U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration NATIONAL WEATHER SERVICE 1325 East-West Highway Silver Spring, Maryland 20910-3283

W/OM15x3 July 11, 1984

TO: All Holders of Operations Manual

SUBJECT: Transmittal Memorandum for Operations Manual Issuance 84-11

1. Material Transmitted:

WSOM Chapter C-11, Zone and Local Forecasts.

2. Summary:

This chapter has been extensively revised. The following are the most significant changes.

     a.  New Section 5, Forecast Headers, incorporates those sections of WSOM Chapter C-63, NOAA Weather Wire Service Dissemination (OML 6-83), that deal with the communications headers of zone and local forecasts. This includes Exhibit C-11-1, Geographical Identifier Codes for Local Forecasts.

     b.  New Section 6, Forecast Format, provides the guidelines for handling the discrete period format for both zone and local forecasts. Included are the rules for appending holiday/holiday weekend forecasts to the zone/local forecasts.

     c.  New Section 7, The Well Written Forecast, discusses the philosophy, styling, and wording for effective forecast presentation.

     d.  The entire WSOM Chapter C-14 (was C-91), Probability of Precipitation Forecasts (POP), has been revised and incorporated into C-11 (section 8.3).

     e.  Section 8.4, Precipitation Events, discusses the handling of beginning/ending precipitation, mixed and multiple precipitation events, and snowfall accumulation.

     f.  Section 9, Forecast Monitoring and Updating, has been extensively revised to reflect the need for more timely forecast updates. Included are definitions and examples for updated and corrected forecasts as well as a more comprehensive list of update criteria.

     g.  New Section 10, Short-Range Weather Summary (NOWCAST), provides guidelines for issuing nowcasts as they relate to the zone/local forecast program.

     h.  New Section 11, Special Weather Statements and Public Information Statements, provides discussion on these products within the framework of the zone/local forecast program.

     i.  New Section 12, Miscellaneous Special Programs and Advisories, provides guidelines on inland lake wind advisories, hazardous wind chill, and prolonged excessive heat/heat stress. The parameter Heat Index (HI) is introduced and fully discussed including examples of forecasts, statements, and civil emergency messages using HI. Included is Exhibit C-11-2, Heat Index Graph.

     j.  Note that Appendix A, Zone Forecast Area Maps, referenced in sections 2.1 and 3.1.1, is not attached at this time. It is being revised and will be published at a later date.

3.  Effect on Other Instructions:

Supersedes:
Chapter C-11, WSOM Issuance 79-18, December 19, 1979 and
                       WSOM Issuance 80-21, November 10, 1980;
Chapter C-14 (was C-91) WSOM Issuance 77-9, June 24, 1977;
OML 14-81, November 12, 1981 (filed with C-11);
OML 6-83, March 25, 1983 (filed with C-63).
 
 

Richard E. Hallgren
Assistant Administrator
for Weather Services

Issue Date Org. Code                            NATIONAL WEATHER SERVICE                Part    Chap.
7-11-84     W/OM15                                      Operations Manual                                    C        11

TABLE OF CONTENTS:

     1.  Introduction

     2.  Responsibilities

         *2.1  Weather Service Headquarters (WSH)

         *2.2  Regional Headquarters (RH)

          2.3  Weather Service Forecast Office (WSFO)

          2.4  Weather Service Office (WSO)

     3.  Zone and Local Forecasts (ZFP and LFP) - Overview

          3.1  Zone Forecast Area
                 3.1.1  Zone Boundaries
                 3.1.2  Combining Zones

          3.2 Local Forecasts (LFP)

               3.2.1  City and Vicinity Area
               3.2.2  Greater Metropolitan Area
               3.2.3 NOM Weather Radio (NWR) Listening Area Forecast

     4.  Forecast Release Schedule

    *5. Forecast Headers

          5.1  Geographical Identifier Turn-On Codes
                 5.1.1 Geographical Identifier Codes for Named and
                          Unnamed Zones and Local Forecasts
                 5.1.2  Geographical Identifier Turn-Off Code

          5.2 Complete Header for Unnamed Zones
          5.3  Complete Header for Named Zones
          5.4  Complete Header for Local Forecasts

      *6.  Forecast Format

          6.1 Headlines
                 6.1.1 Leftover Weather
          6.2  Delimiter and Punctuation
          6.3  Period Designators
                 6.3.1  Holiday Period Designators
          6.4  Combining Periods
          6.5  Abbreviations and Contractions
          6.6  Major Holiday Weather Forecast (Outlook)
                 6.6.1  Major Holiday Weekend Weather Forecast (Outlook)
          6.7  Coding Automated Weather-by-Phone Abbreviated Forecast Messages

    *7. The Well-Written Forecast

      8.  Forecast Content and Wording

          8.1 Forecast Elements
          8.2  Structure of Forecast Periods
                 8.2.1  Stress Important Elements
                 8.2.2  Highlight Significant Changes
                 8.2.3 Emphasize Unusual Weather
                 8.2.4  Watch, Warning, and Advisory Situations
        *8.3  Probability of Precipitation Forecasts (POP)
                 8.3.1 Definitions
                 8.3.2 Basic Policy Rule
                 8.3.3 POP Range
                 8.3.4  POP Statement
                 8.3.5  POP Qualifying Terms
                 8.3.6  Rules for Combining Qualifying Terms
                 8.3.7  Trace Precipitation Events
        *8.4  Precipitation Events
                 8.4.1 Freezing or Frozen Precipitation (and related) Terms
                 8.4.2 Beginning or Ending Precipitation
                 8.4.3  Mixed Precipitation
                 8.4.4 Multiple Precipitation Events
                 8.4.5 Snowfall Accumulation
          8.5  Temperature
               *8.5.1 Temperature Presentation Methods
                 8.5.2  Falling Daytime, Rising Nighttime, or Steady Temperatures
          8.6  Sky Condition
          8.7  Wind
                  8.7.1 Direction
                  8.7.2 Speed
                  8.7.3 Gusts|
        *8.8  Computer Worded Forecasts

          *9.  Forecast Monitoring and Updating

          9.1  Monitoring Responsibility
                 9.1.1 Local Adaptive Forecast Guidelines
          9.2  Updates - Discussion
                 9.2.1  Definitions and Formats
                 9.2.2  Generalized Update Criteria

        *10. Short-Range Weather Summary (Nowcast -- NOW)

        *11. Special Weather Statements (SPS) and Public Information Statements (PNS)

        *12. Miscellaneous Special Programs and Advisories
                 12.1  Inland Lake Wind Advisories
                 12.2 Hazardous Wind Chill
 

Exhibits:

          C-11-1  Geographical Identifier Codes for Local Forecasts
          C-11-2  Heat Index (HI) Graph
 

1. Introduction. Zone and local forecasts are the basic public forecasts of the National Weather Service (NWS). This chapter provides guidelines for the management and operation of this program. All products use Automation of Field Operations and Services (AFOS) identifiers.

2. Responsibilities. Organizational responsibilities are as follows.

2.1 Weather Service Headquarters (WSH). WSH is responsible for the overall management and coordination of the zone and local forecast program. It approves the areal configuration of forecast zones and develops standards for format, content, and preparation of zone and local forecasts. WSH publishes maps depicting all zone forecast areas in Appendix A of this chapter and in "Operations of the National Weather Service." WSH will notify national distributors of weather information about any changes in zone forecast boundaries or configuration.

2.2 Regional Headquarters (RH). RH's conduct necessary quality control to ensure the products are of high quality and provide the information required by the public. They submit to WSH recommended changes in forecast zone configuration. RH's ensure that all state and local mass news media outlets, including cable TV, are notified of the change at least 60 days in advance. RH's assign zone forecast responsibility to Weather Service Forecast Offices (WSFO) and local adaptive forecast responsibility to Weather Service Offices (WSO) and WSFO's. They provide guidance and approval on update criteria and forecast issuance times. RH's may modify portions of this chapter after submitting to WSH draft Regional Operations Manual Letters and other directives for review.

2.3 Weather Service Forecast Office (WSFO). WSFO's issue forecasts for ail zones in their areas of responsibility as well as the local forecasts for their local communities when appropriate. They provide guidance and forecasts for WSO adaptive forecast programs. They recommend to the RH changes in forecast zone configuration. WSFO's maintain quality control over all public weather products issued within their areas of responsibility.

2.4 Weather Service Office (WSO). WSO's share responsibility for a zonal weather watch with the WSFO as described in section 9.1. When authorized by the Regional Director (RD), WSO's prepare and issue local adaptive forecasts. They recommend the areal coverage of local forecast programs and ensure that the wording of these forecasts receives continuing attention.

3. Zone and Local Forecasts (ZFP AND LFP) -- Overview. Zone and local forecasts cover periods of up to 48 hours. There should be sufficient detail to provide the general public with a clear statement of expected weather conditions within a given locality or zone. Elements to be included in local and zone forecasts will be similar to those in state forecasts (WSOM Chapter C-10) but with greater emphasis on detail and timing of weather events, especially for the first 6-12 hours. Particular attention should be paid to localized weather phenomena which cannot be adequately described in state forecasts. See section 8, Forecast Content and Wording, for details.

The zone forecast programs in Alaska and Hawaii are aimed at meeting local needs without providing unnecessary products. The elements to be included, detail of forecast products, and forecast release schedule are determined by the RH with approval of WSH.

3.1 Zone Forecast Area. Ideally, a forecast zone is an area with sufficient climatological and meteorological homogeneity to allow a single forecast to serve as the local forecast for the communities within the area. Each WSFO's area of responsibility is divided into forecast zones. The only exceptions are a few mountainous or largely unpopulated areas of the far western United States, certain wilderness areas in Alaska, island areas of the Pacific Region, and Isle Royale in Lake Superior.

3.1.1 Zone Boundaries. Zone boundaries should be determined by considering:

     o homogeneity of climate and usual weather features
     o population distribution
     o local communications and dissemination capabilities

See Appendix A for maps of authorized zone boundaries with numbers and/or names.

3.1.2 Combining Zones. Zones may be combined when all forecast elements for all time periods are similar. The accuracy or clarity of the forecast should not be compromised for the convenience of combining zones.

3.2 Local Forecast (LFP). A local forecast is a forecast issued for a city (or town) and its vicinity or a large metropolitan area. The local forecast is essentially the applicable zone forecast with adaptive changes to reflect terrain effects and local public service needs. The local forecast contains the same elements and covers the same periods as the applicable zone forecast. The provision of a local forecast need not be restricted to localities having a WSO. If there is sufficient need for a local forecast for cities not having a WSO, the RD may assign the preparation of that local adaptive forecast to a specific WSO or WSFO (see section 9.1.1).

