April 11-? pcpn event, south Ontario to Montreal, rain, freezing rain, snow, pellets, tstorms, the kitchen sink Options

[knorthern_knight]

The rain/snow/etc starts today (11th) and is still going on the 17th at the end of the GFS forecast range. It simply keeps going with hardly any breaks. Here's the output for Toronto. Don't call out the army; call out the navy!

The outputs are similar for London/Kitchener-Waterloo/Hamilton/Ottawa/Montreal. The main difference is that there is more freezing rain and pellets and snow as you head north and east.

CODE

CYYZ Toronto Pearson International Airport - Toronto, Ontario
GFS Model Run: 12Z 11APR 2018
==============================
   HR Valid     2m Tmp 2m Dpt TPrcp PRS WX Max    Min Snowfall
                 Deg F  Deg F  in.  TEXT   Tmp    Tmp    in
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ n_ PCPN  SNOW
    0 04/11 12Z   34     27    0.00       ****   ****    0.0
    3 04/11 15Z   40     28    0.00         40     34    0.0
    6 04/11 18Z   41     32    0.03 -RA     41     34    0.0  0.03
    9 04/11 21Z   40     34    0.02 -RA     41     40    0.0  0.05
   12 04/12 00Z   39     35    0.01 -RA     41     38    0.0  0.06
   15 04/12 03Z   36     32    0.00         38     36    0.0
   18 04/12 06Z   34     30    0.00         38     34    0.0
   21 04/12 09Z   35     31    0.00         35     34    0.0
   24 04/12 12Z   36     34    0.05 -RA     36     34    0.0  0.05
   27 04/12 15Z   38     37    0.10 -RA     38     36    0.0  0.15
   30 04/12 18Z   43     42    0.03 -RA     43     36    0.0  0.18
   33 04/12 21Z   48     45    0.08 -TSRA   48     44    0.0  0.26
   36 04/13 00Z   48     45    0.00 -RA     51     44    0.0
   39 04/13 03Z   42     38    0.00         48     42    0.0
   42 04/13 06Z   39     35    0.01 -RA     48     39    0.0  0.01
   45 04/13 09Z   36     33    0.00         39     36    0.0
   48 04/13 12Z   36     34    0.06 -RA     39     36    0.0  0.06
   51 04/13 15Z   37     35    0.07 -RA     37     36    0.0  0.13
   54 04/13 18Z   38     37    0.04 -RA     38     36    0.0  0.17
   57 04/13 21Z   38     36    0.08 -RA     38     37    0.0  0.25
   60 04/14 00Z   37     36    0.05 -RA     38     37    0.0  0.30
   63 04/14 03Z   38     36    0.09 -RA     38     38    0.0  0.39
   66 04/14 06Z   37     36    0.06 -RA     38     37    0.0  0.45
   69 04/14 09Z   37     35    0.08 -RA     37     37    0.0  0.53
   72 04/14 12Z   35     33    0.22 -RA     37     34    0.0  0.75
   75 04/14 15Z   31     29    0.11 -RA     34     31    0.0  0.86
   78 04/14 18Z   30     28    0.07 -RA     34     30    0.0  0.93
   81 04/14 21Z   29     27    0.13 -FZRN   30     28    0.0  1.06
   84 04/15 00Z   29     27    0.06 -FZRN   30     28    0.0  1.12
   87 04/15 03Z   30     28    0.01 -RA     30     29    0.0  1.13
   90 04/15 06Z   31     28    0.01 -RA     31     29    0.0  1.14
   93 04/15 09Z   31     29    0.01 -RA     31     31    0.0  1.15
   96 04/15 12Z   32     30    0.17 -RA     32     31    0.0  1.32
   99 04/15 15Z   35     34    0.38 RA      35     32    0.0  1.70
  102 04/15 18Z   36     36    0.40 RA      36     32    0.0  2.10
  105 04/15 21Z   37     37    0.29 RA      37     36    0.0  2.39
  108 04/16 00Z   42     42    0.22 RA      42     36    0.0  2.61
  111 04/16 03Z   42     41    0.12 -RA     44     41    0.0  2.73
  114 04/16 06Z   42     42    0.20 RA      44     41    0.0  2.93
  117 04/16 09Z   42     41    0.08 -RA     42     42    0.0  3.01
  120 04/16 12Z   41     40    0.00 -RA     42     41    0.0
  123 04/16 15Z   44     41    0.00         44     41    0.0
  126 04/16 18Z   44     40    0.01         44     41    0.0  0.01
  129 04/16 21Z   40     35    0.01 -RA     43     40    0.0  0.02
  132 04/17 00Z   36     30    0.00 -SN     43     36    0.0
  135 04/17 03Z   34     29    0.01 -SN     36     34    0.0  0.01
  138 04/17 06Z   34     29    0.01 -SN     36     34    0.0  0.02
  141 04/17 09Z   33     28    0.02 -SN     34     33    0.1  0.04    0.1
  144 04/17 12Z   32     27    0.02 -SN     34     32    0.1  0.06    0.2

