RADVOR RV nowcast

RADVOR RV is DWD's radar nowcast in 5-minute steps. Every 5 minutes DWD publishes 25 steps: the latest measured 5 minutes (the analysis) and 24 forecast steps reaching two hours ahead. From those, the integration derives how hard it is raining, how hard it will rain, when rain starts and stops, and the wettest hour ahead.

Precipitation intensity now

Precipitation intensity now (mm/h) is the rain rate in the latest radar analysis: the 5 minutes ending at DWD's release time, scaled to an hourly rate (1 mm in 5 minutes = 12 mm/h). It updates every 5 minutes; the window it describes ended about 4 to 10 minutes before the value appears.

It is unknown when the radar has no data for your location.

Attribute	Meaning
window_start / window_end	Start and end of the 5-minute analysis, ISO-8601 UTC
amount_5min	The rain in that window in mm, before scaling to mm/h; null without data

Peak intensities

The heaviest rain rate (mm/h) expected in a window. They tell drizzle from a downpour; the RS sensors give the amounts.

Sensor	Window
Peak intensity next 60 min	the next hour
Peak intensity next 60–120 min	the second hour ahead
Peak intensity next 120 min	the whole two hours: the larger of the two above

Peak intensity next 120 min suits a single "heavy rain ahead" trigger.

Peak hourly precipitation

Peak hourly precipitation next 120 min (mm) is the most rain forecast to fall in any 60-minute window within the next two hours, checked in 5-minute steps. It is 0 when no rain is forecast.

A downpour that straddles the one-hour mark shows here in full, where Precipitation next 60 min and Precipitation next 60–120 min each only see part of it. This matches how DWD defines its heavy-rain warnings (an amount per hour), so it suits alert automations.

It is calculated from the RV 5-minute forecast, which adds up to the RS rolling hours. In the rare cells where DWD's two products differ, it can read below Precipitation next 60 min (by up to about half a millimetre), which it otherwise never does.

Attribute	Meaning
window_start / window_end	Start and end of the wettest hour, ISO-8601 UTC; null when no rain is forecast. If two windows tie, the earlier one
forecast_rolling_1h	The series of hours the sensor picks from, see below

The rolling-hour series

forecast_rolling_1h has one entry every 5 minutes, each the rain in the hour from its start to its end (in mm); lead is the minutes from the release time to end. At 14:00 the entries run from 14:00–15:00 to 15:00–16:00, 13 entries, and the sensor shows the largest.

With the option Add the past hour to the hourly rain series on, the series starts one hour earlier, at 13:00–14:00 (25 entries), so a chart shows the past hour and the forecast as one curve. The first entry is then the same hour as Precipitation last 60 min, added up from DWD's 5-minute analyses, so in rare cells the two differ slightly. The earlier entries appear once the integration has seen a full hour of releases, so for up to an hour after a restart the series has 13 entries.

Precipitation start and end

Precipitation start is when rain begins, Precipitation end when it stops, within the two-hour forecast.

• Precipitation start is now (or 0 minutes) if it is already raining, and unknown if no rain is forecast within two hours.
• Precipitation end is unknown if rain continues beyond two hours. That means "still raining in two hours", not "never".

What counts as rain is set by the option Only count rain heavier than in the Rain forecast section. By default, any amount DWD detects counts.

Format. The option Show start and end as makes both sensors either timestamps (the default) or durations in minutes. The other form is always available as an attribute:

Attribute	Meaning
at	The time of the event, ISO-8601 UTC (when the state is minutes)
minutes_until	Whole minutes until the event (when the state is a time)

When rain counts as over. The option "Precipitation end" shows picks one of two answers:

• The first dry break (default): the end of the current burst. During showers it moves around, since each gap between two cells is an end.
• When no more rain is forecast: the end of the last rain in the forecast, after which nothing more is expected within the horizon. Steadier, but it stays unknown longer.

Precipitation expected

Precipitation expected is a binary sensor: on if rain is forecast within the next two hours, using the same Only count rain heavier than setting as Precipitation start.

Attribute	Meaning
at / minutes_until	When the forecast rain starts; null when none is expected
forecast_5min	The full 25-step forecast, see below

forecast_5min lists the analysis and the 24 forecast steps (0 to 120 minutes in 5-minute steps). Each step has lead (minutes from the release time), start, end, value (mm in those 5 minutes) and intensity (mm/h). value and intensity are null for a step without data. It is always present, so blueprints and charts can use it, and it is not recorded in history.

A template that sums the forecast rain of the next 30 minutes:

{{ state_attr('binary_sensor.home_precipitation_expected', 'forecast_5min')
   | selectattr('lead', 'gt', 0) | selectattr('lead', 'le', 30)
   | map(attribute='value') | reject('none') | sum | round(2) }}

Good to know

• Radar only, like RS: the values can differ from a rain gauge and from the RADOLAN sensors.
• Two-hour horizon. DWD's nowcast ends two hours ahead. Anything later is not known to these sensors, which is why start and end can be unknown.
• Rain events, if turned on, are built from the same RV steps.