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WxChallenge 2013-14

Quincy

By Quincy,
in Weather Forecasting and Discussion

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Mallow

Mallow

Posted
Posted

You can have your 11F, but I'll take 24 and 0 :P

 

Actually to be honest, I don't even think 10F is impossible. :o

 

24F could happen. I think 21-22 is most likely right now (so splitting our highs). :P

 

As for 0, I think that's pretty unlikely. Though they don't catch windblown snow in the raingauge very well, the band moving in now should give them at least a hundredth or two. :)

 

 

EDIT: To be fair, I got lucky with my low. I went in the "middle" of what I thought the potential range was (7-14), simply because I wasn't sure what was going to happen. Turns out in places not far to the northwest, 14 would have looked good, while in places not far to the southeast, 7 would have been closer to accurate. Just so happened that KGRR got caught right in the middle of these two scenarios.

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Mallow

Mallow

Posted
Posted

Actually to be honest, I don't even think 10F is impossible. :o

 

...

 

Given that it's still 12F on the special obs (anything below 11.4F would round down to 10F on the special obs, and it's unlikely we were exactly 11.4F which would round up to 12F on the special but count as an 11F officially), I'm guessing 10F for a low is unlikely. Probably just not enough time to have dropped that low. 11F is still quite reasonable (before the last obs), though it's possible 12F could be the final low.

 

EDIT: Per morning climo, 12F through 9AM. Still think 11F is possible, but at this point I think 12F is more likely.

 

EDIT 2: Dew point is down to 3F on the latest special obs. And there is a radar hole to the west. Maybe 10-11 still isn't impossible?

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Max

Max

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Given that it's still 12F on the special obs (anything below 11.4F would round down to 10F on the special obs, and it's unlikely we were exactly 11.4F which would round up to 12F on the special but count as an 11F officially), I'm guessing 10F for a low is unlikely. Probably just not enough time to have dropped that low. 11F is still quite reasonable (before the last obs), though it's possible 12F could be the final low.

 

EDIT: Per morning climo, 12F through 9AM. Still think 11F is possible, but at this point I think 12F is more likely.

 

EDIT 2: Dew point is down to 3F on the latest special obs. And there is a radar hole to the west. Maybe 10-11 still isn't impossible?

Climo was issued at 935am, so the time 11F had was from 1435z to 1453z if we assume it warms afterwards, but with this city seems like assuming gets us nowhere fast. Also no snow in the bucket hehe

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Mallow

Mallow

Posted
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Climo was issued at 935am, so the time 11F had was from 1435z to 1453z if we assume it warms afterwards, but with this city seems like assuming gets us nowhere fast. Also no snow in the bucket hehe

 

Climo was issued at 9:35AM, but with obs only through 9AM.

"...THE GRAND RAPIDS MI CLIMATE SUMMARY FOR DECEMBER 10 2013...

VALID AS OF 0900 AM LOCAL TIME."

 

And I still wouldn't rule out the low actually occurring this hour, given the break in precip and "cold advection" out of the south (along with the very low dew points).

 

The main band of precip hasn't moved in yet. Probably won't for another 1-3 hours yet. :P

 

EDIT: Ya, I'm definitely thinking 12F is the lowest they got. But I'm also definitely thinking they see more than traces out of this band. :P

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OHweather

OHweather

Posted
Posted

Looks like KGRR NWS is going to do a human measure. Don't know the exact rules for wxchallenge, but I'm assuming that my goose is officially cooked now.

Based on these couple of rules, I *think* the human measurement overrides whatever the ASOS measures:

 

  • If a National Weather Service observer is present at the ASOS station and recording augmented measurements (e.g. liquid equivalent of snowfall), then their measured values will override an ASOS value in final verification.
  • In extreme circumstances, where an ASOS is unable to reasonably record frozen precipitation, a decision will be made by the Advisory Board based on available observations. This can include, but not be limited to, an estimation for the precipitation or removal of the scoring of the precipitation for that forecast period.

They recorded 0.02" last hour (which is probably less than what actually fell, it's probably snowing 1-2" per hour and ratios aren't 50-100:1) and are still in the heavy snow now and that may hold on for another hour or so, so if they do human measure we'll see how much it comes up to. The snow is evolving a lot like how I thought (heavy snow started to their NW and is slowly swinging SE) which makes me happy, but how much liquid ends up being the final tally still could go either way. If they don't human measure it will still probably be closer to your 0 than my 0.12".

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Mallow

Mallow

Posted
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I'm surprised the wind is as low as it is. I really went all in and it looks like I'm getting burned. :axe:

 

I think the wind will pick up as the precip dies down. I think that "lull" is just the result of the wind direction shift. The gradients supporting strong westerlies should move in over the next couple hours.

 

Latest special has 21F, though that's likely rounded up from 20F. Given the temperature traces of nearby stations, I think it's possible 20F might end up being the high (as long as it's 20F on the hourly obs).

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Max

Max

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I think the wind will pick up as the precip dies down. I think that "lull" is just the result of the wind direction shift. The gradients supporting strong westerlies should move in over the next couple hours.