This post has been edited by knorthern_knight: Apr 11 2018, 01:45 PM

[knorthern_knight]

How grey and depressing is it? Even the forecast is almost entirely grey. I don't recall seeing this before, but Vancouver probably gets its share in the winter. A screen capture...

 grey.gif ( 81.62K ) Number of downloads: 1

[travis3000]

Will be an interesting weekend. That's for sure. I wonder if we will even hit double digits up this way tomorrow? GFS and NAM say no, only models that say yes are the CMC, HRDPS and RGEM. I will say these three models historically are best at getting the temps right so I will say we will prob hit double digits tomorrow. Windsor could even hit 20C.

This post has been edited by travis3000: Apr 11 2018, 09:16 PM

[MrMusic]

HRDPS, HRRR and RAP putting me up to 15-17 tomorrow afternoon. I'll believe it when I see the wind shift.

Newest Global models keep the storms further north on the weekend with just rain here, and not nearly as much as previously advertised. Still a long way to go tho.

[Apocalypse]

How grey and depressing is it? Even the forecast is almost entirely grey. I don't recall seeing this before, but Vancouver probably gets its share in the winter. A screen capture...

 grey.gif ( 81.62K ) Number of downloads: 1

Vancouver get months of rain.

[Lake effect]

Anyone thinking 10 hours of sleet will equal snowfall, it's worth using the snowdepth change map:

Snowfall:

 namconus_asnow_neus_29__2_.png ( 139.93K ) Number of downloads: 2


Vs snowdepth change for same model same time frame:

 namconus_asnowd_neus_29.png ( 126.23K ) Number of downloads: 0

[knorthern_knight]

April 12 00Z GFS text

• decreases precip amounts for southern Ontario. The 17th is within range now, and showing some back end snow.
• meanwhile, Ottawa/Montreal are forecast to be hammered with over 4 inches (100 mm) of water equivalant, mostly rain.
• Here's Montreal's forecast

