Post on 31-Dec-2015
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