Tuesday, April 07, 2009

Favourable weather eases flood threat over southern MB.. flooding still causing travel problems

Dry and cool weather over southern MB has eased the flood threat over the Red River valley, with levels now expected to peak near 2006 levels (around 4th or 5th highest). Sunny skies with temperatures just above freezing during the day and below freezing at night is causing a gradual snow melt, which is exactly what was needed in light of the high flood potential this spring. With no major precipitation expected the rest of the week, that will mean more time for snow levels to gradually decline by the weekend. Nevertheless the river is still flooding in North Dakota and southern MB, which can be seen from the satellite photo here. Note the widening of the Red River (dark areas) south of Morris near St Jean Baptiste, as well as in northern Minnesota on the east side of the Red River. The flooding and dike preparations have required the closing of some roads in southern MB, including much of Hwy 75 between Winnipeg and Morris. which could be closed for up to 3 weeks.

See also higher resolution MODIS satellite image at left taken April 7th showing flooded areas and remaining snowpack over southern MB and North Dakota.


  1. Do you really think that double digit highs are possible for this upcoming weekend or is that just wish-casting!!!!????

  2. I Created a facebook group for our University of Manitoba Storm Chase Team…

    I linked it to Rob's blog because I find it so informative.

    Search 'University of Manitoba Storm Chase Team' and request to join. Open to people experienced in weather, and to whoever has facebook...

  3. It sure looks like it. Once we lose our snowcover, double-digit highs will be the norm. Remember, the average high is +5 to +11 at this time of year.

    P.S. It was +23 in BC today...that warmth has to come here eventually (although it usually finds a way not to).

  4. Scott... You expect to lose that 8 to 20 inch West and Central ND and SASK snowfall that quickly. By the weekend what if any impact will a 200 mile long 10 to 15 mile wide lake of moving ice have.. AKA the RED SEA??

  5. SnowCOVER not snowFall

  6. For the most part there isn't actually 8 to 20 inches of snow in North Dakota. Just like in Manitoba, at least half of that is probably gone now. In Steinbach for example, we had 35cm at our peak last week, but now we barely have 10cm. Obviously there are higher snow drifts, but the actual snowpack isn't very deep now. Even if all the snow melted by this weekend, the actual height of the red river wouldn't change dramatically. The current forecast for levels slightly higher than 2006 will likely stand, but we may approach 1979 levels.

    The models are showing highs of +10 to +14 by the weekend, which will certainly eliminate any remaining snow. By next week the models show us staying around +10 for an indefinite period of time. So yes, our snow should be gone for the most part by this time next week!

  7. Snow cover on its last legs around Winnipeg... visible satellite shows blotches and striations of bare ground. More even, homogeneous snow cover NW of a Brunkild-YWG-Selkirk line. Still a great deal of snow cover in central N Dakota SE to Fargo region as Jim mentioned.

    Models having a tough time resolving split flow pattern. I believe the potential is still there for a significant rain event somewhere over the eastern prairies/ upper midwest in the extended outlook.

    As for temps next weekend, problem will be increasing clouds offsetting warm advection. Best chance for sneaking up to 10 C will be on Saturday before clouds move in. GFS shows trough linking northern stream disturbance over Alberta with the previously advertized Colorado Low. Models show clouds and light precip associated with this feature on Sunday.

    Things get quite murky after this... GFS washes out Northern Alberta disturbance and strengthens Omega block over us. It then generates yet another Colorado low undercutting the upper ridge and sending an inverted trough up thru Saskatchewan. Copious QPF results to our west by Wednesday Apr 15. Dry easterly flow sets up at the surface over RRV eating away low level moisture/clouds.

    Obviously a slight west to east change in this configuration would make the difference between a cold rain/ wet snow mix and sunny balmy temps in the high teens. Uff long post again... but the weather continues to be very interesting and unsettled.

  8. Just had a look at GEM for 168-240 hrs. It is slower with amplification of Omega block. Its evolution of the pattern is down right silly... it show an enormous upper ridge eventually covering BC, AB, SK, MB and NW to SW Ontario.

    Exactly how the upper disturbances interact with this complex blocking pattern remains the key question.

    Any more thoughts Rob?

  9. The satellite seems to contradict (maybe accurately) the Snowcover interactive site 7 hours ago. Update to current shows lots of melting Link on my name.

  10. Snow depth map from NWS still shows a 100 km wide corridor from Minot to Jamestown with 50 to 100 cm snowpack (!!)... that's going to take a long time to melt. Some of that runoff will make its way into the Souris and Assiniboine systems.

  11. Only minor icebergs going by this am (1km north of Bishop Grandin Bridge) The water is a few inches higher than yesterday and still frozen against our sandbags. We've put out a second sump pump and hose over the wall...

    Daniel My mistake yesterday...must have been distracted. I was looking at a water equivalent...

    Whats the status of the latest Col. low

  12. A question for anyone out there.
    Yesterday an interviewee stated on CBC that the river was 2 feet higher than expected in South Winnipeg (reason for opening the floodway on a moments notice )
    Is the south Winnipeg topo(typo?)graphical error still playing havoc with Flood predictions.
    ..IMOFM In 1996 an invisible couple of feet crept into the provinces correspondence (the adjacent land is 2 feet lower or the river is two feet higher than the some maps show)
    In 1997 that same 2 feet appeared to play havoc with predictions. Til now it had been blamed by some on the floodway backing up

    Has that been resolved or did it creep back in with the floodway not operating.

    Or is it that 1995 excel spreadsheet they started out using LOL

  13. Daniel..

    re: 168-240 hr progs. Looks like models are hinting at an upper ridge over the Prairies while pieces of Pacific energy undercut the upper ridge through the central Plains.. which tends to be a favoured storm track with a La Nina pattern. In this type of set up, impulses are generally weak across the Prairies due to the blocking ridge so the GEM solution appears too aggressive with the impulses across us. But I noticed last night's MRF solution was showing a strong system developing over Montana and moving into southern SK for the middle of next week (April 15th) which looked a bit overdone.. but we'll just have to wait and see how future models trend.

    By the way, snowcover almost gone around most open fields around Winnipeg and RRV.. but still a fair bit of snow remaining in sheltered/treed areas. As noted, satellite pix show snowcover still extensive to our west and southwest, especially west of Pembina escarpment through the Pilot Mound area into ND.