Thursday, March 19, 2009

Warming trend this weekend.. system threatens rain by Monday

Temperatures will be on the rise again this weekend as a complex storm system begins to take shape over the northern Rockies. This storm system will draw an increasingly warm and moist southerly flow into southern MB for Sunday into Monday with temperatures rising into the plus 5-10 range. The weather will become increasingly unsettled by Sunday night with an area of rain developing over western MB along an inverted trof slowly moving east towards the Red River valley by Monday morning. This trof may bring some significant rainfall to portions of southern MB, mainly west and north of the Red River valley with 15-25 mm possible. Current indications are rainfall amounts may be less over the Red River valley, with 5-15 mm Monday.. however embedded convection may give locally higher amounts. There should be a break in the precipitation Monday night into Tuesday morning before another wave of precipitation moves in Tuesday into Wednesday as the main storm system over the central plains moves up towards Minnesota. This will likely change precipitation over to snow over southern MB as colder air feeds into the system. There still remains considerable uncertainty in the timing and precipitation amounts with this complex and slowly evolving system.. so residents are advised to listen for updated forecasts and statements over the next few days on this developing situation. Whatever the case, melting temperatures and several days of unsettled weather will bring further flooding concerns throughout the Red River valley. Stay tuned..


  1. Flood watches and warnings out for Grand Forks southward. NWS predicting crest of 45-50 feet on the Red at GFK between March 30th to April 4th. New Canadian GLB tonight doesn't look good showing lots of rain (snow over western MB) coming in Tuesday over Dakotas and southern MB with second wave as main low moves north.

  2. The latest GEM is honestly one of the wettest runs I have ever seen. It shows 45 to 60mm of accumulation in Steinbach, with amounts of 50 to 75mm in the south-western part of the province. It also shows 40 to 60mm of precipitation over North Dakota.

    The models have started to show more snow in Manitoba, however we are still a significant distance from this system.

    P.S. Hopefully all the snow we have now will be gone before more can accumulate!

  3. If the latest GEM is right... then the flood situation will be getting a whole lot worse!

  4. Rob!!!!
    Is there even a slight chance that we could get a thunderstorm here in Southern Manitoba Sunday - Monday???

  5. I think there's a good potential for some thunderstorms over southern MB Sunday into Monday, but it's still too tough to say exactly where. At this point, models are hinting that convection will likely develop over southeast SK/southwest MB Sunday in an area of massive warm advection ahead of the first phase of this upcoming system. That is what's likely contributing to those significant precip amounts noted along the SK/MB border in the latest model runs. Most of this precip is forecast to be heading to the N/NE, so the bulk of it should miss the RRV.. but I think there'll still be a line of showers moving through us Sunday night, possibly with an isolated tstm.

    There will likely be a second area of elevated tstms devloping along the second/southern phase of this system Monday night into Tuesday, but at this point, most of that activity is expected to affect areas south of us through the Dakotas. The remnants of that convection will likely spread north as an area of rain or wet snow over much of southern MB Tuesday, possibly with substantial amounts.

    Messy forecast with lots of variables and uncertainty.. but that's what I'm seeing at this point.

  6. Very good summary. The nose of the associated low level jets (LLJs), from either system, should not target RRV directly. This is a region of mesoscale forcing (convergence) where elevated convection/heavy rain is favored.

    The really big elevated storms will likely form along southern warm front. Could be several rounds of MCSs around central plains before the southern low makes its move NE.

  7. on SHAW channel 48 they are giving some snowfall amounts from a Charleswood location from Nov 1. until March 15!

    Is that your location Rob???

    88 cm for the year!

    Come to think of it that is not a lot of snow! You always here of southern Ontario and the Maritimes getting 200 -350 cm of snow for the year!

    I always used to think that Winnipeg was a "snowy city" but after looking at those stats on the TV ( average snow of 86 cm) I starting to think otherwise!

  8. Well....
    The lastest GFS run is showing some very heavy precip.

    The lastest run has put the red river valley including all of western manitoba in the bulls-eye for two rounds of heavy rain (thunder anyone) then followed by freezing rain mixed with snow!

    Either way this is gonna be one hefty storm!

  9. Daniel..

    Yes, those snowfall stats from Charleswood are from me. I'm an official snowfall observer for EC, and submit my snowfall measurements each day through the winter. You can find all my stats at..