3.2.1 City and Vicinity Area. For towns and smaller cities, the city and vicinity area includes a city and its immediate suburbs out to about 15 miles from the center of the city.

3.2.2 Greater Metropolitan Area. For larger cities, the metropolitan area includes the city and its surrounding suburbs out to about 30 miles from the center of the city. The title of the forecast may vary depending on the area; for example, Greater Boston Metropolitan Area Forecast or San Francisco Bay Area Forecast. In certain cases, this forecast area may be a separate and complete zone. The boundaries of the metropolitan area forecast will be set by the RD.

3.2.3 NOAA Weather Radio (NWR) Listening Area Forecast. This is an adaptive forecast prepared only for use in an NWR broadcast where a transmitter serves an area covered by more than one local or zone forecast. It should include all areas within reliable listening range of the local NWR station, generally about a 40-mile radius. Stations along the Canadian and Mexican borders will forecast only for the United States portion of their listening areas.

The NWR listening area may cover portions of two or more zones. In such cases, the adaptive forecast to be used in the broadcast will be a composite of the zone forecasts involved.

4. Forecast Release Schedule. While it is not practical to prescribe specific release times for all zone and local forecasts, certain standards are required to provide a degree of uniformity.

Zone and local forecasts will be issued a minimum of four times daily: about 0430L-0630L, 1030L-1130L, 1530L-1730L, and 2100L-2200L. Actual release times should be at least 30 minutes before the major media newscasts. The RD's may specify more specific release times, including those for part-time offices.

See section 9.2 for optional early release times of updated forecasts in lieu of mandatory issuances.

5. Forecast Headers. The format for the header blocks to zone and local forecasts are presented. Included are the rules governing the use of geographical identifier turn-on/off codes. For more detailed instructions concerning the use of teletypewriter headings, consult the latest communications handbooks.

5.1 Geographical Identifier Turn-On Codes. Each zone and local forecast will be identified by a specific geographical code. The code will consist of a combination of all alpha/letter characters for local forecasts and a combination of alpha/letters and numeric characters for zone forecasts. A dash will be used as the end-of-address for each specific code. See exhibit C-11-1 for the authorized geographical identifier codes for local forecasts.

Examples:

Zones

a. OK01-OK02-OK04-

b. MT07-

Locals

c. KCMO-

d. BIAL-

5.1.1 Geographical Identifier Codes for Named and Unnamed Zones and Local Forecasts. The geographical codes will be displayed one of two ways only: (1) those offices whose zones are not named will use a plain language identifier on a separate line immediately below the geographical code line or (2) those offices whose zones are named will display each geographical code and corresponding zone name on the same line.

Examples:

     1. Codes with Plain Language Identifiers for Unnamed Zones

          a. KY10-KY11-KY12-
              KENTUCKY ZONES 10 11 12

           b. MI16-
               MICHIGAN ZONE 16

     2. Codes with Zone or Local Names

         Zones

         a. VA01-EASTERN SHORE
             VA02-GREATER HAMPTON ROADS

          b. CA03-BIG SUR COASTLINE

          c. ID06-WEST CENTRAL MOUNTAINS
              ID08-LEWISTON PALOUSE GRANGEVILLE
              ID09-IDAHO PANHANDLE

      Locals

          d. KCMO-KANSAS CITY AND VICINITY

           e. BIAL-BIRMINGHAM METROPOLITAN AREA

Note that dashes (-) are used only after the turn-on codes and not after the identifiers or names.

5.1.2 Geographical Identifier Turn-Off Code. The turn-off code will be the double dollar sign, $$. A specific combination of carriage returns, line feeds, letters, or figures are not required before or after this turn-off code and should be used only in the normal manner of word processing and composition.

The $$ will appear at the extreme left margin on the second line below the last line of forecast text. If space is a problem the $$ may be on the line immediately below the last line of forecast text.

5.2 Complete Header for Unnamed Zones. The header for zones that are not named should be prepared this way.

LBBZFPTX
TTAAOO KLBB 011600
(blank line)
TEXAS ZONE FORECASTS
NATIONAL WEATHER SERVICE LUBBOCK TX
1030 AM CST TUE FEB 1 1983
(blank line)
TX01-TX02-TX03-
TEXAS ZONES 1 2 3
1030 AM CST TUE FEB 1 1983
(blank line)
...HEADLINE...(as required)
Forecast text
(blank line)
$$

5.3 Complete Header for Named Zones. The header for zones that are named should be prepared this way.

PHLZFPPA
TTAAOO KPHL 031500
(blank line)
EASTERN PENNSYLVANIA ZONE FORECASTS
NATIONAL WEATHER SERVICE PHILADELPHIA PA
1000 AM EST THU FEB 3 1983
(blank line)
PA07-UPPER SUSQUEHANNA
PA08-MIDDLE SUSQUEHANNA
PA10-NORTHEAST INCLUDING POCONOS
1000 AM EST THU FEB 3 1983
(blank line)
...HEADLINE...(as required)
Forecast text
(blank line)
$$

5.4 Complete Header for Local Forecasts. The format of the headers for local forecasts is slightly different from the zone header format. The geographical turn-on code and corresponding city name occur before the mass news disseminator (MND) block, thus allowing the viewer to identify the NWS as the originator of the product.

The header for local forecasts will be prepared this way.

FOR APOS SITES:

#CLELFPDAY
#TTAAOO KDAY 071500
(blank line)
DAOH-DAYTON AND VICINITY FORECAST
NATIONAL WEATHER SERVICE DAYTON OH
1000 AM EDT WED SEP 7 1983
(blank line)
...HEADLINE... (as required)
Forecast text
(blank line)
$$

#PDXLFPPDX
#TTAAOO KPDX 221555
(blank line)
PROR-PORTLAND METROPOLITAN AREA FORECAST
NATIONAL WEATHER SERVICE PORTLAND OR
900 AM PDT MON AUG 22 1983
(blank line)
...HEADLINE...(as required)
Forecast text
(blank line)
$$

#FOR NON-AFOS SITES: The communication header (lines 1 and 2) should be formatted according to the specific message entry device in use at the office preparing the forecast (i.e., RTA, teletype ASR 28/43, PC, etc.).

In sections 5.2, 5.3, and 5.4, please note the following:

o Blank lines are important distinguishing separators for users, especially MND's. However, if an extra line or two is needed to prevent the zone forecast from exceeding message composition limitation, an emergency option would be to eliminate either of the last two blank lines, i.e., between the geographical codes and the headline (or forecast text) or between the end of the forecast text and the turn-off code ($$). The first two blank lines of the zone header should never be eliminated. Blank lines in the local forecast format should not be eliminated.

o The date/time line - and its repeat in the geographical code block in zone headers - should be followed exactly. That is, the time will be given in either three digits (900, 630, etc.) or four digits (1030, 1145, etc.) followed by one space, then "AM" or "PM."

o For the proper formats and examples of updated and corrected zone and local forecasts, see section 9.2.1.

6. Forecast Format. Zone and local forecasts will follow a discrete time-period format: TODAY, TONIGHT, TOMORROW (Day of Week), etc. The format will be structured according to the following general example:

HEADER
BLOCKS
DATE/TIME LINE (last line of header)
(blank line)
...HEADLINE(S)... (as required)
.TODAY...Forecast text.
.TONIGHT...Forecast text.
.TOMORROW (Day of Week)...Forecast text.
(blank line)
$$ (Turn-off Code).

The following subsections detail the procedures and rules for the format.

6.1 Headlines. Three dots (...) will precede and follow the headline statement. If more than one headline statement is necessary, each should be on a separate line with three dots preceding and following. The preceding three dot delimiter should begin at the left margin.

Headlines should be reserved for the important weather story, i.e., certain warnings, watches, advisories, and significant events. See section 8.2.4 for instructions and examples. Other examples of headlines are:

a.  ...SEVERE THUNDERSTORMS POSSIBLE THIS AFTERNOON...

b.  ...GALE WARNINGS ALONG THE COAST TODAY...

     ...ABOVE NORMAL HIGH TIDES CAUSING LOW LYING COASTAL
        FLOODING AND BEACH EROSION...

c.  ...TORNADO WATCH IN EFFECT THIS EVENING...

d.  ...WINTER STORM WARNING TODAY...

e.  ...HURRICANE WARNING IN EFFECT FROM MORGAN CITY WEST...

f.  ...RECORD HIGH TEMPERATURES TODAY...

6.1.1 Leftover Weather. "Leftover weather" - the weather that occurs, say, between the time of afternoon issuance (330 PM - 430 PM) and the first period (TONIGHT) - should not ordinarily be headlined. Headlines should be strictly for the important weather story. The "leftover" weather should begin the first period unless it is the important weather story. In this case headlining it may be appropriate.

Example:

TONIGHT...A 30 PERCENT CHANCE OF LINGERING THUNDERSTORMS
THIS EVENING. CLEARING AND COOLER LATER TONIGHT WITH LOW
NEAR 60. NORTHWEST WIND 10 TO 15 MPH.

6.2 Delimiter and Punctuation. One dot (.) will be used as the delimiter preceding the period designator. Three dots (...) will follow the designator. Use two dots (..) for commas and single dots for periods. Do not use commas, colons, or apostrophes.

Examples:

.TODAY...
.TONIGHT...
etc.

6.3 Period Designators. The period designators usually are: TODAY, TONIGHT, TOMORROW (Day of Week), TOMORROW NIGHT (Day of Week), and DAY AFTER TOMORROW (Day of Week).

Example (TODAY is Sunday):

If Release Times Are:                 Period Designators Are:

0430L-0630L                            .TODAY...
                                                  .TONIGHT...
                                                  .MONDAY...

1030L-1130L                           .THIS AFTERNOON...
                                                 .TONIGHT...
                                                 .MONDAY...

1530L-1730L                           .TONIGHT...
                                                 .MONDAY...
                                                 .MONDAY NIGHT...
                                                 .TUESDAY...

2100L-2200L                           .TONIGHT..
                                                 .MONDAY...
                                                 .MONDAY NIGHT...
                                                 .TUESDAY...

In keeping with certain nowcast initiatives, such as extra zone and local issuances per day, appropriate designators can also be THIS MORNING, THIS EVENING, REST OF TONIGHT, REST OF THIS AFTERNOON, etc.

Examples:

Early Morning Issuance                     Late Afternoon or Early Evening Issuance

.REST OF TONIGHT...or                .REST OF THIS AFTERNOON...or
.THIS MORNING...                        .THIS EVENING...
.TODAY...                                       .TONIGHT...
.TONIGHT...                                   .MONDAY...
.MONDAY...                                  .MONDAY NIGHT...
                                                        .TUESDAY...

6.3.1 Holiday Period Designators. Major holidays should also be period designators for all day periods except the first:

Example:

.THIS AFTERNOON...
.TONIGHT...
.CHRISTMAS...

