Upcoming heat and lack of precipitation

Over the past 72 hours, nearly all of SD has gotten at least some precipitation. However, much of the north half of the state saw less than 0.15". But other areas of the state, namely the Rapid City area saw well over an inch. 

I hope you enjoyed it as today is virtually the last day we expect to see any precipitation across the state for some time. The WPC 7-day QPF is showing basically no precipitation and we can look out (maybe into la-la land) to 10 days with the GFS and it is saying the same thing giving up at some higher confidence in the forecast. 

The CPC is showing similar things in their 6-10 and 8-14 day outlooks. Just remember that these outlooks are showing anything except the probability of above or below average temperature and precipitation, not the strength of that anomaly. Recall that 20 degrees is above average and 1 degree is above average. But it still provides us with some useful intelligence that the beginning of August is likely to be warm and dry. 

We'll see what shakes out but I'm betting the fire potential will quickly be on the increase. And just in time of the Sturgis Rally. 

Critical Fire Weather Today

Today is a VERY interesting day from a fire weather perspective. There are a variety of issues that need to be discussed including: drought, prior precipitation, fuels, temperature, wind, RH, and thunderstorms (wind and lightning). 

Drought:

Drought conditions vary across the state but summertime wildfire activity is highly correlated to drought conditions. Here is the current USDM.

Prior precipitation:

Wildfire activity is also well-correlated to short-term precipitation deficits. Over the past 7 days, many areas have not received any precipitation across the state. Below is a map of the accumulated precipitation over the past week. 

Fuels:

The drought and lack of recent precipitation has led to a quick drying of the fuels on the landscape. Below you will see the current (as of 1300 MDT on 6/28) ERC chart for the region. 

From a "preconditioning" standpoint, all of the things are in place in order to get a large wildfire. The one thing holding us back in the lack of curing in the fuels. However, areas of central SD as well as those areas south of I-90 are seeing the herbaceous fuels undergoing a quick dry down and most areas will be receptive to ignitions and fire spread. It's not September dry but it is definitely drying down. 

Temperature:

If you haven't yet heard, it is going to be very hot today. High temperatures will be in the 90s and 100s in most areas. 

RH:

Along with those hot temperatures, the relative humidity will be critically low (note the color scale on the bottom). 

Wind:

Breezy southerly winds are expected over eastern SD and breezy southwesterly winds are expected over western SD through the day (see wind barbs in the RH figure above for wind direction). Winds gusts are shown below, again see the color scale at the bottom. 

Thunderstorms:

To add insult to injury, we are expected high-based thunderstorms this afternoon and evening which could result in scattered dry lightning. The images below show a weather model depiction of the radar reflectivity and associated with gusts today at 1800 MDT. 

Wind gusts from thunderstorms could range from 55-75 mph in an environment characterized by ~2000 J/kg of downdraft CAPE. That will not only be a threat to on-the-ground firefighting resources, but to aerial resources as well. 

It's an interesting day out there. Stay safe.

Current SD Fire Danger

We have an interesting situation across western and southern SD with respect to fuels and fuel greenness. Much of the state has been getting precipitation recently but there have been a few holes in the spatial coverage. Where these holes exist, the fuels are much drier and are currently receptive to ignition and fire spread. The South Dakota Grassland Fire Danger Map is not currently “seeing” these pockets of much drier fuels and is likely underreporting the actual fire danger. 

Below is a an image of the past 7-day precipitation totals. Look at where precipitation has and has not fallen to make a better assessment of where the fire danger may be enhanced. 

Interestingly, the area to the ESE of Rapid City has been notably dry and this is where the 90-acre Box Elder Creek wildfire occurred (photos below from Logan Scott, SDWF). You’ll notice a lack of green in the unburned herbaceous fuels and this is an area that hasn’t seen notable precipitation in at least 7-10 days. 

The regional ERC chart is also attached showing ERCs moving above the 70th percentile over many areas in the state. 

I’ve also gotten word from Brad Christensen, the EM Director for Gregory County, that conditions there are drying down rapidly and the Grassland Fire Danger maps do not appear to be reflective of observed conditions.