    I wasn't happy that they stopped the snowfall observing program at the airport back in 2003 (ending over 100 years of snowfall data for Winnipeg) so I decided to ensure there was *some* record of human-observed snowfall and snowdepth for the Winnipeg area.

    As you say, only 88 cm so far this winter.. and Winnipeg averages about 110 cm between October and April, so we're running a little below normal in our area. Here's hoping we don't make up the deficit next week!

  10. NWS GFK has issued a statement on projected rainfall totals next week. Looking at generally 1-2" (25-50 mm) across the Red River basin between Monday and Wednesday.

    Check HPC (hydromet section) graphics as well for projected precip amounts in the next few days..

  11. 88cm Does that include Feb Rain?

  12. No.. 88 cm is snowfall only. I measured 15 mm of rain from that Feb 9th rain/freezing rain storm.

  13. Special weather statement issued for all of Southern Manitoba.

    Could be up to 1 inch of rain Sunday into Monday. That not even including the upper level low that in gonna affect us Tuesday into Wednesday!

  14. Today's 12Z GLB is giving 30-50 mm of rain across the Red River valley of southern MB for Tuesday, with a rain/snow line running along the western RRV. Yikes..

  15. This complex storm may keep us guessing until the last moment... Two main sources of uncertainty and possible error as I see it.

    First is the evolution of that Montana low/inverted trough... specifically, when and where it will wash out. A clearly defined focusing mechanism seems absent (nose of LLJ, midlevel forcing/frontogenesis) rather there are numerous embedded waves in the SW flow. Tough to say if models are overdoing QPF in this broad warm advection regime especially in the RRV. Whats your hunch Rob?

    Second is the track of the main Colorado low. Latest run of GFS now more in line with GEMglo and ECMWF, supporting a warmer more NW track. Looking like a cold rain followed by a slushy accumulation on the backside.

  16. Interesting... EC is saying 6 C with clouds and showers. GFS suggests a dry easterly flow eating away moisture and diverting it to AB/SK. EC does not provide wind direction for tomorrow.

  17. Daniel..

    I agree that it looks dry tomorrow.. I don't see much in the way of any showers around for us. Forecast calls for winds to pick up to southeast 20 km/h by evening.. although we could be seeing that by afternoon.

    As for the first round of pcpn for the RRV.. I agree that the models *may* be overdoing QPF amounts as the inverted trof swings through us.. best support for pcpn should be well north of the RRV. However, most models suggest a good band of heavier QPF moving through Sunday night with the inverted trof.. with perhaps 10-15 mm possible. We'll see if that holds over the next few runs. I think it's looking like a better bet that we will see a good 15-25 mm on Tuesday with the main low ejecting into the northern plains.

    FWIW.. today's ensembles are giving Winnipeg a 50% chance of at least 25 mm of pcpn Sunday night through Wednesday.. with a 25% chance of at least 45 mm on the high side, and 15 mm on the low side.

  18. So rob.... basically there's no way out of this system!

    The Red River Valley is not gonna dodge this bullet like the last system that passed us to the south!

  19. Oh.. there's a way.. just because the models say it's going to happen, doesn't make it so! However, as we get closer to the event and the models keep giving us the same basic message.. it's looking more and more likely that we're going to get something out of this. The question remains.. how much?? There's still a large spread in the estimates ranging from less than 15 mm to more than 45.. and any of those solutions may be right. Take my latest poll to say how much you think will fall next week!

  20. Am I halucinating or are there two momentous events about to occur besides the second flood of the century.
    1) A serious precip event predicted and followed for 10 to 15 days in advance, (remember those 50 to 75mm predictions)
    2) In 4 days, Robs backyard doubling its winter supply of precip.

  21. The models are starting to settle down a bit. Run to run consistency is starting to show up, which is a good sign (or probably bad in this case). The GEM has been showing a 5 day total of 50 to 75mm for most of the RRV over the last several runs. The GFS has started to come to a conclusion of 30 to 50mm. The NAM appears to be fairly consistent with the GFS solution. I have found that averaging all the QPF forecasts you can find will often yield a forecast close to the actual amounts...keep that in mind!

  22. Another run, another opinion.. GFS now showing more rain for RRV with the trof moving through Sunday night.. and a little less rain from the Tuesday storm. GFS gives a swath of 25-30 mm Sunday night (likely enhanced with embedded convection), then 15 mm of rain Tuesday, before 15 cm of snow Tuesday night into Wednesday.