Winter storm 12/8-9 model discussion part II

[DCAlexandria]

I don't get it. How can one clown map show a inch for DC and another show 6" for the same model.

[ThePhotoGuy]

Good info on the VD Storm

 

February 13-14, 2007: The Valentine’s Day Sleet Storm. The weather map the morning of Tuesday the 13th showed low pressure strengthening over Arkansas, with a stationary front extending eastward across North Carolina. Temperatures in the NWS Sterling forecast area that morning were in the lower 30s. However, with high pressure over upstate New York, surface temperatures dropped below freezing by early afternoon on northerly winds. Of greater importance was what was happening to the temperature of the column of air up to 8000 feet above the surface. Weather balloon soundings taken every six hours at NWS Sterling showed that warm, above freezing air was flowing into the area on southwesterly winds between 5000 feet and 8000 feet. This was causing the snow falling from the clouds to melt, but as these drops descended further to refreeze prior to reaching the surface, forming sleet. East of Washington DC the column of subfreezing air was not as thick, and the drops remained liquid until they reached the surface, where they refroze on contact to form freezing rain. East of the Blue Ridge, sleet accumulated quickly on the morning of the 14th – Valentine’s Day. Totals for the storm ranged from 4-8” of snow and sleet across northern Virginia and central Maryland, to up to ¾ inch of ice in southern Prince Georges County. Almost 69,000 homes lost power in Anne Arundel County. The days after the storm were of little help to road and power crews, as well as those trying to clear driveways, as temperatures remained subfreezing until the afternoon of the 17th.

http://www.erh.noaa.gov/lwx/winter/DC-Winters.htm

[BTRWx]

Good info on the VD Storm

 

February 13-14, 2007: The Valentine’s Day Sleet Storm. The weather map the morning of Tuesday the 13th showed low pressure strengthening over Arkansas, with a stationary front extending eastward across North Carolina. Temperatures in the NWS Sterling forecast area that morning were in the lower 30s. However, with high pressure over upstate New York, surface temperatures dropped below freezing by early afternoon on northerly winds. Of greater importance was what was happening to the temperature of the column of air up to 8000 feet above the surface. Weather balloon soundings taken every six hours at NWS Sterling showed that warm, above freezing air was flowing into the area on southwesterly winds between 5000 feet and 8000 feet. This was causing the snow falling from the clouds to melt, but as these drops descended further to refreeze prior to reaching the surface, forming sleet. East of Washington DC the column of subfreezing air was not as thick, and the drops remained liquid until they reached the surface, where they refroze on contact to form freezing rain. East of the Blue Ridge, sleet accumulated quickly on the morning of the 14th – Valentine’s Day. Totals for the storm ranged from 4-8” of snow and sleet across northern Virginia and central Maryland, to up to ¾ inch of ice in southern Prince Georges County. Almost 69,000 homes lost power in Anne Arundel County. The days after the storm were of little help to road and power crews, as well as those trying to clear driveways, as temperatures remained subfreezing until the afternoon of the 17th.

http://www.erh.noaa.gov/lwx/winter/DC-Winters.htm

Wow, I had the wrong days linked.  Thanks for sharing!

[mitchnick]

markcast

 

 

I expect no less....or should I say no more with his forecasts

 

p.s. anyone see what the ever popular, accurate 84 hr NAM has lurking to the south?

http://mag.ncep.noaa.gov/Image.php?fhr=084ℑ=data%2Fnam%2F18%2Fnam_namer_084_700_rh_ht.gif&model=nam&area=namer&param=700_rh_ht&group=Model+Guidance&imageSize=M

[Ian]

I don't get it. How can one clown map show a inch for DC and another show 6" for the same model.

the NAM4k isn't quite the same as the regular NAM though i'm not 100% sure why other than resolution (12km v 4km). 

[mitchnick]

the NAM4k isn't quite the same as the regular NAM though i'm not 100% sure why other than resolution (12km v 4km). 

plus, it has 1 hr intervals instead of 3 hrs. and only goes out to 48 hours (you probably already know this Ian so I'm just mentioning it for the sake of others)

[WinterWxLuvr]

Its interesting how its trying to take elevation into that map. I would take it in a heartbeat.

I fail to see how elevation plays a role in a situation like this. During the snow period nobody is anywhere near freezing.

