268
NOUS41 KWBC 291925
PNSWSH
SERVICE CHANGE NOTICE 26-11
NATIONAL WEATHER SERVICE HEADQUARTERS SILVER SPRING MD
225 PM EST THU JAN 29 2026
TO: SUBSCRIBERS:
-NOAA WEATHER WIRE SERVICE
-EMERGENCY MANAGERS WEATHER INFORMATION NETWORK
-NOAAPORT
OTHER NWS PARTNERS, USERS AND EMPLOYEES
FROM: WILLIAM F. BUNTING
DEPUTY DIRECTOR, NWS STORM PREDICTION CENTER
SUBJECT: UPCOMING CHANGES TO STORM PREDICTION CENTER (SPC) DAY
1, 2, AND 3 CONVECTIVE OUTLOOK FORECASTS ON OR ABOUT MARCH 2,
2026
ON OR ABOUT MARCH 2, 2026, THE STORM PREDICTION CENTER (SPC)
WILL IMPLEMENT THE FOLLOWING CHANGES TO THE SEVERE WEATHER
OUTLOOK PRODUCTS.
1. SPC WILL BEGIN ISSUING CONDITIONAL INTENSITY FORECASTS OF
SIGNIFICANT SEVERE WEATHER FOR DAYS 1, 2, AND 3. THESE NEW
CONDITIONAL INTENSITY GROUPS (CIG) WILL INCLUDE THREE INTENSITY
DISTRIBUTIONS (CIG1, CIG2, AND CIG3) TO COMMUNICATE INCREASING
INTENSITY OF SIGNIFICANT SEVERE HAZARDS, SHOULD SEVERE HAZARDS
OCCUR.THESE NEW CONDITIONAL INTENSITY GROUPS WILL BE VISIBLE
ON THE SPC SEVERE WEATHER OUTLOOK DAY 1, 2, AND 3 GRAPHICS AND
DISSEMINATED THROUGH THE SPC OUTLOOK PTS PRODUCTS: WUUS01 KWNS
PTSDY1, WUUS02 KWNS PTSDY2, WUUS03 KWNS PTSDY3. THE CONDITIONAL
INTENSITY GROUPS WILL BE LABELED “CIG1”, “CIG2”, AND
“CIG3”
REPLACING THE CURRENT “SIGN” LABEL. ADDITIONALLY, GIS VERSIONS
OF THESE NEW FORECASTS WILL BE AVAILABLE ON THE SPC WEBSITE.
2. THE EXISTING SPC SIGNIFICANT SEVERE HAZARD GRIDS (I.E.,
TORNADO, WIND, HAIL, TOTAL SEVERE) WILL CONTINUE TO BE
DISSEMINATED. HOWEVER, ADDITIONAL DISCRETE PROBABILITY
THRESHOLDS WILL BE ADDED TO THE EXISTING 10% THRESHOLD, AND WILL
NOW BE REPRESENTED AS A SEQUENCE OF EVEN NUMBERS (I.E., 2%, 4%,
ETC.).
3. SPC WILL BEGIN ISSUING WMO GRIB2 FILES OF CONDITIONAL
INTENSITY GROUPS AND UNCONDITIONAL PROBABILITIES OF SIGNIFICANT
SEVERE HAZARDS. THE NEW WMO HEADERS ARE LISTED AT THE END OF
THIS ANNOUNCEMENT.
4. SPC WILL ADD 75% AND 90% FORECAST THRESHOLDS TO THE DAY 1 AND
DAY 2 PROBABILISTIC SEVERE THUNDERSTORM WIND FORECASTS. THESE
NEW THRESHOLDS WILL BE REFLECTED IN THE SPC OUTLOOK PTS
PRODUCTS: WUUS01 KWNS PTSDY1, WUUS02 KWNS PTSDY2, WUUS03 KWNS
PTSDY3.
