The representative conducting the certification visit will ensure that instruments used by the SAWRS meet or exceed the following minimum standards:

A) Cloud Height:

Determined by using balloons for daylight operation and by a ceiling light for night operation. A ceiling light should be installed with a baseline of at least 300 feet. A 500 foot baseline is the recommended standard. Either of the following systems will suffice for the measurement of nighttime cloud height when used with a standard clinometer:

1. a) A standard ceiling light (Lamp 1 each/1 spare) or, b) an improvised ceiling light, approved by the National Weather Service, which will provide an identifiable spot of light on clouds 2000 feet above field elevation or on clouds below VFR field minimums whichever is higher.

Clinometer: (1 each)

Used with a ceiling light in taking cloud-height measurements. Must have capability for indicating elevation angles above the horizon within 1�. Cloud Height Tables for ceiling lights are prepared by NWS.

2. Ceiling Balloons: (100 each)

Are classified according to their weight in grams. For use as a ceiling balloon, the 10-gram balloon is considered standard.

Helium: (2 tanks)

For inflating ceiling balloons. Also required for inflating ceiling balloons is Inflation Kit, consisting of:

• Nozzle, helium for 10 gram balloons (10 gram weight)
• Adapter
• Regulator - helium single stage
• Tubing, inflation, rubber ¼" ID, 6' long w/fittings
• Tubing, inflation, gum rubber ?" ID, 3' long
• Connector, inflation tubing, brass for ?" rubber tubing

Stop Watch: (1 each)

Used in timing ceiling balloons.

B) Temperatures:

Temperature and dew point values shall be obtained from approved thermometers mounted to a sling psychrometer located in a small airways type shelter. This is a white louvered box over sod or earth characteristic of the general area.

1. Thermometers: (2 each/psychrometric thermometers 2 each (if dew point required).

Liquid-in-glass thermometers are the usual temperature sensors used by SAWRS. Thermometers must be etched in 1·F graduations, and be accurate to at least ±1·F throughout the thermometer's temperature range. Thermometers paired for a psychrometer should read within ±0.5·F of each other under like conditions.

2. Shelter, small airways type: (1 each)

This is a louvered shelter installed over sod or earth characteristic of the general area. Where possible such shelters are to be installed at least 100 feet from any concrete or other hard-surface area, and not closer to any other object than four times the height of the object above the floor of the shelter. The shelter should be installed approximately 4 feet above the ground with the opening to the north. Roof installations should be avoided wherever possible. However, where it is necessary to locate the shelter on a roof every effort should be made to ensure that it is at least 30 feet from any exhaust fans or cooling towers or large vertical reflecting surfaces. Alternatively, sling psychrometer stored inside between observations is also acceptable.

Aspirator, hand driven or electric can be installed in shelter. Hand driven aspirators require at least a medium size shelter. Not suitable for use in the airway type shelter.

3. Wicking: (2 feet)

Needed only if dew point required.

4. Psychometric Calculator or tables: (1 each)

Used for computing dew point from a determined wet bulb and dry bulb reading. Only needed if dew point temperature is required.

C) Wind Equipment: (1 each)

With respect to wind speed, values indicated by the indicator should be within 10% of the true value when the wind speed is less than 100 knots. With respect to direction, the indicator must indicate within 10· of the true wind flow. The readouts should indicate direction within 10· of the true wind flow and the speed to the nearest knot. The sensors should be installed so that the distance to any obstruction is at least 10 times the height of the obstructions above the elevation of the ground on which the wind sensor is located. Ideally, the sensors should be installed at a height of 30 feet above nearby portions of the runway. However, any installation providing unobstructed exposure is acceptable.

D) Altimeter: (2 each)

Selection, calibration, installation, and setting of altimeters shall be in accordance with FAA Advisory Circular 91-14, current edition, (see attachment D). Some common pressure-measuring instruments are: Precision Aneroid, Altimeter Setting Indicator (ASI), Digital Altimeter Setting Indicator (DASI), or two Aircraft-type Altimeters.