CODE

The following derived from http://charlie.wxcaster.com/
Station ID: CYUL Lat:   45.46 Long:   73.75
CYUL Montr�al-Pierre Elliott Trudeau International Airport - Montreal, Quebec
GFS Model Run:  0Z 12APR 2018
==============================
   HR Valid     2m Tmp 2m Dpt TPrcp PRS WX Max    Min Snowfall
                 Deg F  Deg F  in.  TEXT   Tmp    Tmp    in
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ n_ PCPN  SNOW
    0 04/12 00Z   37     27    0.00       ****   ****    0.0
    3 04/12 03Z   35     27    0.01 -SN     37     35    0.0  0.01
    6 04/12 06Z   31     27    0.00 -SN     37     31    0.0
    9 04/12 09Z   30     27    0.00         31     30    0.0
   12 04/12 12Z   33     29    0.00         33     30    0.0
   15 04/12 15Z   41     32    0.00         41     33    0.0
   18 04/12 18Z   47     32    0.00         47     33    0.0
   21 04/12 21Z   46     35    0.01 -RA     48     46    0.0  0.01
   24 04/13 00Z   43     38    0.09 -RA     48     42    0.0  0.10
   27 04/13 03Z   41     40    0.21 RA      43     41    0.0  0.31
   30 04/13 06Z   38     35    0.01 -RA     43     38    0.0  0.32
   33 04/13 09Z   35     32    0.00         37     35    0.0
   36 04/13 12Z   36     31    0.00         37     34    0.0
   39 04/13 15Z   42     32    0.00         42     37    0.0
   42 04/13 18Z   45     33    0.00         45     37    0.0
   45 04/13 21Z   44     34    0.00         46     44    0.0
   48 04/14 00Z   41     36    0.06 -RA     46     41    0.0  0.06
   51 04/14 03Z   39     36    0.09 -RA     41     40    0.0  0.15
   54 04/14 06Z   39     35    0.03 -RA     41     38    0.0  0.18
   57 04/14 09Z   31     26    0.04 -SN     38     31    0.3  0.22    0.3
   60 04/14 12Z   27     22    0.10 -SN     38     27    0.9  0.32    1.2
   63 04/14 15Z   26     19    0.02 -SN     27     26    0.2  0.34    1.4
   66 04/14 18Z   25     22    0.08 -SN     27     25    0.7  0.42    2.1
   69 04/14 21Z   25     23    0.17 SN      25     24    1.5  0.59    3.6
   72 04/15 00Z   25     23    0.10 -PL     25     24    0.0  0.69
   75 04/15 03Z   24     23    0.27 PL      25     24    0.0  0.96
   78 04/15 06Z   27     24    0.12 PL      27     24    0.0  1.08
   81 04/15 09Z   25     23    0.01 -PL     26     25    0.0  1.09
   84 04/15 12Z   25     23    0.01 -PL     26     25    0.0  1.10
   87 04/15 15Z   27     25    0.02 -PL     27     25    0.0  1.12
   90 04/15 18Z   30     29    0.23 -FZRN   30     25    0.0  1.35
   93 04/15 21Z   32     32    0.46 RA      32     29    0.0  1.81
   96 04/16 00Z   33     33    0.35 RA      33     29    0.0  2.16
   99 04/16 03Z   34     34    0.20 RA      34     33    0.0  2.36
  102 04/16 06Z   36     36    0.44 RA      36     33    0.0  2.80
  105 04/16 09Z   36     36    0.45 RA      36     36    0.0  3.25
  108 04/16 12Z   36     36    0.10 RA      36     36    0.0  3.35
  111 04/16 15Z   39     39    0.21 RA      39     36    0.0  3.56
  114 04/16 18Z   46     46    0.16 RA      46     36    0.0  3.72
  117 04/16 21Z   50     49    0.28 RA      52     46    0.0  4.00
  120 04/17 00Z   37     35    0.26 RA      52     35    0.0  4.26
  123 04/17 03Z   37     36    0.06 -TSRA   37     36    0.0  4.32
  126 04/17 06Z   36     36    0.06 -TSRA   37     36    0.0  4.38
  129 04/17 09Z   35     33    0.06 -RA     36     35    0.2  4.44    0.2
  132 04/17 12Z   35     32    0.01 -SN     36     34    0.2  4.45    0.4
  135 04/17 15Z   35     31    0.00         35     34    0.0
  138 04/17 18Z   35     32    0.01         36     34    0.0  0.01
  141 04/17 21Z   36     32    0.00         36     36    0.0

[Ottawa blizzard]

HRDPS, HRRR and RAP putting me up to 15-17 tomorrow afternoon. I'll believe it when I see the wind shift.

