WxChallenge 2013-14

[Max]

Good. Wayyyy better than Charlotte.

 

Wish people had any interest in forecasting for Portland, OR

Seattle, Wa wasn't too long ago. Same kind of deal.

[Mallow]

Seattle, Wa wasn't too long ago. Same kind of deal.

 

Seattle was two or three years ago (before I started), and it's actually quite a bit different because of the Gorge.

[Quincy]

05z. (Midnight-midnight)

Climo reports at most stations run from 6z to 6z.

Via WxChallenge:

Forecasts are due Monday evening through Thursday evening at 00 UTC (technically, Tuesday-Friday) and are valid for 06 UTC until 06 UTC for the following day. Each forecast consists of a high temperature (in F), a low temperature (in F), maximum wind speed (in knots; not gusts), and a cumulative liquid precipitation measure (in inches) for that forecast period.

[Mallow]

Climo reports at most stations run from 6z to 6z.

Via WxChallenge:

 

Daily climate reports run at most stations from midnight-midnight local standard time. WxChallenge does not get their high/low/precip from the daily climate reports, but from the 6-hrly METARs that are released at 00z, 06z, 12z, and 18z. Therefore, the high, low, and precip are always 06z-06z (and based on the METARs). But since the METARs don't record highest sustained wind speed, the wind speed comes from the daily climate report. That's why wind speed at PAFA was 09z-09z.

 

Via wxchallenge

 

• Note: The maximum wind speed is determined from the daily climatological report. This report is issued at midnight local time every night. As a result, in many forecast cities, this may be a few hours off 06 UTC. If a higher wind is reported on the hourly observation outside the midnight report time frame but within the 06-06 UTC time frame, it will not be counted as the official result.

 

 

It is important to note that it's midnight to midnight local STANDARD time, not current local time. So when DST arrives, it won't change the utc time that the wind is recorded for the city that we're forecasting for.

[OHweather]

I think it's remarkable that the GFS MOS is actually spitting out 5 for tonight which I believe would tie the all time March record low for BWI.

 

Edit: The newest GFS MOS now has a low of -1 tonight

[phil882]

24/8/13/0.00

 

Honestly, I thought 24 was pushing it high until I saw few 25 to 27 forecasts from other UNCA forecasters... how is everybody getting higher temperatures than me by few degrees even when I thought I was pushing it too high? Ugh...

 

 

4 degrees in an hour without downsloping? Really? !@#$ this place.

 

Strong WAA aloft + mixed layer up to around 850 hPa suggested a high in the mid 20's. This is often the time of year where MOS performs very poorly with regards to surface temperatures because again its just a statistical model based on given parameters. Solar angle + dry atmosphere oftentimes allows substantial warming even in little to no surface warm air advection. 

 

Now tomorrow will be interesting because we have the added element of a decent snowpack, which should counter low-level WAA starting. The GFS MOS is actually looking pretty good tonight given the relatively light winds, clear sky and good snowpack. Should see lower single digits. 

[Mallow]

30/9/9/0

[OHweather]

31/6/9/0

A low of 5 or colder would be very historic and due to some wind for most of the night and some clouds late didn't want to go as cold as some guidance... Almost went a degree or two warmer but with fresh snow pack and generally good cooling conditions didn't. 925mb and 850mb temps will be a good bit warmer than Friday when they did 27...but snow pack and some high clouds will be mitigating factors.

[Max]

30/7/10. I calculated a temperature of 31.8F using HYSPLIT. Since the trajectory was pretty much north to south I didn't assume any downslope component so just used the parcel height change and dry adiabatic lapse rate, but with snowcover I couldn't go 32. Thought about 31, but played it safe with 30F. The low I have no clue and the winds sorta kinda don't know, but the high I'm pretty confident on. 

[Max]

31/6/9/0

A low of 5 or colder would be very historic and due to some wind for most of the night and some clouds late didn't want to go as cold as some guidance... Almost went a degree or two warmer but with fresh snow pack and generally good cooling conditions. 925mb and 850mb temps will be a good bit warmer than Friday when they did 27...but snow pack and some high clouds will be mitigating factors.

I wanted to go 31F, but I chickened out because of this snowcover. Edit: I think you also probably didn't factor in a thinner BL depth compared to day 4. 

[Brewers]

31/6/10/0

[wxmeddler]

Perhaps I just want to see a record fall... I looked at my stations own history when temps were < 20 the day before and 3 - 7 seemed a good range. Also winds, when they die, they really die.

 

29/5/6/0

[OHweather]

I wanted to go 31F, but I chickened out because of this snowcover. Edit: I think you also probably didn't factor in a thinner BL depth compared to day 4.

