Changing Blizzard Warnings?

[rdale]

With the era of automated obs, formal blizzard criteria is awfully hard to reach these days... So we get into a condition where a VERY VERY strong snowstorm, close to blizzard criteria, gets a BZW from one office and a WSW from another. For the exact same forecast.

Anyone think it might make sense to reduce the vis criteria at least, and maybe slighly draw down the winds to make a blizzard warning reachable?

Wilmington popped one last night while Cleveland has just a WSW, but none of the sites I can find even came close to verifying.

 

[Chad Cowan]

Anyone think it might make sense to reduce the vis criteria at least, and maybe slighly draw down the winds to make a blizzard warning reachable?

But wouldn't that make people heed less warning to WSW's? Consider your criticism of Tornado Emergencies before answering.

 

[rdale]

People don't worry about WSW's... We get them around 10-20 times per year, and it doesn't (nor should it) send people to the stores.

I don't show any NWS winter weather headlines other than a Blizzard Warning on my TV station.

They worry about major snow accumulations, and the word "blizzard." Blizzard Warnings should get people worried about travel, but if we keep bending the definition to mean "really really bad snow" -- maybe the criteria should be bent to match?

 

[Robert Dewey]

Here's the current criteria:

A Blizzard Warning will be issued when the following conditions are forecast to last at least 3 hours. Falling and/or blowing snow frequently reducing visibility to < 1/4 mile AND sustained winds or frequent gusts > 35 mph

I guess the problem here is the ambiguous term "frequent" - how many gusts to 35MPH would be considered "frequent" ... or how many observations of 1/4 mile or less?

 

[rdale]

The problem also is that most obs sites don't report < 1/4 mile. They'll do 1/4 mile, but not less than. Frequent would be "enough to be reported in the ob" and again by that criteria, most blizzard warnings, like today, don't verify.

So do we continue to:

1) Have some offices ignore the criteria, and others stick to it, for a patchwork?
2) Keep the criteria strong and enforce the proper issuance, missing some big events?
3) Tweak the criteria down, so we're all on the same page?

 

[Patrick Marsh]

This past week I saw an ob near Abilene, TX report 1/8 mile visibility and Thundersnow - so at least some obs can report less than 1/4 visibility.


If 1/4 visibility is the lowest visibility that most obs can report, then make the threshold be less than or equal to 1/4 mile. It's not like we can really distinguish between .22miles and .25 miles anyways.

 

[rdale]

That must not be an ASOS/FAA site then, because those only report M1/4SM if anything... I'd be happier with the <= instead of <, and I'd drop the winds to 30mph.

 

[Patrick Marsh]

That must not be an ASOS/FAA site then, because those only report M1/4SM if anything...

All I said is that some obs do report less than 1/4 visibility. I believe this is a DoD site.

KDYS 061659Z 02014KT 6SM -SN BR BKN006 OVC020 M01/M02 A3014 RMK AO2A SLP209 COR 1710
KDYS 061651Z 02015G22KT 3SM -SN BR BKN006 OVC015 M01/M02 A3014 RMK AO2A DZB1609E1612 CIG 007V027 PRESRR SLP210 $
KDYS 061555Z 36011G16KT 3SM -SN BR VV005 M01/M01 A3013 RMK AO2A VIS 2 RWY16 UPE1510B1540SNB1510E1540 PRESRR SLP206 P0006 T10081016 $
KDYS 061546Z 01009KT 1 1/4SM -SN VV005 M01/M01 A3012 RMK AO2A UPE1510B1540SNB1510E1540 PRESRR SLP203 $
KDYS 061528Z 01011KT 1/8SM R34/3000V5500FT +TSSN FEW001 OVC006 M01/M01 A3013 RMK AO2A OCNL LTGICCC TS 5 E MOV NE UPE1510SNB1510 CIG 001 RWY16 PRESRR SLP206 $
KDYS 061526Z 01011KT 1/8SM R34/3000VP6000FT +TSSN FEW001 OVC006 M01/M01 A3013 RMK AO2A UPE1510SNB1510 CIG 001 RWY16 PRESRR SLP205 $
KDYS 061455Z AUTO 01009KT 1/8SM R34/P6000FT +TSSNPL VV003 00/M01 A3011 RMK AO2A VIS 1 3/4 RWY16 LTG DSNT NE AND E UPB1414SNB1438E1449RAE1414 TSE1406 CIG 015 RWY16 PRESRR SLP200 P0003 60003 T10051013 53012 $
KDYS 061439Z 35014G21KT 3/4SM R34/P6000FT -TSSN BKN004 OVC025CB 00/M01 A3010 RMK AO2A OCNL LTGICCC TS ALQDS MOV NE
KDYS 061422Z 02014KT 6SM -TSSN BKN055 01/M02 A3009 RMK AO2A OCNL LTGICCC TS ALQDS MOV NE

 

[rdale]

I'm not denying your claim at all, I'm aware that a few sites across the country report actual visibilities when less than 1/4mi. But I don't think that changes the debate, since a LARGE majority of sites do not.