Major holidays also require forecast outlooks (see section 6.6).

6.4 Combining Periods. The first period of any forecast sequence will not be combined with any other period. This will allow convenient updating of the current weather.

Combining any but the first period is allowed when the significant weather elements of each period to be combined are similar. Periods will not be combined just to ease the problem of forecast length.

Examples:

a. .TONIGHT...INCREASING CLOUDINESS AND MORE HUMID. MILD WITH LOW NEAR 70. WIND SOUTHEAST 10 MPH.

.FRIDAY AND FRIDAY NIGHT...WARM AND HUMID WITH PERIODS OF RAIN. HIGH UPPER 80S. LOW MID 70S. WIND SOUTH 10 TO 15 MPH FRIDAY. CHANCE OF RAIN 80 PERCENT BOTH FRIDAY AND FRIDAY NIGHT.
.SATURDAY..A 30 PERCENT CHANCE OF MORNING RAIN. BECOMING MOSTLY SUNNY..HOT AND HUMID IN THE AFTERNOON. HIGH IN THE MID 90S.

b. .TONIGHT...CLEAR AND COOL WITH LOW IN THE MID 50S. WIND LIGHT AND VARIABLE.
.WEDNESDAY THROUGH THURSDAY...SUNNY AND PLEASANT WITH HIGH IN THE 70S. CLEAR AND COOL WEDNESDAY NIGHT WITH LOW IN THE UPPER 50S. LIGHT NORTH WIND WEDNESDAY.

6.5 Abbreviations and Contractions. Generally, abbreviations and contractions are not to be used in the body of the forecast with the exception of the units for wind speed and temperature (e.g., mph, C,F). Do not use "thru" for "through;" this delays dissemination as the wire services will not transmit "thru."

6.6 Major Holiday Weather Forecast (Outlook). All offices issuing zone and local forecasts will include a major holiday (or holiday weekend) forecast when the holiday falls within the period covered by the extended forecast (EFP). The holiday/weekend forecast will be added as the last period in the first routine morning forecast after the holiday appears as day five in the EFP. The holiday forecast will continue to be highlighted until the routine forecast covers the holiday.

The following table shows the day of the holiday and the corresponding first forecast outlook (morning) issuance.

IF HOLIDAY FALLS ON                     BEGIN FORECAST (OUTLOOK) WITH MORNING
                                                               (430L-630L) FORECAST ISSUANCE

SUNDAY            -----                            WEDNESDAY
MONDAY          -----                             THURSDAY
TUESDAY          -----                             FRIDAY
WEDNESDAY   -----                             SATURDAY
THURSDAY       -----                             SUNDAY
FRIDAY             -----                             MONDAY
SATURDAY      -----                             TUESDAY

The six major holidays that require outlooks are:

NEW YEARS DAY
MEMORIAL DAY
FOURTH OF JULY
LABOR DAY
THANKSGIVING
CHRISTMAS

6.6.1 Major Holiday Weekend Weather Forecast (Outlook). When a major holiday falls on a weekend, a holiday weekend weather forecast will be issued in zone and local forecasts according to the following guidelines.

For a 3-day holiday weekend

If Holiday Is          Begin Holiday Forecast                     Begin Weekend Forecast

FRIDAY               Monday Morning                             Wednesday Morning

SATURDAY         Tuesday Morning                            Wednesday Morning
      (Even though Friday may be celebrated as business holiday)

SUNDAY              ...None...                                       Wednesday Morning

MONDAY            ...None...                                       Thursday Morning
      (Also use when Monday is a business day off for Sunday holiday)

For a 4-day Holiday Weekend

If Holiday Is          Begin Holiday Forecast                   Begin Weekend Forecast

Thursday                Sunday Morning                             Wednesday Morning

Tuesday                 ...None...                                        Friday Morning

When the single holiday or holiday weekend is highlighted as a forecast (outlook), it will be appended to the routine zone and local forecast as a period designator, (e.g., .LABOR DAY FORECAST..., or .FOURTH OF JULY WEEKEND FORECAST...). Do not have two separate forecasts for the holiday and the weekend. Highlight only the holiday until the weekend is completely covered, then switch to a weekend forecast only.

When the holiday is the second and third period of the routine forecast, highlighting will consist of using the holiday as a period designator rather than the day of the week (i.e., .MEMORIAL DAY..., .THANKSGIVING..., etc.). For holidays that occur near the beginning or middle of a weekend and the holiday falls within the first three periods of the routine forecast, outlook the remainder of the weekend in the outlook period, i.e., .OUTLOOK FOR REST OF CHRISTMAS WEEKEND... or .REMAINDER OF CHRISTMAS WEEKEND..."

Considering the nature of the EFP, the appended holiday/holiday weekend forecasts should be as brief as possible and confined to general weather conditions and temperatures. Forecasters should not make significant changes to the holiday/holiday weekend forecasts from shift to shift unless trends are clear.

                Examples:

                  1. LBBZFPTX
                      TTAAOO KLBB 300930

                      TEXAS ZONE FORECASTS
                       NATIONAL WEATHER SERVICE LUBBOCK TX
                       430 AM CDT SAT JUN 30 1984

                       TX08-TX09-TX11-
                       TEXAS ZONES 8 9 11
                       430 AM CDT SAT JUN 30 1984

(JUN 30)         .TODAY...SUNNY AND HOT WITH THE HIGH IN THE MID 90S.
                        SOUTH WIND 10 TO 15 MPH.

                        .TONIGHT..A 40 PERCENT CHANCE OF THUNDERSTORMS. LOW
                        AROUND 70. WIND SOUTHEAST 10 TO 20 MPH.

(JUL 1)            .SUNDAY...MOSTLY CLOUDY AND COOLER WITH HIGH IN THE LOWER 80S.
                        .FOURTH OF JULY FORECAST...MOSTLY SUNNY WITH LITTLE OR NO RAIN
                        EXPECTED. HIGH IN THE 90S AND LOW IN THE 70S.

                        $$

          2.           DSMLFPDSM
                        TTAAOO KDSM 212245

                        DMIA-DES MOINES AND VICINITY FORECAST
                        NATIONAL WEATHER SERVICE DES MOINES IA
                        445 AM CST WED DEC 22 1982

(DEC 22)         .TODAY...PARTLY CLOUDY AND MILDER WITH HIGH AROUND 50. SOUTH
                        WIND 5 TO 10 MPH.

(DEC 22, 23)    .TONIGHT AND THURSDAY...PARTLY CLOUDY. LOW 30 TO 35. HIGH THURSDAY
                         IN THE MID 40S. WIND WEST AROUND 10 MPH TONIGHT.

.CHRISTMAS WEEKEND FORECAST...CHANCE OF RAIN OR SNOW CHRISTMAS. OTHERWISE HIGHS IN THE 30S AND LOWS IN THE TEENS.

6.7 Coding Automated Weather-by-Phone Abbreviated Forecast Messages. WSOM Chapter C-61, Telephone Dissemination, contains the policy and instructions for supplying service to automatic weather-by-phone systems. When one of these coded messages is required in a zone or local forecast, it will be placed on a line immediately above the $$ turn-off code.

EXAMPLE A.  For a single zone or local forecast with coded forecast:

                         .MONDAY... (text of forecast for last period/outlook)
                              (blank line)
                         MD06 022
                         $$

                   B.  For grouped zone forecast with two or more coded forecasts:

                        .FRIDAY...(text of forecast for last period/outlook)
                              (blank line)
                        GA04 636
                        GA05 636
                         $$

7. The Well-Written Forecast. Zone and local forecasts are the basic and most important public forecasts of the NWS. They are the most "visible" products, being heard continuously over NWR and frequently over the commercial broadcast media and cable systems. In a significant sense, they are what the public perceives as the NWS.

Due to their exposure, forecasts must closely reflect the observed and imminent weather conditions. This is crucial to NWS credibility (see section 9). Forecasts must also be written in an easy to understand manner and must emphasize significant and unusual events with an appropriate choice of words markedly different from a "normal" situation (see section 8).

Ideally, the forecaster should have a clear mental picture of the meteorological situation and be able to describe it in clear, simple, and commonly used terms. This is especially important for uncertain, complex, or rapidly changing cases. For greater public understanding, forecast wording should be as brief as practicable. This may mean occasionally sacrificing scientific purity or eliminating one or more less important elements, especially when they are implied by other elements in the forecast, i.e., sky cover when precipitation is occurring (or forecast). Also, later periods may be combined to reduce length, but only if meteorologically sound.

Certain terms used to indicate uncertainty in zone/local forecasts, such as "possible," "may," "expect," etc., can be construed as hedging. Therefore, these terms should be used with great discretion and as infrequently as possible. However, the nature of some significant events is such that it would be a disservice not to indicate the uncertainty in the forecasts. For instance, certain coastal zones in winter experience a critical temperature gradient such that the likelihood of rain versus freezing rain/sleet/snow is problematical. Further, if the probability of rain is less than categorical, the wording of its changeover to snow, etc., should also indicate uncertainty. As another example, if a forecast area is marginally within a hurricane warning and the forecast tracks have the storm barely skirting the area, it would be prudent to allow for the possibility, rather than the certainty, of hurricane conditions in the forecast wording. In these cases, simply to give it the best shot and forecast yes or no would not be meteorologically sound. However, for most situations, avoid using these uncertainty terms.

Forecast styling is an important tool in effective communication with the public. Too often, the forecast is structured into a pat formula regardless of the weather situation. This can be detrimental for unusual, dangerous, or fast-breaking events where a sense of immediacy or urgency is required. Appropriately, the occasional use of more descriptive phrasing or more definitive timing of events in the first period is encouraged as long as the forecast remains clear and easily understood.

Written instructions cannot cover every situation. Individual forecaster initiative and professional judgment will help provide the best possible product.

A final thought: Before releasing the forecast, the forecaster should "stand back" and perceive it from the public's point of view. This should help ensure that the forecast states (or implies) exactly what is intended.

8. Forecast Content and Wording. This section provides guidelines for the handling of the forecast elements, associated wording, and a description of the general structure of the forecast periods.

8.1 Forecast Elements. Zone and local forecasts should normally include the following elements, either explicitly or implicitly: certain warnings, watches, and advisories (usually in headline statements - see 6.1 and 8.2.4); precipitation and corresponding probability of precipitation statements; temperature; wind; and state of the sky (as necessary). These "core" elements are described in detail in later subsections. Other elements, such as temperature trend, humidity, frost, fog, blowing snow, other visibility restrictors, certain hazardous conditions, etc., should be included with appropriate emphasis as necessary.