Newest Global models keep the storms further north on the weekend with just rain here, and not nearly as much as previously advertised. Still a long way to go tho.

Morning run of the CMC is back to showing lots of freezing rain and ice pellets for southern Ontario on Saturday night.

[PGM]

Morning run of the CMC is back to showing lots of freezing rain and ice pellets for southern Ontario on Saturday night.

I think the alarm bells should be sounding now... it's time to prepare before the public hysteria begins. Good day to go to the store and get some food, non perishables, ice melt, water, etc.



This post has been edited by PGM: Apr 12 2018, 06:02 AM

[snowball]

Yeah trending appears to be South again. Some big amounts for a large portion of Southern Ontario. I could see it trending worse over better as well...

[PGM]

NAM is all over the place as per usual.... really praying this shifts north a ton. An event over Manitoulin and Algonquin would impact way less people.
 zr_acc.us_ne__1_.png ( 343.77K ) Number of downloads: 15


This post has been edited by PGM: Apr 12 2018, 06:13 AM

[snowball]

NAM brings the cold air further South even, and hints GTA could be saved around the lake. If we see some more of the same tonight I think we'll understand not only the alarming areas but unusual consensus for an ice event this far out (which coincides with ECs early confidence).

[EOsnowmom]

...meanwhile, Ottawa/Montreal are forecast to be hammered with over 4 inches (100 mm) of water equivalant, mostly rain.

I HOPE NOT!! (caps are intentional)

[PGM]

EC

Potential ice storm for parts of Southern Ontario Saturday into Sunday. Heavy rain potential later Sunday.

A significant freezing and ice pellet event is expected for portions of Southern Ontario Saturday and Sunday as a slow-moving low pressure system approaches the area. Precipitation may start as rain, but increasing northeasterly winds will draw colder air from an arctic high pressure system to the north, resulting in a changeover to freezing rain or ice pellets. A few rounds of precipitation are likely during this period with a threat of significant freezing rain in some areas.

There is uncertainty as to which areas will be most affected.

Accumulations in excess of 20 millimetres of freezing rain will be possible. Ice accumulations of this magnitude combined with gusty winds to 60 km/h may result in widespread power outages due to fallen tree limbs and power lines. Travel is also expected to be hazardous.

Freezing rain is expected to change to rain possibly heavy at times on Sunday as temperatures rise above the freezing mark.

London-Middlesex is currently not in the advisory.

[PGM]

EC
London-Middlesex is currently not in the advisory.

 son_e.png ( 25.5K ) Number of downloads: 5


everywhere in grey is^

[knorthern_knight]

Apr 12, 12Z GFS text forecast 04/12 12Z to 04/18 12Z. Note that I'm over-riding precip type with temperatures. E.g. where the forecast calls for straight rain with temps of 30F, I'm calling it freezing rain. As usual, micro-cliimate (elevation, distance from lake, etc) will affect local freezing rain duration and amounts.

• London 2.02 inches water-equivalant mostly rain, except for a bit of (wet?) snow 17th/18th. But with temps at or just below freezing, don't expect it to accummulate. Freezing rain 21Z 14th to 06Z 15th (5PM EDT to 2AM EDT)
• Waterloo 2.48 inches. Freezing rain 11AM 14th to 8AM 15th. Wet snow on 17th/18th
• Hamilton 2.49 inches. Wet snow 17th+18th. Freezing rain 11PM 14th to 2AM 15th. That's the airport. Higher elevations may get more freezing rain.
• Toronto 2.99 inches, Wet snow on the 17th. Freezing rain 2PM 14th to 8AM 15th. That's the airport. As you head north, expect more. Also some wet snow on the 17th
• Ottawa 4.40 inches. Freezing rain 2PM to 5PM of the 15th. Wet snow 17th/18th changing to rain in the morning.
• Montreal 3.84 inches. Freezing rain 11AM to 2PM of the 15th. Wet snow overnight 17th/18th, changing ro rain in the morning
• Quebec City 2.14 inches. Freezing rain 5AM to 11AM of the 16th. Wet snow beginning morning of the 18th

[snowball]

Apr 12, 12Z GFS text forecast 04/12 12Z to 04/18 12Z. Note that I'm over-riding precip type with temperatures. E.g. where the forecast calls for straight rain with temps of 30F, I'm calling it freezing rain. As usual, micro-cliimate (elevation, distance from lake, etc) will affect local freezing rain duration and amounts.

