Friday, May 28, 2021

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. 

Wednesday, May 12, 2021

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. 

Friday, March 5, 2021

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. 

Monday, December 21, 2020

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. 


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. 

Tuesday, November 17, 2020

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. 

Thursday, October 8, 2020

Elevated fire danger today through Sunday

The fire danger will remain elevated through the weekend as warm/dry/breezy conditions persist. 

Today: Red Flag Warnings in place for southwestern SD. The Black Hills and surrounding plains will also see critical to near-critical conditions yet this afternoon as well: southwest winds from 10-25 mph, RHs dropping below 10%, and temperatures in the 70s/80s are expected. Central and eastern SD: Red Flag Warnings in place for southeastern SD for northwest winds from 20-30 mph, gusting to 40 mph and min RH near 20%. RH recovery will be very poor overnight tonight across western SD (max RH in the 15-25% range).

Friday (tomorrow): Winds out of the NW from 10-20 mph statewide, gusting to 30 mph over north-central SD. Temperatures will range from 75-85, warmest over the east. Minimum RH from 12-25% West River and from 20-35% East River. RH recovery overnight into Saturday will be poor: 25-45% statewide.


Saturday: Temperatures in the 70s/80s, southeasterly winds from 10-20 mph with gusts to 30 mph, minimum RH from 15-25% West River and from 30-50% East River. RH recovery overnight into Sunday will be potentially very poor ranging from 20-30% West River and 30-50% East River.


Sunday: Cold front moves through early in the day. A few showers are possible along this front but wetting rains are looking less and less likely anywhere in the state. Frontal timing will dictate weather elements but temperatures look to range from 55-75, minimum RH from 20-50%, and strong northwest winds from 15-30 mph, gusting to 40 mph.


(Sorry East River for not including graphics for your side of the state)

Windy conditions are expected through next week.

Friday, September 25, 2020

Wind Saturday through Tuesday

Breezy to downright windy conditions are expected across SD for at least the next 4 days. The wind combined with humidity in the 20-40% range will dramatically increase the fire danger statewide. 

My thoughts here:

Friday, September 18, 2020

Update: mid-September wildfire potential

We've reached mid-September and have experienced all 4 season in the past 2.5 weeks. Where does that put us in terms of wildfire potential for the rest of the month?

In short, the rest of the month looks to be warm and dry with numerous dry cold fronts to bring us wind. To me, that spells enhanced fire potential. 

Let's look at the precipitation we have received. 

The past 30 days:

The past 7 days:

Over the past 30 days, most of the state has been drier than average. This time period does encompass our rain/snow event over Labor Day. It brought 1-2 inches of moisture to the central and northern Black Hills as well as portions of central SD. But since that time we have been exceptionally dry especially across western and southeastern portions of the state. The lack of recent precipitation tips the scales towards higher wildfire potential for the rest of the month. 

The lack of precipitation has allowed the drought situation to continue. Over most of SD, drought is well-correlated to an increase in wildfires during September. 

Looking ahead, dry and warm (actually hot) conditions are expected in both the short term and long term. The maps below are the current 6-10 day forecasts for temperature (top) and precipitation (bottom). This pattern continues for the 8-14 day outlook and the 3-4 week outlook

Fuels are becoming even more available as the grasses become fully cured with the seasonal dry down. The grasses were struggling to begin with as the lack of moisture over the past few months has led to dry conditions. The Vegetation Drought Response Index (VegDRI) below shows how the drought has affect the vegetation. 

The forecast weather models are showing an active pattern continuing through the rest of the month with several cool fronts (I'd call them cold fronts but the air won't really be that seasonally cold) moving through the state each week through the end of the month. Wildfires tend to grow big in September in the vicinity of a cold front. Remember, just ahead of an impending cold front temperatures are typically well above average with dry and gusty southwest winds. Then as the front passes, the temperature may drop but with dry cold fronts the RH tends to remain low as gusty northwest winds increase. 

The highest wildfire potential remains over southwestern SD but the entire western half of the state has higher-than-average potential. East River areas are a mixed bag but with agriculture activities progressing, there will plenty of opportunity for new fire starts and a big fire or two cannot be ruled out. 

But on the bright side, we may have some good opportunities for prescribed fire! Burn windows are short and the days with less wind may bring optimal RX conditions. 

Thursday, June 11, 2020

Black Hills precipitation updates

Precipitation across the Black Hills continues to lag behind seasonal averages. We did have a few strong/severe storms move through the area June 3 - 6 and those storms brought locally heavy rain. But the rain was not widespread and it fell hard meaning much of it was "lost" to runoff and was not able to efficiently soak into the soils.

Below are several graphs showing precipitation for different stations across the Black Hills. All graphs show precipitation received from April 1 through June 10 and are compared against their historical average at that location.

Southern Black Hills:

Central Black Hills:

Northern Black Hills:

As you can see, every station is lagging behind seasonal average for this time of the year. Don't forget that April, May, June, and July are our 4 wettest months of the year for this area. Precipitation deficits now set the stage for potential drought conditions down the road. 

What is in the forecast?
In the near-term, we look to remain dry. The Weather Prediction Center is only showing light accumulating precipitation over the western Black Hills over the next 7 days. This rain will likely come Saturday evening/night when a few thunderstorms rumble across the area. 

Good news though: the GEFS ensemble models during the time period from June 20 through June 27 are showing above-average precipitation for western SD. There is hope on the horizon at this point!