In short, make your assessments of fire danger locally with your own observed fuels conditions. There are most definitely places that could see rapid growth of wildfires.  

Hot temperatures are expected both today and tomorrow with very low RHs over southwestern SD. Luckily the wind shouldn’t be too strong during this same period. A cold front will bring showers and thunderstorms to the state Friday afternoon and evening with much cooler temperatures expected this weekend. 

Weekly weather discussion 11 April 2022

 

(Climate) We are working into the middle of April and we should be starting to see increases in precipitation across the state but it just isn’t quite working out that way. A few areas of the state did get some moisture this week and the biggest winners were generally on a line from southwestern to northeastern SD where a few tenths to over a half an inch fell. Spotty precipitation was also found over northwestern and southeastern SD but only a few hundredths to a tenth or two was recorded in those areas. Temperatures largely hovered around seasonal averages.

There was no change in the US Drought Monitor last week. (Darren Clabo)

 

(Weather)

Forecast Highlights:

A massive spring blizzard will impact the northern Great Plains this week but unfortunately the beneficial moisture from it will be mostly over ND leaving SD mostly dry but pretty breezy. Temperatures today will range from the 40s over northern SD to the low 60s over southern SD. Winds north of I-90 will be light and variable but south of the interstate, southerly winds with gusts to 25+ mph are possible. Minimum RH will range from 35% north to 15% south. A strong low pressure and cold front will race across the state tomorrow (this is the low associated with the blizzard expected over ND). This will lead to southeasterly winds in the morning becoming westerly to northwesterly by the afternoon. Gusts could exceed 55 mph over central and western SD. Temperatures will range greatly will the cold front: eastern SD will get into the 60s before the front passes while western SD likely won’t get out of the 30s and 40s. Look for temperature drops and winds shifting to the NW after frontal passage. Heavy snow will be possible over far northwestern and extreme northern SD while the rest of the state sees widely scattered rain/snow showers. Wednesday through Friday will bring breezy northwesterly winds with gusts to 35+ mph. Highs will be in the 20/30s over western SD and 30s/40s over eastern SD each day. A few snow showers will linger over northern SD on both Wednesday and Thursday. Temperatures will warm this weekend but how much they will warm remains a question: another low pressure looks to move through the state so we’ll have to monitor the changes due to this new system.    

 

Potential for critical conditions:

Critical fire weather conditions are in place over southcentral SD today. There is potential for more critical fire conditions over the southern half of the state tomorrow as the front pushes through. Be sure to look at your local forecast to determine your risk. Elevated fire danger is also possible on Sunday. (Darren Clabo)

 

(Fire/Fuels) The Wabash Springs Fire that occurred on April 7th burned 111 acres. The fire was driven by strong winds in an open pine stand. The grass burned very well but was checked up by any area that had been mowed previously and had some green component to it. No torching of trees was observed. Most of the Black Hills has seen a little moisture or will have potential for more in the next few days. With the cooler temps and chances of precipitation I do not foresee any fire issues this week. (John Haskvitz)

  

*** NOTE: Next update on Tuesday, April 19 ***

Weather weather discussion 21 March 2022

 

(Climate) It was another dry week across South Dakota, with drought continuing its grip on the state. Most of the state had no precipitation at all. Some far western areas received about one-tenth of an inch. In the north, from Mobridge to the Minnesota state line, there was one event that brought one-tenth to two-tenths of an inch of moisture, with as much as one-third inch in Roberts county.

Air temperatures were above average for the week. The southwest was about three to six degrees above average. Along the Missouri River, from north to south, was nine to fifteen degrees above average, and the northeast was six to twelve degrees above average.

