Looks like another setup for possible severe thunderstorms to develop across Southern MB late Thursday into Thursday evening. A low pressure system and trough will be moving across southern SK Thursday moving to the SK/MB border by Thursday evening. A warm front extending east of this system will lie across the MB/ND border by evening which will be the focus for thunderstorm development. South of the warm front, warm and humid air will be advecting north from the Dakotas and will nose into Southern MB especially south and west of Winnipeg. Favourable low level wind shear and an increasing jet stream aloft will set the stage for supercell storms to develop across the Dakotas and southwest MB, with the potential for large hail and possible tornadoes. The limiting factor in this setup will be how much moisture can de drawn into this system in a short period of time, since dewpoints are quite low across the northern Plains today. As a result, the severe weather threat may be late Thursday before sufficient moisture can be drawn into this system. Stay tuned..
How will this effect winnipeg ? is there going to be better risk south of winnipeg like the north Dakota border? could the the storms weaken before they hit winnipeg ? because enviroment canada says that it will only be about 23 degrees in winnipeg tommorow and it won't be that warm. ThanksReplyDelete
OH I forgot to ask you, where can I go to find websites that let you see future precipitation like were thunderstorms are expected ?ReplyDelete
Looks like the best chance for surface based super cells capable of producing tornadoes will be SE Saskatchewan thru extreme SW Manitoba late Thursday afternoon/early evening. As Rob mentioned, all the shear and dynamics could interact with good instability there.ReplyDelete
Winnipeg will be under the gun for severe but probably elevated storms with heavy rain and hail possible overnite Thursday and Friday morning. Situation is still not very clear.
Convection could initiate along the warm front that should be sitting from Estevan to Fargo by dawn tomorrow. If widespread convection can get going... then all the clouds and outflow will slow the fronts northward progress.
Interestingly, the GFS surges very warm mid-level temps (12 - 14 C at 700 MB) Thursday night well north of where the surface warm front is progged to be. With a strong Low Level Jet tapping juicy air... its not clear where the elevated storms may form.
If they form along the warm front.. then they will stay south of Winnipeg. However they may instead form on the edge of the cap in which case Winnipeg is in prime zone for nocturnal convection.
This is definately a tricky situation. The nocturnal convection is the most difficult. MLCAPE will be over 2500J/kg in most of Southern Manitoba all night Thursday/Friday morning. Helicity will remain EXTREME all evening/overnight/morning with the system (Helicity is literally off-the-charts at over 1000m^2/s^2). I am not very familiar with "after-dark" convective activity, but there doesn't appear to be a reason why surface based convection isn't possible (does SB convection need SBCAPE?) ...Other than what I just mentioned. I have been told that explosive convection is most likely in the area with the highest CAPE, and the highest CINH that a storm could still break through. This seems logical to me...if you secure a lid on a fizzy drink and shake it the lid will fly farthest if the lid is on just loose enough so that it can still get off...ReplyDelete
Storm chasers are coming from the US, so something big must be in the books!
Elevated convection is definitely not as intuitive as surface based convection and is sometimes overlooked. Nocturnal storms are often elevated because at night the lowest levels of the atmosphere stabilize as a radiative inversion forms.ReplyDelete
That means the instability has to be rooted at a higher level as in the case of frontal inversion (like overnite Thursday) or you need lots of large scale ascent (positive vorticity advection) and low level convergence (this happens on the nose of the low level just above the radiative inversion).
And btw.. there is such a thing as 850 MB CAPE.
Warm front across ND/SD border giving some nice elevated thunderstorms across SE ND/central MN this morning with lots of ltg, heavy rain and some large hail. Dew points coming up nicely south of the front with values of 18-20C advecting north as low pressure area deepens over eastern Montana. This low will help to draw warm front up close to the MB border by evening, especially over SW MB which will be the focus for severe tstm development later today. Main target area for supercell storms will be over southeast SK and extreme SW Manitoba this evening with tornadoes possible. Several stormchasers targeting Estevan/Carlyle SK area today. Supercell storms will track to the east-southeast possibly evolving into MCS with bowing segments giving strong winds across southwest MB. Warm front will continue to push north across southern MB tonight, with storms likely becoming elevated as 850 mb jet and warm advection strengthens over southern MB. Could see some strong thunderstorms tonight in Winnipeg/Red River valley/Interlake regions with lots of lightning, heavy rain and hail similar to ND activity this morning. Will be an interesting situation to monitor over the next 24 hours. Stay tuned..ReplyDelete
How long will this severe weather threat last for us here in winnipeg, Because I checked the watches in southern saskachewan and they said it will end later in the evening. Is this the same for manitoba?ReplyDelete
I think the risk of severe storms will last into overnight hours across portions of Southern MB.. although not everyone will see storms. Some dangerous storms over eastern SK this evening with baseball size hail near Yorkton, and a potentially tornadic supercell north of Carlyle. These storms will continue to track into southern MB tonight with most of the severe threat over western areas with large hail and possible tornadoes.. evolving more into heavy rain/lightning/hail event for Red River valley and Interlake areas overnight.ReplyDelete
Interesting... tstorms complexes tonite have remained fairly progressive following the 500-1000 MB mean flow, but at the same time have shown some tendancy to slow down and curve into the low level flow.ReplyDelete
In fact some clusters split earlier this evening.. the northern portion racing off to the northeast while the southern slowed down and propagated into the southerly LLJ.
Depending on the orientation of the gust fronts relative to the mean flow, the strength of the cap to the south, and how well the LLJ and mean flows align... we may even see fast moving bow echo/derecho and slow back building MCS's at the same time. Who knows...
Spectacular light show in Winnipeg, wow.. incredible.ReplyDelete
I have never seen so much cloud to ground lighting strikes in my life!!!ReplyDelete
There must be a lot of strikes in the city here!!!
Yeah I live in northern winnipeg and it hit last night around 3:30 am and yes there was alot of lightning, one strike was so close it sounded like someone used a shot gun in my house LOL! And the rain was so heavy.ReplyDelete
Quite a bit of damage being reported in Carlyle, SK due to suspected tornado last evening. Numerous trees down, some buildings damaged, power's out.. Also lots of large hail reports over eastern SK, with up to baseball size in Rokeby just southeast of Yorkton.ReplyDelete
On the MB side, it was mainly hail and heavy rain, with loonie size hail outside of Roblin, up to 43 mm of rain in Rossburn. Looks like Winnipeg got away with 5 to 20 mm of rain, heaviest in the north end.
Looks like some intense cells forming south of Winnipeg!
Marble sized hail was reported at La Broquerie at 10:15...nothing here in Steinbach except heavy rain (90.0mm/hr rain rate).ReplyDelete
Looks like the excitement will continue...severe thunderstorm watch for all of Southern and Central Manitoba!
Severe thunderstorm warning for the City of Winnipeg !!ReplyDelete
This storm looks intense on RADAR!!!
Nice are clearing just ahead of the inverted trough. With continued southerly flow and heating SB CAPE could punch up a bit more than progged. With a highly sheared environment, potential for severe convection along that inverted trough as it moves east. Sharp line of cumulus forming along the trough... Let's see what happens...ReplyDelete
Did anyone notice the thick dark clouds around 11AM? The weather station at the U of M ( http://www.umanitoba.ca/environment/envirogeog/weather/UMweather_data.htm ) reported the solar radiation dropped right down to 11W/m². UV index right down to 0.0!ReplyDelete
How often do clouds that thick roll around?