Sunday, June 21, 2009

Sunny warm morning for Manitoba marathon

Sunny and warm weather conditions prevailed today for this year’s Manitoba Marathon, coinciding with the first official day of summer  The race started at 7 am with temperatures at a comfortable 19c. However, the strong sun quickly warmed up temperatures to 24c by 9 am and 27c by 10:30 am with southerly breeze of 20 to 25 km/h. Humidity levels were moderate, with dewpoints around 15c.  The conditions were a marked change from the weeks of below normal temperatures leading up to the marathon.


  1. Clouds and showers associated with that Minnesota disturbance spreading into S Manitoba. I suspect the shower activity will brush SE Manitoba this evening.

    Attention then turns to tomorrow... quite a bit of uncertainty here. If we can clear out any debris cloud from Minnesota system, we will be able tap 1500+ J/kg CAPE ahead of surface trough. I would expect a few discrete cells to pop along that trough in SW Manitoba. There will good unidirectional shear present, and with left over instability... convection *may* try to organize itself into smaller line segments affecting RRV by dark.

    LLJ will be a real question mark tomorrow night. NAM and GFS hint at LLJ getting organized ahead of another but more subtle wave embedded in the flow. Exactly where it sets ups will have big impact on where organized convection has potential to form. Right now, NAM is further south in N Dakota will GFS rides a complex along international border.

    Other thoughts/ comments?

  2. Tomorrow looks more interesting than the models had been showing. The latest runs show 1500 to 2000J/kg of CAPE, I suspect 2500J/kg may be possible with 18C+ tds. Several triggers could initiate convection: cold front, "warm front", inverted trough (SK), lake breeze convergence boundaries, etc. I say "warm front", because the front that the models are showing is barely a warm front - should it exist, it would be in SE MB and the Interlake.

    Assuming that storms do fire - probably in the afternoon in SW MB, moving W into the RRV by evening, there is good shear. Unfortunately a LLJ looks to be non-existent until after dark, at which point I'm not convinced that it will materialize at all in S MB. However, there is speed shear (and unidirectional). Here is an approximate profile: 700mb - 30knts (WSW), 500mb - 40knts (SW), 250mb - 80knts + (SW). There looks to be sufficient deep shear for a supercell (note the "a"). The main threat will probably be multicell storms with large hail and strong winds - small line segments are possible as Daniel suggested.

    Tomorrow might be our first "real" severe weather outbreak of the season!

  3. Looks like a small line of showers with embedded thunder seems to have made into south eastern Manitoba!

    Will it hold together for it to reach Winnipeg????

    Im sure we will get a quick shower late this evening!!

  4. Agree with Daniel and Scott's severe weather assessment for tomorrow for southern MB.. severe potential is there as trough is strong enough to trigger convection, some good shear, and adequate instability. Storms in SK today only gave heavy rain, no hail, even though they looked strong enough on radar. Perhaps not enough energy there as temps were only in the low to mid 20s.. CAPES will be higher over southern MB Monday provided we scatter out and get into the upper 20s.

  5. Quite the heavy shower heading through Winnipeg right now!

    I knew the Red River ex could not go the whole time without getting rained out once!!!!

  6. Picked up a quick 4 mm between 9:30-10 pm. Peak rainfall rate was 72 mm/hr. No thunder or lightning noted.

  7. 23/19 in Steinbach this afternoon. Once the sun comes out (likely in <30min), the temperature should climb into the mid twenties. By evening it will be very warm and humid here, perfect for storms.

    Areas in SW MB are already clear, with instability climbing quickly. That energy should move east as the afternoon wears on. Any guesses for initiation time?

  8. There is a an isolated thunderstorm in the Devils Lake area that might make into Southern Manitoba!

    Other than that south western Manitoba has the best chance of a severe thunderstorm!

