Temperatures finally climbed to the freezing mark today in Winnipeg, the first time since November 16th that the temperature did not stay below freezing. In fact, it was milder today in Winnipeg (0.0C) than in Brownsville Texas (-1C with freezing rain and sleet) Temperatures have dipped below freezing this evening but are expected to rise overnight as clouds and southwest winds increase ahead of the next batch of precipitation currently over central SK/MB. This batch of precipitation is falling in the form of rain and some wet snow, and will track into southern MB overnight. This will result in patchy freezing rain developing where surface temperatures remain below freezing. Even if temperatures climb above zero overnight, the light rain falling on cold surfaces will likely result in locally slippery conditions on untreated surfaces such as walkways and side roads, which could create problems for the morning commute. Luckily the temperature should remain above freezing Friday so any ice should quickly melt Friday morning. Saturday looks fairly tranquil before blustery and colder conditions move in Sunday with some snow and blowing snow.
UPDATE: 9 pm: Freezing rain warning issued for Winnipeg and Red River valley.
This weather system is really moving along a good clip!ReplyDelete
Now that we are in snow mode will rain show up as very "bright" returns on the radar???
Yes indeed.. in fact, some brighter returns already showing up west of Lake Manitoba west to Roblin into eastern SK. Currently raining in Dauphin and Yorkton, and moving quickly southeast towards Winnipeg. Should be here by midnight or so.. with a couple mm of freezing rain possible before our temps rise above zero.ReplyDelete
Can someone explain what will determine if the precip. is freezing rain as opposed to sleet or wet flurries???ReplyDelete
It has to do with the temperature profile in the lower layers of the atmosphere. First of all, you need a layer of above freezing air aloft to get rain to start falling towards the surface. If the air is above freezing all the way to the ground, then the pcpn will fall as rain. If the air near the surface is near or below freezing, then that rain will freeze on contact resulting in freezing rain. If the layer of cold air near the surface is deep enough (below freezing) the the rain drops will freeze into ice pellets (sleet) before they reach the ground. So the depth of the cold air near the surface under a layer of warm air aloft will determine whether you get rain, freezing rain or ice pellets (sleet).
Wet snow is the opposite of freezing rain. With wet snow, there is no layer of above freezing air aloft, so the pcpn falls as snow. However, if the surface temperature is above freezing, then the snow will fall as melting snow. So in this case, the warm air is near the ground, while it's colder aloft.
Hope that's not too confusing for you.. If so, google "freezing rain" and I'm sure you'll find some good info with diagrams to explain things a little clearer.
Click on the link see the RUC upper air sounding for Winnipeg valid for midnight. Note the extensive above freezing layer from just above the surface to 800 mb. That would support freezing rain.. or ice pellets if the cold air near the ground is deep enough, which the RUC also shows as a possibility over the next few hours. There's also a chance that the above freezing layer will shrink (go to freezing) with the onset of pcpn, which could change the pcpn to snow.ReplyDelete
Will be interesting to see what form the pcpn comes in for Winnipeg. Could be a messy mix of all three at one point or another..
Freezing rain at Brandon as of 11 pm.. and supposedly at Winnipeg as well, although nothing is falling here that I can see, and radar shows nothing over us at the moment.ReplyDelete
Very heavy radar returns heading toward Winnipeg! Will be interesting to see what falls but looking at the temperature well below freezing could be a heavy freezing rain for a bit!ReplyDelete
Picked up 1.6 mm of freezing rain overnight. Very slippery out there this morning on walkways and untreated surfaces. Several highway closures this morning due to ice including Trans Canada to Virden and Hwy 75 right to the US border..ReplyDelete
2.5mm of rain/freezing rain/snow in Steinbach. Roads in town aren't bad at all, but highways are probably not that great.ReplyDelete
Ignore the precipitation readings from my weather station today.. that's just snowmelt from left over snow in the gauge. One of the side effects from our springlike temperatures!ReplyDelete