The warm air temperatures and lack of snow cover has warmed soil temperature as well. As of this writing, the southwest quarter of the state is frost-free. The remaining locations still have frost, but soil temperatures through the profile are just below freezing and could thaw with a continuation of warmer-than-average air temperatures. (Laura Edwards)

 

(Weather) Forecast Highlights:

A dry and windy week is in store. Strong northwest winds (gusts from 30-50 mph) are expected under mostly clear skies today through Wednesday as a high pressure system drops in from Canada. High temperatures will be in the 40s and 50s each day while minimum RHs drop into the 15-30% range over most of the prairies, higher over the Black Hills and southeastern SD. Temperatures will warm into the 50s and 60s on Thursday while the minimum RH drops into the 15-30% range. Friday will bring highs back down in the 40s/50s with minimum RH from 25-45%. Both Thursday and Friday will remain breezy with northwesterly winds gusting from 25-45 mph, strongest over central and western SD.

There is some uncertainty regarding the forecast for the weekend, but it is looking warmer/drier once again. Highs will likely be back up into the 60s but the details on how far the warmth will spread are not yet clear. Precipitation will be hard to come by this week although a few rain/snow showers are possible over eastern SD later tonight and there is a slight chance of a shower over the Black Hills on Thursday.   

 

Potential for critical conditions:

Near critical fire weather conditions are expected today through Friday with the strong northwesterly winds in the forecast.  Minimum RHs will likely not dip to critical thresholds but they will be close. Any fire that does start will have potential to get large, especially over the prairies of western and central SD. (Darren Clabo)

 

(Fire/Fuels) Once again fuels remain uncovered (and cured) over most of the state, except for the higher elevations of the Black Hills and the far northeastern portion of South Dakota. The drought monitor hasn’t changed since last week. All western South Dakota is in a D1 drought with the northwestern portion of the state in D2. There is still the potential for piles to escape if there is wind present, but I foresee the potential going down day by day. With the warmer temperatures, there are areas that are starting to show the beginning of Spring green up.

 

Talking with the Burn Boss from the Antihorse RX that was conducted on Sunday, March 20th the burn went well. This burn was 15 miles west of Custer. He stated that they used a lot of head fire. The dead and down consumed very well. The grass didn’t burn very well in the morning but once temps came up and RHs came down it burned well. They struggled with the draws, any timber stands with a lot of shading, and north aspects due to moisture. (John Haskvitz)

 

Weather fire weather discussion 6 December 2021

(Climate) A hint of winter arrived in South Dakota this week, but it won’t last long. The coldest temperatures of the season were this morning, with single digit air temperatures and sub-zero windchills across most of the state. Some snowfall created some travel issues over the weekend, particularly in the north central and northeast, but there wasn’t much accumulation on the ground with hardly enough to cover the grass in most areas.

Temperatures were well above normal for the week, until this morning. The 7-day mean temperatures were nine to over 15 degrees F above average for Nov 29-Dec 5. Soil temperatures rose in the last week, with 4” depths today reading 30-33F in the north, and as warm as 39F in Minnehaha County.  With little to no snow cover, soil temperatures responded quickly to air temperature changes. (Laura Edwards)

(Weather) Forecast Highlights: 

Temperatures today will peak in the upper teens to upper 20s across the state as a Canadian high pressure system pushes into the Great Plains. Winds will be light and variable statewide. Tomorrow’s highs will range from the lower 20s across northern SD to the lower 30s over southern SD. Winds will be light and out of the northwest. Wednesday will be the warmest day of the week with western SD seeing 40s and 50s while eastern SD sees 30s and 40s. Winds will generally be out of the south from 5-15 mph. A cold front will then push through SD Wednesday night leading to northwesterly winds and temperatures in the 30s and 40s on Thursday. A low pressure system is expected to move across the region on Friday which could bring accumulating snow to the state. There is a bit of uncertainty to where the snow will actually fall and how much will come so keep your eyes to the forecast as we move through the week. High temperatures on Saturday and Sunday will generally be in the 30s. Minimum RHs will stay above critical thresholds all week. 

Potential for critical conditions: Critical conditions are not expected. (Darren Clabo)

(Fire/Fuels) Fuel temperatures should be low enough this week to significantly reduce if not prevent any new ignitions this week.  If a fire would start this week, rate of spread and fire intensity should be very low and fires should demonstrate a very low resistance to control actions.  No issues anticipated this week. (Jay Wickham)

Weekly fire weather discussion 29 Nov. 2021

 

(Climate) 

The Thanksgiving week was quiet with warm and dry conditions. In the west, temperatures were four to ten degrees above the weekly average. In the east, temperatures were near average in the northeast and east central, and up to six degrees above average elsewhere. 

