National Weather Service Public & Fire Weather Products November 27, 2001 Non-Routine Public Products 1. Severe Weather Products Hurricane Local Statement (HLS) - Issued to keep the media, local decision makers, and the public current on present and anticipated storm effects in their area. The hurricane local statements contain essential hurricane or tropical storm information in a condensed form, but expand on the storm's potential effects on the local area and on any actions declared by local emergency managers. Local Storm Report (LSR) - Used to distribute preliminary severe weather reports to the media, emergency managers, and internal NWS users. It is issued as reports are received, and may also be issued when all reports are returned after the event is over. Severe Thunderstorm Warning (SVR) - Issued when a thunderstorm produces hail 3/4 of an inch or larger in diameter and/or winds equal or exceed 58 mph. Severe thunderstorms can result in the loss of life and/or property. Information in this warning includes: where the storm was, what towns will be affected and the primary threat associated with the storm. Severe Weather Statement (SVS) - Issued to provide additional information on severe weather conditions which have occurred and/or are expected during the severe weather valid time. Tornado Warning (TOR) - Issued when a tornado is highly likely somewhere in a given areas (usually whin the next hour if not already occurring.) Most Tornado Warnings area based on radar and/or actual sightings by storm spotters etc. It is very important the warning include where the tornado was and what towns will be in its path. Watch Redefining Statement (SLS) - Issued by designated offices to identify that portion of a watch included within their state(s). Selected offices also create and transmit this product for state(s) containing adjacent WFO county areas of responsibility. This product identifies the watch number and includes only the counties affected. This product is intended for transmission on the Family of Services and NWWS. 2. Winter Weather Products Blizzard Warning (WSW) - Issued when sustained winds or frequent wind gusts of 35 mph or more for at least 3 hours are expected to combine with sufficient falling and /or blowing snow to frequently reduce visibilities to less than 1/4 mile. Lake Effect Snow Warning (WSW) - Widespread or localized lake effect snowfall accumulation reaching or exceeding locally defined warning criteria threshold values. In general, this is issued when heavy lake effect snow is occurring, is imminent, or has a very high probability of occurring within the next 12 hours. The snow is expected to accumulate at least 7 inches with strong winds producing much high drifts. This is similar to a Winter Storm Warning for Heavy Snow, except Great Lakes induced squalls/showers occur in narrow bands and over limited areas. Lake effect snow squalls/showers can occur quite suddenly and cause blizzard-like conditions. Winter Storm Outlook (SPS) - Issued when there is a good chance of a major winter storm beyond the point normally covered by a watch, i.e., days 3-5. Winter Storm Warning (WSW) - Issued when heavy snow or damaging ice is expected to occur within the next 12-36 hours. If known, a generic "winter storm warning" may be specified as a Heavy Snow Warning, Ice Storm Warning, or Sleet Warning. Winter Storm Watch (WSW)- Issued when conditions are favorable for heavy snow or damaging within the next 12-48 hours. The probability of occurrence of the storm is less than that for a Winter Storm Warning. The potential snow and/or ice accumulations (if the storm develops) are the same as for a winter storm warning. Winter Weather Advisory (WSW)- Issued for a combination of winter weather hazards when the precipitation type cannot be determined, i.e., snow and ice. When hazards can be determined, one of the following specific winter weather advisories (WSWs) should be used: Blowing Snow Advisory - Falling and blowing snow that occasionally reduces visibility to 1/4 mile or less for three hours or more. No wind speed or wind gust requirement. Travel may be hampered. Freezing Rain or Freezing Drizzle Advisory - Light ice accumulation and is expected to remain below locally defined warning criteria and /or does not form on all exposed surfaces. (Generally less than 1/4 inch.) Lake Effect Snow Advisory - Widespread or localized lake effect snowfall accumulation reaching or exceeding locally defined advisory criteria. In general, issued when lake-effect snow squalls are expected to accumulate to 3 to 6 inches in 12 hours over the southern Great Lakes region and up to 8 inches in 12 hours over the northern Great Lakes region. Sleet Advisory - Issued for expected sleet accumulations of less than one inch. Snow Advisory - Snowfall accumulation that is expected to remain below locally defined warning criteria threshold values. In many areas, snowfall advisories are issued when accumulating snow exceeds 2 inches but is not expected to accumulate 6 inches or more in a 12 hour period. May be used for 1 or 2 inch snowfalls if occurring at the beginning of the snow season or after a prolonged period between snow events. Some mountain locations have snow advisories issued for 4 to 7 inch accumulations in 12 hours. 