National Weather Service United States Department of Commerce

WFO GYX Warning Criteria

PRODUCT
PIL
CRITERIA
CONF. LEV.
 
 
Severe Weather Products
 
Tornado Warning
TOR
Tornado Warnings should be issued when there is radar or satellite indication and/or reliable spotter reports of a tornado.
N/A
Severe Tstm Warning
SVR
Severe Thunderstorm Warnings should be issued when there is radar or satellite indication and/or reliable spotter reports of wind gusts equal to or greater than 50 knots (58 mph) and/or hail size of 1 inch (quarter) diameter or larger.
N/A
Special Marine Warning
SMW
Special Marine Warnings should be issued for short-duration (up to 2 hours) sustained marine thunderstorm winds or associated gusts of 34 knots or greater; and/or hail 3/4 inch (penny) or more in diameter; and/or waterspouts.
N/A
Severe Weather Statement
SVS
A Severe Weather Statement should be issued to provide notice a Severe Thunderstorm or Tornado Warning has been canceled for all or portions of the warning. A Severe Weather Statement should be issued at least once during the valid time of a Severe Thunderstorm or Tornado Warning. A Severe Weather Statement may be issued to provide notice that a Severe Thunderstorm or Tornado Warning has expired. A Severe Weather Statement should be issued to notify customers that erroneous counties included in original Severe Thunderstorm or Tornado Warnings (either in the FIPs/Zone UGC code or in the body of the warning) have been removed.
N/A
Watch County Notification
WCN
A Watch County Notification message will be issued after SPC issues the initial Watch Outline Update Message (WOU). Issue updated WCNs to cancel, extend the valid time, or extend in area portions of one or more convective watches in the WFO Gray geographic area of responsibility.
N/A
Special Weather Statement
SPS
SPSs should be issued for ongoing or imminent weather conditions less than warning criteria and to report funnel clouds. SPSs should be issued to report funnel clouds which are not expected to touch the ground and become tornadoes. SPSs may be issued for severe weather outlook information.
N/A
Local Storm Report
LSR
Issue LSRs for severe weather events such as tornadoes, waterspouts, large hail, thunderstorm/marine wind gusts and flash floods. LSRs should be issued for events that meet or exceed applicable warning criteria.
N/A
Hazardous Weather Outlook
HWO
The HWO is a dynamic product that should be updated whenever necessary to always depict the latest expected weather hazards for the seven day forecast period.
N/A
 
 
Winter Weather Products
 
Wind Chill Watch
WSW
Conditions are favorable for WindChill temperatures to meet, or exceed, local WindChill Warning criteria in the next 12 to 48 hours.
50%
Winter Storm Watch
WSW
Conditions are favorable for a Winter Storm event (Heavy Sleet, Ice Storm, Heavy Snow, and Blowing Snow or a combination of events) to meet, or exceed, local Winter Storm Warning criteria in the next 12 to 48 hours.
50%
Blizzard Warning
WSW
Sustained wind or frequent gusts greater than or equal to 35 mph accompanied by falling and/or blowing snow, frequently reducing visibility to less than 1/4 mile for three hours or more.
80%
Ice Storm Warning
WSW
Ice accumulation of ½ (one half) inch or more.
80%
Wind Chill Warning
WSW
Wind chill temperatures reaching -30F or colder.
80%
Winter Storm Warning
WSW
Winter weather event having more than one predominant hazard (i.e., heavy snow and blowing snow, snow
and ice, snow and sleet, sleet and ice, or snow, sleet and ice) meeting or exceeding locally defined 12 and/or 24 hour warning criteria for at least one of the precipitation elements.
80%
Snow Squall Warning
WSW
Heavy Snow reducing visibility to less than one quarter mile with rapidly falling temperatures resulting in a high likliehood of a flash freeze.
80%
Wind Chill Advisory
WSW
Wind chill temperatures of -20F to -29F.
80%
Winter Weather Advisory
WSW
Winter weather event where precipitation type cannot be determined with a high level of confidence, or event having more than one predominant hazard (i.e., snow and ice, snow and sleet, or snow, ice and sleet)
meeting or exceeding locally defined 12 and/or 24 hour advisory criteria for at least one of the precipitation elements, but remaining below warning criteria.
80%
Public Information Statement
PNS
Public Information Statements should be issued at least every three to six hours at a minimum during events, especially prior to scheduled news broadcast times.
N/A
 
