October 14, 1983                                    W/OM14x2

TO:              All Holders of Operations Manual

SUBJECT:   Transmittal Memorandum for Operations Manual Issuance 83-18

1.  Material Transmitted:

ISOM Chapter C-30, Air Pollution Weather Forecasts.

2.  Summary:

The revision has several changes. The most significant are summarized below:

     a.  The Air Stagnation Advisory (ASA) is the only product issued. The Special Dispersion Statement (SDS) and the Daily Dispersion Outlook (DDO) are eliminated.

     b.  The Observational Program is 21 eliminated.

     c.  NMC no longer monitors the issuances of ASA's by WSFO's.

     d.  Termination statement now included in last ASA issued.

3.  Effect on Other instructions:

Replaces WSOM Chapter C-30, TM 75-13, dated June 19, 1975, and Revision 1 TM 75-15, dated July 16, 1975.
 
 

Richard E. Hallren
Assistant Administrator
for Weather Services
 

Issue Date Org. Code                  NATIONAL WEATHER SERVICE       Part Chap.
10-14-83   W/OM14                         Operations Manual                              C     30

     Table of Contents:

          1. Purpose

          2. Objectives

          3. Organizational Responsibilities

          4. Air Stagnation Advisory (ASA)

               4.1 Criteria for Issuance
               4.2 Content
               4.3 Coordination and Consultation
               4.4 Dissemination

          5. Episodes During Nonstagnant Situations

     Exhibits:

          C-30-1 Example of Local Air Stagnation Check Sheet
          C-30-2 Sample Air Stagnation Advisories

1.  Purpose. This chapter describes the air pollution weather forecast program and assigns organizational responsibilities.

2.  Objectives. The objectives of the air pollution weather forecast program are two-fold:

     a. To alert air pollution control agencies of meteorological conditions that may have an important impact on air quality, and

     b. To provide support to local, state, and Federal officials responsible for dealing with the accidental release (actual or potential) of toxic materials into the atmosphere.

     The air pollution weather forecast program does not include: (a) making forecasts of air quality; (b) decision-making relative to the prevention, control, or abatement of air pollution within the control agency's area of responsibility; or (c) providing specialized services to private or commercial interests.

3.  Organizational Responsibilities. Chief, Applied Services Branch, Office of Meteorology (W/OM14) is responsible for matters relative to the program at the Weather Service Headquarters (WSH) level.

Regional headquarters are responsible for the day-to-day management of the program within the region. This includes determining the level of service to be provided by individual forecast offices to air pollution control agencies. The requirement for the issuance of the air stagnation advisory (ASA) will be part of this determination.

In addition to the service for air pollution control agencies, field offices must be prepared to provide whatever assistance they can within their capabilities when dangerous contaminants could be or are accidentally released into the atmosphere. Depending upon the particular circumstances, a local, state, and Federal agency or a private interest may take charge of control or abatement efforts. Assistance may be requested from the National Weather Service (NWS) office nearest the site. If the NWS office involved is a Weather Service Office (WSO), consultation with the parent Weather Service Forecast Office (WSFO) is recommended. There may be instances where the agency leading the abatement effort is not aware of the services which we can provide. If an office becomes aware of such a situation, an attempt should be made to contact the agency involved to discuss assistance that can be provided. Overtime is authorized to provide the necessary meteorological support. The regional headquarters should be immediately notified whenever such situations develop. (See WSOM Chapter I-02).

4.  Air Stagnation Advisory (ASA). The ASA is the only air pollution product which is normally issued. Its purpose is to advise local/regional agencies of meteorological conditions which are conducive to poor dispersion.

4.1  Criteria for Issuance. The ASA, where used, is usually issued when locally established critical values of transport winds, mixing height, and ventilation are expected to persist for at least 36 hours. Use of an air stagnation check sheet is helpful in evaluating stagnation parameters. A sample of such a check sheet is shown in exhibit C-30-1. This is offered only as a general guideline. Each WSFO with an active program should tailor its check sheet to highlight those mesoscale and macroscale parameters which are considered important in the forecast area. ASA's should be issued as frequently as changing conditions dictate. With continued stagnation, a new ASA should be issued at least every 24 hours. To the extent possible, the issuance of an ASA should be timed to facilitate operations of the control agency.

4.2  Content. All ASA's should include the following information:

     (1) Title: Air Stagnation Advisory

     (2) Issuing office

     (3) Date and time of advisory

     (4) Area affected by air stagnation

     (5) Brief description of the stagnant weather situation

     (6) Estimated duration of stagnant condition (if possible)

     (7) Amplifying statement, where appropriate, on potential effects of stagnation; e.g., "as a result of stagnating air, smoke, dust, and other pollutants may tend to concentrate near the ground."

     (8) Time of issuance of next advisory or a statement indicating this is the last advisory.

Sample ASA's are shown in exhibit C-30-2.

At such time as the conditions are forecast to improve sufficiently to allow dispersion of emitted pollutants, the ASA should so indicate. Terminating the ASA will be accomplished by stating that "This will be the last advisory issued." The last ASA issued should be coordinated with the control agencies involved and should not be released until there is a definite indication of improvement in air quality.

4.3  Coordination and Consultation. As with many other weather products, the importance of coordination of ASA's with adjacent WSFO's cannot be overemphasized. Forecasters responsible for issuing ASA's should contact neighboring WSFO's whenever there is any doubt about the issuance, areal extent, or content of the advisory, or the areal extent of the stagnant conditions.

