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Lake Superior. North Shore Climate. Jim Zandlo State Climatology Office DNR-Waters 2006. Superior Climate. 2005-06 snow season Dry summer, low lake. Superior Climate. 2005-06 snow season More-or-less ‘normal’ precipitation spring runoff was (probably) more-or-less ‘normal’

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lake superior

Lake Superior

North Shore Climate

Jim Zandlo

State Climatology Office

DNR-Waters 2006

superior climate
Superior Climate
  • 2005-06 snow season
  • Dry summer, low lake
superior climate1
Superior Climate
  • 2005-06 snow season
    • More-or-less ‘normal’ precipitation
      • spring runoff was (probably) more-or-less ‘normal’
    • Snowfall pattern very similar to 4-year SnowRules! result
    • climate.umn.edu/SnowRules then click on 2005-06 map
superior climate2
Superior Climate
  • 2005-06 snow season
    • Snowfall transect updated
      • Fraction of median (was fraction of max)
      • Log-of-distance spreads out values close to Lake Superior
    • climate.umn.edu/SnowRules then click on 2005-06 map
superior climate3
Superior Climate
  • 2005-06 snow season
  • Dry summer
    • Low Lake Superior
    • Basic hydrology
      • GLERL time series
superior climate4
Superior Climate
  • 2005-06 snow season
  • Dry summer
    • Near record low water levels (1925-26) on Lake Superior
    • Basic hydrology
      • Summer is primary recharge period for Lake Superior
      • GLERL time series
  • What happens next?
lake level
Lake Level:

A range of almost 4 feet in the observational record.

slide18

Basic Lake Hydrology

Lake level =

old lake level

+ precipitation on lake

+ runoff from surrounding land (flow in)

-lake evaporation

- flow out at outlet (Sault Saint Marie, MI)

+/-groundwater flow

slide19

Geography and General Hydrology

  • large, ‘state-sized’ watershed
  • ‘narrow’ along American shore
slide21

Water coming in …

Runoff 37%

Diversion 4%

Deposition 0.2%

Evaporation 43%

Precipitation 59%

on lake

St. Mary’s River 57%

…must go out

(most of the time)

slide22

Water coming in …

Runoff 1.8 ft

Runoff 1.7 ft

Precipitation 3.1 ft

Diversion 0.2 ft

Deposition 0.2%

Precipitation 2.7 ft

Year ending 11/1985

had 10% more water

…varies

Runoff 1.1 ft

Precipitation 2.6 ft

Year ending Feb 2001 had 15% less water

slide23

Water coming in …

Runoff 1.8 ft

Runoff 1.7 ft

Precipitation 3.1 ft

Diversion 0.2 ft

Deposition 0.2%

Precipitation 2.7 ft

Year ending 11/1985

had 10% more water

…varies

Runoff 1.1 ft

Precipitation 2.6 ft

Year ending Feb 2001 had 15% less water

slide24

Water coming in …

Runoff 1.8 ft

Runoff 1.7 ft

Precipitation 3.1 ft

Diversion 0.2 ft

Deposition 0.2%

Precipitation 2.7 ft

Year ending 11/1985

had 10% more water

…varies

Runoff 1.1 ft

Precipitation 2.6 ft

Year ending Feb 2001 had 15% less water

slide28

Lake Superior evaporation …

is not the same as evapotranspiration from nearby land surfaces

slide29

NOAA Buoys

  • meteorological parameters
  • sea measurement
    • wave info
    • water temperature
  • -
lake evaporation equation
Lake Evaporation equation
  • Evaporation = factor * D
    • ‘factor’ varies with weather, surface conditions, etc.
    • ‘D’ is the difference in vapor pressure between two different air masses
  • If this year’s atmospheric humidity was essentially ‘normal’ (don’t know yet) then using the above equation, evap would have been about 0.5 foot more than ‘normal’ this Aug-Oct.
lake evaporation equation1
Lake Evaporation equation
  • September water at

9+°F ’above normal’has cooled to a little more than 5+°F by Oct 23. The water will tend toward 32°F (and be ‘more normal’) as winter progresses.

  • If water temperature becomes ‘normal’ by mid-winter, an additional

0.2 feet or more than ‘normal’can be expected to evaporate from the lake this winter.

lake level1

Where will it actually end up?