I wanted to go 8 for the low but my phone is slow and I missed the deadline by a few seconds

I've seen temps overperform a good bit before even with snow cover and no real surface WAA. It didn't look like a much thinner BL than day 4 on the NAM soundings I glanced at but it will be interesting to see what happens. If things get to 30 that'd be good enough for me.

[Quincy]

30/6/9/0.00

Wouldn't be surprised if they sneak into the lower 30s, but went safe.

[Max]

I wanted to go 8 for the low but my phone is slow and I missed the deadline by a few seconds

I've seen temps overperform a good bit before even with snow cover and no real surface WAA. It didn't look like a much thinner BL than day 4 on the NAM soundings I glanced at but it will be interesting to see what happens. If things get to 30 that'd be good enough for me.

day 4 was 700-750m agl and day 5 will be right around 500m agl for a BL height. That is what bufkit showed at least.

[OHweather]

day 4 was 700-750m agl and day 5 will be right around 500m agl for a BL height. That is what bufkit showed at least.

That sounds right. It's thinner I'll agree with that. I'm pretty sure it'll be warmer than the consensus high of 28, we'll see by how much. Most of the people ahead of me in the rankings for this city went with 30.

[wxmeddler]

I was on the fence between 29 and 30, I went 29 because of the 5" snowpack and the bay temps being around 33 with a freezing point of 30. The coastal areas and inner harbor area should freeze/glaze over tonight. Also the possibility of thin high clouds during peak heating.

[Max]

That sounds right. It's thinner I'll agree with that. I'm pretty sure it'll be warmer than the consensus high of 28, we'll see by how much. Most of the people ahead of me in the rankings for this city went with 30.

I'm wondering if my calculation aren't affected by the snowcover. I guess we'll find out tomorrow. 

[phil882]

I know a lot of people were apprehensive about the record, but really if the winds do go calm, this is a classic scenario for extreme cold. Clouds move in after 9z, but its entirely possible they fall like a rock the next 6 hours IF the winds go calm for a time. 

 

27/1/10/0.00

 

Kinda surprised everyone went so warm tomorrow... the mixed layer is about 50 hPa shallower than friday and its likely to be colder at daybreak tomorrow than it was Friday morning. Combined with likely cloud deck for half of the day, and full snow cover, it doesn't make sense to go warm in my opinion. Now that I've said all this though, the atmosphere will certainly turn against me

[OHweather]

I'm wondering if my calculation aren't affected by the snowcover. I guess we'll find out tomorrow.

One thought would be if they're mixing from 500m tomorrow afternoon that it shouldn't be. I haven't taken the higher up courses yet so I may be wrong but I can't imagine air that high is directly impacted by snow cover.

[phil882]

One thought would be if they're mixing from 500m tomorrow afternoon that it shouldn't be. I haven't taken the higher up courses yet so I may be wrong but I can't imagine air that high is directly impacted by snow cover.

 

Well its called "mixing" for a reason... both air from 500m and air from the surface will be mixed together. Thus the snowpack does have some clout, but mainly only as high albedo should limit the solar angle somewhat (not much melting should occur tomorrow). 

[H2Otown_WX]

Strong WAA aloft + mixed layer up to around 850 hPa suggested a high in the mid 20's. This is often the time of year where MOS performs very poorly with regards to surface temperatures because again its just a statistical model based on given parameters. Solar angle + dry atmosphere oftentimes allows substantial warming even in little to no surface warm air advection. 

 

Now tomorrow will be interesting because we have the added element of a decent snowpack, which should counter low-level WAA starting. The GFS MOS is actually looking pretty good tonight given the relatively light winds, clear sky and good snowpack. Should see lower single digits. 

I could be wrong but I seem to remember BUFKIT not showing a mixed layer much past 900 mb that day. In any case, it was wrong and modeled 850s were too cold.

 

For tomorrow: 31/8/9

[H2Otown_WX]

I could be wrong but I seem to remember BUFKIT not showing a mixed layer much past 900 mb that day. In any case, it was wrong and modeled 850s were too cold.

 

For tomorrow: 31/8/9

[phil882]

 

I could be wrong but I seem to remember BUFKIT not showing a mixed layer much past 900 mb that day. In any case, it was wrong and modeled 850s were too cold.

 

For tomorrow: 31/8/9

 

 

Hmm ok... I haven't been using BUFKIT but some of our in house soundings that are available on our website:

 

http://www.atmos.albany.edu/products/namsndg/sndgbwi.html

 

To be fair though, I didn't objectively measure what the mixed layer was on Friday, so you could be right that they are similar. Still think the temperature suppressors of clouds + snowpack might be detrimental for much warming tomorrow. 

