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REFS · Model Forecast

Severe Storms Index, Sig (3h max)

Short-Range Hours to 3 days

HRRRHigh-Resolution Rapid Refresh RRFSRapid Refresh Forecast System REFSRapid Ensemble Forecast System REFS MembersREFS Members · RRFS Ensemble

Medium-Range Out to 16 days

GFSGlobal Forecast System ECMWFECMWF Integrated Forecasting System GEFSGlobal Ensemble Forecast System NBMNational Blend of Models

Extended & Seasonal Weeks to months

CFS WeeklyClimate Forecast System · Weekly CFS MonthlyClimate Forecast System · Monthly CanSIPSCanadian Seasonal to Interannual Prediction System · Monthly NMMENorth American Multi-Model Ensemble · Monthly

Tropical Hurricane models

HAFS-AHurricane Analysis and Forecast System (A)HAFS-BHurricane Analysis and Forecast System (B)

Regional views Lower 48 Pacific Northern Rockies Northern Plains Great Lakes Southwest Southern Plains Mid-South Deep South & Florida Southeast Northeast Subregions Centered On…

Birmingham, AL Little Rock, AR San Francisco, CA Denver, CO St. Petersburg, FL Des Moines, IA Indianapolis, IN Wichita, KS New Orleans, LA Baltimore, MD Portland, ME Saginaw, MI Minneapolis, MN Charlotte, NC Albuquerque, NM Las Vegas, NV Reno, NV Albany, NY Oklahoma City, OK Salem, OR Pierre, SD Nashville, TN DFW Houston, TX San Antonio, TX Pullman, WA Gillette, WY

State zooms

Alabama Arizona Arkansas California Colorado Connecticut Delaware Florida Georgia Idaho Illinois Indiana Iowa Kansas Kentucky Louisiana Maine Maryland Massachusetts Michigan Minnesota Mississippi Missouri Montana Nebraska Nevada New Hampshire New Jersey New Mexico New York North Carolina North Dakota Ohio Oklahoma Oregon Pennsylvania Rhode Island South Carolina South Dakota Tennessee Texas Utah Vermont Virginia Washington West Virginia Wisconsin Wyoming

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TT Composites

Supercell Threat Index Severe Storms Index, Base Severe Storms Index, Sig Storm Structure Target Index Tornado Chasing Target Index HRRR Structure Index HRRR Tornado Environment Index

Significant Tornado

Probability Sig-Tor Classic

Temperature & Moisture

2m Temperature 2m Dewpoint

Dewpoint Lines (each member)

55 F Dewpoint (each member)60 F Dewpoint (each member)65 F Dewpoint (each member)70 F Dewpoint (each member)

Wind

10m Wind Prob Surface Wind > 50 kt Prob Surface Wind > 60 kt Gusts 50 kt (each member)

Pressure & Clouds

Sea-Level Pressure Total Cloud Cover

925 mb

925 mb Wind

850 mb

850 mb Height 850 mb Wind 850 mb Temperature 850 mb Dewpoint Prob 850 mb Wind > 20 kt Prob 850 mb Wind > 40 kt Prob 850 mb Wind > 60 kt

700 mb

700 mb Wind 700 mb Temperature 700 mb Dewpoint 700 mb RH

550 mb

Prob 550 mb Wind > 20 kt Prob 550 mb Wind > 40 kt Prob 550 mb Wind > 60 kt Prob 550 mb Wind > 80 kt

500 mb

500 mb Height 500 mb Wind 500 mb Temperature

250 mb

250 mb Wind

CAPE

SBCAPE MLCAPE MUCAPE

MLCAPE Probability

Prob MLCAPE > 500 Prob MLCAPE > 1000 Prob MLCAPE > 1500 Prob MLCAPE > 2000 Prob MLCAPE > 3000

Inhibition

MLCIN Prob MLCIN uncapped (0)Prob MLCIN < -50 Prob MLCIN < -100 Prob MLCIN < -400

Bulk Shear

0-6 km Shear 0-2 kft Shear Prob 0-6 km Shear > 20 kt Prob 0-6 km Shear > 30 kt Prob 0-6 km Shear > 40 kt Prob 0-6 km Shear > 50 kt

