Fire Weather Today Through Wednesday

Heat. It really comes down to that one word. Temperatures are going to be excessively hot over the next 72 hours which will push our fire danger up to correspondingly high levels as well. 

Today's maximum temperature, minimum RH, and wind speed/direction are below. Wind speeds will be on the light side over western SD where the driest conditions exist today. This will prevent us from reaching Red Flag Criteria. Southcentral SD has the highest winds speeds but higher dew points as well leading to higher minimum RH values. The other thing missing from this forecast is the thunderstorm activity over central/northern/eastern SD today. There are some wetting rains mixed in but there has been a LOT of lightning. I fully expect new starts from this activity. Additionally, a few storms are likely over the higher elevations of the Black Hills today and I don't expect much rain to come from those storms. 

Let's examine tomorrow's maximum temperature, minimum RH, and wind speed/direction (below). A very similar situation is in store but although thunderstorms are not expected. Once again, light(ish) winds will prevent the issuance of Red Flag Warnings. 

Now for Wednesday's maximum temperature, minimum RH, and wind speed/direction (below). A cold front will move through the state later on Wednesday, hence the shift in winds you see below. Typically wind speeds increase along the front so it wouldn't surprise me to see some local critical fire weather conditions. This would most likely be across northern/northwestern SD where winds speeds will be highest during peak heating.

Regardless of wind, the extreme heat will definitely increase the evaporative demand thus reducing fuel moisture. The Hot-Dry-Windy Index is a good measure for this. The charts below are the probability of exceeding the 90th HDW percentile. At least a few portions of SD will have a good shot at reaching that percentile each of the next 3 days. 

Once again, the lack of wind is really helping to stabilize a situation that could be exceptionally bad for wildfires. Regardless, conditions still look pretty nasty. And for a bonus image, regional ERCs are shown below. Most stations in SD are reporting higher than average ERCs with northcentral SD seeing record high ERCs. The fuels will burn if ignited. 

We remain dry but rains have helped

We've recently seen a bit of precipitation across the state, generally ranging from 0.5 - 1.5" over the past 7 days. This has obviously helped the cause as we have been so incredibly dry over the past few months, especially over eastern and central SD. 

But if we look at the 30-day percent of average precipitation, you can see that the conditions remains very dry relative to historical norms. 

We have also been seeing some hot temperatures over the past month which further dries the soils and the fuels on the landscape. Temperatures over the past 30 days have been from 3-7 degrees above average--pretty incredible over the period of a month. 

The vegetation is really becoming drought-stressed due to the combination of heat and little precipitation. The VegDRI product shows this. Top chart is from a month ago, bottom chart is from this week. The situation is getting worse quickly. 

Ok, so things look pretty bad. Has the recent rain helped at all? In short, yes. The rain has at least dampened the fuels so that they are not as receptive to ignitions or to carrying fire. This is especially true for the 1- to 10-hr fuels (needles and grass up to finger-sized sticks). The recent trends in Energy Release Components (ERCs) have demonstrated this. I've shown Baker Park RAWS and Red Canyon RAWS as examples. Whereas they were near or at record highs a few weeks ago, the ERCs are now trending lower than average. But remember, these stations are in the Black Hills which HAVE been getting decent rains--the prairies haven't been getting those same rains. 

So, at least in the Black Hills, conditions are in a holding pattern. We've gotten enough rain to limited the fire threat in the near term. But the prairies are made almost exclusively of fine fuels or those 1-hr fuels. These fuels only take a day or two to fully dry and be conducive to carrying fire. In short, they respond more to the day-to-day weather conditions. If we get a hot/dry/windy day, they will be ready to burn. 

What scares me is the forecast going out towards the latter half of July. There are some strong hints that more hot weather and above average temperatures are on the way. Here are the CPC forecasts from the 8-14 day timeframe and the 3-4 week timeframe. 

That's a tough outlook for the latter half of the month. There is *high* confidence of these warm and dry conditions as well. 

I'm no plant phenology expert, but from my understanding the herbaceous fuels on the landscape really can't pick up and use the moisture that we've gotten over the past week. They've already crossed the threshold: they are seeded out and curing for the season. So the precipitation really won't help them out too much. Add some heat and additional dry weather and it creates a situation where the fire potential will likely increase going into August. 

