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WxChallenge 2014-2015


Jurg

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58F* on the 18z GFS. I also did a HYSPLIT run and calculations that gave me a high of 59F around 18z tomorrow. And funny enough I used the super cold NAM as my model in the HYSPLIT run. The only way this doesn't work out is if the speed of the system is not modeled correctly more importantly modeled too slow so the onset of precipitation would be quicker and therefore my high won't work. 

 

Yeah, you're right, the 18z run now has 58, the 12z run has 54. That has me worried a lot now...

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The national consensus predictably follows the USL...which isn't much help when an actual synoptic system rolls through.

 

Not buying upper 50s for the high unless the precip ends up being delayed until after 20 UTC. It's going to be cloudy and there is no warm advection ahead of the front. Low 50s seems probable though.

 

For precip and wind, I couldn't help but notice how vigorous the wave looks on the water vapor and the 500 mb maps. Biggest concern is how short lived the best forcing is.

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The question is, do the strong southerlies kick in, or not?

 

 

46-58/29-33/13-25/0.00-0.50

 

But seriously...

49/31/17/0.20

BTW, there is also a chance it is 56F or better at 6z if the wind decides to pick up unexpectedly like it did day 1/2. Temps are 12C+ at about 780mb even at 6/7z tonight, so the low camp will be sweating tonight and praying the wind dies off tonight especially for your sake and 49F LOL

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BTW, there is also a chance it is 56F or better at 6z if the wind decides to pick up unexpectedly like it did day 1/2. Temps are 12C+ at about 780mb even at 6/7z tonight, so the low camp will be sweating tonight and praying the wind dies off tonight especially for your sake and 49F LOL

 

One of the reasons I didn't go lower than 49F is because of the possibility of a 06z high. Still, with how clear it is tonight, even with a little breeze I fully expect they'll be able to get down to 42F-48F by 06z.

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One of the reasons I didn't go lower than 49F is because of the possibility of a 06z high. Still, with how clear it is tonight, even with a little breeze I fully expect they'll be able to get down to 42F-48F by 06z.

Even being clear, if the wind picks up it wouldn't take much to mix to 780mb or slightly higher and then it won't even matter. Clear or cloudy with 12C+ at such a low height mid 50s is plausible. 

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Even being clear, if the wind picks up it wouldn't take much to mix to 780mb or slightly higher and then it won't even matter. Clear or cloudy with 12C+ at such a low height mid 50s is plausible. 

 

Yea that's what I was picking up on too... Those are really warm temperatures at 700-hPa and its pretty much going to have to start precipitating right at sunrise to keep the temp in check. That certainly could happen, but if the rain holds off until 18z or so, any amount of mixing could bring us into the mid to upper 50's. 

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Even being clear, if the wind picks up it wouldn't take much to mix to 780mb or slightly higher and then it won't even matter. Clear or cloudy with 12C+ at such a low height mid 50s is plausible. 

 

True, I just suspect the clearing will aid decoupling and kill the (mixing-strength) winds. If I remember correctly, 10/14-10/15 had a lot of high clouds that prevented said decoupling. We'll see, though. :)

 

EDIT: Or maybe there WILL be clouds. :arrowhead:

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52/31/23/0.16"

I had little confidence in the high because that will depend on precip holding off long enough and getting enough solar insulation to get mixing ahead of the front, so I picked a middle ground number. Can see anything from 48-60 though. Blended the Euro and hi-res models for the low tomorrow evening as they did well day 2 in a similar situation. For precip, it looks like a pretty quick shot of light to moderate precip, so I went low. If a convective cell happens to hit Butte they'll get more than what I have, but wanted to take that chance. NAM has consistently shown 30-35 knot westerly winds at the top of the shallow mixed layer in CAA behind the front and the 18z GFS trended that direction so didn't have an issue going so high on wind. If that works out for me that would help with the consensus only being 13 knots.

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Agree that the key is when the precip / front comes through tomorrow, which is complicated by the complex terrain.

 

If precip starts between 12-15 UTC, the 46-52F camp will likely verify with the precip. keeping in the nocturnal inversion before frontal passage. If precip holds off till after 18 UTC there will be a few hours to warm up with some downsloping, and with 700 hPa temps in the 12-15C range, its not unfathomable to expect temps in the 55-60F range if there is any mixing at all. Low is likely to be in the 30-34F range with some snowfall. Whether or not it gets cooler will depend if the winds die down, not super likely with strong CAA behind the front before 06 UTC. Rain is a total crap shoot... if they can get under a convective cell it could drop a quick .2", but I'm not willing to bet on convection in the valley. 

 

55/33/20/0.10" 

:unsure: Did you mean 750 hPa temps? 

 

54/30/19/0.18

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All of this extra heating that is probably going to provide some extra CAPE for the cells just to the east of Butte. Again its hit and miss with the cells in the mountains, but a quick burst of very heavy rain can drop a few tenths no problem. This line looks reasonably solid, so lets see what happens.

 

Anyone with a tenth or less (including myself) should be pretty worried right now:

 

codnexlab.NEXRAD.MSX.N0Q.20141021.1608.0

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Really should've stuck with 54 because GFS is doing so well with highs, but I got scared by models going under 51 otherwise. A good downpour and winds will help me, but low is where I'm gambling the most and it's not promising when the high get to 58+.

 

EDIT: Someone at UNCA on guidance went from 900th to 90th on high alone. He'll crash back to earth with no precip, but it's little frustrating second-guessing is hurting me in this city. 

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