• London 2.02 inches water-equivalant mostly rain, except for a bit of (wet?) snow 17th/18th. But with temps at or just below freezing, don't expect it to accummulate. Freezing rain 21Z 14th to 06Z 15th (5PM EDT to 2AM EDT)
• Waterloo 2.48 inches. Freezing rain 11AM 14th to 8AM 15th. Wet snow on 17th/18th
• Hamilton 2.49 inches. Wet snow 17th+18th. Freezing rain 11PM 14th to 2AM 15th. That's the airport. Higher elevations may get more freezing rain.
• Toronto 2.99 inches, Wet snow on the 17th. Freezing rain 2PM 14th to 8AM 15th. That's the airport. As you head north, expect more. Also some wet snow on the 17th
• Ottawa 4.40 inches. Freezing rain 2PM to 5PM of the 15th. Wet snow 17th/18th changing to rain in the morning.
• Montreal 3.84 inches. Freezing rain 11AM to 2PM of the 15th. Wet snow overnight 17th/18th, changing ro rain in the morning
• Quebec City 2.14 inches. Freezing rain 5AM to 11AM of the 16th. Wet snow beginning morning of the 18th

Latest GFS is reflecting 24 hours of freezing rain. Totals are way up especially around Goderich to of course Mount Forest.

Pack up on emergency supplies !

[Stl]

Apr 12, 12Z GFS text forecast 04/12 12Z to 04/18 12Z. Note that I'm over-riding precip type with temperatures. E.g. where the forecast calls for straight rain with temps of 30F, I'm calling it freezing rain. As usual, micro-cliimate (elevation, distance from lake, etc) will affect local freezing rain duration and amounts.

• London 2.02 inches water-equivalant mostly rain, except for a bit of (wet?) snow 17th/18th. But with temps at or just below freezing, don't expect it to accummulate. Freezing rain 21Z 14th to 06Z 15th (5PM EDT to 2AM EDT)
• Waterloo 2.48 inches. Freezing rain 11AM 14th to 8AM 15th. Wet snow on 17th/18th
• Hamilton 2.49 inches. Wet snow 17th+18th. Freezing rain 11PM 14th to 2AM 15th. That's the airport. Higher elevations may get more freezing rain.
• Toronto 2.99 inches, Wet snow on the 17th. Freezing rain 2PM 14th to 8AM 15th. That's the airport. As you head north, expect more. Also some wet snow on the 17th
• Ottawa 4.40 inches. Freezing rain 2PM to 5PM of the 15th. Wet snow 17th/18th changing to rain in the morning.
• Montreal 3.84 inches. Freezing rain 11AM to 2PM of the 15th. Wet snow overnight 17th/18th, changing ro rain in the morning
• Quebec City 2.14 inches. Freezing rain 5AM to 11AM of the 16th. Wet snow beginning morning of the 18th

Thanks for the details , i see that the Euro and CMC are quite colder than the GFS for here.

[travis3000]

My thoughts

Friday:
bands of showers roll in Friday morning across SW ON ahead of the low pressure. A steadier band moves in Friday afternoon across the GTA north into Muskoka. This will be moderate but steady band of rain.

Overnight Friday the rain will become mixed with snow and sleet across Muskoka and Sudbury. Expect heavier snow to be falling in this area at some point Fri night. Rain keeps falling across SW ON north to Barrie and east towards Kingston. It will move into the Ottawa area Friday night as well.

