National Weather Service

Steve GohdeWFO Duluth

Observing Program Leader

Craig SchmidtWFO Twin Cities

Service Hydrologist

January 6, 2015

Island Lake Technical Committee Early Winter 2015 Meeting

Weather and Hydrologic Discussion

Weather review for mid-late 2014 (precipitation and temperatures)

Current Conditions (Snow Pack and Frost)Winter Short and Long range outlooksDrought outlook Hydrologic long range outlook for Island Lake Reservoir

Island Lake Basin

Weather and Hydrologic Discussion

Weather review for mid-late 2014 (precipitation and temperatures)

Current Conditions (Snow Pack and Frost)Winter Short and Long range outlooksDrought outlook Hydrologic long range outlook for Island Lake Reservoir

Temperatures Oct. – Dec. 2014 Duluth

•TEMPERATURE HIGHLIGHTS

• TEMPERATURES COMPARED TO NORMAL

• SEPT +1.8• OCT +1.6• NOV -7.0• DEC +6.5 • JAN BIT OF BOTH • SNOW ACCUMULATION BEGAN NOVEMBER 9THRD. MELTED TO 1” BY DECEMBER 15TH.

Precipitation at Duluth

VERY NEAR AVERAGE FOR 2014

July – Dec. Precipitation at Duluth

BELOW AVERAGE STARTING IN SEPTEMBER

July – Dec. Precipitation at Brimson

Observed Precipitation

•PRECIPITATION HIGHLIGHTS

• VERY NEAR AVERAGE FOR 2014. • ANNUAL PRECIPITATION MAY NOT BE A GOOD INDICATION OF CURRENT BASIN CONDITIONS.

• CONSIDER PRECIPITATION SINCE JULY . • DULUTH 4.04 INCHES BELOW NORMAL• BRIMSON 3.80 INCHES BELOW NORMAL.

• ABNORMALLY DRY CONDITION ON DROUGHT MONITOR

Water Year Precipitation at Duluth

Water Year Precipitation

Local ObservationsDecember thaw may have moved a portion of

melt water out of the basin. Rain on snow dramatically reduced snow depths.

Latest Snow Depths range from 3 to 6 inches in the basin. Latest storm fell mostly north of the Laurentian divide.

Frost depth is diving quickly with thin snow pack.

Precipitation – Water Year Percent of Normal(YTD, since Oct 1)

Pcpn: Much of MN well below normal so far, equating to about 1.5 to 2 inches of water

Weather and Hydrologic Discussion

Weather review for mid-late 2014 (precipitation and temperatures)

Current Conditions (Snowpack)Winter Short and Long range outlooksDrought outlook Hydrologic long range outlook for Island Lake Reservoir

Dec 5, 2014 – Snow Depth

Source: NOHRSC

Depth: 4 to 8 inches over the basin when model was run

Snow Water Equivalent (SWE) – Dec 5th

Source: NOHRSC

SWE: only up to about an inch when model was run

Source: NOHRSC

SWE: slight increase since early December

Snow Water Equivalent (SWE) – Jan 5th

Dec 31, 2014 – Snow Depth

Source: NOHRSC

Depth: 4 to 8 inches over the basin when model was run

Weather and Hydrologic Discussion

Weather review for mid-late 2013 (precipitation and temperatures)

Current Conditions (Snowpack)Winter Short and Long range outlooksDrought outlook Hydrologic long range outlook for Island Lake Reservoir

Extended Outlook – 8 to 14 Days

Temperatures: potentially milderpattern next week

Pcpn: continued below normal

http://www.cpcpara.ncep.noaa.gov/

30 Day Outlook – January 2015

http://www.cpcpara.ncep.noaa.gov/

Temperatures: Rest of Jan a littlebelow normal

Pcpn: Equal Chances

Jan, Feb, Mar 2015 Outlook

Pcpn: Equal chances Normal Precip (liquid):

• Jan -- 1 to 1.5 inches • Feb – ~1 inch • Mar – 1 to 2 inches

http://www.cpcpara.ncep.noaa.gov/

Temperatures: Equal Chances

Mar, Apr, May 2015 Outlook

Pcpn: Equal Chances Normal Precip (liquid):

• Mar 1 – 2 inches • Apr – 1.5 to ~2 inches • May – 3 to 4 inches

http://www.cpcpara.ncep.noaa.gov/

Temperatures: Equal Chances

Ocean and Atmospheric Influences on MN Weather Patterns

Conditions in the east Pacific are still considered ENSO Neutral this week, though there is a 65% chance of a weak El Nino later this winter and spring. Pacific Ocean water temperatures are expected to be about 0.5 to 1.0 degrees above normal. However, weak El Nino conditions do not have a strong signal on precipitation patterns over the upper midwest.

“Equal chances” seems about right for the upcoming winter.

Typical El Nino Precipitation

January and February – No clear signal in departure from normal

Typical El Nino Precipitation

March – No clear signal; April tends to be a little drier than normalSummer months (not shown) – mixed bag, some wetter, some drier

Environmental Canada ForecastsJan, Feb, Mar -- Precipitation

http://www.weatheroffice.gc.ca/saisons/index_e.html#forecasts

Chance of above normal pcpn to the northwest

Environmental Canada ForecastsJan, Feb, Mar -- Temperatures

http://www.weatheroffice.gc.ca/saisons/index_e.html#forecasts

Increased chances of below normal temperatures nearby

Weather and Hydrologic Discussion

Weather review for mid-late 2013 (precipitation and temperatures)

Current Conditions (Snowpack)Winter Short and Long range outlooksDrought outlook Hydrologic long range outlook for Island Lake Reservoir

Drought Information

Change from normal to D0 (abnormally dry) in the region

Drought Information

Drought outlook: Little change through the winter for our area of interest

Weather and Hydrologic Discussion

Weather review for mid-late 2013 (precipitation and temperatures)

Current Conditions (Snowpack)Winter Short and Long range outlooksDrought outlook Hydrologic long range outlook for Island Lake

Reservoir

Soil Moisture Components in Basin

• SWE -- very low, but early

• UZ (Upper layers): Little free water, tension water in the lower half of normal

• LZ (Lower layers): tension water low, free water normal

• ADI (Above ground): just below normal

Chance of Reaching Refill Demands (Normal Operating Conditions)

Summary: using “normal” condition operating rules, we have a 20-30% chance of reaching target pool level by June 1st

(vs. normal chance of 60%) Lower confidence than average

Chance of Reaching Refill Demands (Dry Operating Conditions)

Summary: using “dry” condition operating rules, we have a 65% chance of reaching target pool level by July 15th

(vs. normal chance of 80%) Close to average confidence

Summary

Precipitation – Slightly below normal for the past 6 months Temperatures – Temperatures have been around normal.Drought / Soil Conditions– Slight degradation to D0Short Range outlook (Jan) – Nothing spectacular either wayLonger Range – No strong indicators to forecast above or below

normal temperatures or precipitationHydrologic Outlook – Confidence is lower than average for

successful fill in normal (20-30%) operating conditions; much more confident (65%) at dry operating conditions