FOR MORE INFORMATION ABOUT THESE CHANGES, INCLUDING SAMPLE
FORECAST PRODUCTS, PLEASE VISIT:
HTTPS://WWW.SPC.NOAA.GOV/EXPER/CONDITIONAL-INTENSITY-INFORMATION
THE FOLLOWING NEW GRIB2 OPERATIONAL PRODUCTS BY WMO HEADER
INCLUDE:
DAY 1:
HMNE01 KWNS DISCRETE CONDITIONAL INTENSITY GROUP (CIG) TORNADO
HMNE02 KWNS DISCRETE CONDITIONAL INTENSITY GROUP (CIG) HAIL
HMNE03 KWNS DISCRETE CONDITIONAL INTENSITY GROUP (CIG) WIND
YSUZ95 KWNS CONTINUOUS UNCONDITIONAL PROBABILITY OF TORNADO EF0+
HMNE05 KWNS CONTINUOUS UNCONDITIONAL PROBABILITY OF TORNADO EF1+
HMNE06 KWNS CONTINUOUS UNCONDITIONAL PROBABILITY OF TORNADO EF2+
HMNE07 KWNS CONTINUOUS UNCONDITIONAL PROBABILITY OF TORNADO EF3+
HMNE08 KWNS CONTINUOUS UNCONDITIONAL PROBABILITY OF TORNADO EF4+
YTUZ95 KWNS CONTINUOUS UNCONDITIONAL PROBABILITY OF HAIL 1.0+
HMNE09 KWNS CONTINUOUS UNCONDITIONAL PROBABILITY OF HAIL 1.5+
HMNE10 KWNS CONTINUOUS UNCONDITIONAL PROBABILITY OF HAIL 2.0+
HMNE11 KWNS CONTINUOUS UNCONDITIONAL PROBABILITY OF HAIL 3.5+
YUUZ95 KWNS CONTINUOUS UNCONDITIONAL PROBABILITY OF WIND 50 KT+
HMNE12 KWNS CONTINUOUS UNCONDITIONAL PROBABILITY OF WIND 56 KT+
HMNE13 KWNS CONTINUOUS UNCONDITIONAL PROBABILITY OF WIND 65 KT+
HMNE14 KWNS CONTINUOUS UNCONDITIONAL PROBABILITY OF WIND 74 KT+
HMNE15 KWNS CONTINUOUS UNCONDITIONAL PROBABILITY OF WIND 83 KT+
HMNE16 KWNS CONTINUOUS CONDITIONAL INTENSITY GROUP (CIG) TORNADO
HMNE17 KWNS CONTINUOUS CONDITIONAL INTENSITY GROUP (CIG) HAIL
HMNE18 KWNS CONTINUOUS CONDITIONAL INTENSITY GROUP (CIG) WIND
DAY 2:
HMNI01 KWNS DISCRETE CONDITIONAL INTENSITY GROUP (CIG) TORNADO
HMNI02 KWNS DISCRETE CONDITIONAL INTENSITY GROUP (CIG) HAIL
HMNI03 KWNS DISCRETE CONDITIONAL INTENSITY GROUP (CIG) WIND
YSUZ96 KWNS CONTINUOUS UNCONDITIONAL PROBABILITY OF TORNADO EF0+
HMNI05 KWNS CONTINUOUS UNCONDITIONAL PROBABILITY OF TORNADO EF1+
HMNI06 KWNS CONTINUOUS UNCONDITIONAL PROBABILITY OF TORNADO EF2+
HMNI07 KWNS CONTINUOUS UNCONDITIONAL PROBABILITY OF TORNADO EF3+
HMNI08 KWNS CONTINUOUS UNCONDITIONAL PROBABILITY OF TORNADO EF4+
YTUZ96 KWNS CONTINUOUS UNCONDITIONAL PROBABILITY OF HAIL 1.0+
HMNI09 KWNS CONTINUOUS UNCONDITIONAL PROBABILITY OF HAIL 1.5+
HMNI10 KWNS CONTINUOUS UNCONDITIONAL PROBABILITY OF HAIL 2.0+
HMNI11 KWNS CONTINUOUS UNCONDITIONAL PROBABILITY OF HAIL 3.5+
YUUZ96 KWNS CONTINUOUS UNCONDITIONAL PROBABILITY OF WIND 50 KT+
HMNI12 KWNS CONTINUOUS UNCONDITIONAL PROBABILITY OF WIND 56 KT+
HMNI13 KWNS CONTINUOUS UNCONDITIONAL PROBABILITY OF WIND 65 KT+
HMNI14 KWNS CONTINUOUS UNCONDITIONAL PROBABILITY OF WIND 74 KT+
HMNI15 KWNS CONTINUOUS UNCONDITIONAL PROBABILITY OF WIND 83 KT+
HMNI16 KWNS CONTINUOUS CONDITIONAL INTENSITY GROUP (CIG) TORNADO
HMNI17 KWNS CONTINUOUS CONDITIONAL INTENSITY GROUP (CIG) HAIL
HMNI18 KWNS CONTINUOUS CONDITIONAL INTENSITY GROUP (CIG) WIND
DAY 3:
HMNK19 KWNS DISCRETE CONDITIONAL INTENSITY GROUP (CIG) TOT SVR
HMNK20 KWNS CONTINUOUS CONDITIONAL INTENSITY GROUP (CIG) TOT SVR
HMNK21 KWNS CONTINUOUS UNCONDITIONAL PROBABILITY TOT SVR
HMNK22 KWNS CONTINUOUS UNCONDITIONAL PROBABILITY TOT SIG SVR+
FEEDBACK CAN BE DIRECTED TO:
RANDY BOWERS
NWS SEVERE WEATHER SERVICES MANAGER
BARRY.BOWERS@NOAA.GOV
AND
PATRICK MARSH
CHIEF OF SCIENCE AND SUPPORT
STORM PREDICTION CENTER
PATRICK.MARSH@NOAA.GOV
NATIONAL SERVICE CHANGE NOTICES ARE ONLINE AT:
HTTPS://WWW.WEATHER.GOV/NOTIFICATION/
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