[Scarlet Pimpernel]

Good info on the VD Storm

 

February 13-14, 2007: The Valentine’s Day Sleet Storm. The weather map the morning of Tuesday the 13th showed low pressure strengthening over Arkansas, with a stationary front extending eastward across North Carolina. Temperatures in the NWS Sterling forecast area that morning were in the lower 30s. However, with high pressure over upstate New York, surface temperatures dropped below freezing by early afternoon on northerly winds. Of greater importance was what was happening to the temperature of the column of air up to 8000 feet above the surface. Weather balloon soundings taken every six hours at NWS Sterling showed that warm, above freezing air was flowing into the area on southwesterly winds between 5000 feet and 8000 feet. This was causing the snow falling from the clouds to melt, but as these drops descended further to refreeze prior to reaching the surface, forming sleet. East of Washington DC the column of subfreezing air was not as thick, and the drops remained liquid until they reached the surface, where they refroze on contact to form freezing rain. East of the Blue Ridge, sleet accumulated quickly on the morning of the 14th – Valentine’s Day. Totals for the storm ranged from 4-8” of snow and sleet across northern Virginia and central Maryland, to up to ¾ inch of ice in southern Prince Georges County. Almost 69,000 homes lost power in Anne Arundel County. The days after the storm were of little help to road and power crews, as well as those trying to clear driveways, as temperatures remained subfreezing until the afternoon of the 17th.

http://www.erh.noaa.gov/lwx/winter/DC-Winters.htm

 

Good info, and more or less how I remember it.  Brutally cold right after that storm, and everything turned into a block of ice for several days.

 

 

Wow, I had the wrong days linked.  Thanks for sharing!

 

I think you highlighted the Feb. 25th event that year, which was a pleasant surprise storm.  4-6" when it looked like we'd get mostly ice originally.

 

What a month that was, all around!!

[Scarlet Pimpernel]

I expect no less....or should I say no more with his forecasts

 

p.s. anyone see what the ever popular, accurate 84 hr NAM has lurking to the south?

http://mag.ncep.noaa.gov/Image.php?fhr=084ℑ=data%2Fnam%2F18%2Fnam_namer_084_700_rh_ht.gif&model=nam&area=namer&param=700_rh_ht&group=Model+Guidance&imageSize=M

 

Extrapolating for wave #2!!

[Ian]

I fail to see how elevation plays a role in a situation like this. During the snow period nobody is anywhere near freezing.

well you could still get orographic enhancement etc. 

[BTRWx]

No notable changes on the happy hour GFS through hr 18

[mitchnick]

Extrapolating for wave #2!!

no extrapolating necessary really...it's got a dead aim right at us

http://mag.ncep.noaa.gov/Image.php?fhr=084ℑ=data%2Fnam%2F18%2Fnam_namer_084_sim_radar.gif&model=nam&area=namer&param=sim_radar&group=Model+Guidance&imageSize=M

[lsukev]

Those NAM clown maps on WxBell are definitely weird, Ian.  Judging from the MAG page, it looks like DC proper gets a whole lot more snow than that 4km map shows.  The 12km looks more reasonable, albeit overdone as the NAM usually does it.

[WinterWxLuvr]

well you could still get orographic enhancement etc.

I guess so Ian but not to the extent that map would show. I could see the BR getting that but not the hills in and around Frederick Co

[mitchnick]

gfs a little drier (down south) this run thru 39 hrs

[Bob Chill]

18z is going to disappoint. Notably slower and drier. 

[snow.]

GFS is a pretty lousy run for most of us compared to Euro/NAM

[Ian]

I guess so Ian but not to the extent that map would show. I could see the BR getting that but not the hills in and around Frederick Co

well it's a snowmap from a model so it's probably wrong anyway 

[mitchnick]

18z is going to disappoint. Notably slower and drier. 

we toss

go with Euro and NAM

[Ian]

GFS is a pretty lousy run for most of us compared to Euro/NAM

18z............. toss it.  

[Scarlet Pimpernel]

18z............. toss it.

 

Maybe happy hour will begin at 00Z...

[Ian]

Hmm, it is pretty ugly. We aren't that good at winter here.. could be right. 

[BTRWx]

Hmm, it is pretty ugly. We aren't that good at winter here.. could be right. 

Right where we want it at its ugly stage 1-2 days before the event.

[Scarlet Pimpernel]

So after a fair bit of consistency of late, the GFS now throws in a monkey wrench less than 2 days out to make one re-think.

[Ian]

Right where we want it at its ugly stage 1-2 days before the event.

It's passable I guess but too bad the nam came first.

[WinterWxLuvr]

No happy hour drinks today guys.

[Scarlet Pimpernel]

No happy hour drinks today guys.

 

The NAM took over bartending duties, and closed the bar early.

[TSSN+]

GFS has the precip come way later, monday afternoon as plain rain. No other models show this. Toss it. 

[Ji]

18z gfs's are not suppose to do that

[Ian]

GFS has the precip come way later, monday afternoon as plain rain. No other models show this. Toss it.

dont think it's plain rain but haven't seen too much detail