes through, since her winery (and her home) are both squarely in the current warning zone.

“I’m extremely lucky,” says Corison, who typically harvests grapes two to four weeks earlier than many of her neighbors. “Everything is ticking down to dryness. Not being here for a couple of days won’t be a huge problem, though I am currently in the hunt for a commercial air filter, because I’m worried about all this smoke even though the winery is sealed up as tight as we can get it.”

This evacuation would come at the absolute worst time for most of the winemakers in and around St. Helena. Along with evacuations, power will almost certainly be cut to the area (a strong possibility even without an evacuation) meaning pumps and other equipment won’t work to keep wine tanks cool or move wine around, AC units won’t work, and anything without an attached gas tank will be out of commission unless the winery has a generator on hand.

As with previous fires in 2017, some winemakers will be unable to access their wines in mid-fermentation. In combination with the potential loss of temperature control, this can make for unplanned extended macerations that can wreak havoc with a wine’s balance and tannic profile.

While many wineries harvested grapes in advance of the heatwave that spawned the current fires, there are still grapes on the vine in and around St. Helena. Worries about smoke taint in the vineyards have been occupying winemakers for weeks, but a fire tearing across the valley would put an unfortunate end to those worries.

The one thing that St. Helena and its immediate environs have going for it is the sheer extent of vineyards on the valley floor. As we have seen in the past few years’ fire seasons, vineyards, especially at this time of year, serve as particularly good fire breaks, given how little easily combustible material they contain.

Consequently, even if windblown burning embers (which I would guess are the main concern driving this latest evacuation warning) are thrown into the heart of the valley, any fires that are started will have a hard time spreading through the areas occupied by vineyards.

That doesn’t mean homes and wineries can’t burn if embers land in the wrong spot, but it does mean that the kind of destruction we’ve seen in some of the wooded sections of the valley won’t be repeated on the valley floor.

In case you can’t tell, I’m worried for Napa. I’m worried for the people who live and work there. The people who depend upon the wine industry and its associated tourist traffic to put food on their table. Wealthy winery owners can, and do rebuild. But for every one of them there are dozens of field workers, restaurant workers, tasting room employees, and hotel maids that were already suffering thanks to the pandemic.

The list of wineries that have already burned or been damaged continues to grow.

After the 2017 fires, which only marginally impacted the main tourist areas of the valley, Napa saw a huge dip in visitation, as consumers feared (incorrectly) arriving to find a disaster area. The Napa Wine Train, for instance, saw a 75% drop in ridership following the 2017 fires.

These fires, and the images that will accompany them in the aftermath, already have the potential to have the same effects, even without the inundation of a well-known town like St. Helena.

It’s terrifying and painful to think about the impact that this disaster, combined with the pandemic, may have on Napa. But there are more important, pressing things to worry about right now, and that’s the health and safety of the people who live and work in the area.

If that’s you, please be safe, and if you can, take a couple of days and go somewhere else, ideally before the police arrive and force you to do so.

We’re all praying it doesn’t come to that, and rooting for the incredible heroism of all those on the front lines of this disaster.

If you’re safely at home somewhere else, like me, I hope you’ll drink some Napa (and while you’re at it, some Sonoma) wine, and pray to the weather gods or whatever source you might petition for a little relief.

Image courtesy of the ESRI ArcGIS Fire Situational Awareness web site.