The big fire out by Pickstown over the 4th of July weekend goes to show that the fuels in the Missouri River breaks will readily carry fire. The eastern red cedar had no problem torching out. Remember that big fires are not limited to the Black Hills here in SD--we have a lot of fuel on the landscape and this might be the year where it burns. 

Still in drought? But is has rained!

As I look out my office window this morning, I can finally start to see the impacts of the recent precipitation in the green grass coming up through last year's dead crop on the hills south of campus. Green up is here and the precipitation over the past week has really given things a boost. 

I've been fielding quite a few questions over the past few days with respect to the moisture and the upcoming summer fire season. Will the moisture help diminish the fire activity this summer? What has the precipitation done to the drought? Will it be a dry summer? A hot summer? So here we go, a little blog to help answer some of these questions. 

Yes, western SD has gotten a decent amount of precipitation over the past 2 weeks (below top). Note also how central and eastern SD have missed out on a lot of that precipitation. And if we look at it from the standpoint of percent of average, you can see that western SD has been anomalously wet while eastern SD is anomalously dry. (below bottom). 

But let's stretch it back 60 days. Similar graphs as above but now for the last two months. 

A different picture starts to emerge. April was exceptionally dry statewide (and April is generally a wet month for the state). Much of western SD has gotten below average precipitation during the period, one reason you may still see lingering drought issues. 

Let's stretch it back to 120 days. Again, similar graphs as above. 

The dryness across the state really starts to emerge. The Black Hills has been one area of the state that actually has seen some decent moisture but the good precipitation there has been limited to the central and southern Black Hills--this is a result of more southerly storm tracks for the major precipitation systems this winter. Look at southeastern WY and CO east of the Rockies: it's been super wet down there. 

So where do we sit today with respect to drought? The most recent US Drought Monitor is below.

We remain in drought across much of the state. The good winter precipitation over much of the Black Hills has lifted those areas out of Abnormally Dry conditions and parts of SD in the Watertown area have been fairing well also. But look at the rest of the state: it remains pretty darn dry. And this is critically important as we are dead in the middle of the wettest time of year for the state! The precipitation we get now "carries" us through the rest of the year. So how do things look in the near future?

First, let's take a look at the short term. Below is the 7-day precipitation forecast from the Weather Prediction Center (WPC).

Alright, SD does have some green in it. That's good, right? Well... not really. We should be getting on the order of 0.75 - 1.0" of precipitation per week this time of year, depending on location in the state. Eastern SD may see that but western SD looks like we'll have a relatively dry week. So what's the two-week forecast look like? The Climate Prediction Center (CPC) has a forecast for that: top is temperature probabilities and bottom is precipitation probabilities. 

Note how conditions across the state are favoring warmer than average conditions while western SD also is likely to see drier than average conditions. Warm temperatures will increase evaporative demand which will pull the moisture out of the soil and transpiration will increase pulling water out of the plants. And if western SD is drier than average, we will start to see conditions deteriorate further during the month of June (again, another generally wet month for the state). 

Is there any relief in sight? Not really, if you trust the CPC. The 3-month outlook is below (June/July/August). Temperature outlook on top, precipitation on bottom. 

But can we trust the CPC? Well they base some of their forecasts from information obtained from the North American Multi-model Ensemble (NMME) projections. I'll leave it to you to look at it but, by and large, these projections are largely showing dry/hot conditions for SD. There is much more confidence in the temperature forecast than the precipitation forecast but still, not a rosy outlook. 

Think back to our last "bad" fire season across SD: 2012. What did it look like precipitation-wise then? Here is the monthly precipitation for the year from both 2012 and for 2021 (from Rapid City). 

Rapid City is actually drier than 2012 at this point in the year. The reason 2012 was so bad fire-wise was that July - August was ridiculously dry and hot (spring moisture was half-way decent that year).

To summarize, I still have major concerns regarding the summer fire potential (and the impacts to statewide agriculture). We've been dry, many areas of the state are current dry, and we are expected a hot/dry summer. I hope I'm wrong but the current data suggests we are in for a rough summer. 

Recent conditions across SD

In terms of temperature and precipitation, it's been an odd start to the spring. We've seen some ample precipitation across some areas of the state while other areas remain remarkably dry. The figure below is accumulated precipitation since April 1. 

