http://www.spc.noaa.gov/exper/dy1-3example/

Changes are coming. The current 4 tier outlook is looking to go to a 5 tier outlook. Marginal will be replacing the infamous "SEE TEXT" and then a new level of Enhanced (ENH) will go in to replace upper end SLGT risk areas that don't meet the threshold for a MOD risk.

Current Way...

http://www.spc.noaa.gov/exper/dy1-3example/day1otlk_20130210_1630_prt_sm.gif

New format...

http://www.spc.noaa.gov/exper/dy1-3example/day1-20130210-1630_sm.gif

The new thresholds...

Day 1:
a. General Thunderstorms
- 10% or greater probability of non-severe or near severe thunderstorms.

b. Severe Category 1 - Marginal
- 2% or greater tornado probability, or
- 5% or greater severe hail or severe wind probability.

c. Severe Category 2 - Slight
- 5% or greater tornado probability, or
- 15% or greater severe hail or severe wind probability.

d. Severe Category 3 - Enhanced
- 10% or greater tornado probability, or
- 30% or greater severe hail or severe wind probability.

e. Severe Category 4 - Moderate
- 15% or greater tornado probability AND 10% or greater probability
of an EF2+ tornado, or
- 30% or greater tornado probability, or
- 45% or greater severe wind probability AND 10% or greater
probability of a wind gusts 75 mph or greater, or
- 45% or greater severe hail probability AND 10% or greater
probability of hail 2 inches or greater in diameter, or
- 60% or greater severe wind probability, or
- 60% or greater severe hail probability.

f. Severe Category 5 - High
- 30% or greater tornado probability AND 10% or greater probability
of an EF2+ tornado, or
- 45% or greater tornado probability, or
- 60% or greater severe wind probability AND a 10% or greater
probability of a wind gust 75 mph or greater.

http://www.spc.noaa.gov/exper/dy1-3example/day1prob2cat_sm.png


Days 2 and 3: (Top (http://www.spc.noaa.gov/exper/dy1-3example/#top))
a. General Thunderstorms
- 10% or greater probability of non-severe or near severe thunderstorms.

b. Severe Category 1 - Marginal
- 5% or greater total severe probability.

c. Severe Category 2 - Slight
- 15% or greater total severe probability.

d. Severe Category 3 - Enhanced
- 30% or greater total severe probability.

e. Severe Category 4 - Moderate
- 45% or greater total severe probability AND 10% or greater
probability of an EF2+ tornado, a wind gust 75 mph or greater, or
hail 2 inches or greater in diameter, or
- 60% or greater total severe probability (Day 2 only).

f. Severe Category 5 - High (Day 2 only)
- 60% or greater total severe probability AND 10% or greater
probability of an EF2+ tornado or a wind gust 75 mph or greater.

http://www.spc.noaa.gov/exper/dy1-3example/day2probs_sm.png http://www.spc.noaa.gov/exper/dy1-3example/day3probs_sm.png

Public period has ended and SPC has finalized changes to outlooks and will release them probably in September...

The Day 1-3 outlooks will now include the two additional categories - marginal and enhanced as previously posted.

The new Day 4-8 will now in a 15% and 30% risk area.

http://www.spc.noaa.gov/exper/dy4-8example/day4otlk.gif

Venture, there have been a lot of changes lately, or at least you've made us aware of a lot lately.
Is there an change in leadership or philosophy in NOAA? or are these changes rather commonplace and I only recently have become aware of them?

Venture, there have been a lot of changes lately, or at least you've made us aware of a lot lately.
Is there an change in leadership or philosophy in NOAA? or are these changes rather commonplace and I only recently have become aware of them?

They've been tweaking things over the last few years. SPC's role has increased since it was firmly established in Norman after moving from Kansas City (then the National Severe Storms Forecast Center). We've seen winter products added, their expanding role in fire weather forecasting, and of course fine tuning of the severe weather side. I look at it as more of a natural evolution of their product offerings.

I've been torn on the expanded outlooks with 5 categories now, but to a point it does make sense. The general population doesn't pay attention to the probability products put out in association with the category outlooks. They just hear "Slight" and think nothing major, when the probabilities could call for giant hail or a decent number of tornadoes. Then there is also the issue of having a slight risk and only a couple isolated storms pop up, so the marginal category will help with that.

I think the changes are good. Overall I would also like to see us get back to where High Risk days are very rare and only used in extreme circumstances.