3. Non-Precipitation Products Blowing Dust Advisory (NPW) - Issued for expected widespread blowing dust that reduces visibility enough to cause a hazard, but does not meet warning criteria of a "Dust Storm" Dust Storm Warning (NPW) - When strong winds blow over dry ground, that has little or no vegetation, lifting particles of dust or sand into the air, a dust storm may develop. A Dust Storm Warning is issued when these airborne particles are concentrated enough to produce a widespread reduction in visibility to 1/4 mile or less for an hour or more. Under these conditions , the dust may cause respiratory problems, have an abrasive affect on machinery and pose hazards for motorists. Dense Fog Advisory (NPW) - Issued when dense fog is expected to cause widespread visibilities of 1/4 mile or less for at least several hours. Excessive Heat Outlook/Watch/Warning (NPW) - Issued when expected daytime heat indices are expected to reach 105øF or above (for more than 3 hours) and nighttime lows are expected to remain above 80øF for two or more consecutive days, or heat indices are expected to reach 115øF for any period of time. (Criteria may be adjusted regionally). Freeze Watch/Warning/Advisory (NPW) - Issued when the temperature at or near the earth's surface is expected to drop to 32 degrees Fahrenheit or lower during the growing season. A Freeze Warning normally implies that more precautions are necessary than a Frost Warning and is usually restricted for those times when wind or other conditions prevent frost. Frost Watch/Warning/Advisory (NPW) - Issued when widespread and heavy frost is expected during the growing season. Heat Advisory (NPW) - Issued when expected daytime heat indices are expected to reach 105øF or above (for less than 3 hours) and nighttime lows are expected to remain above 80øF for two or more consecutive days. (Criteria may be adjusted regionally). High Wind Outlook/Watch/Warning (NPW) - Issued when high winds (sustained at 40 mph or more and/or gusting to 58 mph [50 kts] or greater) are expected to last for an hour or more within the next 24 hours (warning)/48 hours watch). Inland Tropical Storm/Hurricane Wind Watch/Warning (NPW) - Issued when winds area expected to reach tropical storm/hurricane force, but a Tropical Storm/Hurricane Warning isn't appropriate due to the type of storm and /or inland location. Such a warning is reserved for relatively rare and extreme events (as is the case with Blizzard Warnings). Smoke Advisory (NPW) - Issued when widespread high concentrations of smoke which (such as from forest fires) reduce visibilities to 1/4 mile or less. Ashfall Advisory (NPW) - Issued for expected conditions resulting from a volcanic eruption which may send an ash plume into the atmosphere reducing visibility in the air and near the ground. The chemical composition and abrasive characteristics of the particles varies widely and can seriously affect people and machinery on the ground and aircraft. There is no national minimum threshold for NWS action for the public. Wind Advisory/ & Lake Wind Advisory (NPW) - Issued when sustained winds of 31 to 39 mph are expected to last for one hour or more, or gusts between 46 and 57 mph for any duration. Lake Wind Advisories are issued for area lakes in some of the Northern Plains states when sustained winds of 30 mph or more are expected. Wind Chill Outlook/Watch/Warning/Advisory (NPW) - Issued when a combination of wind and low temperatures is expected to produce a significant or dangerous effect on exposed skin. 4. Miscellaneous Public Products Avalanche Advisory - A preliminary notification that conditions may be favorable for the development of avalanches in mountain regions Civil Emergency Message (CEM) - Disseminated upon the request of federal, state, county or local government officials. Information and appropriate actions necessitated by nuclear incidents, hazardous material releases, unstable explosive materials or other occurrences are relayed. Earthquake Information Report (EQR) - Issued to disseminate earthquake information within the NWS and to the public. The report contains information on how strongly the quake was felt, who observed and by how many, locations of