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 Northern Mariana Islands: 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
Northern Mariana Islands briefing
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.