Measurable precipitation was limited to the northern Black Hills, with just one-tenth of an inch or so. Some light sprinkles wetted the ground in the northeast on the evening of Nov 28. The ground remains snow-free across South Dakota as we end the month of November. (Laura Edwards)

(Weather) 

Forecast Highlights: 

A warm week is in store. High temperatures today will be in the 50s/60s statewide with NW winds from 10-20 mph. Minimum RH will range from 25-45%, driest over the southern third of the state. Winds will turn out of the south to southwest tomorrow with speeds generally from 10-20 mph but a few gusts in the 25-35 mph range are possible over the northern Black Hills and the northwestern SD prairies. High temperatures and minimum RHs to will be similar to today. A couple of light rain/snow showers are possible over the Black Hills late tonight, but the rest of the state will remain dry. Highs on Wednesday will range from near 50 over eastern SD to near 70 over the western SD prairies. Winds will be out of the west statewide with gusts from 25-40 mph possible over western SD. Minimum RH will range from 20-30% West River and from 25-50% East River. Near-record temperatures are expected over West River on Thursday as highs climb into the 60s and 70s. Eastern SD will see highs from 45-60 F. Winds are expected to be light and variable while the minimum RH ranges from 18-28% over western SD and from 25-50% over eastern SD. Northerly winds are expected on Friday with high temperatures back into the 40s and 50s. Minimum RH will be above 30% statewide. Cooler temperatures are expected this weekend with highs in the 30s/40s on Saturday and 20s/30s on Sunday. Light southeasterly winds are expected Saturday with breezy northwesterly winds on Sunday. A few snow showers are possible over the northern Black Hills and northern SD prairies overnight Saturday night. 

Potential for critical conditions:

I doubt we’ll see Red Flag conditions this week as the RH will likely not quite drop to critical levels. Regardless, it will be a warm and dry week with some breezy winds, strongest on Wednesday. Look fire elevated fire danger through the week. (Darren Clabo)

(Fire/Fuels) 

This week looks very similar to last week.  A majority of the state is either abnormally dry or in moderate drought.  The warm weather and lack of precipitation will impact the thousand hour fuels as we move through winter.  The long term impact won’t be known until next spring but we need to monitor these fuel moistures as we move through winter.  The warm temperatures throughout the first part of the week will keep the potential for new starts probable.  With the shortened burn window most fires should be contained during the first burn period. (Jay Wickham)

Weekly Fire Weather Discussion 22 Nov. 2021

(Climate) The last week in South Dakota was warmer than usual, ranging from near average in the northeast to six to eight degrees F above average in the southwest. Average highs are around 40-46F this time of year, and average lows are around 20-23F. 

It was also a very dry week, with only a few locations receiving any precipitation at all. These areas included areas south of Rapid City, parts of Harding, Day and Marshall counties, and the far southeastern counties. Precipitation totals for the week in these areas was .01 to .15 inches. 

Soil moisture has dried some over the last two weeks, but there are still some very wet soils in the northeast and some near Minnehaha county. 4” Soil temperatures have dropped and are currently reporting in the 30-38F range statewide.  (Laura Edwards)

(Weather) Forecast Highlights: 

