SCIENCE ROOM
''ftSill®
. .niiir^TUWIS OF
"OKEGONS CLIMAX
FOR THE
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FOREST INDUSTRyy
CLIMATOLOGICAL NOTE NUMBER 1
April 1959
FREQUENCIES OF VARIOUS FORMS OF PRECIPITATION AND RESTRICTIONS
TO VISIBILITY AT MEDFORD, OREGON
Question: "During a given 10-day period at Medford, what is the likelihood that
visibility will be restricted by smoke and/or haze some time during
the day?"
Table:
As an example of how to read the table, look at the row of figures for
the period 1-10 January. The figures tabulated are based on the
actual observations made at Medford during the years 1948-58 and
are presented on the basis of "days per 100 days".
That is, during
the first third of January smoke and/or haze has been observed at
the rate of 61 days per 100 days, or 61%. The likelihood that smoke
and/or haze will be observed during this period on a given day in the
future, therefore, is about 6 chances in 10.
Similar interpretations can be placed on the data for other periods
and for the other weather variables shown.
The data
One must keep in mind that the data in the table summarize obser
vations made at the U. S. Weather Bureau Station at Medford
Municipal Airport. This means that, for example, sleet in the
general vicinity of Medford would not necessarily have been counted
as a day of sleet in these records. The sleet must actually have been
observed to fall at the station itself. Similarly, an observer may
not have heard a roll of distant thunder even though it did occur.
These circumstances, therefore, must be kept in mind when drawing
conclusions from or applying the data presented. Even so, the
tabulations presented will give the user a good idea of roughly when
and to what degree various weather variables may be expected to occur
in the Medford area.
William P. Lowry
Research Meteorologist
OREGON)FOREST LANDS RESEARCH CENTER
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