8.2 Structure of Forecast Periods. Each period of zone and local forecasts typically has the following general structure:

o A general statement of expected (or occurring) weather conditions.

o A forecast of measurable precipitation will be accompanied by its point probability (see section 8.3).

o A forecast of maximum temperature for day periods and minimum temperature for night periods (see section 8.5).

o A forecast of wind speed and direction for the first two periods. Later periods may require general wind statements (or wind speed and direction) if the wind is considered to be significant (see section 8.7).

Examples:

a.     .TODAY...SUNNY AND QUITE COOL. HIGH TEMPERATURE NEAR 50. NORTH WIND
        AROUND 10 MPH.
        .TONIGHT...FAIR AND NOT QUITE SO COOL. LOW IN THE MID 40S. LIGHT WIND.
        .TUESDAY...INCREASING CLOUDINESS AND WARMER WITH A 30 PERCENT CHANCE
        OF SHOWERS LATE IN THE DAY. HIGH IN THE MID 60S.

b.     .TONIGHT...CLOUDY AND FOGGY WITH A CHANCE OF DRIZZLE. LOW IN THE LOWER 50S.
        LIGHT WEST WIND.
        .WEDNESDAY THROUGH THURSDAY...CONTINUED CLOUDY AND FOGGY..
        WITH OCCASIONAL DRIZZLE ALONG THE COAST. PARTIAL AFTERNOON CLEARING
        INLAND. HIGHS IN THE MID 60S COAST TO UPPER 70S INLAND. LOW IN THE 50S. WIND
        WEST 10 TO 20 MPH EXCEPT LOWER AT NIGHT.

c.      .THIS AFTERNOON...VERY COLD AND BLUSTERY WITH OCCASIONAL FLURRIES. NO         ACCUMULATION EXPECTED. HIGH IN THE UPPER TEENS. WIND NORTHWEST 15 TO 25
        MPH AND GUSTY.
        .TONIGHT...CONTINUED VERY COLD WITH CLEARING SKIES AND DIMINISHING NORTH
        WIND. LOW 5 TO 10 ABOVE ZERO.
        .SATURDAY...MOSTLY SUNNY AND NOT AS COLD. HIGH NEAR 30.

8.2.1 Stress Important Elements. To get the important weather story across, forecasts should be arranged in a journalistic style to emphasize the significant elements first; e.g., precipitation, high winds, heat or cold, etc. One or more elements could be eliminated if it aids in writing a clear and not overly complicated forecast statement that emphasizes the more significant weather conditions. Certainly, the elimination of state of the sky is preferable if it can be inferred from the forecast statement, especially in ongoing precipitation events.

Examples:

a.      .TODAY...RAIN..HEAVY AT TIMES..AND WINDY. WIND NORTHEAST 20 TO 30 MPH WITH
         HIGHER GUSTS. HIGH IN THE LOWER 50S. (POP optional see 8.3.2 [3])

b.      .THIS AFTERNOON...HOT..HUMID AND HAZY. HIGH IN THE UPPER 90S. WIND SOUTH 5 TO
         10 MPH.

c.      .TONIGHT...A 30 PERCENT CHANCE OF THUNDERSTORMS THIS EVENING.. OTHERWISE
         MOSTLY CLEAR AND MILD. LOW IN THE 70S. WIND BECOMING SOUTHWEST 10 TO 15 MPH.

d.      .TODAY...RAIN..MIXED WITH SNOW IN FOOTHILLS THIS MORNING. BECOMING WARMER
         THIS AFTERNOON WITH HIGH IN THE UPPER 40S. WIND SOUTHEAST AROUND 10 MPH. CHANCE
         OF PRECIPITATION NEAR 100 PERCENT.

8.2.2 Highlight Significant Changes. Significant changes in important elements of the forecast should be emphasized. A frequently overlooked but important change that should also be stressed is the expectation of pleasant weather following a period of inclement or uncomfortable weather.

Examples:

a.      .TONIGHT...RAIN ENDING AFTER MIDNIGHT AND BECOMING WINDY. NORTHWEST WIND
         20 TO 30 MPH AND GUSTY. TURNING COLDER WITH LOW NEAR 40.
         .TUESDAY...CLEARING..WINDY AND MUCH COLDER. TEMPERATURE FALLING TO THE
         LOWER 30S BY LATE AFTERNOON. WIND NORTHWEST 20 TO 30 MPH SLOWLY DIMINISHING
         TOWARD EVENING.
         .TUESDAY NIGHT...CLEAR AND BITTERLY COLD WITH LOW OF ZERO TO 5 BELOW.
         .WEDNESDAY...SUNNY BUT CONTINUED VERY COLD. HIGH IN THE TEENS.

b.      .TONIGHT...CLEAR AND QUITE COOL. LOW IN THE LOWER 40S EXCEPT 30S WITH
         POSSIBLE LIGHT FROST IN OUTLYING AREAS. CALM WIND.
         .THURSDAY...SUNNY..BECOMING BREEZY AND MUCH WARMER WITH AFTERNOON
         HIGH IN THE MID 70S. WIND SOUTHWEST 10 TO 20 MPH.
        .THURSDAY NIGHT...PARTLY CLOUDY..WARMER AND MORE HUMID. LOW IN THE UPPER 50S.
        .FRIDAY...VERY WARM AND HUMID WITH A 40 PERCENT CHANCE OF SHOWERS OR        THUNDERSTORMS. HIGH IN THE 80S.

8.2.3 Emphasize Unusual Weather. When (extremely) dangerous or (highly) unusual weather is expected, the forecast writer must emphasize this fact and ensure that there is a marked difference in the wording as compared to a "normal" situation. The wording [and usually a headline(s)] should immediately alert the public that something dangerous and/or rare is about to occur. This means certain "standard" elements may be omitted or rearranged to allow for more important information to be highlighted.

Examples:

b.      ...STAGNANT WEATHER TO PERSIST THROUGH WEEKEND...
         .TODAY...HAZY..HOT AND HUMID WITH VISIBILITIES OCCASIONALLY ONE MILE OR LESS. CALM          WIND. HIGH IN THE MIDDLE 90S.
         .TONIGHT...CLEAR THIS EVENING. DENSE FOG FORMING AFTER MIDNIGHT WITH VISIBILITY          NEAR ZERO. LIGHT WIND. LOW NEAR 70.
         .SATURDAY...FOG DISSIPATING DURING THE MORNING BUT CONTINUED VERY HAZY DURING          THE AFTERNOON. HOT AND HUMID WITH HIGH IN THE UPPER 90S. LIGHT WEST WIND.

8.2.4 Watch, Warning, and Advisory Situations. Watches, longer lead time warnings, and advisories should be placed in a headline preceding and separate from the main body of the forecast (see section 6.1). Further details are found in WSOM Chapters C-40, C-41, C-42, and E-13. The period affected will be included in the headline statement(s); e.g., "...WINTER STORM WARNING TODAY..." Short-fused warnings (severe thunderstorm, tornado, flash flood, etc.) are not normally presented in zone and local forecasts; if they are, however, they should be headlined.

Examples:

a.     ...STOCKMENS ADVISORY CONTINUED THROUGH THURSDAY...
        .THIS AFTERNOON...CLOUDY AND QUITE COOL WITH A 40 PERCENT CHANCE OF RAIN. RAIN         MAY BECOME MIXED WITH SNOW. HIGH AROUND 40. NORTH WIND 10 TO 20 MPH.
        .TONIGHT...WINDY AND COLD WITH OCCASIONAL WET SNOW. LOW IN THE LOWER 30S.         NORTHEAST WIND 20 TO 30 MPH. CHANCE OF SNOW 80 PERCENT.
        .THURSDAY...PERIODS OF SNOW CHANGING TO RAIN AND CONTINUED WINDY. HIGH IN THE         LOWER 40S. GUSTY NORTHEAST WIND 20 TO 30 MPH. CHANCE OF PRECIPITATION 80 PERCENT.

b.     ...WINTER STORM WARNING TONIGHT AND FRIDAY...
        .THIS AFTERNOON...TURNING COLDER AND BREEZY WITH SHOWERS DEVELOPING.                     TEMPERATURE FALLING INTO THE 40S. WEST WIND 15 TO 25 MPH. CHANCE OF RAIN 80 PERCENT.
        .TONIGHT AND FRIDAY...SNOW..HEAVY AT TIMES. TOTAL NEW SNOW ACCUMULATION OF 6 TO         12 INCHES BEFORE ENDING FRIDAY. MUCH COLDER AND WINDY WITH AREAS OF BLOWING AND         DRIFTING SNOW. LOW TONIGHT IN THE 20S. HIGH FRIDAY IN THE LOWER 30S. NORTHWEST WIND         15 TO 25 MPH AND GUSTY.

8.3 Probability of Precipitation Forecast (POP). This section presents the guidelines for using POP forecast statements in zone and local forecasts. An understanding of the two definitions below is essential for proper operational handling of POP's. Also, examples throughout the entire chapter containing precipitation illustrate the guidelines presented here.

8.3.1 Definitions.

a. Precipitation Event. The occurrence of a measurable amount (>.01 inch/.2 mm) of liquid precipitation or the water equivalent of frozen precipitation during a specific period of time (normally 12 hours) at any given point in the forecast area.

b. POP Forecast. The likelihood of occurrence (expressed as a percent) of a precipitation event at any given point in the forecast area. The time period to which the POP applies must be clearly stated (or unambiguously inferred from the forecast wording) since, without this, a numerical POP value is meaningless.

8.3.2 Basic Policy Rule. When measurable precipitation is mentioned in the body of the forecast for any period, a POP forecast will be included for those periods except as noted below.

a.     The inclusion of POP's is optional for the following:

      (1) Those WSFO's that include POP's for specific cities at the end of each individual zone or grouped zone forecast.

      (2) Those zones in the western U.S. of large size (greater than 10,000 square miles) or high precipitation variability, and low population density.

      (3) Occurring or imminent (within an hour or so) precipitation that is expected to affect the entire forecast area.

      (4) Major storms (winter, tropical, etc.) requiring an advisory, watch or warning, and the forecast wording strongly implies categorical POP.

      (5) The Alaska and Pacific Regions where POP's will continue to be at the discretion of the RD's.

b.     POP's will not be included for:

     (1) Trace Events

     (2) Holiday forecasts (3-5 day) appended to zone and local forecasts.

8.3.3 POP Range. Generally, the POP range (to the nearest whole 10 percent) will be from (near) 100 percent to a standardized lower limit of 20 percent, below which precipitation is not normally mentioned in the body of the forecast.

An exception that might justify use of a lower POP is for those areas, such as the high plains and the West, where widely scattered, high-based thunderstorms may -- by virtue of their areal coverage or sub-cloud evaporation -- result in any given location having only a 10 percent chance of measurable rainfall.