Western SD will see temperatures in the 50s to near 60 today with minimum RH in the 20-30% range while eastern SD will see highs in the upper 30s to upper 40s with minimum RH from 25-45%. Winds will generally be light and out of the west, but the southern Black Hills may get a few gusts in the 10-20 mph range. Clear skies are expected. Temperatures tomorrow will rise into the 50s and 60s statewide. Winds will be out of the south over East River but will be out of the west/northwest West River. Strong westerly winds are expected south of I-90, west of the Missouri River. Gusts from 25-35+ mph are possible across the prairies with some potential for gusts from 40-60 mph across the central and southern Black Hills and eastern foothills. Minimum RH will range from 8-15% over southcentral and southwestern SD with RHs from 15-35% elsewhere. A cold front moves through on Tuesday night leading to breezy northwesterly winds on Wednesday. Highs on Wednesday will range from the mid-20s north to the mid-30s south. A few flurries or sprinkles are possible as the front passes across the prairies and an inch or two of snow can’t be ruled out over the northern Hills. Minimum RH will be well-above critical thresholds. Thursday will bring highs from the upper 20s east to the upper 40s west. South to southwest winds are expected. Friday through Sunday will bring highs in the 40s and 50s to the state. Northwest winds are likely Friday/Saturday with southerly winds on Sunday. No precipitation is expected through the period and minimum RH will stay above critical levels statewide. 

Potential for critical conditions:

Critical fire weather conditions are expected Tuesday over southcentral and southwestern SD, including the central and southern Black Hills. This is looking like a big downsloping wind event for the central/southern and eastern Black Hills. Strong winds will extend into the prairies across the southwestern and southcentral SD prairies. A Fire Weather Watch is in effect for those areas. (Darren Clabo)

(Fire/Fuels) Conditions in the Black Hills are at or slightly above normal for this time of year.  All vegetation is cured and available to burn.  With the cool evenings and the angle of the sun the burn window is shortened this time of year.  Winds will be the primary driver of any fire growth this week.  The forecasted wind for Tuesday will increase the potential for new starts from powerlines and any potential smoldering campfire left from a deer hunter.  The potential for large fire growth on Tuesday will be elevated if we get a new start. Additional resources may be needed to contain a fire on Tuesday. (Jay Wickham)

Weekly Fire Weather Discussion 15 Nov. 2021

(Climate) Winter weather finally arrived (for a long holiday weekend visit) in South Dakota. Snow and wind affected travel over Veteran’s Day weekend and cold temperatures came along with the wintry weather. Snowfall totals in the northeast on Nov 11-12 were highest around Webster with about five inches. Most other locations in the region reported less than two inches of snow. Some warmer areas had icy conditions as well. The northwest was dry this week. Precipitation totals were about one-tenth to one-half inch moisture in the west central. The northeast and east central regions received about one-half to one inch of moisture for the week.

The week started out very warm, and despite cold temperatures over the weekend, the 7-day temperature was above average. The west was about two to four degrees warmer than the weekly average, and the east was generally one to three degrees above average. 

On Nov 13, high winds came across the state with highest wind gusts reported at Reliance (81 mph). There were a handful of locations reporting gusts in the 70+ mph range at McLaughlin, Trail City, Midland and other areas in the northwest and south-central regions. (Laura Edwards)

 

(Weather)

Forecast Highlights:

There is a lot going on this week. Big temperature range across the state today: highs over western SD will be in the 60s/70s with 30s/40s over eastern SD. The areas with the warmest temps will see RHs drop to near 20%, the cooler areas will have much higher RHs. Winds will be light statewide. Breezy westerly winds will develop over western SD overnight with poor RH recovery. A cold front will then move through the state tomorrow morning leading to strong NW winds throughout the day across the state. Gusts from 30-50+ mph are possible, strongest over NW SD. Temperatures will drop throughout the day as the front passes. Minimum RH will range from 15-25% over western SD and from 25-50% over eastern SD. Breezy NW winds will continue Wednesday with gusts from 30-45 mph statewide. Highs will be in the 30s/40s and minimum RH will range from 25-50%. High pressure then moves across the state on Thursday with light winds and highs in the 30s and 40s. Friday will warm with highs in the 40s and 50s with some 60s possible over the far southwestern part of the state. Minimum RH will range from 30-50% with light winds statewide. Highs this weekend will range from the upper 30s to lower 50s and northwest winds are expected both days. No significant precipitation is in the forecast for this week or even next week.

