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WxChallenge 2014-2015


Jurg

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16/4/24/0.03. I'm making a play at precipitation. I like the good lift as the arctic front passes and enhances those snow squalls. They actually picked up 0.02" last time an arctic front of this magnitude moved through and that had wind speeds more intense than this one, so I'm thinking a good squall will put down at least 0.02". That's my play for an extra point for day 6. Otherwise, I like all my numbers. I feel the high will depend on the snow squalls and saturating the atmosphere because if one comes through before 6z that will bump the temp down and then recovery might only be up to 16F, but who knows.

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Welp, all my precip is occurring before 6z. Looks like I will have 1.2 points on top of whatever other error I get tomorrow. Hopefully not much more.

This is exactly why I went 0.00 tomorrow. HRRR consistently had all the measurable precip before 06z. Sure had zero for today, but so did most everyone else!

17/4/23/0.00

Looks like the 6z high was 17! Good start ;)

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Doesn't the metar report not include the minutes prior to 6z? So technically it could still drop to 16F in the 7 minutes before actual 6z right?

Edit: Hopefully a speci ob comes in at 0559z of 16F ;)

Without any sort of special METAR they will go with the climo report I believe which should be conveniently 12am-12am in this case.
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Without any sort of special METAR they will go with the climo report I believe which should be conveniently 12am-12am in this case.

 

No, that's not how it works.

 

The only thing they use from the climo is the winds. The high/low always comes from the 6-hourly METAR reports (unless there is a problem with the METARS, i.e. they don't have the 6-hourly report, which I've never seen during WxChallenge).

 

 

Also... wasn't expecting the low in the morning! But then, I wasn't expecting yesterday's low to be at the EARLY 06z!

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This low tonight is tough. Could be some clouds through the first half of the night and they will stay windy with a well-mixed boundary layer all night. I'd normally stay above 0 in this situation with no snow pack and so far south but would expect a few degrees below 0 with a snow pack. It looks like they have 1-2" on the ground which is so marginal but could be enough. Euro has a low of +1, HRRR and RAP look like they're on their way to -5 or colder, GFS is right near 0 but the NAM is below. The NMM is -1 for a low and the ARW +2...GFS MOS -3 and NAM MOS -4. USL is -2.

 

17z HRRR looks a few degrees too cold upstream.

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It may end up getting just as cold or colder by 6z making the morning drop moot. We shall see! Need the winds on my end, 15 knots gusting to 29 last hour

Edit: I see they had a 24 knots gusting to 30 ob earlier. Bingo for 25+

 

Look like my 17/1/25 will do well for D6.

 

Anyway, tomorrow's forecast is interesting...

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This low tonight is tough. Could be some clouds through the first half of the night and they will stay windy with a well-mixed boundary layer all night. I'd normally stay above 0 in this situation with no snow pack and so far south but would expect a few degrees below 0 with a snow pack. It looks like they have 1-2" on the ground which is so marginal but could be enough. Euro has a low of +1, HRRR and RAP look like they're on their way to -5 or colder, GFS is right near 0 but the NAM is below. The NMM is -1 for a low and the ARW +2...GFS MOS -3 and NAM MOS -4. USL is -2.

 

17z HRRR looks a few degrees too cold upstream.

 

Yes this is very much shaping up to be a nerve racking temp forecast tonight... all hanging on whether or not the boundary layer decouples at the surface. NAM says no, and we stay above 0F. HRRR says yes and we are approaching -10F. Winds will slacken off tonight. If they do manage to go below 5 knots... lookout!

 

NAM: http://www.atmos.albany.edu/products/namsndg/sndgspi.html

 

SRwiRjG.gif

 

HRRR: http://www.atmos.albany.edu/student/ppapin/lb13_img/hrrr/hrrr_ncep_snd_spi.php

 

hrrr_ncep_skewt_KSPI_16.png

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No, that's not how it works.

 

The only thing they use from the climo is the winds. The high/low always comes from the 6-hourly METAR reports (unless there is a problem with the METARS, i.e. they don't have the 6-hourly report, which I've never seen during WxChallenge).

 

Also... wasn't expecting the low in the morning! But then, I wasn't expecting yesterday's low to be at the EARLY 06z!

 

Thanks for giving the correct info... I forgot they only used the climo report for winds. Looks like it will be 17F after all for day 6.

 

My #'s: 

 

12/-7/13/0.00

 

And this bolded statement in the quote is why I am so bullish on the low tonight. As soon as the winds got below 10 knots last night, the temperature nosedived to 2F (which was largely unexpected). The HRRR is going super cold tonight (like -10F) and has winds getting down into the 5 knot range. It wouldn't take much for things to decouple from there and cause a similar temperature nosedive especially with snowpack and clear skies. Its a risky forecast, but there was simply too much risk reward to not go for it! (I am definitely prepared to eat crow tomorrow ;) )

 

It would be one thing if the HRRR was showing no decoupling and these very low temp values. The NAM doesn't decouple the boundary layer and hence its much warmer (along with the rest of the guidance). May the best boundary layer physics win! 

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16/-6/16/0.

 

Thanks for giving the correct info... I forgot they only used the climo report for winds. Looks like it will be 17F after all for day 6.

 

My #'s: 

 

12/-7/13/0.00

 

And this bolded statement in the quote is why I am so bullish on the low tonight. As soon as the winds got below 10 knots last night, the temperature nosedived to 2F (which was largely unexpected). The HRRR is going super cold tonight (like -10F) and has winds getting down into the 5 knot range. It wouldn't take much for things to decouple from there and cause a similar temperature nosedive especially with snowpack and clear skies. Its a risky forecast, but there was simply too much risk reward to not go for it! (I am definitely prepared to eat crow tomorrow ;) )

 

It would be one thing if the HRRR was showing no decoupling and these very low temp values. The NAM doesn't decouple the boundary layer and hence its much warmer (along with the rest of the guidance). May the best boundary layer physics win! 

 

Thank you for having faith in going below NWS/USL combo! Making me feel better actually, haha. I also like your high, Phil ;)

 

Last night's low is exactly why I'm siding with locals for tonight and going cold.

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