 

Latest special has 21F, though that's likely rounded up from 20F. Given the temperature traces of nearby stations, I think it's possible 20F might end up being the high (as long as it's 20F on the hourly obs).

Most likely 22F. MKG got to 22F. I don't remember the last time MKG was warmer than GRR.

edit: 21F this ob so still expecting at least 22F.

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Mallow

Mallow

Posted
Posted

Don't you worry it's still warming with that wsw wind coming off the lake. Upstream at KLWA its 23.5F, so I still have hope for 24F.

 

With precip dying off and drier air mixing down, evaporational cooling could counteract any weak warm advection (the temperature gradient is weak, even if the winds are strong). Modeling generally showed areas near the lake being the warmest all day, so just because it's 24F upstream does not mean it'll be 24F at KGRR. I'm thinking 21 or 22 (which is what I said this morning :P ), but again, I've been wrong before!

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Max

Max

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With precip dying off and drier air mixing down, evaporational cooling could counteract any weak warm advection (the temperature gradient is weak, even if the winds are strong). Modeling generally showed areas near the lake being the warmest all day, so just because it's 24F upstream does not mean it'll be 24F at KGRR. I'm thinking 21 or 22 (which is what I said this morning :P ), but again, I've been wrong before!

I didn't say it would be 24F b/c upstream is 24F. I just said I still have hope. To be honest this city annoys me more than Norman.

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H2Otown_WX

H2Otown_WX

Posted
Posted

I think the wind will pick up as the precip dies down. I think that "lull" is just the result of the wind direction shift. The gradients supporting strong westerlies should move in over the next couple hours.

 

Latest special has 21F, though that's likely rounded up from 20F. Given the temperature traces of nearby stations, I think it's possible 20F might end up being the high (as long as it's 20F on the hourly obs).

Hopefully, the temperature profile would certainly support mixing. Looking like a 06z high 06z low kinda day tomorrow. Always fun...

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OHweather

OHweather

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They've been at 21 for two hourly observations now so I'd like to hope they snuck up to 22 in there somewhere. 0.03" of liquid in the ASOS bucket so far, and they're back to heavy snow right now on a special, so we'll see what that turns out to be. I'd be very surprised if they got less than 3-4" of snow and somewhere between 0.1-0.2" of liquid so we'll see if they do in fact do a human measurement at some point...if not then 0.03 or 0.04" of liquid will do it. Winds are slowly coming up and are gusting to 29 knots at MKG and BIV and they were gusty this morning so regardless 21 knots will in all likelihood not verify...but we'll see how much higher it ends up being.

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Metsfan

Metsfan

Posted
Posted

22F.

 

Really, though, I'll take 24F if we can get this damn wind to come up! That'll kill me more than anything today.

Any idea on what is up with precip? kgrr is back under a band again, and  I am having a hard time believing that 0.03 is the only amount that has fallen.

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Mallow

Mallow

Posted
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Any idea on what is up with precip? kgrr is back under a band again, and  I am having a hard time believing that 0.03 is the only amount that has fallen.

 

Wind + snow = hard to catch it all in the rain gauge. I actually forecasted my low number based on that, but it looks like they reserve the right to use another measurement method if applicable. In which case I should have gone higher. If they do that today (use an alternate measurement), then I'll have to assume they'll do the same tomorrow. If they don't, the inconsistency would be unfair, since it's impossible to know which variable we're actually supposed to be forecasting for (that is, are we forecasting the amount of rain gauge tips, or the melted snow lwe measured by an NWS employee?).

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Max

Max

Posted
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Wind + snow = hard to catch it all in the rain gauge. I actually forecasted my low number based on that, but it looks like they reserve the right to use another measurement method if applicable. In which case I should have gone higher. If they do that today (use an alternate measurement), then I'll have to assume they'll do the same tomorrow. If they don't, the inconsistency would be unfair, since it's impossible to know which variable we're actually supposed to be forecasting for (that is, are we forecasting the amount of rain gauge tips, or the melted snow lwe measured by an NWS employee?).

Wind should be lighter tomorrow, so just based on that fact I'm forecasting precipitation more than today actually, so higher than 0.03 lmao.

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Metsfan

Metsfan

Posted
Posted

The 5:30PM climo only has 0.02" of precip and 0.05" snow (which, there's no way) and 22 knot winds (which isn't what I'm looking for either), we'll see. 22/11 for the high and low, which is OK.

Yeah will we see with the precip, because that is what is killing me. Went with .10.

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Mallow

Mallow

Posted
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The 5:30PM climo only has 0.02" of precip and 0.05" snow (which, there's no way) and 22 knot winds (which isn't what I'm looking for either), we'll see. 22/11 for the high and low, which is OK.

 

26mph = 23kts.

 

It shows 0.6" of snow, interestingly. If that's right, 0.02" sounds reasonable (given the high LES ratios). Is it possible that while we all thought the 0.03" was low, the NWS's "by hand" measurement actually measured an even LOWER liquid equivalent?

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