1 / 17

Spring Flood Outlook

Spring Flood Outlook. National Weather Service Chanhassen - Twin Cities North Central River Forecast Center. March 6, 2014 craig.schmidt@noaa.gov 952-368-2542. Summary Up Front. Overall, the spring flood threat west of the Mississippi remains near or below historical average

aimee-william
Download Presentation

Spring Flood Outlook

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Spring Flood Outlook National Weather Service Chanhassen - Twin Cities North Central River Forecast Center March 6, 2014 craig.schmidt@noaa.gov 952-368-2542

  2. 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

  3. Background: Precipitationsince last briefing (Feb 19) Since last outlook: added .50 – 1.0 inch of water to the snowpack Almost no melting

  4. 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 Shown as percent of normal precipitation Source of map: Regional Climate Centers

  5. 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

  6. 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

  7. 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

  8. Weather Outlook8–14 Days • Temperatures: likely below normal, somewhat moderate • Precipitation: No clear signal

  9. Weather Outlook90 days – March through May Temps: Likely below normal through the spring Precipitation (not shown): no clear indication of above or below normal

  10. Other Factors 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

  11. Flood OutlookMar-Apr-May 2014 • Orange: 50% or greater chance of minor flooding • Red: 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) Forecasts take into account all current conditions, 7-day forecast weather, and climatological normals for the remainder of the spring.

  12. Flood Outlook – Durand WI 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.

  13. Flood Outlook – Fall Creek 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.

  14. Flood Outlook – Stillwater MN 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.

  15. Threat Factors Main 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.

  16. 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

  17. 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

More Related