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WxChallenge 2014-2015


Jurg

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50/35/28

 

Anything from 46 to 68 wouldn't surprise me. I'm hoping the "fronts tend to come through faster than modeled in the plains", in addition to the "the front is currently ahead of schedule", equals the front is through Abilene before 06z for me. But it wouldn't surprise me at all if it was after.

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50/35/28

 

Anything from 46 to 68 wouldn't surprise me. I'm hoping the "fronts tend to come through faster than modeled in the plains", in addition to the "the front is currently ahead of schedule", equals the front is through Abilene before 06z for me. But it wouldn't surprise me at all if it was after.

Ahead of schedule is one thing. 2 hours ahead of schedule is another.

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63/34/27/0

 

After checking the high res models, the timing looks steady between 6z and 7z. I'm hoping the front due to the lessening gradient out in front will check back the speed just a touch and keep it from coming into ABI sooner. The winds along the frontal boundary have been running low 30's so far, but with a slight relaxation of the winds along the front by nightfall, I like upper 20's in knots wind speed.

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Ahead of schedule is one thing. 2 hours ahead of schedule is another.

 

By my estimation, it's about 2 hours ahead of the Euro. About 1 hr ahead of the hi-res NAM. But will that be enough?

 

Based on the radar, I think the front will be literally at Abilene at 06z. But that's probably not enough for my temperature. I need it to be there by around 0540z for my temperature to verify. Going to be a nail-biter for sure.

 

EDIT: I had done a lot of analysis (obviously) to come up with my number, but I wish I had done that radar analysis before the deadline. Right now I'm thinking the front gets there between 0600z and 0615z. That would be a win for the high camp.

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By my estimation, it's about 2 hours ahead of the Euro. About 1 hr ahead of the hi-res NAM. But will that be enough?

 

Based on the radar, I think the front will be literally at Abilene at 06z. But that's probably not enough for my temperature. I need it to be there by around 0540z for my temperature to verify. Going to be a nail-biter for sure.

 

EDIT: I had done a lot of analysis (obviously) to come up with my number, but I wish I had done that radar analysis before the deadline. Right now I'm thinking the front gets there between 0600z and 0615z. That would be a win for the high camp.

It is not off by 2hrs on the Euro. I just did an estimation using mesowest and the wind plot of the 12z euro on Wunderground. At most it is off by 50 to 75 miles too slow. I don't know how to use the forum posting to post my images on here but they are on my alumni wxchallege group page. Here's the link to the page if you want to view the images. Don't know if you will be able to but have a go at it.

https://www.facebook.com/groups/403062826428098/

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It is not off by 2hrs on the Euro. I just did an estimation using mesowest and the wind plot of the 12z euro on Wunderground. At most it is off by 50 to 75 miles too slow. I don't know how to use the forum posting to post my images on here but they are on my alumni wxchallege group page. Here's the link to the page if you want to view the images. Don't know if you will be able to but have a go at it.

https://www.facebook.com/groups/403062826428098/

 

The Euro analysis was based on observations out of eastern CO from earlier today. I haven't looked at it more recently, but honestly, I just don't trust the Euro in these situations anyway.

 

I just looked at the Hi-Res NAM again, and it appears to be off by about an hour and a quarter to an hour and a half in the TX panhandle. IF that's the case, and IF the front continues with the Hi-Res NAM's speed, then I still have a chance.

 

The 22z HRRR seems to be about 30 to 45 minutes slow over the TX panhandle, which would put the front just at Abiliene by 06z, too.

 

Still, based on my radar estimation, I think I'd give myself only a 20% chance.

 

My best guess is that the 06z obs (at 0552z) will have the wind mostly switched (maybe NNW), but the temperature not having fallen very far yet (say still 60F-64F).

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The Euro analysis was based on observations out of eastern CO from earlier today. I haven't looked at it more recently, but honestly, I just don't trust the Euro in these situations anyway.

 

I just looked at the Hi-Res NAM again, and it appears to be off by about an hour and a quarter to an hour and a half in the TX panhandle. IF that's the case, and IF the front continues with the Hi-Res NAM's speed, then I still have a chance.

 

Still, based on my radar estimation, I think I'd give myself only a 20% chance.

Did you look at wind shift or temperature change when estimating the speed?