 
Non-Precipitation Wx Products
 
Freeze Watch
NPW
Issue a Freeze Watch when the minimum temperature is forecast to be 32o or less during the frost/freeze season. The season begins on the average date of the last spring freeze and ends on the date of the first hard autumn freeze. The average date of the last spring freeze is:
NHZ014-MEZ023>028: May 1
NHZ003>010-013-MEZ012>014-018>022: May 11
NHZ001-002-MEZ007>009: May 21
50%
High Wind Watch
NPW
Issue a High Wind Watch for high winds excluding those directly associated with severe local storms, hurricanes, and winter storms for a) sustained wind speeds of 40mph or greater lasting for 1 hour or longer,
or b) winds of 58 mph or greater for any duration.
50%
Dust Storm Warning
NPW
Issue a Dust Storm Warning for widespread or localized blowing dust reducing visibilities to 1/4 mile or
less.
80%
Excessive Heat Warning
NPW
Issued when the heat index is expected to reach 105 or greater lasting for 2 hours or more.
80%
Freeze Warning
NPW
Issue a Freeze Warning when the minimum temperature is forecast to be 32o or less during the frost/freeze season. The frost/freeze season begins on the average date of the last spring freeze and ends on the date of the first hard autumn freeze. The average date of the last spring freeze is:
NHZ014-MEZ023>028: May 1
NHZ003>010-013-MEZ012>014-018>022: May 11
NHZ001-002-MEZ007>009: May 21
80%
High Wind Warning
NPW
Issue a High Wind Warning for high winds excluding those directly associated with severe local storms, hurricanes, and winter storms for a) sustained wind speeds of 40 mph or greater lasting for 1 hour or longer, or b) winds of 58 mph or greater for any duration.
80%
Air Stagnation Advisory
NPW
Issued when atmospheric conditions are stable enough to cause air pollutants to accumulate in a given area. Criteria developed in conjunction with the local or state EPA and the product issued at their request.
80%
Ashfall Advisory
NPW
Issued when an ash plume resulting from a volcanic eruption reduces visibility at the ground and in the air. There is no minimum visibility threshold for the issuance of this product.
80%
Blowing Dust Advisory
NPW
Issued when widespread or localized blowing dust reduces visibilities to 1 mile or less, but greater than 1/4 mile. Winds or 25 mph or greater are usually required.
80%
Dense Fog Advisory
NPW
Dense Fog Advisory Issued when widespread or localized fog reduces visibilities to 1/4 mile or less.
80%
Dense Smoke Advisory
NPW
Issued when widespread or localized smoke reduces visibilities to 1/4 mile or less.
80%
Freezing Fog Advisory
NPW
Issued for very light ice accumulation from freezing fog.
80%
Frost Advisory
NPW
Issued when the minimum temperature is forecast to be 33F to 36F with light wind
and mostly clear skies during the frost/freeze season. The frost/freeze season begins on the average date of the last spring freeze and ends on the date of the first hard autumn freeze. The average date of the last spring freeze is:
NHZ014-MEZ023>028: May 1
NHZ003>010-013-MEZ012>014-018>022: May 11
NHZ001-002-MEZ007>009: May 21
80%
Heat Advisory
NPW
Issued when the heat index is expected to reach 95 degrees lasting 2 hours or more or 100-104F for any amount of time.
80%
Wind Advisory
NPW
Issued for winds excluding those directly associated with severe local storms, tropical cyclones, and winter storms for a) sustained wind speeds of 31-39 mph lasting for 1 hour or longer; or b) wind gusts of 46-57 mph for any duration.
80%
 