observation, and damage amount/ description. Other Public Products (OPU) - Among other miscellaneous information, may contain the latest snowfall reports fo an ongoing or recently completed storm. Public Information Statement (PNS) - Issued to provide information on a current or expected non-hazardous event of general interest to the public that can usually be covered with a single message. This may include: unusual atmospheric phenomena such as sun dogs, halos, rainbows, aurora borealis, or lenticular clouds; and stories about a long-term dry/cold/wet/warm spell (although any new records are also to be reported under the record report (product category RER) Record Report (RER) - A narrative product to report meteorological and hydrological events that equal or exceed existing records. The following are examples that should be reported as data availability allow. Short Term Forecast (NOW) - An event driven product used to describe detailed significant hydrometeorological conditions expected to occur within the time frame from an hour or less, up to 3 or 4 hours during more slowly evolving events. The length of the valid time is flexible according to how quickly conditions change, but should not normally extend to 6 hours. The Short Term Forecast provides information on the forecast evolution of precipitation (including freezing/frozen precipitation), convective events; including severe storms and flood information; winter weather; including frost/freeze conditions and wind chills, tropical cyclone landfall events, fronts, marine events, fog, high winds, or temperatures (especially excessive heat or extreme cold). Special Avalanche Warning (NPW) - Issued when avalanches are imminent or occurring in the mountains, usually for a 24 hour period Special Weather Statement (SPS) - Issued to provide information complementing zone forecasts regarding forecast weather events, such as outlooks for severe weather, winter weather, or non-precipitation weather events in the time period beyond 6 hours. 5. Fire Weather Products Fire Weather Watch - (RFW) Fire Weather Watch is issued to advise of conditions which could result in extensive wildfire occurrence or extreme fire behavior which are expected to develop in the next 12 to 48 hours, but not more than 72 hours. In cases of dry lightning, a Fire Weather Watch may be issued for the next 12 hours. Fire Weather Watch meteorological and fuel criteria will be defined in the AOP. Red Flag Warning - (RFW) Red Flag Warning is used to warn of impending or actually occurring critical weather conditions that could result in extensive wildland fire activity. A warning will be issued when the forecast time of onset is less than 24 hours. Red Flag Warning meteorological and fuel criteria will be defined in the AOP. Site Specific (SPOT) Suppression Forecasts (FWS) - Site-specific forecasts are issued when requested by Customers for wildland fires or special Federal projects. These forecasts differ from routine fire weather forecasts by incorporating greater detail in timing, higher resolution of terrain influences, and incorporate meso-scale and sometimes micro-scale weather influences impacting the site. These may be generated from an office with user supplied information (i.e., location, weather observations, objectives) or generated by an Incident Meteorologist assigned to the incident. Routine Public Products Area Forecast Discussion (AFD) - A scientific and semi-technical explanation of forecast team's deliberations and reasoning behind its decisions. This narrative product is issued routinely at least 2X per day, but is usually issued more frequently to provide reasoning for forecast updates or to provide an explanation of rapidly-evolving mesoscale trends. Coded Cities Forecast (CCF) - These are abbreviated forecasts for particular cities within a WFO area of responsibility. They are a multiple-use product prepared by each WFO providing an integral input for the Selected Cities Weather Summary and Forecasts and Travelers' Forecasts. Recreational Report (REC) - Use this product to relay reports on conditions for resorts and recreational areas and/or events. This report may also contain forecast information. Reports for recreational areas and resorts are often routine products, typically for a season, but possibly year-round. Regional Weather Summary (RWS) - This routine product provides a brief narrative on the weather situation for a multistate area. The Regional Headquarters may designate WFOs to prepare this product. Where prepared, it should be consistent with forecasts and summaries issued for states within the region covered. This product describes recent past weather (up to 24 hours back), present weather, and forecast conditions (up to 24 