E) Visibility Charts: (2 each)

Charts are available from NWS. Two scales: 0-3 and 0-25 miles. Shows location of your visibility markers.

F) Station Clock: (1 each)

For time checks. Should have second hand.

When calling the NWS supervising office representative for his certification visit you are in reality saying to him, "we are ready to start taking observations right now, just give us the word." What does this require of you in order to be "ready"?

FIRST: Recommended equipment installed. (adequate amounts shown with "Recommended Equipment")

1. Wind equipment installed, reading according to "true" directions, not magnetic); exposure of the speed and direction transmitters is satisfactory enough to get an accurate reading of the winds. Not mounted between buildings or other obstructions.
2. Instrument shelter installed, (white louvered box); not on station somewhere, in storage, or on the way. Properly oriented (door faces north). Exposure satisfactory; not near heat, air conditioner or exhaust vents. Thermometers in the shelter and ready for use. Adequate Supplies and easily accessible, i.e., thermometers and wicking.
3. Helium and ceiling balloons in adequate amounts, not waiting to be delivered. Weights, hoses, balloon timer and regulator available; not in storage, but easily accessed.
4. If aircraft-type altimeters are to be used, two are required; calibrated by an FAA approved instrument repair station within 30 days prior to installation or retention as a spare. Calibration correction cards with altimeters. Altimeters mounted and protected from direct sunlight and rapid temperatures changes.
5. Suitable quarters for recording observations includes desk to write on with drawers to keep SAWRS supplies, i.e., spare thermometers, wicking, MF1M-10Cs, carbons, balloons, balloon timer, spare lamp for ceiling light, etc. Generally this will be in the same room where altimeters and wind speed and direction indicators are located.
6. Station clock for time checks. This should have a second hand or give the seconds. A source that can be used for time checks is by calling: 303-499-7111

SECOND: Visibility Charts, prepared and available at the station before the certification visit. The National Weather Service representative can assist in preparing these charts prior to his certification visit. This should not be put off until the day of the visit.

THIRD: Observers have demonstrated proficiency in taking and recording of aviation observations and successfully passed observation examination. Observers's certificates are to be on readily accessible at the station.

By complying with these requirements your station will be ready for certification and you will avoid any delays in the certification process.

A SAWRS site will be terminated if that SAWRS site has a commissioned ASOS. The former SAWRS site can apply for certification as a SAWRS-II site. SAWRS-II may be established when the cooperator agrees to provide certified observers and equipment, and meets all other provisions contained within an amended WS Form B-12.

SAWRS-II cooperators must have at a Minimum the following equipment available in order to conduct backup operations.

1) Aircraft-type Altimeters: (2 each)

These are compared against each other at each observation.

2) Sling Psychrometer: (thermometers-2 each/psychrometric thermometers-2 each)

To determine dry bulb and wet bulb readings.

3) Psychometric Calculator or Tables: (1 each)

For computing dew point from dry bulb and wet bulb readings.

4) Visibility Charts: (2 each)

Two scales : 0-3 and 0-25 statute miles. Shows location of your visibility markers.

The equipment requirements apply specifically towards ASOS sites. Sky Condition, Present Weather, and Wind are elements that do not require backup equipment, and can be visually determined or estimated.

Upon establishment, the National Weather Service considers each SAWRS as an approved source of official aviation weather observations. Thereafter, the National Weather Service will perform quality control and assistance visits to assure that equipment and observing standards are being maintained.

A SAWRS will be inspected by a representative of the Southern Region Headquarters or by the supervising station. The purpose of these inspections is to:

1. Determine whether the observational program is being conducted in accordance with standards outlined in the current NWS handbook.
2. Inspect the installation, maintenance, and exposure of meteorological instruments.
3. Explain NWS policies and procedures as they apply to the station.
4. Assist in matters relative to the station weather observing program.
5. Oral review and practice examinations will be administered at the discretion of the inspecting official.

The conditions listed below are considered unsatisfactory. If any of these conditions are found to exist, the cooperator must rectify the condition by the grace period specified; otherwise, the National Weather Service is obliged, in the interest of aviation and public safety, to immediately terminate the SAWRS agreement.