The mention of POP's below 20 percent may also occur when indicating the ending of precipitation (see section 8.4.2).

8.3.4 POP Statement. The POP statement can be worded and placed in a forecast period in a variety of ways. This allows the forecaster the flexibility to convey the most accurate and concise description of the event.

A few guidelines:

o Use the equivalent term "Chance" instead of the term "Probability" when using a separate POP statement; it is shorter and easier to pronounce.

o Use specific precipitation types, i.e., rain, snow, etc., when at all possible.

o Use the term "Precipitation" where precipitation type is uncertain, for mixed or certain multiple precipitation events, and for trace and measurable event combinations (e.g., drizzle and showers, etc.).

o Do not use the term "by" in the POP statement -- as in, "CHANCE OF RAIN X PERCENT BY EVENING." Used in this context, "by" implies an increase or decrease in POP value that is not consistent with the definition of POP: a single probability for a specific time period.

The term "by," however, may be used in the forecast narrative to indicate the beginning or ending of precipitation, e.g., "rain ending by evening," with the associated POP statement used to express the time period to which the POP applies. See Section 8.4.2 for discussion and examples on splitting 12-hour POP into two 6-hour subperiods.

POP Statement Wording Placement:

a.   Separate statement at the end of the period.

     .TODAY...(text of forecast). CHANCE OF RAIN X PERCENT.

b.   Statement as part of forecast narrative.

      .TODAY...PARTLY CLOUDY WITH A 40 PERCENT CHANCE OF SHOWERS.

(remainder of text).

8.3.5 POP Qualifying Terms. As guidance, expressions of uncertainty and areal qualifying terms have the following relationship to POP values:

POP                                                  EXPRESSIONS OF                    EQUIVALENT AREAL
PCT.                                                 UNCERTAINTY                         QUALIFIERS (CONVECTIVE ONLY)
______________________________________________________________________________

0 ^a/                                                    (NONE USED)                            (NONE USED)
10 ^a/                                                  SLIGHT CHANCE                      ISOLATED, FEW
20                                                     SLIGHT CHANCE                      WIDELY SCATTERED
30,40,50                                           CHANCE                                     SCATTERED
60,70                                                 LIKELY                                       NUMEROUS (OR NONE USED)
80,90,100 (CATEGORICAL)           (NONE USED)                            (NONE USED)

______________________________________________________________________________

Uncertainty terms, such as "chance," "likely," etc., will be used within the narrative of the forecast when POP's takes the form of a statement at the end of the forecast period. Avoid phrases such as "threat of..." or "risk of..."

Equivalent areal qualifiers, such as "isolated" or "scattered," may be used in convective situations instead of uncertainty terms (see section 8.3.6). However, these areal qualifiers may be used only when the chance of convective precipitation somewhere in the forecast area is very high (i.e., areal probability approaches 100 percent). In this case the POP (point probability) also expresses the expected coverage within the forecast area.

Other precipitation qualifying terms are:

Duration --

Brief (periods of)
Occasional
Intermittent
Frequent (periods of)

Duration terms imply categorical occurrence of precipitation at any given point and, therefore, require very high (categorical) POP's.

Intensity -

Very light (trace) ^b/
Light
Heavy
Very Heavy

For "moderate" rain/snow, do not use a modifier.

_____________________
^a/ Used only in certain specific cases (see section 8.3.3).
^b/ "Sprinkles," "drizzle," "snow flurries," may be used for very light (trace) precipitation events.

8.3.6 Rules For Combining Qualifying Terms. Combining uncertainty terms with other qualifying terms may be technically correct, i.e., "chance of scattered" (or occasional, etc.). Confusion may arise, however, since it is not clear to which the uncertainty term applies: the precipitation event (as it should) or the terms "scattered" or "occasional." Also, certain other combinations, such as areal and duration (e.g., "occasional scattered") may be perceived as undue hedging. Avoid combining these terms as much as possible.

Situations will occur that may require combining terms to accurately describe the forecast event. Use the following guidelines when combining terms becomes necessary.

a.  Uncertainty, Areal, and Duration qualifying terms must stand alone; they may not be combined with each other.

Therefore, do not use the following examples:

     (1) Uncertainty with Areal -- "CHANCE OF SCATTERED SHOWERS (FLURRIES)."

     (2) Uncertainty with Duration "CHANCE OF OCCASIONAL RAIN (SNOW)."

     (3) Areal with Duration -- "A FEW BRIEF SHOWERS (FLURRIES)."

b.  Uncertainty, Areal, and Duration terms may be combined with Intensity terms.

Examples of Acceptable Wording:

     (1) Areal with Intensity -- "SCATTERED LIGHT SHOWERS"

     (2) Duration with Intensity -- "BRIEF PERIODS OF HEAVY RAIN"

     (3) Uncertainty with Intensity - "CHANCE OF HEAVY RAIN"

c.  Do not use more than one term from the same qualifier category, i.e., Uncertainty, Areal, or Duration.

Do not use:

"AFEW SCATTERED...," (Areal category)
"AN OCCASIONAL BRIEF...," (Duration category)

8.3.7 Trace Precipitation Events. Trace precipitation events (drizzle and snow flurries, primarily) are, by definition, non-measurable events. Therefore, a POP statement should not be used. Instead, use precipitation qualifiers within the forecast narrative to indicate the probability of occurrence of the trace episode, e.g., "occasional drizzle," "scattered snow flurries," "snow flurries likely," or "drizzle this morning" (categorical), etc.

If drizzle or snow flurries are expected to be the dominant weather in the period or to persist or be of sufficient intensity so that the likelihood of measurable precipitation was high, then a POP statement should be considered. In these cases, it may not be desirable to use the terms "drizzle" or "snow flurries"; it may be better to use terms such as "light (or very light) rain" for drizzle and "light snow" or "scattered (light) snow showers" for snow flurries. Also, both drizzle and light rain should not be included in the forecast for the same time frame. Considering the definition of POP, a Probability of Measurable Precipitation also is not required. The term "snow," however, is often an emotional trigger. In snow flurry situations, therefore, an accumulation statement may sometimes be advisable such as "little (or no) accumulation expected" or "no appreciable accumulation..." etc.

8.4 Precipitation Events. When precipitation is forecast, specify and, as appropriate, qualify the type and intensity of the precipitation. The approximate time of the beginning and ending of precipitation should be mentioned but particular attention should be placed on more specific timing for the first period.

This section provides guidelines for handling certain precipitation events. Also, descriptions are given for certain freezing or frozen precipitation (and other related) terms commonly used in zone and local forecasts whose meanings have occasionally been misinterpreted. More detailed information on these terms and, especially, the guidelines for invoking winter-related watches and warnings, etc., are found in WSOM Chapter C-42, Winter Weather Warnings.

8.4.1 Freezing or Frozen Precipitation (and related) Terms.

a. Snow - Unless qualified by such words as "occasional" or "intermittent," a prediction of snow indicates a steady fall for several hours or more.

b. Snow Flurries - Short duration of snowfall at intermittent periods (generally light snow showers). Generally, there is little or no accumulation (trace category).

c. Snow Showers - Short duration of intermittent snowfall. Some accumulation is possible.

d. Snow Squalls - Intense snowfall, accompanied by gusty surface winds and possibly lightning (generally moderate to heavy snow showers). Accumulation may be significant.

e. Blowing Snow - Wind-driven snow which reduces surface visibility.

f. Drifting Snow - An uneven distribution of snowfall caused by surface winds of variable direction and/or speeds.

g. Freezing Rain and/or Freezing Drizzle - Liquid rain or drizzle which freezes on contact with the ground and other exposed surfaces.

h. Sleet (ice pellets) - Generally frozen raindrops (or refrozen melted snowflakes) which, like small hail, usually bounce when hitting a hard surface. Sleet does not "stick" to exposed surfaces.

i. Frost - The formation of thin ice crystals which develop under conditions similar to dew, except for the minimum temperatures involved. Phrases such as "frost in low-lying areas" or "scattered light frost" are used in zone and local forecasts.

j. Freeze - Conditions when the temperature at or near the surface is expected to be 32° F or below during the growing season. Adjectives such as "killing," "severe," or "hard" may be used in zone and local forecasts when appropriate.

k. Undesirable Precipitation Terms -

     1. Snow pellets (use "snow")
     2. Snow grains (use "snow")
     3. Ice pellets (use "sleet")
     4. Glaze (use "freezing rain" or "freezing drizzle")

8.4.2 Beginning or Ending Precipitation. The terms "beginning" or "ending" should be used when it is highly likely that widespread precipitation will begin or end in a period (usually the first period, occasionally the second). Since it will be precipitating (at least for awhile) during the period, the associated 12-hour POP is categorical.

Concerning the categorical 12-hour POP: The first and occasionally the second period forecast may be split into two separate 6-hour subperiod POP statements in those cases where it is clear precipitation will begin or end during one of the 6-hour subperiods. Two POP numbers can be used but more often one is used and the other inferred.

Examples

a.    Split first period. Precipitation first subperiod.

       .TODAY...RAIN ENDING THIS MORNING THEN MOSTLY SUNNY. HIGH 70 TO 75. WIND SOUTH
      AROUND 10 MPH. CHANCE OF RAIN NEAR ZERO (OR LESS THAN 20 PERCENT) THIS AFTERNOON.

b.    Split first period. Precipitation second subperiod.

       .TODAY...INCREASING CLOUDS THIS MORNING WITH RAIN BEGINNING BY EARLY AFTERNOON.
      HIGH 50 TO 55. SOUTHEAST WIND 10 TO 20 MPH. CHANCE OF RAIN 80 PERCENT THIS AFTERNOON.

c.  Split second period.

     .THIS AFTERNOON...RAIN WITH FREQUENT HEAVY DOWNPOURS. HIGH NEAR 60. GUSTY
     SOUTHEAST WIND 15 TO 25 MPH.
     .TONIGHT...RAIN BECOMING LIGHT AND INTERMITTENT BEFORE ENDING AROUND MIDNIGHT.
     LOW AROUND 50. WIND BECOMING SOUTHWEST 10 TO 20 MPH. CHANCE OF RAIN LESS THAN 20
     PERCENT AFTER MIDNIGHT.

Do Not Say:

d.   .TODAY...CLOUDY WITH A 30 PERCENT CHANCE OF RAIN ENDING THIS AFTERNOON (remainder of
      text).

e.   .TODAY...INCREASING CLOUDINESS WITH A 50 PERCENT CHANCE OF RAIN BY AFTERNOON       (remainder of text).

8.4.3 Mixed Precipitation. When forecasting one precipitation type changing to or being mixed with another, be sure the associated POP statement clearly indicates the chance of the measurable precipitation occurrence and not the chance of occurrence of changing or mixing precipitation types.

