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Southern Ontario Winter '14-'15 Discussion


harrisale

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Might be thinking about another one. There was one in December of 2000 that dropped locally 50cm in eastern Oakville and western Mississauga. That one may have been a 6-8 hr blast. I don't remember.

 

The January 2004 one started in the evening of the 25th around Burlington, shifted north to the bullseye zone by midnight and just sat all night. Then during the mid morning of the 26th it shifted slightly further to the north to hit mby and YYZ. Then as WAA continued the band weakened early in the evening of the 26th. Then the synoptic took over.

 

Incredible gradient during the afternoon of the 26th. I had shoveled my grandma's driveway in Mimico and they were easily approaching 40cm at that point. Had about 15cm imby in central Etobicoke when I got home. Called my mom who works in North York. NOT A FLAKE! Wild, wild stuff. When she was driving home on the 401 it hit like a wall at the 400,

 

Live for east wind LES. It's so cool.

Ya I must be thinking of a different one. From what I remember it was as if the rest of the city continued on as if nothing happened yet down here was hit hard. Would also make sense from the geographic region you mentioned since thats a very small portion of the GTA

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Sure. Here's 12z on the 26th (more: http://mp1.met.psu.edu/~fxg1/NARR/2004/us0126.php).Classic setup. Arctic high pressure over QC and a synoptic storm approaching from the Plains/MW.

 

012612.png

Thanks for clearing up the dates for me, this one is having a tough time coming back to me for some reason. The western end of Lake Ontario can definitely cash in and normally experience snow squalls a couple times a year. Today was a tight gradient which I happened to luck out on. 427/401 was mix of sun and cloud and little snow. While down here south of the QEW in Mississauga we got 3 inches. 

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Yup! Any initial thoughts for the clipper on Thursday-Friday? Still uncertainty among models on the exact intensity of the precipitation, but track does seem promising for something (>3cm). 

2-3" looks like a pretty good initial call IMO. The OP models are on the higher end of this range with both the GFS/EC near 3" for the entire GTA with the GEM above 6" and clearly an outlier. The main reason i'm not siding with the drier NAM/UKM is due to the nature of the flow which could be out of the ESE for quite a while, opening the door for some Lehs.

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2-3" looks like a pretty good initial call IMO. The OP models are on the higher end of this range with both the GFS/EC near 3" for the entire GTA with the GEM above 6" and clearly an outlier. The main reason i'm not siding with the drier NAM/UKM is due to the nature of the flow which could be out of the ESE for quite a while, opening the door for some Lehs.

Yeah the 0z Euro had 0.25 qpf in Toronto proper which translates to 2-3". 6z GFS had around 10cm, but the NAM remains bullish on its more northern track.

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Even the NAM keeps the 2m temps below freezing though. Just barely.

 

Yeah the NAM is an outlier atm. Here's the 0z Euro text output. 

 

ECMWF FORECAST FOR: YYZ    LAT=  43.67 LON=  -79.63 ELE=   568

                                            00Z JAN27

                 2 M     850     SFC     SFC     700    6 HR     500    1000 

                 TMP     TMP     PRS     RHU     RHU     QPF     HGT     500 

                 ©     ©    (MB)    (PCT)   (PCT)   (IN)    (DM)     THK 

THU 18Z 29-JAN  -0.8    -5.0    1010      46      98    0.01     547     539    

FRI 00Z 30-JAN  -1.0    -6.3    1007      93      99    0.12     541     535    

FRI 06Z 30-JAN  -1.4   -10.4    1008      80      17    0.12     533     527    

FRI 12Z 30-JAN -10.4   -14.4    1018      73      56    0.01     525     511

 

   

 

10:1 ratios look like a good bet atm. 

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As for the Sunday-Monday storm, the 12z Euro spits out around 0.60 qpf for the GTA with 12:1 and 15:1 snow ratios. Amazing hit. Lets hope for some consistency.

 

lol, our standards have been lowered this winter.