  9. Tonight could certainly use some debriefing.
    To summarize:
    1500 to 2000J/kg of CAPE - uncapped
    -4 to -8 LIs
    30 to 40knts 0-6km shear
    trough/cold front
    Small, but adequate CU/TCU field

    There is no logical reason I can think of for storms to not fire. The dynamics were there, the trigger was there and the atmosphere was uncapped. It happened in W ND, but not in a similar environment in S MB. Can someone else offer an explanation?

  10. BTW...

    Today is the 2nd anniversary of the Elie tornado...all of this severe weather season and last severe weather season combined weren't as active as those four days on a weekend in 2007.

  11. I have a feeling in might turn out to be a hot summer after all here in Southern Manitoba!!!

    Look at the "VERY HOT" and "HUMID" weather conditions in the deep south and central plains of the U.S.

    It looks like there long range forecast is for this Torrid conditions to continue.....
    Looks like southern Manitoba will be on the northern edge of the heat. Which means good news for night time storms as they form along the "ring of fire"!!!

  12. Thermodynamics and shear were decent today... but we only had low level convergence from surface trough to work with.

    We were lacking forcing from shortwave or large scale ascent/ omega (PVA + warm air advection). In this sense the dynamics were not very good. Most of the energy transferred north with the stacked low and the surface trough became stretched out and weaker.

  13. ...there is still chance a convective complex may form as shortwave rides up from central plains and interacts with front (which will stall out to our SE).
    Convection may brush extreme SE Manitoba tomorrow morning.

  14. Post frontal convection firing up ahead of that shortwave disturbance coming up from the southwest. Strong thunderstorms in the moist unstable air down over Fargo.. further north there are some lines and clusters which will clip extreme southern RRV and SE Manitoba that bear watching...

  15. More post frontal convection associated with mid level shear axis and elongated region of vorticity. This line will likely affect Winnipeg... problem is lack of instability, but we may at least get a few heavy downpours.

  16. I was surprised by yesterdya's lack of activity as well.. I think Daniel's right about the overall lack of large scale forcing.. the surface trof was just too weak to get things going on its own. Plus, there was a bit of a cap above 850 mb that seemed to suppress convection, and we needed to get to about 30C to break it.. We just didn't get warm enough fast enough to do it. Convective forecasting.. always a challenge!

  17. Here is an encouraging precipitation forecast for Interlake my name for details.

  18. Friday looks tornadic for Southern Manitoba and areas South...Elie F5?

  19. I don't like what I see in the models. They are showing our pleasant weather pattern coming to a screeching halt this weekend.

    First the storms...The latest runs completely collapsed on Friday's potential. For the RRV, the models were showing 4000J/kg + of CAPE last night, now they show 100J/kg. The best chance looks to be in SW MB now, but even there CAPE is only 2000J/kg at the most, with relatively poor shear. They also show a huge cap over S MB, which is also bad news. However, we can't give up this early. After all, 48 hours can be the equivalent of years in model land.

    The worst news from the models comes for Saturday. They are showing a low pressure system spreading 50 to 150mm of rain over S MB. I'm not sure what to make of this...I've never seen such high rainfall totals in the models. Hopefully this is just a blip in the radar.

    After the system departs, we could end up back in that nasty N/NE flow from Hudson Bay. The low would open the back door and allow arctic air in.

    Maybe I'm just being overly pessimistic, but that is truthfully what I see in the models.

  20. Tomorrow looks potentially tornadic around Regina and that translates Eastward toward the Brandon area for Friday. Shear isn't as great as last night's models were predicting, but there's still a good chance for severe weather. There will definitely be convective debris on if we heat out enough...severe chances will increase as a response to the clearing. There will be numerous boundaries left over from Thursday night's convection that will aid in providing the focus for severe thunderstorms in Southern Manitoba.

    I'd definitely pay attention to Friday for areas around here and points West.

    Saturday looks crazy over the Winnipeg area due to a large convective complex that erupts late Friday night. 2'' of rain is estimated by the NAM radar. I hope this doesn't pan out as I have a baseball tournament all day Saturday and Sunday!