This can be handled best by placing a separate POP statement at the end of the period. It allows for more flexibility in narrative wording and a clearer indication that the POP refers solely to the chance of precipitation.

Examples:

a.    .TODAY...RAIN LIKELY AND TURNING COLDER. RAIN POSSIBLY CHANGING TO SNOW DURING
       THE AFTERNOON. TEMPERATURE FALLING INTO THE 30S. WIND NORTHWEST 10 TO 20 MPH.
       CHANCE OF PRECIPITATION 70 PERCENT.

Alternately, this type of forecast can be handled by using a POP percentage in the forecast narrative affixed to the precipitation event and not to the "changeover" event. Using short declarative sentences will make the POP meaning clear.

b.    .TODAY...A 70 PERCENT CHANCE OF RAIN. TURNING COLDER WITH RAIN POSSIBLY CHANGING
      TO SNOW. ETC...

c.    .TODAY...NEAR 100 PERCENT CHANCE OF RAIN. RAIN CHANGING TO SNOW LATER THIS
      AFTERNOON. ETC...

In example "b," do NOT say:

      .TODAY...A 70 PERCENT CHANCE OF RAIN CHANGING TO SNOW. ETC...

Users could easily be confused as to what the 70 percent applies: chance of rain or chance of rain changing to snow

8.4.4 Multiple Precipitation Events. Occasionally, a situation can best be described by mentioning more than one precipitation event in a period, such as rain and thunderstorms, drizzle and showers, etc. As with mixed precipitation events, the wording becomes tricky when the POP statement is included as part of the forecast narrative. It is better to use a separate POP statement either at the end of the period or immediately after the "event" wording to ensure that the POP refers solely to the chance of precipitation. A note of caution: use multiple events sparingly since unnecessarily long and/or complicated forecasts may result.

Examples:

a.    .TODAY...RAIN LIKELY..POSSIBLY PRECEDED BY FREEZING RAIN OR SLEET IN NORTHERN SUBURBS THIS MORNING. HIGH IN THE UPPER 30S. WIND NORTHEAST 10 TO 15 MPH. CHANCE OF PRECIPITATION 60 PERCENT.

b.   .TODAY...OCCASIONAL RAIN..WITH THE POSSIBILITY OF AN AFTERNOON THUNDERSTORM.      BREEZY AND MILD WITH HIGH IN THE MID 70S. WIND SOUTHWEST 15 TO 25 MPH. CHANCE OF      PRECIPITATION 80 PERCENT.

Another difficult situation occurs when combining measurable and trace events since POP's are not required for the latter (see example below and section 8.3.7).

c.    .TONIGHT...DRIZZLE AND FOG THIS EVENING FOLLOWED BY PARTIAL CLEARING. A 30 PERCENT       CHANCE OF SHOWERS AFTER MIDNIGHT. LOW NEAR 50. WIND BECOMING SOUTHWEST AROUND       10 MPH.

Alternately, the example above could be worded with a separate POP statement at the end of the period: "CHANCE OF SHOWERS 30 PERCENT AFTER MIDNIGHT."

Do NOT say in the POP statement: "CHANCE OF PRECIPITATION 30 PERCENT" (or 80 to 100 percent in an attempt to account for the drizzle).

8.4.5 Snowfall Accumulation. Total storm snowfall accumulation estimates should be placed in the period the snow is forecast to end. Interim snowfall estimates may be mentioned in earlier periods since the public would benefit from this knowledge. However, as a general rule, confine snowfall estimates to the first and second period. If snow is forecast to continue into a third or later period, try to be as general as possible about total snow accumulation (i.e., "TOTAL SNOW ACCUMULATION LESS THAN (OR MORE THAN) X INCHES POSSIBLE"). It may also be appropriate at times to include expected total snowfall amounts in the headlines (see example c) so that users can see at a glance the significance of the storm. If snow is forecast to begin in a third or later period, use the term snow but with no mention of accumulation.

Forecasts with low or medium POP's in the first or second period should not mention specific accumulation amounts. Qualifying terms, such as "LIGHT SNOW" or "LITTLE OR NO ACCUMULATION," may be used. On the other hand, higher POP values forecast in the first or second period should have some mention of accumulation.

Example - one period:

a.    .TONIGHT... PERIODS OF LIGHT SNOW ENDING BEFORE MIDNIGHT. ACCUMULATION OF 1 OR 2       INCHES EXPECTED. LOW IN THE MID 20S. WIND NORTH 10 TO 15 MPH. CHANCE OF SNOW NEAR       100 PERCENT.

Examples - more than one period:

b.   ...TRAVELERS ADVISORY FOR SNOW THIS AFTERNOON AND TONIGHT...
      .TODAY...LIGHT SNOW LIKELY BY AFTERNOON. HIGH IN THE LOWER 30S. WIND NORTHEAST 10       TO 20 MPH. CHANCE OF SNOW 70 PERCENT.
      .TONIGHT...SNOW GRADUALLY DIMINISHING AFTER MIDNIGHT. TOTAL SNOWFALL OF 2 TO 4       INCHES. LOW IN THE 20S. WIND BECOMING NORTHWEST 10 TO 20 MPH. CHANCE OF SNOW NEAR       100 PERCENT.
      .FRIDAY...WINDY AND COLD WITH A FEW MORNING FLURRIES. HIGH NEAR 30. WIND NORTHWEST       15 TO 25 MPH WITH HIGHER GUSTS.

c.   ...WINTER STORM WARNING FOR HEAVY SNOW TONIGHT AND THURSDAY...
     ...TOTAL SNOWFALL NEAR ONE FOOT BY LATE THURSDAY...
     .THIS AFTERNOON...SNOW LIKELY WITH AN INCH OR SO ACCUMULATION BY RUSH HOUR.      TEMPERATURE FALLING INTO THE 20S. NORTHEAST WIND 10 TO 20 MPH. CHANCE OF SNOW 70      PERCENT.
     .TONIGHT... HEAVY SNOW AND BLOWING SNOW. SNOWFALL MAY REACH 4 TO 8 INCHES WITH      HIGHER DRIFTS BY DAWN. NORTHEAST WIND 20 TO 30 MPH. TEMPERATURE REMAINING IN THE      20S.
     .THURSDAY...SNOW DIMINISHING TO FLURRIES DURING THE AFTERNOON. TOTAL SNOW      ACCUMULATION APPROACHING ONE FOOT. WIND NORTHWEST 15 TO 25 MPH CAUSING      CONTINUED DRIFTING. HIGH IN THE UPPER 20S.

8.5 Temperature. Zone and local forecasts will include expected maximum and minimum temperatures for day and night periods, respectively, and, when appropriate, a statement of the trend of temperature change. In addition, qualifying terms and phrases may be used to clarify temperature changes or add to the smooth flow of the forecast narrative. The use of descriptive terms and phrases, such as mild, hot, cool, cold, much colder, not as warm, not quite as hot, slightly cooler, etc., can also be quite effective in improving user/listener understanding.

8.5.1 Temperature Presentation Methods. Numerical temperature values may be presented in four ways.

a.  "Near," "around," or "about" a specific value that has been rounded to the nearest 5 or zero. Above 100 or below 10 degrees, any number may be used.

NEAR 40
AROUND 15
ABOUT 85
NEAR 106
AROUND 6 BELOW

b.  A general range where the terms are defined by the following:

LOWER 50S (50, 51, 52, 53, 54)
MID 50S (53, 54, 55, 56, 57)
UPPER 50S (56, 57, 58, 59)
60S (60 THROUGH 69)

c.  A specific range -- rounded to the nearest 5 or zero. For ranges below 10 or above 100, any numbers may be used.

70 TO 75
10 TO 15
102 TO 108
5 BELOW TO 12 BELOW

d.  A specific unqualified number may be used only for site-specific forecasts for cities appended to the zone forecasts, e.g.,

ESTES PARK 43 22 38          LIMON 44 17 43

NOTES: 1. Care must be taken when using a specific range format. Too many numbers may confuse the users.

2. The range should be kept as small as possible.

3. Avoid such expressions as "LOW IN THE 50S TO AROUND 60," "UPPER 50S TO LOW 60S," or "MOSTLY IN THE 50S." Instead say "LOW IN THE 50S," "AROUND 60," or "LOW 55 TO 60."

4. Do not use potentially confusing expressions such as "HIGH IN THE LOW 70S." Instead say, "HIGH IN THE LOWER 70S" or "70 TO 75."

5. Do not use the narrative form in an expression such as "HIGH IN THE LOW ONE HUNDREDS" or "HIGH ABOVE ONE HUNDRED." Instead use a specific number such as "HIGH NEAR 108" or a specific range such as "HIGH 102 TO 108.

8.5.2 Falling Daytime, Rising Nighttime, or Steady Temperatures. If the temperature is expected to fall throughout the day or rise throughout the night or remain steady, (try to) indicate the temperature expected at the end of the period and use the phrases "STEADY OR SLOWING FALLING/RISING TEMPERATURES" in the zone or local forecasts, e.g.:

a.   .TODAY...MUCH COOLER THIS AFTERNOON WITH THE TEMPERATURE FALLING INTO THE UPPER      40S.

b.   .TONIGHT...SLOWLY RISING TEMPERATURES REACHING THE UPPER 50S BY MORNING.

c.   .THIS AFTERNOON... TEMPERATURES REMAINING IN THE MID 30S.

8.6 Sky Condition. Forecasts may include information about the state of the sky; however, it should be omitted if its inclusion would unnecessarily complicate or lengthen the forecast or if it can readily be inferred from the precipitation forecast.

Term                                                   Expected Predominant or Average
                                                                                                  Sky Condition

Cloudy                                                      9/10 to 10/10 opaque clouds

Mostly Cloudy or
Considerable Cloudiness                     7/10 to 8/10 opaque clouds

Partly Cloudy or
Partly Sunny                                            3/10 to 6/10 opaque clouds

Mostly Clear or                                       A Few Clouds and
Mostly Sunny                                          1/10 to 3/10 opaque clouds

Clear or Sunny                                       0/10 to 1/10 opaque clouds

Fair (Recommend using above            Less than 4/10 opaque clouds,
         terms rather than                          no precipitation, and no
        "Fair" - especially                           extreme conditions of visibility,
        during day.)                                     wind, or temperature (generally
                                                                 pleasant weather conditions).

Terms other than those listed above may be used if they convey a better picture of what is expected. The terms listed below are viewed as hedge terms and should be used sparingly and with great discretion.

Clear to partly cloudy
Partly cloudy to cloudy
Fair to partly cloudy
Scattered clouds
Variable cloudiness
Variable high clouds

Specialized terms should not be used, such as:

Broken clouds

8.7 Wind. Wind (direction and speed) will be included in the first two periods of zone and local forecasts. The only exception, at the RD's discretion, is for those western zones containing significant topography where wind speed and direction normally vary greatly. For these zones, wind will be included when considered significant.

