Dec 11-13 MW/Lakes/OV Snow Event? Part V

[baroclinic_instability]

alot of western IA obs showing +SN with gusts to near 45kts

Prolly getting some good snow out there per radar trends, but the observer in me says it is likely just ASOS being fooled by the blowing snow. If it is 1/4 SM and snowing (or less than 1/4 sm) it will report +SN if no observer is on board. Can become tough for an observer because it is tough to tell if it is truly snowing hard with vis reduced because of snow or blowing snow.

[Hoosier]

alot of western IA obs showing +SN with gusts to near 45kts

Some place called Carroll Iowa was heavy snow, sustained 46 mph and gusting to 56 mph on the last ob.

[The_Global_Warmer]

Some place called Carroll Iowa was heavy snow, sustained 46 mph and gusting to 56 mph on the last ob.

I can't even imagine that.

[weatherbo]

Thought this was of some interest and worth noting to keep an eye on.

IWX:

SOME CONCERN THAT SIGNIFICANT DRY SLOT NOTED

UPSTREAM ACROSS WESTERN IL WILL MOVE IN LATE. HOWEVER...WITH

DEEPENING UPPER LOW MOVING SOUTHEAST AND INCREASING LAPSE RATES WILL

STICK WITH PREVIOUS THINKING OF DRY SLOT FILLING IN WITH SNOW

OVERNIGHT.

[Baum]

That's what I've been saying all along. MKE gonna eat crow on this Bliz warning.

don't think so

[JoMo]

Prolly getting some good snow out there per radar trends, but the observer in me says it is likely just ASOS being fooled by the blowing snow. If it is 1/4 SM and snowing (or less than 1/4 sm) it will report +SN if no observer is on board. Can become tough for an observer because it is tough to tell if it is truly snowing hard with vis reduced because of snow or blowing snow.

I dunno, it might be true judging by the number of Civil Emergency Messages coming out of that area mentioning that roads would be snow covered because at 5 PM, Iowa DOT was pulling all their plows off and that rescue may be impossible.

ABSOLUTELY NO TRAVEL IN DICKINSON COUNTY TONIGHT.

ABSOLUTELY NO TRAVEL IN SIOUX COUNTY TONIGHT.

[csnavywx]

Some place called Carroll Iowa was heavy snow, sustained 46 mph and gusting to 56 mph on the last ob.

ASOS can't really distinguish the difference between falling snow and snow thats being lofted into the air by blowing.

[wisconsinwx]

Cromartie, at least your city is not 39 degrees. It's sad when the Weather Channel is more accurate than weather.gov; yesterday weather.gov said the high would be 36, while TWC said it would be 38. Turns out, it has hovered near 40 for most of the day...hmmm.

[buckeye]

4-6"

Which has to be with the deformation zone, since we've got maybe 1/4 to 1/2" of slush this evening. So unless that part of the system overperforms (they don't, a majority of the time with these systems), we're not going to meet that.

I was thinking we might end up with 2". There's a nice trowal tomorrow morning, but with so much mid-level dry air being wrapped and thrown around, it may be tough to get a good band going again. Dry slots are really efficient and cleaning out the ice-crystal bearing decks.

looks like that whole deform band is slowly sinking east southeast.....wouldn't that eventually hit ya?

[Chicago WX]

Thought this was of some interest and worth noting to keep an eye on.

IWX:

SOME CONCERN THAT SIGNIFICANT DRY SLOT NOTED

UPSTREAM ACROSS WESTERN IL WILL MOVE IN LATE. HOWEVER...WITH

DEEPENING UPPER LOW MOVING SOUTHEAST AND INCREASING LAPSE RATES WILL

STICK WITH PREVIOUS THINKING OF DRY SLOT FILLING IN WITH SNOW

OVERNIGHT.

Looking at the radar right now, I can't imagine how the dry slot misses the IWX CWA. I guess the devil in the details will be if it fills in as they suspect.

Heck looking at things right now, as someone said earlier in the thread, MSN and MKE may get dry slotted for a time.

[Hoosier]

ASOS can't really distinguish the difference between falling snow and snow thats being lofted into the air by blowing.

Good point. In any case, the winds are awfully impressive.