4.4  Dissemination. Normally the ASA will be given only to the air pollution control agency via telephone or a dedicated circuit.

Where the control agency requests it, NOAA Weather Wire Service and/or other available systems may be used to distribute control agency statements to the public.

5.  Episodes During Nonstagnant Situations. In some instances, pollution concentrations in a localized area may approach episodal levels even though meteorological factors are not critical. This may occur because of excessive vehicular activity, wildfires, agricultural or forestry burning, release of unusual amounts of industrial materials, or, sometimes, for unknown reasons. In such instances, the WSFO, within its capability, will provide the government agencies involved with the meteorological support necessary for pollution control or abatement procedures.

/wsom/manual/IMAGES/c301.gif
 
  

BHMASABHM

AIR STAGNATION ADVISORY
NATIONAL WEATHER SERVICE BIRMINGHAM AL
200PM CST MON NOV 15 19_

AN AIR STAGNATION ADVISORY HAS BEEN ISSUED FOR NORTHERN ALABAMA...NORTH OF A LINE FROM TUSCALOOSA TO BIRMINGHAM TO ANNISTON.

A HIGH PRESSURE SYSTEM OVER GEORGIA AND NORTHERN ALABAMA WILL REMAIN STATIONARY...OR DRIFT SLOWLY WEST...DURING THE NEXT 36 HOURS. THIS WILL CAUSE SMOKE...DUST...AND GASES TO CONCENTRATE NEAR THE GROUND...ESPECIALLY DURING THE NIGHT AND EARLY MORNING HOURS.

THE NEXT ADVISORY WILL BE ISSUED AT NOON CST TUESDAY NOVEMBER 16 19_...OR EARLIER IF NEEDED.
 
 

BHMASABHM

AIR STAGNATION ADVISORY
NATIONAL WEATHER SERVICE BIRMINGHAM AL
1100AM CDT WED MAY 21 19_

AN AIR STAGNATION ADVISORY HAS BEEN ISSUED FOR ALABAMA AND NORTHWEST FLORIDA.

A HIGH PRESSURE SYSTEM WILL REMAIN OVER THE SOUTHEASTERN STATES FOR THE NEXT TWO OR THREE DAYS...AND LITTLE CHANGE IS EXPECTED.

VERY LIGHT WINDS...AND AN EARLY MORNING TEMPERATURE INVERSION...ARE CONTRIBUTING TO THE STAGNATION. BECAUSE OF THIS...SMOKE AND GASES WILL ACCUMULATE NEAR INDUSTRIAL AREAS.

THE USUAL TEMPORARY IMPROVEMENT WILL TAKE PLACE THIS AFTERNOON BECAUSE OF HEATING...BUT A RETURN TO STAGNANT WEATHER WILL OCCUR TONIGHT.

THE NEXT ADVISORY WILL BE ISSUED AT 11AM CDT THURSDAY MAY 22 19_ OR EARLIER IF NEEDED.
 
 

Exhibit C-30-2:   Sample Air Stagnation Advisories
                                  (page 1 of 2)

SDFASASDF

AIR STAGNATION ADVISORY
NATIONAL WEATHER SERVICE LOUISVILLE KY
1100AM EDT WED OCT 10 19_

AN AIR STAGNATION ADVISORY HAS BEEN ISSUED FOR EASTERN KENTUCKY.

THE NATIONAL WEATHER SERVICE EXPECTS THE HIGH PRESSURE SYSTEM OVER THE MID ATLANTIC COAST TO REMAIN STATIONARY FOR THE NEXT 24 HOURS. THIS WILL RESULT IN POOR ATMOSPHERIC DISPERSION OVER EASTERN KENTUCKY... DAYTIME HEATING WILL IMPROVE THE ATMOSPHERIC DISPERSION A LITTLE...BUT LIGHT WINDS WILL PREVENT ANY OVERALL CHANGE.

THE NEXT ADVISORY WILL BE ISSUED AT 11AM EDT THURSDAY OCTOBER 11 19_.
 
 

CRWASACRW

AIR STAGNATION ADVISORY
NATIONAL WEATHER SERVICE CHARLESTON WV
1200 NOON EDT WED OCT 10 19_

THE AIR STAGNATION ADVISORY FOP ALL OF WEST VIRGINIA IS BEING EXTENDED UNTIL NOON THURSDAY...EDT.

THE HIGH PRESSURE SYSTEM RESPONSIBLE FOR THE STAGNANT CONDITIONS WILL NOT SHIFT MUCH DURING THE NEXT 36 HOURS AND LITTLE CHANGE IS EXPECTED IN THE WINDS.

BECAUSE OF LIGHT WINDS AND LIMITED MIXING...SMOKE...DUST...AND GASES WILL TEND TO CONCENTRATE NEAR THE GROUND. THIS WILL BE MOST NOTICEABLE IN INDUSTRIAL AREAS AND IN THE VALLEYS.

SIGNIFICANT RAINFALL AND STRONGER WINDS MAY NOT DEVELOP OVER WEST VIRGINIA UNTIL LATE SATURDAY...WHEN THE FRONTAL SYSTEM NOW IN THE PLAINS MOVES EAST.

THE NEXT ADVISORY WILL BE ISSUED AT 12 NOON EDT THURSDAY OCTOBER 11...OR SOONER IF NEEDED.

Exhibit C-30-2:   Sample Air Stagnation Advisories
                                   (page -2 of 2)

WSOM Issuance
83-18 10-14-83