Lake Level:

A range of almost 4 feet in the observational record.

slide35

Winter 2006-07 Outlook

(a strong ‘el nino’ influence)

lake superior1

Lake Superior

North Shore Climate

(thermochrons)

Jim Zandlo

State Climatology Office

DNR-Waters 2006

thermochrons transects
Thermochrons, transects

Thermochrons, the dime sized devices that measure and store thousands of temperatures, are being used throughout the SnowRules! study area to gather temperatures where the snow falls, namely on snowboards. They are also being used to get air and water temperatures at a few other locations. See the data at climate.umn.edu/SnowRules

slide40

f

° F at 5/28/2006 12:00

superior climate5
Superior Climate
  • 2005-06 snow season
  • Dry summer
    • Near record low water levels (1925-26) on Lake Superior
    • Basic hydrology
      • Summer is primary recharge period for Lake Superior
      • GLERL time series
  • What happens next?
lake level2
Lake Level:

A range of almost 4 feet in the observational record.

superior climate6
Superior Climate
  • Geography and Hydrology
  • Summarizing the observations
    • Normal Temperature
    • Satellite-based measurements
    • Is it ‘elevation’ or ‘the lake’
    • Normal Precipitation
    • Snowfall patterns
    • Temperature versus snow
great lakes hydrology climate
Great Lakes Hydrology (climate)
  • Basin maps: limited detail
  • Balance of incoming/outgoing
    • Superior evaporation smaller fraction of precipitation than other great lakes
  • Lake levels are ‘integrator’
slide52

Cold!

Cool

Dry

evapo transpiration
Evapo-transpiration

Evapo-transpi-ration

lake level3
Lake Level:

A range of almost 4 feet in the observational record.

hydrology is forced by climate
Hydrologyis ‘forced’ by climate
  • How do patterns arise?
    • ‘weather patterns’
    • cool/warm water nearby
    • topography
      • (Water flows downhill)
      • topo temp evap runoff
    • All the above interacting (!)
  • What do patterns of ‘climate’ variables look like?
wind winter transect
Wind – winter transect
  • Inland: mostly N-NW or S-SW
  • Shore: strong tendency to ‘follow’
  • Can transport air masses across the shoreline

Hibbing Grand Marais airport Grand Marais shore

wind winter along shore
Wind – winter along shore
  • ‘Everywhere’ along shore has strong tendency for ‘along shore’ winds in winter

Two Harbors Silver Bay Grand Marais shore

wind seasons at grand marais
Wind – seasons at Grand Marais

Tendency to be ‘along shore’ less in summer

normal temperature
Normal Temperature
  • Biggest near shore influences near equinoxes
    • Land near seasonal extremes
    • Lake ‘lags’ land by a month or two
  • Detail limited by 25-mile NWS observer spacing

winter(DJF) spring(MAM) summer(JJA) fall(SON)

satellite based ice observations
Most of Minnesota averages less than 2 months.

Much of north shore not until Feb

‘ice out’ by early to mid-March

Satellite-based ice observations
slide64

20 years of buoy data at red circle. No mid-winter buoy data is available.

Commonly open water in mid-winter means a large wet surface near 32 degrees is often near the north shore anytime during winter.

land versus sea
Land versus ‘sea’

Two Harbors and Grand Marais temps ‘buoyed up’ in winter, ‘anchored’ to lower values in summer.

Water maximum lags land maximum.

land versus sea1
Land versus ‘sea’

Land versus ‘sea’

Shore virtually identical in winter to MSP 150 miles south!

At Babbitt about 6 F cooler than MSP year-round.

slide67

Temperature is also affected by elevation. Some of the steepest gradients of the Great Lakes are along Minnesota’s north shore.

thermochrons transects1
Thermochrons, transects

Thermochrons are dime sized devices that measure and store thousands of temperatures. A contact sensor is later used to download the data.

normal precipitation
Normal Precipitation
  • Everywhere in Minnesota…
    • Summer is wettest
    • Winter is driest
  • North shore ‘bands’ most apparent fall, winter
    • Warmer lake provides energy and moisture

winter(DJF) spring(MAM) summer(JJA) fall(SON)