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Let's just say the front is moving at a speed of 40mph and that it just passed through Cheyenne, Ok at 0z. So it has 6 hours to get to Abilene, TX which is almost due south from Cheyenne, Ok. It is about 240 miles to get from point A to B in this situation travelling at 40mph. So it does look like that the front will be right on the doorstep of KABI. Only if that 40mph speed stays constant of course. Nail biter indeed mates. Gonna be a long night lol.

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Let's just say the front is moving at a speed of 40mph and that it just passed through Cheyenne, Ok at 0z. So it has 6 hours to get to Abilene, TX which is almost due south from Cheyenne, Ok. It is about 240 miles to get from point A to B in this situation travelling at 40mph. So it does look like that the front will be right on the doorstep of KABI. Only if that 40mph speed stays constant of course. Nail biter indeed mates. Gonna be a long night lol.

 

Yep.

 

I think one thing to keep in mind is that with a weakening temperature gradient, the front can slow down, but in this case I think the models are underdoing temperatures ahead of the front (which is why it's been faster all day), and I feel like that will only continue tonight. So I think I still have a little room to make up ground on the models, assuming a stronger-than-forecast temperature gradient. That was another piece of my argument.

 

Still, I think your analysis is right on and that the front will literally be AT Abilene by 06z, which is not enough for me.

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I tried to gauge the front forward speed based on the radar depicted density gradient (I looked between . I got a speed in the 12-13 m/s range, with it needing to cross about 330 km of distance from Amarillo. This should put the leading edge of the front within 50 km of Abilene at 0600 UTC, but probably not fast enough to get there. 

 

64/33/27/0

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Let's just say the front is moving at a speed of 40mph and that it just passed through Cheyenne, Ok at 0z. So it has 6 hours to get to Abilene, TX which is almost due south from Cheyenne, Ok. It is about 240 miles to get from point A to B in this situation travelling at 40mph. So it does look like that the front will be right on the doorstep of KABI. Only if that 40mph speed stays constant of course. Nail biter indeed mates. Gonna be a long night lol.

 

Its easy to calculate the front propagation speed using the Amarillo radar... each square county in Texas is about 48.5 km long from N to S... and the frontal passage on the Amarillo radar took ~45 minutes to move this distance. This gives us a propagation speed of around 36.4 km/hr... quite a bit slower than 40 mph

 

Edit: I'm an idiot, should be around 64.7 km/hr... so 40 mph is quite reasonable.

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I was just looking at the radar--it's covering about one row of counties every hour and it has 5.5 rows to go. It probably doesn't make it.

 

I was seeing the something similar, and would even say it has 6.25 rows to go at Abilene's longitude. But if it's more like phil's 1 county every 45 minutes (I think the truth is somewhere in between, but maybe closer to 50 minutes), that gives 6.7 rows by 06z.

 

So... couldn't be closer, I think.

 

Here's a table from 01z.

If the front is covering 1 county every x minutes, it will have covered y counties by 06z, and will by z minutes past Abilene:

x ... y ... z

40 ... 7.5 ... 50.00

43 ... 6.98 ... 31.25

45 ... 6.70 ... 18.75

48 ... 6.25 (this would have the front AT Abilene by 06z)

50 ... 6.00 ... -12.50

53 ... 5.66 ... -31.25

55 ... 5.45 ... -43.75

60 ... 5.00 ... -75.00

 

You can see how much difference even a few minutes makes. My best guess is ~52 minutes per county, but with an 8 minute error bound. :P

 

EDIT: If you look at the longitude of the TX/OK border, in the last two hours, the front has moved at a pace of 52 minutes per county. On the other hand, at the longitude of the TX/NM border, it has moved at a pace of 42.5 minutes per county. The former would argue for a mid-60s high, the latter would argue for my 50F high. Unfortunately for me, the former makes more sense given Abilene's longitude.

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65/34/27/0

 

I was actually quite confident on this forecast, but we'll see!

 

EDIT: I did this forecast few hours earlier, but HRRR/RAP combo looked darn good with 12 USL, 4km-NAM, and 13km-GFS backing it up. For low, I just went slightly below USL. For winds, I went slightly above USL.

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I'd still be much more comfortable where you are right now than where I am.

 

I don't blame you. Even if the front start hitting right at 6z, it might take 15 minutes for full cool down to your temperature.

 

Additional note, winds are seriously gusting up to 40-45 mph in Oklahoma.  I think 25+ knots is gonna happen.

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