Wind (direction and speed) may be included in the third or later periods if considered significant. When wind is expected to be significant for any period, also include a qualifying term or phrase in the forecast narrative (see section 8.7.2).

8.7.1 Direction. Direction will be given to eight points of the compass. Except for very large forecast areas, only one direction will normally be given. However, when the wind is expected to shift, two directions may be given; e g., "WIND SOUTHEAST 10 MPH BECOMING (or SHIFTING TO) NORTHWEST 10 TO 20 MPH" or, depending on the emphasis given, "WIND SHIFTING TO NORTHWEST 10 TO 20 MPH," etc.

Normally, the wind direction should be given as "SOUTH," "WEST," "NORTHEAST," etc., not "SOUTHERLY," etc.. The "ERLY" suffix adds nothing to the meaning and may be harder for the listener to understand.

Light wind (usually 5 mph or less) may be handled the following ways:

LIGHT SOUTH WIND or

LIGHT AND VARIABLE WIND or

LIGHT WIND (where light wind implies variability)

8.7.2 Speed. Wind speed will be given in miles per hour and should be abbreviated mph in written narratives. It is not practical to describe all variations in wind speed, so a range should be given. The maximum range for sustained wind speeds should be 10 mph. Under unusual or stormy conditions a greater range is permitted. Wind speeds will be rounded to the nearest 5 mph, e.g., 15 to 25 mph, 10 to 15 mph.

To help improve user/listener understanding, use a descriptive term.in the narrative of the forecast when wind is expected to be significant (usually above 15 mph). Below are some general guidelines for use of terms in the forecast narrative. The numbers may vary since local wind climatology may be different in some parts of the country.

          Sustained Wind Speed                      Descriptive Term

                        0-5                                              Light or Light and Variable
                        5-15                                            None
                        15-25#                                       Breezy (usually for mild weather)
                                                                           Brisk (usually for cold weather)
                        20-30                                          Windy
                        30-40                                          Very Windy
                        40 or greater                              Strong, Damaging, Dangerous, High.
                                                                            A high wind warning is required.
                                                                            (see C-40, C-41, C-42)

_____________
The term "blustery" may occasionally be used, especially in gusty situations (see 8.7.3).

8.7.3 Gusts. In gusty situations, no more than three numerical wind speed values should be included. Three suggested formats follow.

a.     Range which includes both sustained and gust values.

                  GUSTY EAST WIND 30 TO 40 MPH.

b.     Range which includes the maximum sustained value plus a gust statement.

        NORTHEAST WIND 25 MPH WITH OCCASIONAL GUSTS TO 40 MPH.

c.     Range which includes sustained wind values and a gust statement.

        WEST WIND 30 TO 40 MPH WITH OCCASIONAL GUSTS TO 60 MPH.

8.8 Computer Worded Forecasts. Computer worded forecasts (CWF) are prepared for a number of selected cities' (local forecasts) and zone forecasts throughout the country. The number may increase and its use expanded depending on future AFOS capabilities. Please refer to the latest Technical Procedure Bulletin for up to date details on the CWF. Being available before local issuance time, they can be valuable early guidance.

9. Forecast Monitoring and Updating. Each zone and local forecast will be monitored and updated as required to ensure timeliness, consistency, accuracy, and completeness.

9.1 Monitoring Responsibility. Responsibility for forecast monitoring will be assigned as follows.

a. Each WSFO should review all public weather products issued within its area of state forecast responsibility.

b. Each WSO will monitor each local forecast it prepares. WSO's should also assist the WSFO in monitoring zone forecasts and initiate coordination calls promptly to the WSFO if existing weather is at a variance with the zone forecast. The WSO will apprise the WSFO of the general applicability of the zone forecast to the local area. This information will assist the WSFO in maintaining or improving the utility of the zone forecast.

9.1.1 Local Adaptive Forecast Guidelines. Offices which are authorized by regional headquarters to prepare local adaptive forecasts will normally adjust, if needed, the first period of the zone forecast for local effects and local needs. First period changes, whenever possible, should be coordinated with the WSFO. However, short-fused situations may be handled independently. Changes to later periods of the zone forecasts require coordination with the WSFO. The local offices may paraphrase the zone forecast to meet local public weather needs or to improve the wording of the forecast for local use.

Updates to the local forecast should be issued when the criteria of section 9.2.2 are met. The WSO may update only the first period of the forecast without prior coordination with the WSFO. When a local forecast requires updates and the corresponding zone forecast also requires updates, the wording of both updated forecasts should be coordinated before issuance.

9.2 Updates -- Discussion. It is of primary importance for NWS credibility that the first period of zone and local forecasts reflects (as close as possible) the observed or imminent weather conditions. Therefore, updates to the first period should be issued as frequently as possible, considering available resources, to ensure this "freshness" -- with deletion of all reference to the expired portion of the original forecast.

If an update to a zone or local forecast is needed within 2 hours or so of the next scheduled forecast issuance time an option can be to release it as the mandatory issuance in lieu of an update. For this option to be exercised, however, it must be approved by RH and then thoroughly coordinated with the user community before implementation.

Considering the wide variety of climatic conditions across the country, it is not practical to list the many different sets of update criteria and numerical ranges that would be required. Therefore, area managers, aided by regional guidelines and approval, should establish update criteria uniquely tailored to their forecast area. In developing these criteria, consideration should be given to resources and technology and thoroughly coordinated with the user community before implementation.

As an important factor to the success of this program, on-station quality control should be set up. This should consist not only of training on the operational use of the update criteria but also to ensure the wording is clear and, particularly in difficult or complex weather situations, an appropriate style is used to emphasize the important weather story.

9.2.1 Definitions and Formats. The terms "UPDATED" and "CORRECTED" will be appended to zone and local forecasts according to the following definitions:

When transmitting an update (amendment) or correction, the letter A or C, respectively, should be typed in the MESSAGE TYPE block. An "AMD" or "COR" will be automatically put at the end of the second line (World Meteorological Organization) of the header.

This will ensure that the update or correction flows on NOAA Weather Wire Service (NWWS) immediately instead of waiting for the next scheduled time. In general, within the first hour after scheduled release time for zone forecasts, an update or correction should be sent as an entire package; not just the individual, affected zone(s). However, beyond 1 hour, the individual updated or corrected zone(s) may be sent. See latest AFOS asynchronous operating instructions for specific details.

The terms "UPDATED" or "CORRECTED" will be appended to the MND block according to the following examples. As an option, a short (usually one line) reason for the update or correction may be added to the affected zone(s) or local forecast. This should be placed between the MND and geographical code on zone forecasts and after the $$ turn-off code on local forecasts.

Examples:

ZONES

 
LOCALS

9.2.2 Generalized Update Criteria. As generalized guidelines, updates should be issued as soon as practical under the following circumstances. However, it is understood that more specific update parameters - e g., amount (say, 3-5 degrees) of temperature variance from predicted max/min, etc. - will be approved by RH's.

a. A winter weather watch, warning, or advisory is issued for any part of the forecast area (see WSOM Chapter C-42).

b. A hurricane warning is issued for all or part of the forecast area (optional for hurricane watch). (See WSOM Chapter C-41.)

c. Beginning or ending of precipitation is not expected to match current forecast.

d. Type and/or intensity of precipitation changes or is expected to differ significantly from the original forecast within the first period, e.g., freezing versus liquid precipitation, light versus heavy, etc.

e. Widespread precipitation occurs on low to medium POP forecast.

f. In action forecasts when the event has finally "increased," "decreased," "changed to," "become," etc., update the forecast.

g. Sky condition, other than cirrus, changes from clear to cloudy, cloudy to clear, or any other condition considered significant.

h. Observed temperature is higher/lower than forecast. Also, temperature steady or falling during the day or steady or rising at night and not forecast.

i. Unanticipated changes in other conditions considered significant to the area, e g., fog, other visibility restrictors, local wind effects, etc.

j. For tornado, severe thunderstorm, and flash flood situations, use the following guidelines.

If forecast includes:                    Always update for:                    Update at forecaster's
                                                                                                         discretion for:

Severe thunderstorms c/         Flash Flood Watch                      Severe Thunderstorm/
                                                                                                        Tornado Watch

Thunderstorms                         Tornado/Flash                              Severe Thunderstorm
                                                  Flood Watch                                  Watch

Heavy rains with                      Severe Thunderstorm/                  Flash Flood Watch
possible flooding                     Tornado Watch

_________
c/ Offices are strongly encouraged to add the phrase "with large hail and damaging winds" to the term "severe thunderstorms" when it is used in forecasts. This addition will give the public a better appreciation of the threat.

Generally, zone and local forecasts need not be updated to include short-fused warnings (flash flood, severe thunderstorm, or tornado).

10. Short-Range Weather Summary (Nowcast - NOW). A short-range weather summary is a combination of reports of current weather conditions in the local area and a short-range (up to several hours) forecast - or "NOWCAST." Generalized information on this type of product is found in WSOM Chapter C-21. The following guidelines are presented for nowcasts as they relate to zone and local forecasts.

Nowcasts are a very effective way to keep the public up to date -- especially during rapidly changing weather conditions. They should be issued to "expand upon" or "refine" less critical but important aspects of the first period of zone and local forecasts.

Although many of the conditions that warrant a first period update may also determine the issuance of a nowcast, nowcasts may also be issued to refine a forecast that doesn't need updating. For instance, when predicted thunderstorms occur, a nowcast could be used to describe their location and present movement and give a short-range forecast.

When nowcasts are issued, they should be updated at least every 2 hours to keep the public properly informed -- although the frequency of the updates should be determined by the rapidity with which the weather is changing. The nowcast would be used as an NWR product with dissemination on AFOS and NWWS determined by the importance of the event(s) and user needs. A nowcast may be a routine or non-routine product.

Examples:

a. WBCNOWWBC

AT 410 PM THUNDERSTORMS WERE SCATTERED JUST EAST OF THE BLUE RIDGE FROM NEAR CHARLOTTESVILLE..VIRGINIA TO NEAR FREDERICK..MARYLAND. THEY WERE MOVING EAST ABOUT 20 MPH AND SHOULD REACH THE WASHINGTON METROPOLITAN AREA BETWEEN 500 PM AND 600 PM.

b. LITNOWFSM

AT 730 AM FOG PERSISTED IN THE ARKANSAS RIVER VALLEY FROM JUST WEST OF FORT SMITH TO NEAR CONWAY..ARKANSAS. GRADUAL LIFTING IS EXPECTED TO BEGIN ABOUT 900 AM. BY LATE MORNING BRIGHT SUNSHINE WILL CAUSE THE TEMPERATURE TO RISE RAPIDLY INTO THE 70S.

