Pittsburgh, PA

Weather Forecast Office

NWS PBZ Watch Warning and Advisory Criteria

🌪️ Convective/Severe

💧 Flooding

❄️ Winter Weather

🌡️ Non-Precipitation

⚠️ Watches

Severe Thunderstorm Watch

SV.A

Issued when conditions are favorable for the development of thunderstorms which contain winds of at least 58 mph and/or hail 1 inch or larger.

Tornado Watch

TO.A

Issued when conditions are favorable for thunderstorms to produce tornadoes.

🚨 Warnings

Severe Thunderstorm Warning

SV.W

Thunderstorm winds of 58 mph or greater and/or hail 1 inch in diameter or greater.

Tornado Warning

TO.W

A tornado is spotted or detected on radar.

ℹ️ Advisories

Significant Weather Advisory

SPS

Gusty winds less than 58 mph and/or small hail less than 1 inch below Severe Thunderstorm Warning thresholds. These storms may strengthen to prompt the issuance of a Severe Thunderstorm Warning.

⚠️ Watches

Flash Flood Watch

FF.A

Potential for flash flooding due to non-convective causes (e.g., dam or levee failure or ice jam), or the possibility of flash flooding and debris flows caused by excessive rainfall on burn scars or in debris flow- and landslide-prone areas.

Flood Watch

FA.A

Conditions are favorable for flooding caused by excessive rainfall and runoff. As of 2021, this combines what was formerly (convective) Flash Flood Watches and Areal Flood Watches.

River Flood Watch

FL.A

Issued for river forecast points when river flooding is possible, but flooding is not expected to begin within the next 24 hours.

🚨 Warnings

Flash Flood Warning

FF.W

Short duration (usually less than six hours), flash flooding resulting from storms with rainfall rates of 1 to 2 inches per hour or greater. Also issued when a dam has failed or when a dam failure is imminent.

(Areal) Flood Warning

FA.W

Long duration (slow to evolve), flooding resulting from steady stratiform rain with rates typically less than 1 inch per hour. Most common during long duration spring rains resulting in widespread flooding.

River Flood Warning

FL.W

River flooding is occurring or is forecast for a point. Normally issued when flooding is forecast within 24 hours based on accumulated rainfall.

ℹ️ Advisories

Flood Advisory

FA.Y

Localized flooding resulting from heavy rain. Water may start to threaten homes and businesses, and minor flooding of roads is possible.

⚠️ Watches

Winter Storm Watch

WS.A

Potential for a blizzard, heavy snowfall, or ice storm within the next 18 to 48 hours. Issued when there is a 50% confidence or greater of at least 6 inches of snow and/or a ¼ inch of ice.

Extreme Cold Watch

EC.A

Potential for reach Extreme Cold Warning criteria (see below) within the next 18 to 48 hours.

🚨 Warnings

Winter Storm Warning

WS.W

Snow accumulations 6 inches or greater; Freezing rain accumulations ¼ inch or greater.

Blizzard Warning

BZ.W

Sustained winds 35 mph or greater AND falling/blowing snow reducing visibility to less than ¼ mile for at least three hours.

Ice Storm Warning

IS.W

Freezing rain accumulations ¼ inch or greater resulting in significant, widespread power outages, tree damage, and dangerous travel.

Lake Effect Snow Warning

LE.W

Lake effect snow accumulations 6 inches or greater in 12 hours (8 inches or more in 24 hours). This is issued only for northernmost portions of our area.

Snow Squall Warning

SQ.W

A short-duration (less than 1 hour), polygon-based warning issued when strong snow squalls and flash freezing will cause dangerous and life-threatening conditions, especially for roadways. Usually issued when ground/road temperatures are sub-freezing and visibility is less than ¼ mile.

Extreme Cold Warning

EC.W

Lowest of either air temperature or wind chill that is -20°F (-25°F for Mercer/Venango/Forest Counties) or colder with wind speeds 5 mph or greater for at least 3 hours.

ℹ️ Advisories

Winter Weather Advisory

WS.Y

Snow accumulations of 3 inches, any freezing rain accumulations less than ¼ inch, or a high impact snow/ice event.

Cold Weather Advisory

CW.Y

Lowest of either air temperature or wind chill that is -10°F to -20°F (-15°F to -25°F for Mercer/Venango/Forest Counties) for at least 3 hours.

⚠️ Watches

High Wind Watch

HW.A

Conditions are favorable for development of sustained winds of 40 mph or greater and/or gusts of 58 mph or greater within the next 24 to 48 hours.

Freeze Watch

FZ.A

Potential for the first freeze of the fall season or for a late spring freeze within the next 18 to 24 hours. Product is discontinued for the season following the first fall "killing" freeze.

Extreme Heat Watch

XH.A

Potential for heat index values of 105°F or hotter within the next 24 to 48 hours.

🚨 Warnings

High Wind Warning

HW.W

Non-convective sustained wind speeds 40 mph and greater and/or wind gusts 58 mph and greater.

Freeze Warning

FZ.W

When temperatures will be at or below 32°F over a large area for a significant time during the growing season.

Extreme Heat Warning

XH.W

Heat Index of 105°F or greater.

Red Flag/ Fire Weather Warning

FW.W

Dangerous fire behavior expected within the next 12-24 hours based on weather conditions and dry fuels.

ℹ️ Advisories

Wind Advisory

WI.Y

Non-convective sustained wind speeds 30-39 mph with wind gusts 46-57 mph.

Frost Advisory

FR.Y

When frost is expected during the growing season.

Heat Advisory

HY.Y

Heat Index of 100°F to 104°F.

Dense Fog Advisory

FG.Y

Fog reducing visibilities to a ¼ mile (0.4 km) or less for at least 3 hours.

*Please note: winter and heat related criteria are based on local climatology. Therefore, NWS Pittsburgh area thresholds for heat and winter related products may differ slightly from neighboring NWS offices' criteria.