fss 107.1 - rules for recording precipitation; characters; intensities

The following order must be used when two or more present weather groups are required:

1. Tornado, waterspout and funnel cloud

2. Thunderstorm

3. Freezing precipitation

4. Liquid with frozen precipitation, in order of decreasing intensity

5. Obstructions to vision, in order of decreasing predominance

6. Additional phenomena

7. In the vicinity phenomena

When thunderstorms and ___________ are forecast to occur at the same time, the groups must be separated by a space, e.g. ____

freezing precipitation, TS FZRA

Do not report _____ and _______ in the same observation.

additional phenomena, in the vicinity phenomena

The occurrence of precipitation which originates aloft is recorded in ______.

the HWOS Precipitation field

The occurrence of precipitation that does not originate aloft (dew, hoar, frost, rime and glaze), if required, is recorded and reported in _______

HWOS Comment field or in Remarks

The physical states for precipitation are:

Liquid, freezing, frozen

When an observation is made during rain or drizzle with temperatures below zero degrees Celsius, ______ must be reported.

freezing precipitation

When an observation is made during rain or drizzle with temperatures near freezing, ______ must be examined.

If precipitation is freezing on it, or on other objects at or near the earth’s surface, ______ must be reported with ______ in Remarks.

the ice accretion indicator, freezing precipitation, the type of icing

At temperatures higher than _______, the branched snow crystals are generally clustered to form snowflakes.

about -5°C

What type of precipitation bounces or breaks when hitting the ground?

Snow pellets (SHGS)

What precipitation is composed of very small white and opaque grains of ice that are fairly flat or elongated?

Snow grains (SG)

Snow grains mostly fall from ____ or occasionally from fog, and never in the form of _____.

Stratus, a shower

What type of precipitation is made up of transparent or translucent pellets of ice that are spherical or irregular, and rarely conical?

Ice Pellets (PL)

Both small hail and snow pellets are coded as SHGS. When it is _____ a remark should be made to indicate _____.

small hail, the diameter of hailstones

What types of precipitation are always showery?

snow pellets and hail

Showery precipitation is associated with _____ clouds.

cumuliform

______ cannot be paired with the descriptor ‘showers’, because it does not fall from ______.

Drizzle, cumuliform cloud

Continuous or intermittent precipitation is associated with _____ clouds, except for ______ that usually fall with no cloud present.

stratiform, ice crystals

What type of precipitation must not be reported together with showery precipitation?

Drizzle and freezing drizzle

Rainfall and snowfall water equivalent must be measured in _____ starting at _____.

millimeters to the nearest tenth, 0.2 mm

Rainfall and snowfall water equivalent amounts of ______ must be reported as _____ and no rainfall or snowfall water equivalent must be reported as _____.

0.1 mm or less, TRACE, 0

Snowfall height must be measured in _____ to the nearest ___ increment starting at 0.2 cm.

centimeters, 0.2 cm

Snowfall height amounts of ______ must be reported as _____ and no snowfall must be reported as _____.

0.1 cm or less, TRACE, 0

Intensity must be indicated for the following:

• Tornadoes or waterspout (_____)

• Precipitation, _______ (light, moderate, heavy)

heavy, dust storm and sand storm

For what type of precipitation does intensity not apply?

Ice crystals

When multiple precipitation types are observed, the intensity assigned to the group must be that of the predominant precipitation type as determined by _______.

the greater intensity

The predominant precipitation of a group must be reported first within the combined report, except when ________ occurs. It must be reported as a separate group.

freezing precipitation

______ and _____ precipitation must not be reported in the same observation.

Liquid, freezing

Intensity must not be applied to precipitation associated with ____

the proximity qualifier VC

Report predominant moderate snow mixed with rain only if the prevailing visibility is ________ or heavy snow mixed with rain if the prevailing visibility is ________.

3/8 SM to ½ SM, 0 SM to ¼ SM

When occurring alone (no other precipitation and/or obstruction to vision), visibility for _____ must be defined using visibility criteria.

snow, snow showers, snow grains, snow pellets, drizzle, and freezing drizzle

The intensity of _________ is always determined by the rate-of-fall criteria.

rain (any form), hail, and ice pellets

Light intensity (visibility)

5/8 SM or more

Moderate intensity (visibility)

½ or 3/8 SM

Heavy intensity (visibility)

1/4, 1/8 or 0 SM

Light intensity (rate-of-fall for big precip)

2.5 mm/h or less

Medium intensity (rate-of-fall for big precip)

2.6 to 7.5 mm/h

Heavy intensity (rate-of-fall for big precip)

7.6 mm/h or more

When precipitation occurs together with an obstruction to vision, the intensity of the precipitation must be determined on ________. However, they must be consistent with ______.

a rate of fall basis, visibility criteria

When the intensity of ______ cannot be determined by visibility, rate of fall can be used.

Light intensity (rate-of-fall for small precip)

Less than 0.2 mm/h

Moderate intensity (rate-of-fall for small precip)

0.2 to 0.4 mm/h

Heavy intensity (rate-of-fall for small precip)

0.5 to 1.0 mm/h

When the rate of fall for liquid or freezing precipitation exceeds _____, the precipitation should be classified as rain or freezing rain rather than drizzle or freezing drizzle.

1.0 mm/h

A remark is mandatory when showers end but are expected to recommence within 15 minutes. The code _____ will be used.

OCNL

When intermittent precipitation is occurring at time of observation, INTMT is included _____, e.g. _____.

after the phenomenon, RMK -RA INTMT

When intermittent precipitation has ended but is expected to recommence within 15 minutes, INTMT is included _____, e.g. _____.

before the weather phenomena that ended, RMK INTMT -RA

The /Sss/ group for increasing depth of newly fallen snow must be reported only for the hours when the snowfall accumulated since last period equals or exceeds _____ or exceeds the previously reported value by ______.

1 cm (rounded), 1 cm (rounded)

If all the snow melts as it hits the ground, /Sss/ ____

must not be reported

The /Sss/ and /Rrr/ group is reset at the beginning of _____.

each period of precipitation amount totals

The /Rrr/ group must be reported only at the hours when the rainfall accumulated since the last period equals or exceeds _____ or exceeds the previously reported value by ______.

10 mm (rounded), 10 mm (rounded) or more