hours in the future). The emphasis should be on past and current weather. The synoptic features causing the weather may be mentioned but only in the very simplest nontechnical terms. State Forecast Product (SFP) - The SFP provides a general public forecast of hydrometeorological conditions over a WFO forecast area of responsibility for the next 5 days. The forecast area typically includes an entire state or part of one or more states. State Maximum/Minimum Temperature and Precipitation Table (STP) - This tabular product contains the maximum and minimum temperatures (in Fahrenheit) and 24-hour precipitation totals from available reporting stations within the state or WFO management area. Items, such as current weather and snow depth, may be included. State Weather Roundup (SWR) - This product provides routine, standardized hourly observations within the state through NWWS. This product is automatically composed and transmitted at each WFO by use of a standard applications program that decodes the surface aviation observations. State Weather Summary (SWS) - This product provides a brief narrative for recent past weather (up to 24 hours back), present weather, and forecast conditions (up to 24 hours in the future). The emphasis should be on past and current weather. Travelers' Forecasts (TAV[10,12,13] WBC) - These are tabular arrays of only the one-word forecasts for some cities based on data from the CCF. Zone Forecast Product (ZFP) - The ZFP explicitly states expected weather conditions within a zone forecast area through seven days. Weather conditions include headlines, precipitation and probability of precipitation forecasts, sky condition, temperature, wind, and visibility restrictions. The first 36 hours reflects the observed and imminent weather conditions, with an emphasis on details and timing. Routine Fire Weather Products Daily Pre-suppression Fire Weather Forecast (FWF) - A Routine Fire Weather Forecast is a scheduled forecast of weather parameters pertinent to fire management activities in support of protection of life, property, and resources at risk in a given area. These forecasts normally cover the next 48 hours and may include input for the computation of National Fire Danger Rating System indices. These forecasts may also include longer range outlooks Hydrometeorological Prediction Center (HPC) Selected Product Descriptions Excessive Rainfall Potential Product Issuance Time (Valid Period) 94E 0215Z (03-00Z) 0615Z (12-12Z) 1415Z (15-12Z) 1815Z (00-00Z) QPFERD Discussion 0300Z, 0700Z, 1500Z, & 1900Z QPFSRD Discussion after 1900Z (when necessary) This product outlooks the potential for flash flooding based on current flash flood guidance issued by RFC's. The graphic and discussion are issued 3 times a day, at 0615Z, 1430Z, and 1815Z for the current 24 hour period ending at 12Z. Special rainfall discussions (NFDQPFSRD) and an updated graphic (94E) are issued after 1930Z if significant changes to the flash flood outlook are necessary before the next scheduled issuance time. Three categories are used to indicate flash flood threat: An Exceeding area outlines a geographical area to the right of a solid arrow drawn using station identifiers as anchor points where conditions are favorable for rainfall to exceed flash flood guidance values. An Approaching area is generally used in winter-time or for synoptic-scale situations where flash flood guidance values are relatively high but accumulated precipitation amounts from a larger scale system may lead to run off problems. It outlines an area with a dashed arrow and labeled "APCHG". An Isolated area is mainly intended for use in the Western U.S. where events tend to be more isolated than over the rest of the conterminous U.S. It is drawn with a dashed-dotted line and labeled with "ISOLD". Other labels on the Excessive Rainfall Graphic: "SEE FOUS 30/CCCQPFERD" over the area affected or with an arrow pointing to the general area of concern indicates that there is not sufficient cause or confidence to draw an area, but that the QPFERD discussion talks about the situation. Selected Cities Forecast Description Selected Cities Product Part 1 (Abilene, TX to Columbus, OH) SCS9 / WMO: FPUS20 KWNH Part 2 (Concord, NH to Lexington, KY) SCS10 / WMO: FPUS21 KWNH Part 3 (Lincoln, NE to St. Thomas, V.I.) SCS11 / WMO: FPUS22 KWNH Part 4 (Salem, OR to Yuma, AZ) SCS12 / WMO: FPUS23 KWNH The Selected Cities Summary is a highly visible product that is issued two times per day at 0100 and 1300 UTC. It includes a tabular array of the previous day's maximum and minimum temperatures along with temperature and weather forecast for the next two days. The Selected Cities Summary covers 158 cities in the United States, Puerto Rico, and the Virgin