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David Helms Profile picture
@davidhelms570
May 5 • 13 tweets • 6 min read Twitter logo Read on Twitter
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1. A backgrounder on how soil moisture changes over time. A #NAFOWeather 🧵
2. Soil moisture is one element of the water balance / hydrologic cycle which includes precipitation, terrain, vegetation state, and atmosphere (temperature, humidity, winds, sunshine/solar radiation). Image
3. Rate of soil moisture changes over time:
Over Weeks to Months - Controlled by vegetation growth
Cite: Reference evapotranspiration in water requirement: Theory, concepts, and methods of estimation, Handbook of Hydroinformatics, 2023
sciencedirect.com/book/978012821… Image
4. Rate of soil moisture changes over time:
Over Days to Weeks - Controlled by recent rainfall / # Days Since "Wetting"
Reduce Need for Irrigation by Maintaining Crop Residue and Reducing Soil Tillage
water.unl.edu/article/agricu… Image
5. Rate of soil moisture changes over time:
Over Hours to Days: Controlled by atmospheric evaporative demand
What is Evaporative Demand?
cnap.ucsd.edu/wp-content/upl… Image
6. Rate of soil moisture changes over time: Soil moisture is controlled by soil texture and % of organic material, sand dries rapidly, silt dries more slowly. Most of the soil type near the Line of Conflict is Silty Loam. Image
7. This graphic is an example of a trafficability prediction for agriculture purposes. It is very likely overly optimistic for the "go" (green) trafficability for military applications, but useful to access factors impacting soil moisture.
Source: meteoblue.com/en/weather/agr… Image
8. These graphics are "meteograms" for agriculture for Chaplynka and Svatove. Meteograms are simply graphics of meteorological variables plotted in a time-series. These graphics are way too busy, so let's break the info down.
Source: meteoblue.com/en/weather/agr… Image
9. Lining up the agriculture trafficability forecast for Volnovakha, Donetsk, with the temperature, precipitation, humidity, Evapotranspiration (E), Evapotranspiration Demand and wind speed to get a snap-shot of variables impacting soil moisture. Image
10. Previous tweet: Note the daily (diurnal) ramping down of soil moisture/improved trafficability during the daylight period (until 8 May when it rains!). This is a close-up of the same data for 5 May 2023 indicating factors controlling the amount of moisture loss. Image
11. These graphics are forecast at points near the LoC. This graphic is a 2-D (planar) view of changes to soil moisture (volume %, surface to 10 cm) for the next 7 days. The forecast indicates rapid drying in the south but more modest drying in the east and north. Image
12. Soil moisture doesn't tell the full story. Understanding necessary soil strength for the expected # of vehicles & vehicle ground pressure "foot print" must also be evaluated to assess mobility requirements for a specific "package" of vehicles. /end
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More from @davidhelms570

David Helms Profile picture
May 7
1. Ruschist operation of Kakhovka HPP (K-HPP) dam has been reckless. Kakhovka Reservoir (KR) water level has alternated from record low to record high in just 3 months. Loop (6 FEB-6 MAY 2023) shows sand bars receding with rising KR water. #NAFOWeather🧵
2. These images are of the K-HPP from Left: 6 FEB, and Right: 6 MAY 2023 (enhanced from data included in loop). ImageImage
3. North Crimean Canal intake, Left 20 FEB 2023 Right 6 May 2023: Latest image show water gushing through NCC intake gate at Tavrisk as record KR level is pushing water through gravity fed NCC at high rates. ImageImage
Read 7 tweets
David Helms Profile picture
May 6
1. Russians are once again attempting to frighten residents in occupied Kherson and Zaporizhzhia on the left bank of Kakhovka Reservoir into evacuating. This is part of a larger information operation ahead of the Ukrainian offensive. A #NAFOWeather 🧵
2. TASS reported (some western media repeated) that the Kakhovka HPP dam could burst and this would flood Zaporizhzhia NPP and surrounding communities. This is pure rubbish. If the Kakhovka HPP dam burst, Kakhovka Reservoir would dramatically LOWER as these location are upstream. ImageImage
3. Russian propaganda uses facts, often reported by the west, with other false statements to create an environment of fear and uncertainty. It is TRUE Kakhovka Reservoir is at record high levels and the K-HPP controls water discharge for K reservoir.
Read 15 tweets
David Helms Profile picture
Apr 25
1/ It has been almost a month since I provided a #MudSeason trafficability forecast. My assumption of a "normal" spring rainfall & improving trafficability were way too optimistic as it has rained Every. Damn. Day. since late March 2023. A #NAFOWeather 🧵
2/ #BLUF The trafficability forecast (below) is based on current and predicted rainfall which are well above normal for near the Line of Conflict (LoC). In general, trafficability is delayed about 1 month versus normal. Image
3/ Some input on #MudSeason from authoritative sources: @DefenceHQ "severe mud is highly likely slowing operations vor both sides" but "conditions can be expected to improve in the coming weeks".
Read 17 tweets
David Helms Profile picture
Apr 4
1/ Some thoughts on the flooding in Kramatorsk today (4 April 2023).
2/ To be sure, it snowed in Kramatorsk recently, probably 20-25 cm on March 30-31.
3/ For Donetsk Oblast, area-wide precipitation received in the past 10 days was about 35 mm. This puts the most recent 30 day period +16% above normal, but the past 90 days are -16% below normal. Thus, recently precipitation was a nice catch-up from winter precipitation deficit.
Read 6 tweets
David Helms Profile picture
Mar 29
1/ Heavy Precipitation/Snowfall *ALERT*
Wednesday Evening (MAR 29) to Friday Morning (MAR 31)
* Heavy snow likely in Luhansk and Donetsk
* Drone operations will be severely restricted
* Trafficability will be severely restricted
* Rising water will make creeks dangerous to ford
2/ 10 Day Forecast of weather for Bakhmut and Kreminna shows rate of precipitation, snowfall, & snow depth Thursday-Friday. Additional rainfall next WED. Most snow will melt by Saturday. Melting snow will make trafficability extremely difficult & rising creeks impassable.
3/ Comparing major global weather models, but agree on extreme precipitation potential next 72 hours (50-75 mm), but position of maxima varies by about 100 km which is relevant to the line of conflict.
Read 8 tweets
David Helms Profile picture
Mar 28
13.1/ This 🧵 is a follow-up to the soil moisture variance (tweet 13) providing some recent climate data details for comments included on the table.
13.2/ Temperature and precipitation along the Line of Conflict (LoC) at control points. April and May have the greatest temperature increase but lower precip from winter and summer seasons = increasing evapotranspiration (ET) (e.g., soil water loss). Source: @meteoblue
13.3/ Ukraine spring season (MAM) maps show northwest to southeast gradient of lower to higher temperatures & higher to lower precipitation indicating lower to higher ET/water loss. Source: University of East Anglia
crudata.uea.ac.uk/~timo/climgen/…
Read 12 tweets

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