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Post by landscaper on Jan 23, 2023 13:10:32 GMT -6
Coz what are your thoughts on that ? What does that -5 mean? Better for snow I assume
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Post by koll27–Waterloo, IL on Jan 23, 2023 13:12:25 GMT -6
I believe anything below zero supports snow.
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Post by bdgwx on Jan 23, 2023 13:16:43 GMT -6
Browne & Younkin 1970 list two rules. 1.The highest probability of heavy snow lies approximately 90 n.mi. to the left of the track of the 850-mb low center. and 2. On the average, the initially observed - 5°C isotherm nearly bisects the observed subsequent 12-hr heavy snowfall area. Note the authors say there is a 5% chance the axis of heaviest snow falls on the right side of the track. That's why the GYB 90 nm left rule is a statistical rule only. The 2-sigma envelope is actually bounded by about 90 nm to the right and 360 nm to the left with 90 nm to the left having peak likelihood. This is inferred from figure 2 in the publication. The point is that the modeled snowfall field we see that is south of the metro area is not inconsistent with what the authors are saying.
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Post by bdgwx on Jan 23, 2023 13:26:14 GMT -6
The 13Z NBM has about 2-4" for the metro area with the highest amounts around Farmington.  |
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Post by Snowstorm920 on Jan 23, 2023 13:33:07 GMT -6
Topography is playing a strong role in that NBM map
Remove the snow totals and that could almost pass for an elevation map
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Post by Chris Higgins on Jan 23, 2023 13:39:22 GMT -6
Browne & Younkin 1970 list two rules. 1.The highest probability of heavy snow lies approximately 90 n.mi. to the left of the track of the 850-mb low center. and 2. On the average, the initially observed - 5°C isotherm nearly bisects the observed subsequent 12-hr heavy snowfall area. Note the authors say there is a 5% chance the axis of heaviest snow falls on the right side of the track. That's why the GYB 90 nm left rule is a statistical rule only. The 2-sigma envelope is actually bounded by about 90 nm to the right and 360 nm to the left with 90 nm to the left having peak likelihood. This is inferred from figure 2 in the publication. The point is that the modeled snowfall field we see that is south of the metro area is not inconsistent with what the authors are saying. Excellent points! |
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Post by BRTNWXMAN on Jan 23, 2023 13:40:21 GMT -6
I get the feeling some of these models are overestimating surface temps during the heavier snowfall. Low-level THKN is well below 130dm nearly area-wide for basically the entire event. Proceed with caution when looking at those output charts for sure.
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Post by Worldserieschampions (Chicago) on Jan 23, 2023 13:43:00 GMT -6
That was a key to the magic chart in predicting snow Not really magic. Literally the authors of the GYB detail it as a condition lol |
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Post by bdgwx on Jan 23, 2023 13:44:13 GMT -6
Topography is playing a strong role in that NBM map Remove the snow totals and that could almost pass for an elevation map That is especially true for the Boston Mountains in NW Arkansas. |
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Post by Snowstorm920 on Jan 23, 2023 13:45:31 GMT -6
I get the feeling some of these models are overestimating surface temps during the heavier snowfall. Low-level THKN is well below 130dm nearly area-wide for basically the entire event. Proceed with caution when looking at those output charts for sure. I'd be much more concerned about surface temps if this was a daytime event.
The warm layer at the surface is incredibly shallow tomorrow night. I can't see it putting up much of a fight when heavy snow starts falling into it.
Although I know I've said that before and It's come back to bite me.
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Post by landscaper on Jan 23, 2023 13:46:06 GMT -6
These types of storms often drop the temp down to 32 rather quickly during the heaviest lift and snow rates
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Post by Worldserieschampions (Chicago) on Jan 23, 2023 13:48:08 GMT -6
15z sref is further north.
It has a minority cluster pretty far north skewing the average.
There is a larger cluster further southeast.
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Post by Chris Higgins on Jan 23, 2023 13:58:36 GMT -6
As I sit here waiting on 18z updates... I am reminded how when they first started running them, the 06/18z runs were notoriously aweful... to the point of being useless. As a person who was a huge "dont trust off model run" guy... I must say they have come a looooooooong way... to the point that there is no appreciable difference in quality IMO. That is a place the science has come a long way.