Islands. It is composed of four parts with the last part including the observed maximum and minimum temperatures from around the nation. Forecast data is obtained from WFO CCFs. Storm Summaries (SCC) - are issued by the HPC after any named tropical or sub-tropical cyclone has moved inland and public advisories are no longer issued by the National Hurricane Center (NHC). In addition, storm summaries are issued for any major winter storms that produce widespread snow or ice. The Storm Summaries will continue to be issued as long as there is a threat of severe weather or flash flooding from the storm or its remnants. They are numbered sequentially (continuing from the last numbered advisory issued on the storm by the NHC for tropical systems). Storm Summaries are transmitted four times a day at or before 0300Z, 0900Z, 1500Z, and 2100Z. Traveler's Forecast Description Travelers Product Part 1 (Albany, NY - Reno, NV) TAV10 / WMO: FPUS10 KWNH Part 2 (Salt Lake City, UT - Wash., D.C.) TAV12 / WMO: FPUS12 KWNH Part 3 (Abbreviated Version) TAV13 / WMO: FPUS13 KWNH The Travelers Forecast Bulletin is an abbreviated version of the Selected Cities Bulletin. The Travelers Forecast, like the Selected Cities is transmitted two times per day, one hour before the Selected Cities, for thirty (30) cities in the U.S. The Travelers Forecast consists of three parts which contain the weather and high and low temperature forecasts extracted from your CCFs. Appendix A - HPC Proposed Services This appendix describes in some detail the individual products and services proposed to be added to the HPC product suite. These would assist WFOs in providing winter weather watches, warnings, etc. for the public and help the NWS achieve a seamless suite of winter related products. National Winter Storm Potential Narrative (NWSPN) - Forecasters at times see indications in the numerical models of potential winter storms several days in advance. Their confidence in the model information varies and the models are sometimes misleading. However, WFOs issue winter weather outlooks to the public when they have reasonable confidence in the occurrence of a significant winter event. The outlooks provide external customers with advance notice of significant events which they can use in planning their response or to marshal resources. HPC meteorologists are recognized as experts in model interpretation. The forecasters who prepare the Day 3 through 7 guidance products for the field offices would write the NWSPN after they complete their other products. The NWSPN would discuss the potential for significant winter systems affecting the contiguous United States in the 3-7 day period. Significant is defined as potentially reaching winter storm warning criteria and covering several WFOs' areas of responsibility. It would be written in a nontechnical manner so it could be used not only by the NWS field offices but also by external users who require the information. There would be one issuance per day with no updates. To avoid the problem of one NWSPN containing a reference to a significant system followed by another NWSPN that does not discuss that system, only to have it reappear in a succeeding narrative (i.e., flip-flopping on the forecast), the HPC operating procedure would be to continue to describe the potential of a system once it is mentioned in the NWSPN even if it no longer appears to have the potential to reach a significant level as described above. The continued monitoring of systems would provide continuity from forecast to forecast and help to eliminate the perceived "surprise" snowstorms occurring each winter season across the country. In most of these cases, NWS forecasters often were aware of the possibility of significant winter weather, but a clear message was not delivered to the public well in advance. The NWSPN would serve to address this perception problem. Winter Weather Watch/Warning Guidance Graphic (WGG) - As described above, the WGG would be prepared by HPC following a coordination call or chat session with the impacted WFOs. It would reflect the latest thinking of the field offices on the placement of winter weather watches/warnings but may not reflect the final placement of watches by those offices as later data comes in, further coordination occurs, etc. The WGG would reflect the bulk of the area under a watch and serve as a coordination tool for offices not involved in the WWCC, to alert external customers to the WFO actions, and provide a single product depicting the location and extent of winter weather watches. Typically, the period covered by this product would be 12-36 hours, but at times may extend to 48 hours depending upon the size of the threat and the certainty of the event by the WFO