 

And you should stop throwing these snowfall ratios around as model output unless it's actually that. Just guessing ratios based on the sfc or 850 temps doesn't work. It has to do with how large the snow growth region is and whether or not the best lift intersects that region.

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And you should stop throwing these snowfall ratios around as model output unless it's actually that. Just guessing ratios based on the sfc or 850 temps doesn't work. It has to do with how large the snow growth region is and whether or not the best lift intersects that region.

Agree, 15:1 snow water ratio would be pretty generous. 10:1 I feel would be an appropriate tool for first guesses on snowfall with this system at this juncture. Not seeing much evidence to confidently bump up from there, especially since that Euro text data posted had surface temps at a mere -0.8C at the onset of precipitation.

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Agree, 15:1 snow water ratio would be pretty generous. 10:1 I feel would be an appropriate tool for first guesses on snowfall with this system at this juncture. Not seeing much evidence to confidently bump up from there, especially since that Euro text data posted had surface temps at a mere -0.8C at the onset of precipitation.

 

On this run temps are anywhere between -4 and -10c in and around YYZ for the early week system so a higher ratio/more classic S On setup is on the table if it verifies though I haven't looked deeply at the DGZ/Omega profiles. The latest euro run had ENE winds for an extended period of time with a Lehs signature especially across the typical regions(YYZ down towards Miss-Oak-YHM). Models have been trending more progressive with the SW cutoff meaning the N stream is less dominant and the S vort can push further N. Since these S branch setups usually tend to trend more amped, I'm liking where we are sitting right now.

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lol, our standards have been lowered this winter.

 

And you should stop throwing these snowfall ratios around as model output unless it's actually that. Just guessing ratios based on the sfc or 850 temps doesn't work. It has to do with how large the snow growth region is and whether or not the best lift intersects that region.

 

Yeah your right. It's to early to be throwing out ratios so I'm sorry for that. However, I know what your saying. I based them on the parameters that i analyzed and atmospheric conditions looked good on that run for good ratios. I guess I'll just stick to posting numbers.  

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Based strictly on the snow maps, the 0z GFS shows a nice 5-10cm in the GTA as well. Nice agreement between the RGEM and GFS atm. 

 

For the following storm, this clipper will be a key piece to the puzzle. How fast it moves will determine how fast the leading HP's will move and allow the storm to cut more northward and allow for a better phasing potential. Timing is everything. From a teleconnection standpoint, the PNA looks to be slightly negative and that will help position the trough alignment in the West/East. NAO looks to be neutral with some minimal ridging on the Western end of Greenland (-NAO East based), which favours a more inland track as it helps to shear out any strong 50/50 Low from developing. Lets see! 

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On this run temps are anywhere between -4 and -10c in and around YYZ for the early week system so a higher ratio/more classic S On setup is on the table if it verifies though I haven't looked deeply at the DGZ/Omega profiles. The latest euro run had ENE winds for an extended period of time with a Lehs signature especially across the typical regions(YYZ down towards Miss-Oak-YHM). Models have been trending more progressive with the SW cutoff meaning the N stream is less dominant and the S vort can push further N. Since these S branch setups usually tend to trend more amped, I'm liking where we are sitting right now.

 

Temps certainly trended much colder over the last 24hrs of model runs. Nice trend to see of course. 

 

Thinking 2.5" likely IMBY for tomorrow's clipper system. These arctic front systems always seem to die as they head over the escarpment but temps look good in YYZ for all snow with whatever moisture makes it that far east.

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I like 3-4" for the GTA, with slightly higher amounts from downtown and points eastward. The dreaded SW downsloping wind off the Escarpment will be a minimal factor, if any at all. In fact, the 4km NAM shows some nice lake enhancement potential in the GTA, especially towards the east, as the general wind flow will be out of the SE or S.

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Latest RUC shows 2-4" across the GTA. The precipitation is still continuing through 24 hours btw. 

 

Yes, a really nice pivot point on the RUC. I don't like to put much stock in the RUC due to its lower res but this type of evolution is similar to the 4kNAM and the RDPS which is encouraging for at least a couple hours of SN to +SN.

 

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