 

Potential for critical conditions:

Elevated fire weather conditions are likely on Tuesday and Wednesday with western SD being the primary threatened area. Tuesday will see the highest danger with the strongest winds and lowest RHs and a Fire Weather Watch is in effect for southwestern SD. (Darren Clabo)

 

(Fire/Fuels) The fuels in the Black Hills area remain relatively unchanged, the grass and timber litter categories are susceptible to ignition and fire spread. The Badger Clark Fire in CSP was wind driven with 3–5-foot flame lengths in the grass and 2-foot flame lengths in the timber litter. The 1000-hour fuels did not consume very well and were easy to mop up. With the reduced daylight (we are losing 2 to 3 minutes of sunlight per day) the burn window is significantly shorter, but as usual at this time of the year fires will spread with the wind. It looks like Tuesday and Wednesday could be days to watch with significant wind gusts and RHs in the 20s. (James Bachelor)

November wildfire potential outlook

The South Dakota Wildfire Potential Outlook for November 2021 has been released. Click on the image to get there!

Today's Red Flag Warning

I've got concerns with the fire weather conditions today and there is a Red Flag Warning in effect for much of western SD. Will we technically reach RFW criteria (RH < 15% and gusts > 25 mph) in all locations that are under the warning? Probably not. 

So why the concern? I am going to preface this post with a note about the Auburn fire. On Monday we saw the Auburn fire grow to nearly 1000 acres on the north side of Rapid City. Wind gusts peaked at 23 mph (Ellsworth AFB observations). The RH bottomed out at 11%. 

1) Dry conditions

The Auburn fire exhibited large wildfire growth near a major city in western SD. Why does location matter? Resources! The "world" was sent to the Auburn fire to assist in suppression. There were 3 SEATS, one air tanker, helicopters, engines from numerous VFDs, USFS and other federal assets, and leadership/resources by the RCFD and SDWF (obviously this is not a complete list of resources). These resources were on scene very quickly because of the proximity to town yet the fire still grew. This tells me that the fuels conditions are ripe for large fire growth. Short-range spotting with nearly a 80%+ PIG is exceptionally problematic and will resist suppression efforts. Since then, we've seen 48 additional hours of very dry conditions and very poor RH recovery during the nights. The fuels are more dry today than they were on Monday and that's kind of a scary thought. 

2) Humidity

I get it, the RH today will be higher than the past two days. But this is a pretty negligible difference. There really is no functional difference to fine fuel moisture, and its effect on fire behavior, between an RH of 11% and 15-20% (forecast for today). 

3) Wind

The wind is key. The potential for gusts from 30 - 40 mph on the prairies to the east and to the north of the Black Hills is concerning. These forecast winds are much stronger than what we saw on Monday and the functional difference between a gust of 23 mph and 33 mph is significant when it comes to fire behavior. The wind makes today a far different day than Monday was. And it makes the fire danger that much worse. I computed the Grassland Fire Danger Rating for the conditions last Monday and for the expected conditions for today. The GFDI breakpoints are:

And the values from Monday are on the top of the next figure while the expected values are on the bottom for today. 

I assumed similar temperatures for today as to Monday. I also assumed fully cured fuels on both days. What I want to emphasize is that even with the lower RH on Monday, the much higher wind gusts today result in nearly double the value for the GFDI digit (59 on Monday vs. 107 for today). Both represent "Extreme" fire danger but, while Monday's event was a low-end "Extreme" day, today's GFDI value represents a high-end "Extreme" day. 

You cannot get a fire without an ignition source, however. There won't be any lightning today so let's hope our fellow humans play nice. 

Yesterday's RFW Bust

This was originally posted to my twitter account:

A thread: So the Red Flag Warning for western SD yesterday was a bust. Why? Answer: smoke. See all of the grey stuff in the satellite image? That is incredibly thick smoke moving over central/western SD yesterday late afternoon.

Smoke limits solar heating at the surface which limits convection, or the vertical movement of air. So why did this matter? Drier air existed higher up in the atmosphere. As did stronger winds.

If you limit sunlight, you limit surface heating, thus limiting convection, thus limiting the mixing down of drier air that has higher momentum ("stronger winds").