forecasters. Winter Storm Tracks Graphic (WSTG) - This product would likely use short term ensemble forecast information to highlight those areas of the contiguous U.S. threatened by significant winter storm systems during the next 48 hours. How this information would be depicted and the level of the quality of the science to create this product need to be explored and developed further before this product is available for comment by the WFOs. Storm Prediction Center (SPC) Selected Product Descriptions Severe Weather Watches When conditions become favorable for severe thunderstorms and tornadoes to develop, SPC usually issues a severe thunderstorm watch or a tornado watch. Tornadoes can occur in either type of watch but tornado watches are issued when conditions are especially favorable for tornadoes. Watches encourage the general public to stay alert for changing weather conditions and possible warnings. For emergency managers, storm spotters, and the broadcast media, watches provide valuable lead time to gear up operations and increase staffing. Watch "boxes" are designated by a set of coordinates which form a parallelogram. A typical watch might include as many as 20,000 to 40,000 square miles. They are numbered sequentially (the count is reset at the beginning of each year). A typical watch has a duration of about four to six hours but it may be canceled, replaced, or reissued as required. A watch is not a warning, and should not be interpreted as a guarantee that there will be severe weather! Mesoscale Discussions When conditions actually begin to shape up for severe weather, SPC often issues a Mesoscale Discussion (MCD) statement anywhere from roughly half an hour to several hours before issuing a weather watch. SPC also puts out MCDs for hazardous winter weather events on the mesoscale, such as locally heavy snow, blizzards and freezing rain (see below). MCDs are also issued on occasion for heavy rainfall, convective trends, and other phenomena, when the forecaster feels he/she can provide useful information that is not readily available or apparent to field forecasters. MCDs are based on mesoscale analysis and interpretation of observations and of short term, high resolution numerical model output. The MCD basically describes what is currently happening, what is expected in the next few hours, the meteorological reasoning for the forecast, and when/where SPC plans to issue the watch (if dealing with severe thunderstorm potential). Severe thunderstorm MCDs can help you get a little extra lead time on the weather and allow you to begin gearing up operations before a watch is issued. The MCD begins with a numerical string that gives the LAT/LON coordinates of a polygon that loosely describes the area being discussed. The string "424,0812 433,0784 413,0784 404,0812" would be read as "the discussion area is bounded by a line that runs from 42 degrees 40 minutes North/81 degrees 20 minutes West to 43 degrees 30 minutes North/78 degrees 40 minutes West to 41 degrees 30 minutes North/78 degrees 40 minutes West to 40 degrees 40 minutes North/81 degrees 20 minutes West." Convective Outlooks Day 1 Convective Outlook Graphic (940 or PGWE46) and Discussion (SWODY1 or ACUS01) The Day_1 Convective Outlook, sometimes called the "AC", and 2nd Day Severe Weather Outlook are guidance products issued by the Operational Guidance Branch (OGB) unit of the Storm Prediction Center (SPC) in Norman, Oklahoma. The Day 1 outlook outlines areas in the continental United States where severe thunderstorms may develop during the next 6 to 30 hours. The Convective Outlook is issued 5 times daily: at 06Z (the initial day_1 outlook, valid 12Z that day until 12Z the following day), 13Z and 16Z (the "morning updates," valid until 12Z the next day), 20Z (the "afternoon update, " valid until 12Z the next day), and the 01Z (the "evening update," valid until 12Z the following day). Day 2 Convective Outlook Graphic (980 or PGWI47) and Discussion (SWODY2 or ACUS02) The Day 2 Outlook is very similar to the Day 1 Outlook. It is issued only twice a day, at 08Z and 18Z, and covers the period from 12Z the following day to 12Z the day after that. For example, if today is Monday then the Day 2 Outlook will cover the period 12Z Tuesday to 12Z Wednesday. The outlook issued at 08Z now qualifies the degree of risk like the Day 1 has (i.e. SLGT, MDT, and HIGH risk areas). The Day 2 Outlook also includes a general thunderstorm outline. Day 3 Convective Outlook Graphic (990 or PGWK48) and Discussion (SWODY3 or ACUS03) On November 7, 2001, the SPC began issuing Convective Outlooks for the Day 3 period to the public. These outlooks are similar to the Day 2 outlooks in that the probabilities represent the probabilities of any type of