Model guidance: what the models forecast
REFS · Rotating storms · initialized · valid
REFS / HRRR: feeds current
REFS: Feed current; checked .
HRRR: Feed current; checked .
Checked means retrieved, not newly issued. Each graphic retains its issue, observation, initialization or valid time. Site publishing status is separate.
Rotating storms
How many of the ensemble’s members grow a storm with a strongly rotating updraft near each point in the hour: the model’s sign of a supercell, which can bring tornadoes, large hail and damaging wind.
A forecast’s own uncertainty, not a forecast of coverage: REFS is a set of runs of NCEP’s RRFS model, each started a little differently, and the share is how many of them put the event near a point. 30% is three runs in ten. It is guidance forecasters weigh, not SPC’s outlook and not a warning.
Share of members
- 10–30%
- 30–50%
- 50–70%
- 70–90%
- 90% or more
- under 10%: not drawn
In District of Columbia: under 10% of members anywhere in the state.
Highest anywhere in the hour: 28% of members.
Pre-operational: NCEP’s parallel REFS, which it plans to make operational on 3 November 2026 (Service Change Notice 26-48). Until then it may be late, missing or changed without notice.
Model, field & forecast hours
Retention & comparison limits
Only rolling current frames and limited previous copies are retained. Complete historical runs are not archived, so two-run comparison is unavailable. Only the published forecast hours are stepped; gaps are explicit. Rainfall uses WPC’s existing forecast, not an unprovided model rainfall field.
REFS (NOMADS) checked · Data: NOAA/NCEP
HRRR pictures (MAG) checked · Data: NOAA/NCEP
Not an official warning service. Warnings and watches are the National Weather Service’s, outlooks and reports the Storm Prediction Center’s and the Weather Prediction Center’s (Data: NOAA/NWS, NOAA/SPC, NOAA/WPC). When a warning is issued for you, act on it, and use weather.gov or a NOAA Weather Radio for where you are.