National Weather Service Chanhassen - Twin Cities North Central River Forecast Center

SPRING FLOOD OUTLOOK

March 6, 2014craig.schmidt@noaa.gov952-368-2542

Summary Up Front• Overall, the spring flood threat west of the Mississippi remains near or below historical average• East of the Mississippi, the St. Croix, Chippewa and Eau Claire basins have a higher probability of flooding (50-60%)• Due to higher water content in the snowpack over

WI/northeast MN

• As always…the true threat lies in how the spring temperatures and rainfall hit us – currently, long range models show a good likelihood of below normal temperatures and rainfall

Background: Precipitationsince last briefing (Feb 19)

Since last outlook: added .50 – 1.0 inch of water to the snowpack

Almost no melting

Background: PrecipitationLast 30 Days

About 1 to 2 inches of water equivalent has fallen over eastern MN/ WI during the last 30 days

Less than one inch in western MN

Source of map: Regional Climate Centers

Shown as percent of normal precipitation

Background: PrecipitationDec/Jan/Feb Percent of Normal

Winter precipitation has been well above normal north and east of MSP (4 to 7 inches)

Below normal over western MN (1 to 3 inches)

Source of map: Regional Climate Centers

Background: PrecipitationSnow Water Equivalent (SWE)

SWE on the ground:•< 2 in. west and southwest• 3-4.5 in. MSP area• 4-6 in. WI portion

Background: PrecipitationSnow Water Equivalent (SWE) Ranking

Summary of graphic: SWE falls in the middle of those observed (30-70 percent) over the past 60+ years for much of our area Some basins in western/northern WI and northern MN near the most seen in 60+ years

Weather Outlook8–14 Days

• Temperatures: likely below normal, somewhat moderate• Precipitation: No clear signal

Temps: Likely below normal through the spring

Precipitation (not shown): no clear indication of above or below normal

Weather Outlook90 days – March through May

Soil Moisture: Near to below normal over most of area, but higher than last year at this time

Frost Depth: Generally 20 to 40 inches over the area, except well below 6-8 feet under pavement. Depth is greatest where snowpack is light or bare ground, shallower where snowpack has insulated the ground

River Ice: Thick layers of ice on most rivers; breakup jams will be a concern

Other Factors

Orange: 50% or greater chance of minor floodingRed: 50% or greater chance of moderate flooding (none in MPX area)In MPX area …the main threats are:• Chippewa at

Durand• Eau Claire at Fall

Creek • St. Croix at

Stillwater • Minnesota at

Savage (backwater from the Miss. R.)

Flood threat is greater in the Red River of the North (but fairly typical)

Flood OutlookMar-Apr-May 2014

Forecasts take into account all current conditions, 7-day forecast weather, and climatological normals for the remainder of the spring.

Black Line is current forecast: shows about a 75 percent chance of minor flooding, compared to about 50 percent chance in a normal year (blue line). About a 35 percent chance of moderate flooding, compared to 15 in a normal year.

Flood Outlook – Durand WI

Black Line is current forecast: shows about a 55 percent chance of minor flooding, compared to about 30 percent chance in a normal year (blue line). About a 40 percent chance of moderate flooding, compared to 15 percent in a normal year.

Flood Outlook – Fall Creek WI

Black Line is current forecast: shows about a 60 percent chance of minor flooding, compared to about 20 percent chance in a normal year (blue line). About a 40 percent chance of moderate flooding, compared to 17 percent in a normal year.

Flood Outlook – Stillwater MN

Threat FactorsMain things to watch for that would increase flood threat…• Extended period of well above normal temperatures, staying

above freezing at night• Normal highs in lower 30s early March, close to 50 by April 1• Moist air melts snow much faster than dry air, so look for

dewpoints well above freezing when the air is warm• Any major rainfall event that adds a significant amount of

water to wet snow

Things to watch for that keep the flood threat manageable…• Temps in the 30s to mid 40s, dropping below freezing at night• Below to average precipitation – light to moderate snow or

light rain is fine• Dry air – dewpoints in the teens and 20s.

Summary• Overall, spring flood threat over MPX area of responsibility is near to below historical average, but has increased slightly since late February• EXCEPTIONS are the Chippewa and Eau Claire basins in Wisconsin, and St. Croix in MN and WI• Also the lower Minnesota R around Savage due to

backwater from the Mississippi R

• As always…the true threat lies in how the spring weather unfolds

More Info?• Text version of this outlook available at• http://forecast.weather.gov/product.php?

site=NWS&product=ESF&issuedby=MSP • Weather information: • http://www.crh.noaa.gov/mpx/

• River information: • http://water.weather.gov/ahps2/

index.php?wfo=mpx

• For further information or if you have questions, please contact us at the NWS Twin Cities office• 952-361-6671 (forecaster desk, 24/7)• 952-368-2542 (Craig Schmidt, Service

Hydrologist)craig.schmidt@noaa.gov