[Baum]

Prolly getting some good snow out there per radar trends, but the observer in me says it is likely just ASOS being fooled by the blowing snow. If it is 1/4 SM and snowing (or less than 1/4 sm) it will report +SN if no observer is on board. Can become tough for an observer because it is tough to tell if it is truly snowing hard with vis reduced because of snow or blowing snow.

radar looks fairly impressive that way:

SOUTHWEST IOWA

CITY SKY/WX TMP DP RH WIND PRES REMARKS

CLARINDA * HVY SNOW 14 10 85 NW30G44 29.81R VSB 1/4 WCI -7

COUNCIL BLFS * MIX PCPN 14 9 79 NW30G45 29.90R VSB 1/2 WCI -7

CRESTON * HVY SNOW 14 9 79 NW38G49 29.66R VSB 1/4 WCI -9

HARLAN * HVY SNOW 18 14 86 NW46G53 29.87R VSB<1/4 WCI -5

LAMONI LGT SNOW 15 11 83 NW31G41 29.63S FOG WCI -6

6HR MIN TEMP: 14; 6HR MAX TEMP: 16; 6HR PCP: TRACE;

RED OAK * LGT SNOW 14 10 85 NW28G39 29.84R VSB 3/4 WCI -6

SHENANDOAH * LGT SNOW 14 9 79 NW28G37 29.88R WCI -6

if this is as intense a storm as many built it up(track not withstanding) to be backlash snow and wind should be more impressive then usual

[Howie]

I'll show my age. Didn't blizzard warnings use to have some sort of temperature requirement?

I thought so...falling temps during that phase?

[baroclinic_instability]

I dunno, it might be true judging by the number of Civil Emergency Messages coming out of that area mentioning that roads would be snow covered because at 5 PM, Iowa DOT was pulling all their plows off and that rescue may be impossible.

ABSOLUTELY NO TRAVEL IN DICKINSON COUNTY TONIGHT.

ABSOLUTELY NO TRAVEL IN SIOUX COUNTY TONIGHT.

Right, travel is awful either way. What I was suggesting was it is quite typical for ASOS to report +SN during blizzards when they are not manned. What happens is blowing snow fools the sensor into thinking it is actually snowing and sine the vis is reduced due to blowing, it will report a certain intensity. There are criteria...and 1/4SM and snow is reported +SN, 1/2SM and snow is reported as moderate snow, etc.

I had my share of these in Grand Forks

Tough call to report a snow intensity when vis is zero due to 55 mph winds and blowing.

[csnavywx]

You just needed a farther south track.

Kind of hard to do in a strong La Nina year. We may score a hit here or there, but expect to see many more big hits up in MN/WI.

[csnavywx]

I thought so...falling temps during that phase?

20F or below.

[Hoosier]

Looking at the radar right now, I can't imagine how the dry slot misses the IWX CWA. I guess the devil in the details will be if it fills in as they suspect.

Heck looking at things right now, as someone said earlier in the thread, MSN and MKE may get dry slotted for a time.

December 11 2000 did that...the dryslot kept trying to make it up through Kankakee but it kept filling in. Obviously this is a different system but some runs have been hinting at precip trying to redevelop and halt it to some extent.

[Chicago WX]

DSM gusting to 41MPH with snow and...small hail?

SPECI KDSM 120009Z 34022G36KT 1 1/2SM GSSN BLSN BR OVC014 M04/M06 A2957 RMK AO2 PK WND 33036/0001 TWR VIS 2 GSB05 P0000

SPECI KDSM 120028Z 34025G34KT 1/2SM R31/4000VP6000FT GSSN BLSN BR OVC016 M04/M06 A2960 RMK AO2 PK WND 34036/0018 TWR VIS 2 GSB05 P0003 $

[TugHillMatt]

Snow has been mixing in with the rain for the past 45 minutes here in western Michigan right along the coast. It seems like every time there is a strong gust of colder air from the northeast, it transitions over to more snow, and then it goes back to a mix. Hopefully it will go over to all snow very soon (as it looks like it's trying to do! Here's a webcam from about 20 miles north of me...In the little town of Hart in Oceana county.

http://www.oceanaheraldjournal.com/webcam/downtown.php

[cyclone77]

We've been in the dry slot for a few hours now, and I gotta say it's pretty quiet in here lol.

Seriously though, I'm just hoping we get at least a period of heavy snow early tomorrow morning while the winds are ripping. All the latest guidance still suggests 55-60mph wind gusts look possible. 18z GFS still depicts a fat band of 60-65kts between H9-H8.

[Chicago WX]

December 11 2000 did that...the dryslot kept trying to make it up through Kankakee but it kept filling in. Obviously this is a different system but some runs have been hinting at precip trying to redevelop and halt it to some extent.