Northeastern SD and the Black Hills really have been the primary benefactors of the recent precipitation. But when looking at departures from average during the same timeframe, the picture isn't quite as rosy. 

Let's stretch it back to the start of the year over western SD. The next three figures represent year-to-date precipitation in Buffalo, Rapid City, and Custer. Custer had been doing pretty good precipitation wise up through the middle of April, but they are starting to see the effects of the recent dryness over the past few weeks. 

Buffalo is pretty much bone dry. They did get some beneficial rainfall last week but definitely not enough to break the D3 Extreme Drought situation that they currently are in. It was probably enough to green things up a bit but that is about all. 

My concern is starting to become laser-focused on the temperatures forecasts for the next 1 to 2 months. We are running deficits in precipitation but if we get some serious heat in June to early July, that will push us over the edge and dramatically increase wildfire potential across the region. We don't have the moisture in the soils right now and if we increase the evaporative demand with warmer temperatures, it will tap out the moisture completely--bad news for wildfires and agriculture across the state. If we do get some heat, we'll likely see much expansion in the USDM. The forecasts for temperature in June and July (top and bottom, respectively) from the National Multi-Model Ensembles are below. 

That is a forecast that does not bring much hope to the region. Oh and by the way, the same models are showing drier than average conditions for the same time period. 

My current thinking hasn't changed much from my outlooks: I fully expect us to have a busy fire season in SD. 

Elevated Fire Weather conditions March 6, 2021

 It's looking like critical fire weather conditions for much of western and south-central SD tomorrow, March. 6. You can find my fire weather briefing here. 

In short, it will be warm, dry, and windy through the day on Saturday. 

Evolving fire weather threat on Dec. 22

Record to near-record high temperatures are expected over much of western and southern SD on Tuesday, Dec. 22. These "hot" temperatures will occur just ahead of a strong cold front that will push through western SD tomorrow afternoon and evening. Historically, this is a classic fire weather setup for the western half of the state.

High temperature and wind direction:

Furthermore, the wind will be strong ahead of the cold front. Potentially very strong. Gusts could definitely be in the 30-50 mph range, maybe even higher. 

Winds:

As it is winter, there isn't a lot of moisture around. Thus low RHs will accompany these warm temperatures. Often, we think of critically low RH as those less than 15%, but in the winter I get concerned when the RH is below 35%. (But I think we could get close to the 15% range anyhow.)

Minimum RH:

And it has been dry. We just haven't been getting widespread precipitation. Below is the total precipitation for the last 30 days. Note how much of the state has been completely dry!

This is going to be an evolving threat through the day and the forecast images above only show conditions for 2:00 pm MST tomorrow. But know that southerly to southwesterly winds are expected during the morning, these will transition to more westerly winds in the mid afternoon. The cold front will then push through tomorrow afternoon bringing strong northwesterly winds. If a wildfire does occur, be sure to remember the wind will likely shift dramatically as the front moves through. 

Oh and don't forget that the strong northwest winds will persist on Wednesday, albeit with colder temperatures in the post-frontal environment. Some upslope-induced snow is expected over the northern Black Hills late on Tuesday and through Wednesday but the show will likely be limited to just that area. 

In summary, my concern is growing for the potential of critical fire weather conditions across all of western and southern SD over the next 36 hours. 

Fire weather on Wednesday, November 18, 2020

Near-critical to critical fire weather conditions will set up over much of western SD tomorrow, November 18, 2020. 

A potentially strong downslope wind event is expected overnight tonight over the central, northern, and northeastern Black Hills. Southwest winds may gust into the 30-50 mph range as a very strong pressure gradient sets up over the Hills. These winds will also keep temperatures elevated and humidity low throughout the night, potentially "priming" the fuels for tomorrow. 

Wednesday will bring temperatures that are well-above average, minimum RH near critical thresholds, and gusty west-southwest winds to western SD. The strongest winds will be along and south of the I-90 corridor, west of the Missouri River. 

Fuels are completely cured and available to burn. As such, the projected Grassland Fire Danger Index map for tomorrow shows elevated fire danger across the affected areas. 

Keep your situational awareness up and be ready for the elevated fire danger tomorrow.