[Max]

Hmm ok... I haven't been using BUFKIT but some of our in house soundings that are available on our website:

 

http://www.atmos.albany.edu/products/namsndg/sndgbwi.html

 

To be fair though, I didn't objectively measure what the mixed layer was on Friday, so you could be right that they are similar. Still think the temperature suppressors of clouds + snowpack might be detrimental for much warming tomorrow. 

That is why I went 30F, not 32F based off the air parcel trajectory, but I still don't believe it will be 5F colder than calculated or colder than the euro/usl combo of 28F. This is March of course and the clouds will be of the high level variety so if those are not as widely scattered as modeled than of course middle ground probably will work out.

[H2Otown_WX]

Hmm ok... I haven't been using BUFKIT but some of our in house soundings that are available on our website:

 

http://www.atmos.albany.edu/products/namsndg/sndgbwi.html

 

To be fair though, I didn't objectively measure what the mixed layer was on Friday, so you could be right that they are similar. Still think the temperature suppressors of clouds + snowpack might be detrimental for much warming tomorrow. 

I didn't argue anything about tomorrow lol. TBH, I sort of just blindly went above guidance because of what happened to me last week. The snowpack idea was in the back of my mind but, meh. As far as clouds, I'm not sure how cloudy it will really be....they seem to jump a lot with any breaks and with such a warm air mass aloft, it won't take much for a spike. It isn't all that comforting to see a top grad. student from SUNY Albany having a vastly different forecast from mine though, I will give you that.

[phil882]

That is why I went 30F, not 32F based off the air parcel trajectory, but I still don't believe it will be 5F colder than calculated or colder than the euro/usl combo of 28F. This is March of course and the clouds will be of the high level variety so if those are not as widely scattered as modeled than of course middle ground probably will work out.

 

You have to be careful though... the March solar angle is nice to have on your side, but it will be diluted by those mid-high level clouds, and then the snowpacks' high albedo will limit how much solar absorption will occur (much more sunlight will be radiated back to space)

 

I didn't argue anything about tomorrow lol. TBH, I sort of just blindly went above guidance because of what happened to me last week. The snowpack idea was in the back of my mind but, meh. As far as clouds, I'm not sure how cloudy it will really be....they seem to jump a lot with any breaks and with such a warm air mass aloft, it won't take much for a spike. It isn't all that comforting to see a top grad. student from SUNY Albany having a vastly different forecast from mine though, I will give you that.

 

Haha... definitely not the top grad student if you look at my score (i'm kpap88). I was one of those that went warm on Friday last week and cashed in big, so I am fully aware of how poorly most of the MOS+raw model guidance was performing. The ECMWF actually did pretty well though, and I stayed closed to the ECMWF tomorrow and didn't go much colder because I really do trust its 2m output. The thing to me though is that there are a lot of negative suppressants that could limit solar insolation tomorrow, so I was a lot more cautious. I actually initially had 30 then when I started looking at the forecast I quickly dropped my numbers back down. Certainly could be wrong, but I was happy to find myself on the left side of the PDF for the distribution. 

 

Already down to 14F after a 4F drop in the last hour, and they haven't even fully cleared yet or reached calm winds. This is gonna be fun to see if they break their all time March record!

[Quincy]

Freefallin'. Down 8F last two hours, now sitting at 10/2.

[wxmeddler]

METAR KBWI 040154Z 00000KT 10SM SCT250 M12/M17 A3035 RMK AO2 SLP278 T11221167

[H2Otown_WX]

You have to be careful though... the March solar angle is nice to have on your side, but it will be diluted by those mid-high level clouds, and then the snowpacks' high albedo will limit how much solar absorption will occur (much more sunlight will be radiated back to space)

 

 

Haha... definitely not the top grad student if you look at my score (i'm kpap88). I was one of those that went warm on Friday last week and cashed in big, so I am fully aware of how poorly most of the MOS+raw model guidance was performing. The ECMWF actually did pretty well though, and I stayed closed to the ECMWF tomorrow and didn't go much colder because I really do trust its 2m output. The thing to me though is that there are a lot of negative suppressants that could limit solar insolation tomorrow, so I was a lot more cautious. I actually initially had 30 then when I started looking at the forecast I quickly dropped my numbers back down. Certainly could be wrong, but I was happy to find myself on the left side of the PDF for the distribution. 

 

Already down to 14F after a 4F drop in the last hour, and they haven't even fully cleared yet or reached calm winds. This is gonna be fun to see if they break their all time March record!

Well, it doesn't matter what happens with the high because I'm going to have at least 6 points of error on the low. Where are you getting raw ECMWF output anyway?