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Post by beaker - Dardenne Prairie, MO on Jan 23, 2023 14:03:40 GMT -6
Browne & Younkin 1970 list two rules. 1.The highest probability of heavy snow lies approximately 90 n.mi. to the left of the track of the 850-mb low center. and 2. On the average, the initially observed - 5°C isotherm nearly bisects the observed subsequent 12-hr heavy snowfall area. Note the authors say there is a 5% chance the axis of heaviest snow falls on the right side of the track. That's why the GYB 90 nm left rule is a statistical rule only. The 2-sigma envelope is actually bounded by about 90 nm to the right and 360 nm to the left with 90 nm to the left having peak likelihood. This is inferred from figure 2 in the publication. The point is that the modeled snowfall field we see that is south of the metro area is not inconsistent with what the authors are saying. Excellent points! But isnt this more than just about the track of the 850? What about the track of the 500? Weve talked alot about both the 850 and 500 in past storms, but it doesnt seem like the 850 will produce all our snow. |
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Post by bdgwx on Jan 23, 2023 14:07:54 GMT -6
They are expecting 8-12" in the Boston Mountains. A Winter Storm Warning has been issued for NW Arkansas.
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Post by Chris Higgins on Jan 23, 2023 14:15:41 GMT -6
But isnt this more than just about the track of the 850? What about the track of the 500? Weve talked alot about both the 850 and 500 in past storms, but it doesnt seem like the 850 will produce all our snow. 500mb vort max is a huge factor and they all work together. |
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Post by cozpregon on Jan 23, 2023 14:17:00 GMT -6
Coz what are your thoughts on that ? What does that -5 mean? Better for snow I assume Back when we had the difax print out our charts- the NGM had a net vertical displacement charts for 700mb- it would be in mb. We would place the 850 -3 to -5* isotherms on top of the chart. If the vertical displacement was 100mb and intersected the 850 -3 to -5... you would roughly have 10". 80mb would be 8 and so forth. |
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Post by thechaser on Jan 23, 2023 14:18:06 GMT -6
WSW for STL Metro. Text says 5-10"
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Post by Snowstorm920 on Jan 23, 2023 14:19:00 GMT -6
Winter storm warning out
Text says 5-10”
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Post by Spaz(Wrestlerdude) on Jan 23, 2023 14:19:25 GMT -6
Nam coming in north also
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Post by koll27–Waterloo, IL on Jan 23, 2023 14:19:37 GMT -6
Winter Storm Warning issued
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Post by mchafin on Jan 23, 2023 14:20:37 GMT -6
Winter storm warning out Text says 5-10” 4-6” plus additional light accum Wed morning (for immediate metro) |
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Post by STGOutdoors on Jan 23, 2023 14:21:28 GMT -6
Any thunder potential at all?
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Post by landscaper on Jan 23, 2023 14:21:44 GMT -6
NAM is a beast
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Post by snowjunky on Jan 23, 2023 14:23:25 GMT -6
Please sweet baby Jesus let us all get 6”+
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Post by thechaser on Jan 23, 2023 14:24:16 GMT -6
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Post by BRTNWXMAN on Jan 23, 2023 14:25:01 GMT -6
As I sit here waiting on 18z updates... I am reminded how when they first started running them, the 06/18z runs were notoriously aweful... to the point of being useless. As a person who was a huge "dont trust off model run" guy... I must say they have come a looooooooong way... to the point that there is no appreciable difference in quality IMO. That is a place the science has come a long way. The assimilation of data with these newer models is light years ahead of what they had just 5-10 years so. It seemed like once GOES16 went on line, they improved dramatically. What really impresses me is their ability to pretty consistently "sniff out" storms in the D10+ range and the stability of wave patterns. That range used to be a virtual crapshoot. |
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Post by Worldserieschampions (Chicago) on Jan 23, 2023 14:25:59 GMT -6
It would be cool if the nam was right for once.
Maybe move it north 20 miles too lol
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bob
Junior Forecaster
Posts: 334 
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Post by bob on Jan 23, 2023 14:26:59 GMT -6
Did the heavy snow band shift north on the NAM
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Post by Snowman99 on Jan 23, 2023 14:27:01 GMT -6
Nam is always tight...
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