    Anyways...stay tuned...tomorrow (Regina) and Friday (Brandon area) could be under the gun for some Severe Weather!

  21. Interesting nite.. left exit of upper jet and well defined shortwave produced nice round of showers. Friday looks interesting, but at this point I have to say that severe, surface based convection does not look very likely over the RRV. The main threat as mentioned will be heavy rain.

    Upper ridge builds in starting tomorrow ahead of a large upper disturbance tracking across N Prairies. At the same time, lee trough and its surface reflection start migrating up from the central Rockies. Overnite Thursday into Friday morning will feature warm/ moist advection into western Manitoba. I do not expect anything to reach RRV... deepest moisture and LLJ will be along the Manitoba/ Saskatchewan border.

    As others have noted, we will be left with a lot of debris cloud and a SE flow. Best moisture and instability will stay south of warm front associated with the southern system coming up from the Rockies. This yields the much lower CAPE that the models are now advertizing. With only an inverted trough to play with at the surface (connecting the two systems), I do not expect a whole lot to get going during the day Friday.

    Models then suggest the southern low becomes captured by the mid and upper level energy moving across the Prairies. Very strong SE LLJ dumbbells around 850 hPa low.. and along with copious moisture, instability and right entrance of upper jet, the stage is set for heavy convective rain overnite Friday thru the early part of Saturday. Depending on where exactly the low tracks, we may influenced by an unstable/ warm advection regime transitioning to a more stratiform region of precip associated with deformation zone and shear axis of upper low (as deep moisture and instability get cut off to the SE).

    NAM is most aggressive and bullish on this, while GFS is more progressive with surface low and show the system becoming stacked further east (along with QPF bullseye).

  22. Rob!!
    What is your view on the severe thunderstorm potential for tomorrow??

  23. Chris - St. Vital12:43 PM, June 25, 2009

    What kind of temps are the models showing for next week? High teens? Low twenties? I can live with low twenties, but I don't want to have to wear jeans again until September.

  24. Chris..

    The models have backed off a little in terms of the changing weather pattern. Last night they were showing temperatures in the low to mid teens for a day or two, followed by warmer, but still below normal temperatures.

    They now show perhaps a day or two of below-normal temperatures, but with highs in the high teens or low twenties. These colder temperatures will occur this weekend, behind a strong low pressure system. It is still unclear what will happen with that system, and thus it is hard to tell what temperatures will be like.

    Let's not forget that we have had two weeks of above-normal weather (without a break), that can't last forever.

  25. Environment Canada is calling for 20 to 30 mm of rain for tomorrow night in Southern Manitoba!

    I wonder if "training" of thunderstorms cells will be an issue for tomorrow night?????

  26. This area has been drowning in precip lately? Drove thru the Souris( RRV) Brandon to Rugby to Minot 10 days ago and many ND fields are still full of standing water ? Many still not or just planted. The US side of Turtle mtn had record snowfall as well. And now this on NOAA fgf forecast which has become a regular occurrence.

    Heavy Rain Threat Friday night

    A very moist airmass will move into eastern North Dakota and northwest and west central Minnesota on Friday. A cold front will move into western North Dakota early Friday and be located near a Brandon Manitoba to Rugby to Bismarck line by 6 pm Friday. The airmass will become very unstable late Friday causing thunderstorms to develop along and just east of the front in the mid to late afternoon. Thunderstorms will increase in coverage as the system moves through the area overnight Friday...with the system persisting over much of northern Minnesota through early afternoon on Saturday. Widespread heavy rainfall of 2 or more inches is possible in the area....but the exact location of heaviest rains and timing is still a bit unclear. Some thunderstorms may also briefly become severe with large hail and damaging winds....mainly over eastern North Dakota Friday evening. Stay tuned for later forecasts for further updates. Anyone camping Friday night should be prepared for heavy rainfall and thunderstorms.