Thursday, January 21, 2010
Snow moving in this weekend.. colder next week
After an extended period of mild and snowfree weather, it looks like southern MB will finally be seeing some snow this weekend. A complex storm system will develop to the lee of the American Rockies Friday and begin to affect the eastern Prairies into the weekend. The storm system will initially spawn a low over Montana that will spread snow over southern SK and southwest MB Friday into Friday night. This low is expected to weaken by Saturday, as the main energy is transferred to a more intense Colorado low that will track into Minnesota over the weekend. This low will bring snow to much of southern MB Saturday into Sunday, with amounts of 5-15 cm possible, with heavier amounts likely south of the border. The snowfall may be mixed with freezing rain or ice pellets on Saturday over the RRV and southeast MB as warmer air aloft feeds into the system. By Sunday, increasing northerly winds on the backside of the storm will bring colder temperatures over southern MB along with snow and areas of blowing snow. In the wake of the storm, colder and drier weather is expected Monday through next week as Arctic air pushes back into southern MB for the first time in two weeks.
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The latest ECMWF models continue to show a northward trend with the latest 12z ecmwf indicating a surface low almost to Minot before re-forming southeast again. It like the GFS brings precip way way north past Dauphin. HPC prelim snowfall graphics we see go with this idea and have 1-3 day totals of 10-12 inches in se sask and sw mb Portage westard and 8 to 10 Winnipeg to Grand Forks. The northward trend seems to be your friend...we will how the GEM handles it later. Be interesting to see how it plays out. For such a El-Nino like storm it is going way north.
ReplyDeleteI would assume Environment Canada will be issuing a winter storm watch with the latest northward trend of the models!
ReplyDeleteThis storm will be very difficult forecasting the type of precip with temperatures hovering around the freezing mark!!!
ReplyDeleteSounds like everything with this storm is difficult. Seems like noone knows where it's going, when its comming or what its comming as. Why can't we just have a good old fashined normal storm.
ReplyDeleteAnybody know what's wrong with Woodlands Radar?
ReplyDeleteDaryl,
ReplyDeleteWoodlands is down for maintenance right now. Should be up by Friday evening at the latest.
That sucks. We finally have some weather happening and the radar is down. Thanks for the info
ReplyDeleteDan GF
ReplyDeleteIs the weather office considering a Blizzard watch with the potential for blizzard conditions on Sunday into Monday????
Interesting tidbit.. Record low barometric pressure set in LA this afternoon, 980 mb beats old record of 990 mb back in January 1988. Just gives you an idea of the intensity of this Pacific storm system coming in.. they've been hammered out there these past few days..
ReplyDeleteRob!
ReplyDeleteAnother thing to note is the tornado watch , blizzard warnings and flash flood warnings in Arizona today!
We will see what the next runs bring, but so far lots of uncertainty remain. GFS atleast struggling to resolve evolution of surface pressure pattern... montana low or inverted trough will cause initial shot of precip to spread NE and reach Winnipeg early hours Saturday (maybe 2 am or so).
ReplyDeletePhase type will depend on how much warm advection can reach us before energy consolidates south. NAM is most aggressive with warming... under this scenario expect freezing rain until temps edge above freezing possibly by midday Saturday. GFS colder at 850 hPa.. would expect mix of snow and ice pellets with temps around -1/-2 C. Somehow, thermal fields at 850 hPa just don't look right to me on GFS. I think it has to do again with complex structure and evolution of storm.
We will have to watch how far NW dry slot will wrap up... if northward trends continue we may actually see band of mixed precip lift north of the city by overnite Sat into Sun.. even in the GFS scenario we may reach 0 C at this time.
Another problem is evolution of deformation zone on Sunday as inverted trough begins to wash out. Models suggest it will persist and slump SE again as cold air sweeps in and changes precip to all snow... but with energy shifting yet again to a new low (a 3rd low.. crazy) forming in Illinois question becomes will moisture get cut off and is QPF being overdone? Thoughts?
@ Rob, just to pick up on your post about LA's low pressure. Out west, we've had mild weather but low pressure readings for almost a week now. I think Abbotsford has been below 1000mb since late day Jan 16, occasionally dipping below 980. Not sure if there are any records for this kind of a thing, but I cannot recall this long of a stretch of low pressure (minus the windstorms that usually accompany such low pressures).
ReplyDeleteWest Coast.. thanks for the update. Yes, quite the persistent trough of low pressure over the eastern Pacific.. with anchoring lows from Gulf of Alaska down to California. Looks like pressure will be on the upswing for you guys this weekend as the trough pushes inland and gives us some messy weather for a change!
ReplyDeleteLatest NAM run (00z) is quite impressive. Looks like Southern Manitoba will be under the trowal zone of the Low for the majority of the time. This could lead to vast amounts of snow with embedded ACC convection. Some Slantwise Convection may develop too.
ReplyDeleteMonitoring tephigrams will be critical for this event. Precip phases may be difficult with the ample supply of warm air with this storm. Even though the model paints high QPF values, these precip totals could come from ice pellets and not snow. I imagine Winnipeg will be launching balloons before the storm hits!
This might be one for the books...
I wish I was there to witness the storm. I'll be watching this storm from the sidelines in Montreal. I'll get my turn though on Monday when this monster moves East...Ice storm anyone?