severe weather hazard (tornadoes, large hail, damaging wind) within 25 miles of any point. Because of the large and increasing amount of uncertainty forecasting severe weather 3 days ahead of time no attempt is made to forecast areas of significant severe weather hazards. Public Severe Weather Outlooks (PWOSPC or WOUS40) The Public Severe Weather Outlooks (PWO) are issued when a potentially significant or widespread tornado outbreak is expected. This plain_language forecast is typically issued 12_24 hours prior to the event and is used to alert NWS field offices and other weather customers concerned with public safety of a rare, dangerous situation. The PWO is reserved for only the most serious weather situations where a HIGH risk is forecast for a potential tornado outbreak. SPC averages 5_10 PWO days a year. Storm Prediction Center Rough Log The SPC rough log is compiled by an automatic PC logging program running at the Operational Guidance Branch (OGB) unit of the Storm Prediction Center at Norman, OK, and is issued daily. On the Web, you can find it here. It is also available via the BITNET autofeed list WX_MISC served by LISTSERV at VMD.CSO.UIUC.EDU. The log is a raw listing of all continental U.S. severe weather reports that SPC received during the 24 hour period from 6:00 AM CST the previous day up until 6:00 AM CST on the day of issuance. This is only a preliminary list. Because the logging process is automated, improperly formatted reports from NWS field offices may not get into the data base. Also, reports could arrive after the daily log is compiled, and be missed in the list. All occurrence times are referenced to Central Standard Time __even if the event occurred in a different time zone or during Daylight Savings Time. Reports are lumped under three basic categories: tornado reports, large hail/strong wind reports, and other severe reports. The "tornado reports" section is self explanatory. The "large hail/strong winds reports" section contains information on very large hail and major wind damage. The "other severe reports" section contains miscellaneous reports of marginally severe weather such as hail one inch in diameter or smaller. The log is a raw listing of all reports received. The final list of reports is found in the monthly publication Storm Data. Probabilistic Outlooks 6-Hour Thunderstorm The SPC has begun issuing a 6_hour thunderstorm outlook that covers areas where organized thunderstorms are expected between 0600 and 1200 UTC. The forecasts depict areas where 10% or greater coverage of thunderstorms are expected. Day 1 The most specific Convective Outlooks are those issued during the Day 1 period. Accordingly, the SPC forecasters have the most information available to them to differentiate the threats of the individual severe weather hazards. During this period, the SPC produces probabilistic outlooks for each primary severe weather hazard (tornadoes, damaging wind, and large hail) separately. By producing separate forecasts for tornadoes, damaging wind, and large hail, the user is given substantially more information upon which to make decisions than in the traditional outlook. In addition to the probabilities for separate types of severe weather occurring, areas are shown where there is a 10% or greater chance of significant severe weather occurring. Significant severe weather is defined as F2 or greater tornadoes, damaging winds with speeds greater than 65 knots, or large hail 2" or greater in diameter. If the forecaster believes that there is less than a 10% chance of significant severe weather occurring in the outlook area, then that threat will not appear on the graphics. Day 2 Probabilistic Outlooks are issued for the Day 2 period as well. Because many of the specific details of severe weather forecasting can only be known hours ahead of time, rather than several days, the severe weather probabilities for the Day 2 Outlooks represent the probability of any severe weather hazard (large hail, damaging wind, or tornadoes) occurring (rather than producing individual forecasts for each hazard). Areas where there is a 10% or greater probability of significant severe weather events (again, defined as 2" or larger hail, 65 knot or stronger winds, and F2 or stronger tornadoes) are also indicated on the graphics. Day 3 (0A3, PZNK00) These outlooks will be similar to the Day 2 outlooks in that the probabilities represent the probabilities of any type of severe weather hazard (tornadoes, large hail, damaging wind) within 25 miles of any point. Because of the large and increasing amount of uncertainty forecasting severe weather 3 days ahead of time no attempt is made to forecast areas of significant severe weather hazards like is done for the Day 2 period.