Helicity

0-3 km SRH Prob 0-3 km SRH > 100 Prob 0-3 km SRH > 200 Prob 0-3 km SRH > 400

Simulated Reflectivity

Simulated Reflectivity Reflectivity 40 dBZ (each member)

Reflectivity Probability

Prob REFC > 20 dBZ Prob REFC > 40 dBZ Prob REFC > 50 dBZ Prob REFC > 40 dBZ (hourly)

Rotation

UH 2-5 km magnitude Prob UH 2-5 km > 75 Prob UH 2-5 km > 150 UH 75 Tracks (each member)

Updrafts & Lightning

Prob Max UVV > 10 m/s Prob Max UVV > 20 m/s Prob Lightning

Rain Totals

6h QPF (PMM)Run Total QPF (PMM)

1-hour Rainfall

Prob 1h Rain > 0.5 in Prob 1h Rain > 1 in Prob 1h Rain > 2 in Prob 1h Rain > 3 in

12-hour Rainfall

Prob 12h Rain > 0.5 in Prob 12h Rain > 1 in Prob 12h Rain > 2 in Prob 12h Rain > 3 in Prob 12h Rain > 5 in Prob 12h Rain > 8 in

Rain Agreement (EAS)

EAS 3h Rain > 0.25 in EAS 3h Rain > 0.5 in EAS 12h Rain > 0.5 in EAS 12h Rain > 1 in EAS 12h Rain > 2 in EAS 24h Rain > 1 in EAS 24h Rain > 2 in EAS 24h Rain > 3 in

Moisture & Storm Motion

Precipitable Water Prob PWAT > 1 in Prob PWAT > 1.5 in Prob PWAT > 2 in Prob Weak Steering Flow

Flash Flood Guidance

Prob 1h Rain > FFG Prob 3h Rain > FFG Prob 6h Rain > FFG

Recurrence Interval

Prob 6h Rain > 2-Year Prob 6h Rain > 10-Year Prob 6h Rain > 100-Year Prob 24h Rain > 2-Year Prob 24h Rain > 10-Year Prob 24h Rain > 100-Year

Freeze

Prob Temp < 32°F 32 F Line (each member)28 F Line (each member)

Precipitation Type

Prob Rain (precip type)Prob Snow (precip type)Prob Freezing Rain (precip type)Prob Sleet (precip type)

Snowfall

Prob 1h Snow > 1 in Prob 1h Snow > 3 in Prob 12h Snow > 1 in Prob 12h Snow > 3 in Prob 12h Snow > 6 in Prob 12h Snow > 12 in Prob 12h Snow > 18 in

Freezing Rain

Prob 1h Freezing Rain > 0.01 in Prob 1h Freezing Rain > 0.1 in Prob 1h Freezing Rain > 0.25 in Prob 12h Freezing Rain > 0.01 in Prob 12h Freezing Rain > 0.1 in Prob 12h Freezing Rain > 0.25 in Prob 12h Freezing Rain > 0.5 in

Latest window Speed

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Current field

Severe Storms Index, Sig

REFS · Forecast

0255075100

About this field

Proprietary 0-100 outcome gate. Same construction as SSI Base but with the ingredient thresholds tightened (CAPE 2500+, shear 40+, SRH 300+, Td 62+, lapse 7.5+). Meant to flag significant-severe environments specifically.

Contours (REFS mean) MSLP contours 500 mb height contours 850 mb height contours 2m temperature contours 2m dewpoint contours 850 mb temperature contours 700 mb temperature contours 500 mb temperature contours MLCAPE contours SBCAPE contours MLCIN contours 0-3 km SRH contours 0-6 km shear contours PWAT contours 700 mb RH contours

Wind barbs (REFS mean) 10m wind barbs 925 mb wind barbs 850 mb wind barbs 700 mb wind barbs 500 mb wind barbs 250 mb wind barbs

Outlook overlays SPC Convective SPC Fire WPC Excessive Rainfall WPC Winter / WSSI

Model refresh

Every 6 hours. Ensemble guidance through forecast hour 60 on every cycle and through hour 72 on the 00Z cycle. Fields are probabilities across ensemble members, so higher values mean the atmospheric setup is more agreed-upon by the ensemble.

Use with care

Model output is guidance, not a warning. Follow official National Weather Service information for life-safety decisions.

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