Justin!
ReplyDeleteWhat is ACC convection?????
WHOA!
ReplyDeleteI almost fell out of my chair when I saw the latest NAM run!
Talk about a storm!!!
Bon soire Justin!
ReplyDeleteYeah, I saw the NAM output tonight.. personally I think it's overdone. General details are similar among models but precip amounts vary from the dry GFS to the wet NAM, with GEM taking in the in-between road. Personally, I think that the GEM is a good compromise with precip amounts from this upcoming system.
Consensus is that area of snow will push into southwest MB Friday afternoon ahead of Montana low spreading into southern MB/RRV Friday night into Saturday morning.. possibly mixed with ice pellets or even freezing rain for awhile which will limit snowfall amounts in our area. This area of snow will push northward into Interlake and central SK while dry slot pushes into SW Manitoba on Saturday bringing end to heavier snow over the south, with patchy light snow or freezing drizzle persisting in dry slot. Main energy then focuses on Colorado low moving into Minnesota Saturday night into Sunday with wrap-around snow giving another 5-10 cm over southern MB along with increasing north winds and colder temperatures.
Putting it all together.. looks like about 5 cm of snow for Winnipeg Friday night into Saturday morning, possibly mixing with ice pellets or freezing rain.. then 2-5 cm Saturday, then another 5 cm or so Sunday. Storm totals 10-15 cm in Winnipeg by Sunday night with heavier amounts possible over western RRV and eastern slopes of Riding Mtns due to upslope enhancement.
Daniel P
ReplyDeleteJust saw the post....no. It would be too confusing to the public to have multiple headlines for the storm. We try to play it simple. We will likely go with winter storm warnings issued sometime Fri aftn....and mention psbl blizzard conditions Sun into early Mon...and then if needed we can always update to BZW on Sunday. If we mention the B word in our statements, etc that is good. Also we have conf calls each day with Emergency Managers from ND and MN in our area and give them web briefings and also conf calls with media folks so they are well aware of our thoughts and we share info. This sharing of info among the media and Emergency Management community is one of the biggest improvements the NWS nationwide has seen in the last 5 years. It helps out so much to get the word out and to have everyone on the same page. It was a great help last flood season and will be this one too.
Justin--agreed. I'll be working the weekend and may just have to send up a balloon.
ReplyDeleteForgot to mention that worst of this storm for Winnipeg/RRV will be Sunday night into Monday morning with strong winds and blowing snow giving possible blizzard conditions.. as Dan also noted..
ReplyDeleteI don't think we'll kick the split flow of typical El Nino form soon enough for the Olympics, unfortunately. Here's to hoping the local North Shore mtns can scrape together enough snow for freestyle skiing! Or that we get a drastic change in the weather pattern during the first week of February...
ReplyDeletehttp://www.cbc.ca/canada/british-columbia/story/2010/01/20/bc-cypress-mountain-no-snow.html
The ensemble gives a near 100% chance of 10mm QPF or more for all of southern Manitoba with this storm. The ensemble is a fairly conservative models, so this is significant.
ReplyDeleteOn another note, I was quite happy to see the EC SWS this morning. They are predicting 10 to 25cm of snow for southern Manitoba, which I think is a good estimate right now.
GFS is now the model with smallest amounts. Like Rob, I prefer the GEM. It it sort of a compromise between the NAM and GFS. It doesn't show much mixing of precip towards the beginning of the storm, but the QPF amounts look good. Right now I'm expecting about 5mm of mixed precip towards the beginning of the storm in Steinbach. Followed by around 15cm of snow.
The temps aloft are going to be a big factor in the amt of snow we get. If it is all snow, the Fri-Mon totals would be a little over 20cm in Winnipeg. Hopefully we will get some of that freezing pcpn or snow pellets, as this will reduce the quantity of snow we will get.
ReplyDeleteRob!
ReplyDeleteWhat are the odds that this could turn into a ice storm for Winnipeg tonight into Saturday???
12z NAM is very impressive in terms of QPF amounts. If this model is right, Winnipeg will see significant accumulations of precip.
ReplyDeleteWV imagery is quite impressive too. The clouds associated with this monster low is showing a classic mid-latitude cyclone!
Dave...can you email me (gmail/hotmail) the sounding graphic in WADS when you send up a balloon tomorrow. I'm very curious about the atmospheric profile tomorrow. I want to know if Winnipeg may see significant ice pellet accumulations before the changeover to snow!
The trowal forecast by the models looks to remain anchored over Southern Manitoba starting Saturday evening and persisting through Sunday. This system at its peak will look like the classic Colorado Low with a warm moist feed coming in from the south...cool moist feed from the east...and cold and dry air descending behind the main cold front.
If embedded convection does indeed form...if the tephi comes back somewhat unstable...I think Winnipeg may see around 25cm of snow. If no convection is present...I'll say 15cm at this time, based on the 12z run.
Winds later Sunday will be insane too...I wonder how tall the drifts in my yard will be after this storm!
A messy mix is starting to blossom in the Dakota's!
ReplyDeleteSPC has issued a discussion concerning freezing rain!
Justin--I work the night shift Sat and Sun but will do!
ReplyDeleteHow much rain/freezing rain would we get? If we get more than 3-4 mm, we break the record for wettest January =D.
ReplyDelete