 
Marine/Coastal Products
 
Coastal Flood Watch
CFW
Issue a coastal flood watch when conditions are favorable for a coastal flood event to develop over part or all of the local coastal area, but the occurrence is uncertain.
50%
Coastal Flood Warning
CFW
Issue coastal flood warnings when hazardous coastal flooding is imminent, occurring or highly likely over part or all of the local coastal area.
80%
Coastal Flood Advisory
CFW
Issue coastal flood warnings when minor coastal flooding is imminent, occurring or highly likely over part or all of the local coastal area.
80%
Coastal Flood Statement
CFW
Issue coastal flood statements:
1. To keep customers and partners updated on existing watches and warnings; or
2. To cancel a watch or warning, remove areas from a watch or warning, or to announce the expiration of a warning;
3. To address less severe coastal flood events when a warning is not appropriate; or
4. To direct customers to a Hurricane Local Statement (HLS) when an HLS replaces a CWF.
N/A
Small Craft Advisory
MWW
Sustained winds ranging between 25 and 33 knots (except 20 to 25 knots, lower threshold area dependent, to 33 knots for harbors, bays, etc.) and/or seas/waves 5 to 7 feet and greater, area dependent.
N/A
Gale Warning
MWW
A warning of sustained surface winds, or frequent gusts, in the range of 34 knots (39 mph) to 47 knots (54 mph) inclusive, either predicted or occurring, and not directly associated with a tropical cyclone.
N/A
Storm Warning
MWW
A warning of sustained surface winds, or frequent gusts, in the range of 48 knots (55 mph) to 63 knots (73 mph) inclusive, either predicted or occurring, and not directly associated with a tropical cyclone.
N/A
Hurricane Force Wind Warning
MWW
A warning for sustained winds, or frequent gusts, of 64 knots (75 mph) or greater, either predicted or occurring, and not directly associated with a tropical cyclone.
N/A
Freezing Spray Advisory
MWW
An advisory for an accumulation of freezing water droplets on a vessel at a rate of less than 2 centimeters (cm) per hour caused by some appropriate combination of cold water, wind, cold air temperature, and vessel movement.
N/A
Heavy Freezing Spray Wrn
MWW
A warning that may be issued within the Coastal Waters Forecast. An accumulation of freezing water droplets on a vessel at a rate of 2 cm per hour or greater caused by some appropriate combination of cold water, wind, cold air temperature, and vessel movement.
N/A
High Surf Advisory
CFW
For Waves 7ft or greater OR 5ft or greater with period of 10 seconds or longer. Issued Memorial Day weekend through Columbus Day weekend.
N/A
Rip Current Statement
CFW
For rip current risk of High without meeting High Surf Criteria. Issued Memorial Day weekend through Columbus Day weekend.
N/A
 
 
Tropical Cyclone Products
 
Hurricane Local Statement
HLS
WFO Gray will issue HLSs when its area of responsibility is affected by a tropical cyclone watch/warning or evacuation orders. HLSs may also be issued as needed to dispel rumors or to clarify tropical cyclone related information for their CWA. Inland counties may be included in the HLS as an option.
N/A
Extreme Wind Warning
EWW
EWW is a short term product issued when winds a) Tropical cyclone is a category 3 or higher AND b) sustained tropical cyclone winds of 100kts or greater are occurring or expected to occur within 1 hour
N/A
Post-Tropical Cyclone Report
PSH
If HLSs are issued, PSH will be issued.
N/A
 
 
Flood/Flash Flood Products
 

Hydrologic Outlook

(Flood Potential Outlook)

ESF

a. A product needs to be issued to convey the possibility of flooding, with possible occurrence typically 24 hours or more into the future, but as low as 12 hours in some cases when near-term certainty is still low, or

b. A hydrologic outlook was previously issued indicating the possibility of flooding, but none materialized. In this case the new product issued under the ESF identifier would indicate there is no longer a possibility of flooding.

N/A

Hydrologic Outlook

(Winter/Spring Flood Potential Outlook)

ESF
Hydrologic Outlooks describe the potential for winter/spring flooding in general terms based on observed snow depths and water contents, soil moisture conditions, river and ice conditions, and antecedent precipitation conditions. Outlooks are typically issued at two week intervals starting in mid January and continuing into April (until spring runoff occurs).
N/A

Hydrologic Outlook

(Drought/Water Resource Statement)

ESF

HYDROLOGIC OUTLOOKS describe drought conditions where

a) precipitation deficiencies over the last 6 to 12 months are 15% or more below normal, and/or;

b) there is local or regional concern or interest, and/or;

c) the U.S. Drought Monitor shows D1 - Drought first stage or greater within the HSA. The U.S. Drought Monitor is available on the Climate Prediction Centers web site http://enso.unl.edu/monitor/monitor.html.