11. Special Weather Statements (SPS) and Public Information Statements (PNS). Special weather statements should be used to deal with non-severe storms or other critical weather conditions where increased public awareness of a potential hazard is desired. SPS's should not be used to "explain" the routine forecast. Any public forecast discussion should be the province of the public information statement unless there is some potential for hazard.

IMPORTANT NOTE: It should be evident that nowcasts and special weather and public information statements are not to be used as a replacement for a needed first period update. Indeed, as this chapter makes clear, the first priority should be given to the "freshness" of the first period -- with the nowcast or other statement serving in a more auxiliary role.

12. Miscellaneous Special Programs and Advisories. There are a number of important special events that do not fit well into any other major program area. These weather events, however, have an impact on a broad spectrum of the public and will be highlighted or emphasized in the basic public zone/local forecasts. This section contains rather broad and generalized guidelines for integration of these special events into the zone and/or local forecast.

12.1 Inland Lake Wind Advisories. Zone and local forecasts will include inland lake wind advisories where there is a significant user community. RH's will determine the criteria (and threshold values) for inclusion. Public forecasts will not include boater information where a separate marine forecast is available.

Place a short statement at the end of each forecast period for which the advisory is in effect.

Example:

.TODAY...MOSTLY CLOUDY..WINDY AND COOL. HIGH IN THE UPPER 50S. WIND NORTHWEST 20 TO 30 MPH. A WIND ADVISORY IS IN EFFECT FOR AREA LAKES.

If the advisory is expected to carry over into only a small part of the next period, a time of expiration can be added, e.g., "A WIND ADVISORY IS IN EFFECT FOR AREA LAKES UNTIL 700 PM." The statement would not need to be repeated in the TONIGHT period.

12.2 Hazardous Wind Chill. WSOM Chapter C-42, Winter Storms, contains the basic information and guidelines on this subject. The zones/local forecasts are the most effective means to alert the public to significant or hazardous low temperatures accentuated by strong wind. As a general rule, the actual wind chill values will not be placed in the body of the forecast. A plethora of numbers (i.e., probabilities, temperatures, wind chill values) would only confuse the user. Minimum wind chill values may be included in a headline to the actual forecast as well as in the headlines or body of special or severe weather statements. Narrative word descriptions of the expected minimum wind chill should be used in the body of the forecast to preface the actual temperature forecast, such as:

For a 15 below wind chill: "BITTERLY COLD WITH LOW AROUND 5 ABOVE. WIND.." etc.

For a 40 to 60 below wind chill: "EXTREMELY/DANGEROUSLY COLD WITH LOW 5 BELOW TO 10 BELOW. WIND..." etc.
 

ALABAMA		CALIFORNIA
Birmingham	BIAL	Bakersfield	BACA
Huntsville	HUAL	Bishop	BICA
Mobile	MOAL	Crescent City	CCCA
Montgomery	MNAL	Eureka	EUCA
		Fresno	FRCA
ALASKA		Los Angeles	LACA
Anchorage	ANAK	Mt. Shasta	MSCA
Barrow	BAAK	Red Bluff	SACA
Fairbanks	FAAK	San Bernardino Valley	SBCA
Glenallen	GLAK	San Diego	SDCA
Haines	HAAK	San Fernando Valley	SNCA
Homer	HOAK	San Francisco	SFCA
Kenai	KEAK	San Gabriel Valley	SGCA
Ketchikan	KTAK	San Jose	SJCA
Kodiak	KDAK	Santa Maria	SMCA
Kotzebue	KOAK	Stockton	STCA
Juneau	JUAK
McGrath	MCAK	COLORADO
Nome	NOAK	Alamosa	ALCO
Palmer	PAAK	Colorado Springs	CSCO
Petersburg	PEAK	Denver	DECO
Seward	SEAK	Grand Junction	GJCO
Sitka	SIAK	Limon	LMCO
Skagway	SKAK	Pueblo	PUCO
Talkeetna	TAAK
Valdez	VAAK	CONNECTICUT
Willow	WIAK	Bridgeport	BRCT
Wrangell	WRAK	Hartford	HACT
Yakutat	YAAK
		DELAWARE
ARIZONA		Wilmington	WLDE
Flagstaff			FLAZ
Phoenix	PHAZ	FLORIDA
Sedona	SDAZ	Apalachicola	APFL
Tucson	TUAZ	Daytona Beach	DBFL
Winslow	WIAZ	Ft. Myers	FMFL
Yuma	YUAZ	Jacksonville	JAFL
		Key West	KWFL
ARKANSAS		Miami	MIFL
Ft. Smith	FSAR	Orlando	ORFL
Little Rock	LRAR	Pensacola	PEFL
		Tallahassee	TAFL

FLORIDA		KANSAS
Tampa	TMFL	Concordia	COKS
West Palm Beach	PBFL	Dodge City	DCKS
		Goodland	GOKS
GEORGIA		Topeka	TOKS
Athens	ATGA	Wichita	WIKS
Atlanta	ALGA
Augusta	AUGA	KENTUCKY
Columbus	COGA	Jackson	JAKY
Macon	MAGA	Lexington	LEKY
Rome	ROGA	Louisviile	LOKY
Savannah	SAGA	Paducah	PAKY
HAWAII		LOUISIANA
Develop as needed		Alexandria	ALLA
		Baton Rouge	BRLA
IDAHO		Lake Charles	NOLA
Boise	BOID	New Orleans	NOLA
Lewiston	LEID	Shreveport	SHLA
Pocatello	POID
Twin Falls	TFID	MAINE
		Caribou	CRME
ILLINOIS		Portland	POME
Cairo	CAIL
Chicago	CHIL	MARYLAND
Moline	MLIL	Baltimore	BAMD
Peoria	PEIL
Rockford	ROIL	MASSACHUSETTS
Salem	SLIL	Boston	BOMA
Springfield	SPIL	Worcester	WOMA
INDIANA		MICHIGAN
Evansville	EVIN	Alpena	ALMI
Ft. Wayne	FWIN	Detroit	DEMI
Indianapolis	ININ	Flint	FLMI
South Bend	SBIN	Grand Rapids	GRMI
		Houghton Lake	HLMI
IOWA		Lansing	LAMI
Des Moines	DMIA	Marquette	MAMI
Dubuque	DUIA	Muskegon	MUMI
Sioux City	SCIA	Sault Ste Marie	SSMI
Waterloo	WAIA
MINNESOTA		NEW HAMPSHIRE
Duluth	DLMN	Concord	CONH
International Falls	IFMN
Minneapolis/St. Paul	MSMN	NEW JERSEY
Rochester	RSMN	Atlantic City	ACNJ
St. Cloud	SCMN	Newark	NENJ
		Trenton	TRNJ
MISSISSIPPI
Jackson	JAMS	NEW MEXICO
Meridian	MZMS	Albuquerque	ALNM
Tupelo	TPMS	Clayton	CLNM
		Roswell	RONM
MISSOURI
Columbia	COMO	NEW YORK
Kansas City	KCMO	Albany	ALNY
St. Louis	SLMO	Binghamton	BINY
St. Joseph	SJMO	Buffalo	BUNY
Springfield	SPMO	New York	NYNY
		Rochester	RCNY
MONTANA		Syracuse	SYNY
Billings	BIMT
Glasgow	GLMT	NORTH CAROLINA
Great Falls	GFMT	Asheville	ASNC
Havre	HAMT	Charlotte	CANC
Helena	HEMT	Greensboro	GRNC
Kalispell	KAMT	Raleigh	RANC
Livingston	LVMT	Wilmington	WINC
Missoula	MIMT	Cape Hatteras	CHNC
Red Lodge	RDMT
		NORTH DAKOTA
NEBRASKA		Bismarck	BIND
Grand Island	GINE	Fargo	FAND
Lincoln	LNNE	Williston	WLND
Norfolk	NRNE
North Platte	NPNE	OHIO
Omaha	OMNE	Akron	AKOH
Scottsbluff	SCNE	Cincinnati	CIOH
Valentine	VLNE	Cleveland	CLOH
		Columbus	COOH
NEVADA		Dayton	DAOH
Elko	ELNV	Mansfield	MAOH
Ely	EYNV	Toledo	TOOH
Las Vegas	LVNV	Youngstown	YOOH
Reno	RENV
Winnemucca	WINV

OKLAHOMA		TEXAS
Oklahoma City	OCOK	Abilene	ABTX
Tulsa	TUOK	Amarillo	AMTX
		Austin	AUTX
OREGON		Brownsville	BRTX
Astoria	ASOR	Corpus Christi	CCTX
Burns	BUOR	Dallas	DFTX
Eugene	EUOR	Del Rio	DRTX
Klamath Falls	KFOR	El Paso	EPTX
Medford	MDOR	Ft. Worth	DFTX
Pendleton	PEOR	Galveston	GATX
Portland	PROR	Houston	HOTX
Roseburg	RBOR	Lubbock	LUTX
Salem	SAOR	Midland	MITX
		Port Arthur	PATX
PENNSYLVANIA		San Angelo	SJTX
Allentown	ALPA	San Antonio	SATX
Erie	ERPA	Victoria	VITX
Harrisburg	HAPA	Waco	WATX
Philadelphia	PHPA	Wichita Falls	WFTX
Pittsburgh	PIPA
Wilkes-Barre/ Scranton	WSPA	UTAH
Williamsport	WIPA	Milford	MIUT
		Salt Lake City	SCUT
RHODE ISLAND
Providence	PRRI	VERMONT
		Burlington	BUVT
SOUTH CAROLINA
Charleston	CHSC	VIRGINIA
Columbia	COSC	Lynchburg	LYVA
Greenville- Spartanburg	GSSC	Norfolk	NOVA
		Richmond	RIVA
SOUTH DAKOTA		Roanoke	ROVA
Aberdeen	ABSD	(District of Columbia)	DC01
Huron	HUSD
Rapid City	RCSD	WASHINGTON
Sioux Falls	SFSD	Olympia	OLWA
		Seattle	WA01
TENNESSEE		Spokane	SKWA
Bristol	BRTN	Walla Walla	WWWA
Chattanooga	CHTN	Wenatchee	WEWA
Knoxville	KNTN	Yakima	YAWA
Memphis	METN
Nashville	NATN

WEST VIRGINIA
Beckley	BEWV
Charleston	CHWV
Elkins	ELWV
Huntington	HUWV
Parkersburg	PAWV
WISCONSIN
Green Bay	GBWI
La Crosse	LAWI
Madison	MAWI
Milwaukee	MIWI
WYOMING
Casper	CAWY
Cheyenne	CHWY
Lander	LAWY
Sheridan	SHWV