Yes it did...saved the day for me at the time. Totals dropped off considerably south of there with 12/11/00.

[baroclinic_instability]

Good point. In any case, the winds are awfully impressive.

You can tell it is prolly blowing from looking at the latest obs since it is automated and is an older AWOS site equipped with a precip sensor.

KCIN 120015Z AUTO 33036G48KT M1/4SM +SN OVC001 M11/M13 A2979 RMK AO2

KCIN 112355Z AUTO 34040G49KT M1/4SM +SN OVC001 M10/M12 A2977 RMK AO2

KCIN 112335Z AUTO 34040G49KT M1/4SM +SN OVC001 M10/M12 A2975 RMK AO2

KCIN 112315Z AUTO 33034G44KT M1/4SM +SN OVC001 M10/M12 A2973 RMK AO2

KCIN 112255Z AUTO 33034G46KT M1/4SM +SN OVC001 M09/M11 A2972 RMK AO2

KCIN 112235Z AUTO 33035G45KT M1/4SM +SN OVC001 M09/M11 A2970 RMK AO2

KCIN 112215Z AUTO 33037G44KT M1/4SM +SN OVC003 M09/M11 A2968 RMK AO2

KCIN 112155Z AUTO 33032G37KT M1/4SM +SN OVC003 M08/M11 A2966 RMK AO2

You can tell it is an AWOS by the time it updates at since ASOS only reports METARs hourly.

[baroclinic_instability]

DSM gusting to 41MPH with snow and...small hail?

SPECI KDSM 120009Z 34022G36KT 1 1/2SM GSSN BLSN BR OVC014 M04/M06 A2957 RMK AO2 PK WND 33036/0001 TWR VIS 2 GSB05 P0000

SPECI KDSM 120028Z 34025G34KT 1/2SM R31/4000VP6000FT GSSN BLSN BR OVC016 M04/M06 A2960 RMK AO2 PK WND 34036/0018 TWR VIS 2 GSB05 P0003 $

Prolly ice pellets/graupel.

[csnavywx]

DSM gusting to 41MPH with snow and...small hail?

SPECI KDSM 120009Z 34022G36KT 1 1/2SM GSSN BLSN BR OVC014 M04/M06 A2957 RMK AO2 PK WND 33036/0001 TWR VIS 2 GSB05 P0000

SPECI KDSM 120028Z 34025G34KT 1/2SM R31/4000VP6000FT GSSN BLSN BR OVC016 M04/M06 A2960 RMK AO2 PK WND 34036/0018 TWR VIS 2 GSB05 P0003 $

Probably snow grains and snow. Indicates that there's barely enough ice crystals to get the snow formation (Bergeron) process going. Snow grains are essentially a tiny ice crystal surrounded by rime.

I've seen some observers put GS instead of SG. Not really a big difference either way.

[Thundersnow12]

small line of precip developing back southwest in the dry slot on the back edge of precip heading northeast at me.

[Chicago WX]

Prolly ice pellets/graupel.

Yeah I know or I guess figured. Just the designation of small hail was a little funny, that's all. BTW, radar looks good over DSM right now, they should start making some hay soon.

[cromartie]

Cromartie, at least your city is not 39 degrees. It's sad when the Weather Channel is more accurate than weather.gov; yesterday weather.gov said the high would be 36, while TWC said it would be 38. Turns out, it has hovered near 40 for most of the day...hmmm.

I hear ya. This same sh*t happened last year Dec 8-9 and also Feb 2007. Blizz warning and ended up with few inches of slop both times. Inland cashed out.

[baroclinic_instability]

Yeah I know or I guess figured. Just the designation of small hail was a little funny, that's all. BTW, radar looks good over DSM right now, they should start making some hay soon.

Yeah it is silly. Believe it or not, some of the machines don't allow SG. We weren't allowed to report SG at KGFK.

One of the most annoying was we were not allowed to append SH to anything. That was annoying.

[Thundersnow12]

[wisconsinwx]

I hear ya. This same sh*t happened last year Dec 8-9 and also Feb 2007. Blizz warning and ended up with few inches of slop both times. Inland cashed out.

Agree about Dec 8 and 9 from last year, but I thought the snowstorm in Feb 2007 was fruitful for everyone in SE Wisconsin. Then again, I happened to be at a retreat near Hartland at the time. Was that the one that had two phases: a smaller snowfall on a Friday night, and a larger blizzard for many that next Saturday night and Sunday morning?