Saturday: Rain becomes mixed with sleet and wet snow early Sat AM across Bruce County and Simcoe County east to Bobcaygeon and Kawarthas. Its still snowing in North Bay down to Muskoka and Tobermory area. Its still raining in Toronto on SW.

Periods of freezing rain begin Sat early afternoon across S ON from Goderich across to Kitchener, Guelph. Orangeville, Shelburne and could become very heavy. The freezing rain will start impacting the GTA Sat afternoon as well. Freezing rain continues off and on through the night across the Goderich to Mount Forest, Kitchener, Toronto corridor. All rain from Windsor to London.

Heavy wet snow mixed with sleet will come about as far south as Barrie by Saturday afternoon and evening but accumulations will be under 5-7cm. Freezing rain continues to impact the Goderich to Kitchener to Hamilton and Niagara, possibly going as far south as London.

Sunday

Periods of freezing rain will continue into the morning hours, after a bit of a lull overnight Sat, things will ramp up early Monday morning with another band in the similar area. Im concerned for an area from Goderich to Kitchener/Guelph, Orangeville, Mount Forest. Basically all of Huron County, Wellington County, Dufferin County where up to 25mm of ice is possible (power outages). The GTA will also see ice, just not near the lakes…more inland by 5km or so. Im thinking 8-12mm of ice there.

Freezing rain and sleet will eventually give way to plain rain Sunday afternoon (1-4pm) as temps rise above 0C. Heavy rain will continue Sun night and Monday AM before temps drop Monday and flurries develop in a NW flow. The flurries will continue right into Tuesday on the west side of the low. Some areas could pick up 1-5cm in backlash snows.

[dsichewski]

My thoughts

Friday:
bands of showers roll in Friday morning across SW ON ahead of the low pressure. A steadier band moves in Friday afternoon across the GTA north into Muskoka. This will be moderate but steady band of rain.

Overnight Friday the rain will become mixed with snow and sleet across Muskoka and Sudbury. Expect heavier snow to be falling in this area at some point Fri night. Rain keeps falling across SW ON north to Barrie and east towards Kingston. It will move into the Ottawa area Friday night as well.

Saturday: Rain becomes mixed with sleet and wet snow early Sat AM across Bruce County and Simcoe County east to Bobcaygeon and Kawarthas. Its still snowing in North Bay down to Muskoka and Tobermory area. Its still raining in Toronto on SW.

Periods of freezing rain begin Sat early afternoon across S ON from Goderich across to Kitchener, Guelph. Orangeville, Shelburne and could become very heavy. The freezing rain will start impacting the GTA Sat afternoon as well. Freezing rain continues off and on through the night across the Goderich to Mount Forest, Kitchener, Toronto corridor. All rain from Windsor to London.

Heavy wet snow mixed with sleet will come about as far south as Barrie by Saturday afternoon and evening but accumulations will be under 5-7cm. Freezing rain continues to impact the Goderich to Kitchener to Hamilton and Niagara, possibly going as far south as London.

Sunday

Periods of freezing rain will continue into the morning hours, after a bit of a lull overnight Sat, things will ramp up early Monday morning with another band in the similar area. Im concerned for an area from Goderich to Kitchener/Guelph, Orangeville, Mount Forest. Basically all of Huron County, Wellington County, Dufferin County where up to 25mm of ice is possible (power outages). The GTA will also see ice, just not near the lakes…more inland by 5km or so. Im thinking 8-12mm of ice there.

Freezing rain and sleet will eventually give way to plain rain Sunday afternoon (1-4pm) as temps rise above 0C. Heavy rain will continue Sun night and Monday AM before temps drop Monday and flurries develop in a NW flow. The flurries will continue right into Tuesday on the west side of the low. Some areas could pick up 1-5cm in backlash snows.

Should be a fun time in Guelph!