N/A
Areal Flood Watch
FFA

Areal flood watches will be issued when one or more of the following conditions are met:
a. The possibility exists for meteorological, soil, and/or hydrologic conditions to lead to flooding within a 48-hour period; or

b. The possibility exists for meteorological, soil, and/or hydrologic conditions to lead to flooding more than 48 hours into the future and the forecaster determines that the flood watch is the best way to convey this possibility; or

c. A dam or levee may fail and threaten lives or property, but the threat is not deemed to be imminent, or

d. The effective time of a previously issued flood watch changes; and/or

e. The geographic area covered by a previously issued flood watch increases; and/or

f. An update to a previously issued flood watch is required; and/or

g. A cancellation of all or part of a previously issued flood watch is required; and/or

h. The expiration of a previously issued flood watch is to be announced (optional).

N/A
Flash Flood Warning
FFW

Issue a FLASH FLOOD WARNING if

a) flash flooding is reported;

b) precipitation capable of causing flash flooding is indicated by radar, gage reports, and/or satellite;

c) local tools indicate flash flooding is likely;

d) an existing flash flood warning is expiring and needs to be extended;

e) the area covered by an existing flash flood warning increases; or

f) a dam failure, or failure of a naturally caused stream obstruction (debris slide, ice jam) is imminent or occurring.

N/A
Flash Flood Statement
FFS
Flash Flood Statements should include the following:
a. Appropriate headline (...THE FLASH FLOOD WARNING THAT WAS IN EFFECT FOR SULLIVAN COUNTY IN CENTRAL NEW HAMPSHIRE UNTIL 630 PM HAS BEEN CANCELLED...)
b. Area affected
c. Cancellation notice or updated warning information
d. Call-to-action statement (if appropriate)
e. Updated impact information
f. Additional information including reports, observed data, etc.
N/A

Flood Warning

(River Forecast Points)

FLW

Issue a FLOOD WARNING for river forecast point locations when

a) flood monitoring and prediction tools and/or RFC guidance indicate a river forecast point will crest at or above flood stage, or

b) when flooding is reported, or

c) when an existing Flood Warning is expiring and needs to be extended, or

d) when the area
covered by an existing Flood Warning increases, or

e) the magnitude of flooding changes category (e.g. minor to moderate, etc.).

N/A

Flood Warning

(County Based)

FLW

Issue a FLOOD WARNING for counties or portions of counties when

a) flood monitoring and prediction tools and/or RFC guidance indicate flooding is likely, or

b) when flooding is reported, or

c) when an existing Flood Warning is expiring and needs to be extended, or

d) when the area covered by an existing Flood Warning increases, or

e) the magnitude of flooding changes category (e.g. minor to moderate, etc.).

N/A

Flood Statement

(Flood Warning for River Forecast Points)

FLS

Issue a FLOOD STATEMENT to

a) cancel an existing Flood Warning for specific river forecast points; or

b) to provide new or updated information to supplement an existing Flood Warning for specific river forecast points.

N/A

Flood Statement

(Flood Warning for Counties)

FLS

Issue a FLOOD STATEMENT to

a) cancel an existing Flood Warning for counties or portions of counties; or

b) to provide new or updated information to supplement an existing Flood Warning for counties or portions of counties.

N/A

Flood Statement

(Flood Advisory)

FLS

Issue a FLOOD STATEMENT to

a) issue an advisory for non-threatening, nuisance flooding of streams and ponding of water on roads or in urban areas; or

b) to update an existing advisory; or

c) to cancel an existing advisory.

N/A
Hydrologic Statement
RVS

Issue a HYDROLOGIC STATEMENT

a) to provide information on significant rises on rivers and streams when no flooding is expected; or

b) to provide other hydrologic information of interest to customers and partners when no flooding is expected.

N/A
Daily River and Lake Summary
RVD
Issue a DAILY RIVER AND LAKE SUMMARY daily after the River Forecast Center river forecast guidance product (BOSRVFGYX) is received.
N/A
   
Fire Weather Products
 
Fire Weather Watch  
Wind 10 - 15 mph 15 - 20 mph 20 - 30 mph 20 - 30 mph
RH 30% to 35%
-
-
-
W
RH 25% to 30%
-
-
W
W
RH 20% to 25%
-
W
W
W
RH Less 20%
W
W
W
W
N/A
Red Flag Warning  
Wind 10 - 15 mph 15 - 20 mph 20 - 30 mph 20 - 30 mph
RH 30% to 35%
-
-
-
W
RH 25% to 30%
-
-
W
W
RH 20% to 25%
-
W
W
W
RH Less 20%
W
W
W
W
N/A