And even if they did, I wouldn't put much faith in an automated ob when vis is that low?

 

[Evan Bookbinder]

Rob, actually the overwhelming majority of vis sensors *can*. The M1/4 used by ASOS/AWOS sites translates to less than a quarter. The various sensor models (mainly Vaisala) are actually extremely accurate, and there are a number of papers (plus the manufacturer specs) on this. The accuracy actually increases with lower visibilities due to the inherent nature of the sensor's mechanics.

While manual sites do use 1/16 and 1/8th (I even saw 0 at JFK this afternoon), automated sites (which are designed for aviation) do not. The reason for this is regardless of the airport, ground visibility < 1/4 mile will shut them down regardless of their size or status.

Regarding why this event didn't verify, I think the wind was the main issue being discussed, no? I think the only 35 mph gusts I saw were along the Erie lake front.

Evan

 

[rdale]

Hmmm, guess that makes the argument to weaken the criteria (at least in this case) even more of an issue! I looked over IN/OH/KY to find obs with less than 1/4mi listed, and Dayton had 1/8 reported twice and Canton was M1/4 once. That was it over the tri-state area. If I look for 1/4SM, then the list is dramatically higher.

 

[David Wagener]

Not exactly what Rob is talking about, but at least some of the 5 bajillion advisories are getting simplified (hopefully) this year. Now if there could just be a way to get Gary England to stop using "Travelers Advisory" on anything not a Winter Storm Warning/Watch.

On the Blizzard Warning criteria...definitely think it needs to be revisited. The trick is on visibilities are they being caused by wind blowing the snow, or fog. Obviously wind around 30mph fog is pretty unlikely. I agree that just making it include 1/4 mi and below would help.

http://www.crh.noaa.gov/crnews/display_story.php?wfo=iwx&storyid=13402&source=0

TABLE 1 - WINTER ADVISORIES

CURRENT WINTER ADVISORIES PROPOSED WINTER ADVISORIES

FREEZING RAIN --------------------- FREEZING RAIN
LAKE EFFECT SNOW ------------------ LAKE EFFECT SNOW
LAKE EFFECT SNOW AND BLOWING SNOW - LAKE EFFECT SNOW
WIND CHILL ------------------------ WIND CHILL
WINTER WEATHER -------------------- WINTER WEATHER
SNOW ------------------------------ WINTER WEATHER
SNOW AND BLOWING SNOW ------------- WINTER WEATHER
SLEET ----------------------------- WINTER WEATHER
BLOWING SNOW ---------------------- WINTER WEATHER

TABLE 2 - WINTER WARNINGS

CURRENT WINTER WARNINGS PROPOSED WINTER WARNINGS

BLIZZARD -------------------------- BLIZZARD
ICE STORM ------------------------- ICE STORM
LAKE EFFECT SNOW ------------------ LAKE EFFECT SNOW
WIND CHILL ------------------------ WIND CHILL
WINTER STORM ---------------------- WINTER STORM
HEAVY SNOW ------------------------ WINTER STORM
SLEET ----------------------------- WINTER STORM

 

[Chris Nuttall]

FYI...Dense Fog Advisories are for visibilities less than 1/4 mile.

 

[rdale]

Now if there could just be a way to get Gary England to stop using "Travelers Advisory" on anything not a Winter Storm Warning/Watch.

Actually if I were forced by management to report NWS forecasts, I'd prefer to use that designation vs the current ones.

Thankfully my bosses realize I'm not there as a NWS conduit

 

[David Wagener]

I don't think there are going to be any dense fog advisories issued during snow storms, when it is snow causing the vis issue.

Rob - yeah I agree that it is easier having one term to cover the 75 similar meaning advisoies. Maybe its just being differet from what I grew up with - of course you've seen the "quality" weather products that come out of Toledo.