And we can see this in last night's radiosonde from Rapid City. Our observed mixing height was roughly 1.4 km (up to 750 mb, horizontal black line) with a surface temperature of 86 F. Winds peaked at 10 kts in that layer.

If we would've reached 92 F or so, our mixing height would've reached 3.8 km (up to 580 mb, horizonal black line). Winds up there are at 30 kts. And these could have mixed to the surface as gusts ~25-35 mph.

So the smoke limited surface heating by 5-7 degrees F, which limited vertical mixing by over 2 km! Thus we didn't get the stronger winds mixing down to the surface (nor the drier air shown by lower dew points up there).

That leads me to predictability. Should we have known this? Well the HRRR smoke model (0600 MDT forecast run) showed dense smoke over the area yesterday afternoon (shown at 1600 MDT).

So yesterday early morning, we all had a good idea there would be a lot of smoke in the air. We also know that smoke blocks sunlight, in turn reducing convection. But to what extent? What if there was a break in the smoke for a few hours?

Meteorologists typically hedge their bets towards worst case scenarios. The potential existed for a RFW day BUT we knew smoke was coming. What does one do? Let folks know that critical conditions may develop and that's what was done.

Elevated Fire Weather Conditions today, tomorrow, and Saturday.

Elevated Fire Weather Conditions for Western SD

Red Flag Warnings are in effect for much of western SD today with a Fire Weather Watch in effect for tomorrow. These will be borderline critical weather events but considering the fuels conditions, it's definitely something to keep your eye on. 

Today's RH:

Today's wind speeds: 

The relative humidity (RH) will drop to critical levels today with minimums in the 10-15% range across much of SD. Winds will be borderline critical but should gust in the 15-25 mph range over much of western SD with some gusts near 30 in Harding/Butte Counties, as well as in the "pinch" area along I-90 in the vicinity of Rapid City. Winds will be out of the northwest and this wind direction can allow the winds locally accelerate around the Black Hills near Rapid City. It's a subtle thing but a very important thing to fire managers if a fire breaks out in that area. High temperatures today (not shown) will generally be in the mid-80s to mid-90s. 

Another thing to pay attention to is the very poor RH recovery expected overnight tonight. Below is the graphic from the NWS but I honestly think these values might be too high: RHs from 15-25% might be the best we get to overnight, especially on the east side of the Black Hills. 

So take a look at tomorrow as it will be another day of elevated fire danger. 

The forecast for RH tomorrow:

And the tomorrow's forecast wind gusts:

The RH will be lower tomorrow, most notably across southwestern SD where values might range from 7-15%. Winds speeds, however, are generally expected to be lighter and below critical thresholds. The wind will be blowing out of the west over far western SD and from the south over west-central and central SD. I think we could see a couple of gusts above 25 mph but they shouldn't persist over a widespread area for long. Temperatures (not shown) will be in the mid- to upper-90 across the affected region. Needless to say, fires will resist suppression efforts. 

Recall that we are still in a drought and fuels conditions remain dry. Here is the new USDM released today:

And recall ERC values are trending upwards:

Don't forget that we haven't seen any precipitation over the past 5 days which has allowed the fine fuels to completely dry back out. Here is the 5-day accumulated precipitation (since last Saturday at 0900 MDT). 

All in all, this isn't an event that will lead me to scream warnings from the rooftops but it is still concerning enough. Luckily (??) there is a lot of smoke over the region which will lead to cooler temperatures that what would otherwise be expected. And this might lead to lowered max wind gusts as the vertical mixing will be less than expected. But that is a conversation for a different day. 

Bonus graphics:

Today's Grassland Fire Danger Index:

And tomorrow's Grassland Fire Danger Index:

With regards to Saturday, I won't post graphics as things will likely change a bit but I do expect elevated to critical fire weather conditions over southwestern SD once again. Winds will be out of the west to northwest, gusting to 30 mph. The minimum RH will likely drop to 12-20% over much of western SD, driest across Fall River and Custer Counties. Look for high temperatures to be in the 80s and 90s. 

Sunday should bring some relief as light southeasterly winds spread across the state bringing higher dew points and lowering the fire danger.