Impacts of "Normal" Climate
Specific features of the "normal" Newfoundland and Labrador climate
can be either positive (beneficial), or negative (cause difficulties).
Positive features
(1) Potentially damaging or life-threatening thunderstorms,
accompanied by frequent lightning, hail, torrential rain,
severe wind gusts and possibly tornadoes occur very infrequently
over interior sections of the island and Labrador. Together with the low population density,
this means a low risk or probability of injury or death, or significant costly
damages, arising from such storms.
(2) Over southern and southeastern Newfoundland winters are relatively mild
(prolonged low temperatures < -15°C are rare) and of
shorter duration compared with northern parts of the island and Labrador. This means
reduced indoor heating demand, and lower fuel or power costs for domestic, commercial and
industrial users, a significant proportion of whom are located in southeastern Newfoundland.
Negative features
(1) From late fall through early spring, a high frequency of temperature
fluctuations above and below 0°C (freeze-thaw cycles) is characteristic of
southern and southeastern parts of the island. Such temperature oscillations are
often accompanied by precipitation changing between frozen and liquid forms. As a
result, road surfaces deteriorate due to repeated expansion and contraction in the
presence of water or ice. Repairs are needed more often than would be the case
under a more stable and drier winter climate. Similar problems may affect building
walls and roofing materials, if not properly designed, selected or maintained.
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Potholes, Torbay Road (left) and Rennie's Mill Road (right), St. John's.
Potholes are a common sight on Newfoundland roads and streets, despite
repeated efforts by maintenance crews to repair them.
Reproduced by permission of the Newfoundland and Labrador
Heritage Web Site Project. © 2000.
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(2) Storm force winds (sustained velocity above 70 km/hr, with gusts well over
100 km/hr) accompany the most intense cyclones that pass over or near the island
and southeastern Labrador numerous times each year, especially in winter. Such
winds constitute a potential hazard to highway traffic, particularly if road
surface conditions and visibility are also impaired.
Wreckhouse area, Codroy Valley.
Valleys cut through the Long Range Mountains funnelling violent,
gusty winds capable of overturning transport trucks.
Reproduced by permission of Geological Survey of Canada, Natural
Resources Canada. ©1987.
with more information
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Velocities may be further strengthened by the local terrain, as in the case of
the well-known southeasterly downslope winds at Wreckhouse, near the Codroy Valley,
which have caused many accidents and delays over the years. Such potential highway
hazards require suitable warning procedures to be in place. There is also a risk of
property damage from trees uprooted or snapped by severe winds, as was the case at
St. John's on October 6-7th, 1992; in this case a combination of saturated soils and
heavy fall foliage on deciduous trees contributed to the damage.
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Wind damage to deciduous trees, St. John's, October 1992.
Reproduced by permission of Carole Anne Coffey. ©1992.
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In addition, marine
transportation is occasionally hindered by the combination of high winds and sea state,
particularly during the precise manoeuvring required near a dock. Ferry schedules
requiring short turnaround intervals are especially vulnerable to the most inclement wind and sea
state conditions, which are most probable during the period from November though March.
(3) During periods of freezing rain or drizzle in winter and early spring, the accumulation of
clear glaze ice (ice accretion) on exposed surfaces can result in difficult or hazardous driving
and walking conditions, interruptions to electrical power supply due to icing of transmission
system components, and the need to de-ice aircraft at terminals.
Ice accretion from freezing rain.
Often referred to colloquially as "glitter", "glaze" or "silver thaw".
Reproduced by permission of Ben Hansen.
From Ben Hansen, Newfoundland Gems (St. John's, Newfoundland: Vinland Press, ©1996).
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Ice
accretion is most frequent over eastern coastal sections of the island, where the average annual
duration is at least four times as great as over western Newfoundland and in Labrador. In most
years the individual occurrences are fairly brief (3-8 hours), with the amount of ice build-up
creating only temporary inconvenience, relatively few instances of personal accident and injury
and limited power failures. Much more serious consequences arise from prolonged episodes of
freezing precipitation.
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Ice Accretion on Power Grid Sub-Station.
Newfoundland Hydro sub-station, Mt. Scio Rd., St. John's, spring 1995.
Reproduced by permission of Colin Banfield. ©1995.
with more information (28 kb).
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(4) Periods of heavy windblown snow (blizzards) pose a threat to personal safety outdoors
and on isolated highways, during situations involving extended, inadequately protected human
exposure to such conditions, especially when accompanied by air temperatures well below
freezing. Restrictions on movement increase the
risk of frostbite and hypothermia. Blizzards may occur in any part of the
province from late fall through early spring, though the probability is relatively high, on average,
over topographically exposed parts of the northeast and west coasts of the island and coastal
Labrador.
©2000, Newfoundland and Labrador Heritage Web Site Project
