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Winter Storm - February 11-13, 2019


AppsRunner
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23 hours ago, cyclone77 said:

Less than 36hrs from the event and still pretty up in the air what will fall here in the QCA.  The models have bumped the snow/mix line south compared to the past few days, and now some of the guidance shows mostly snow for the north half of the DVN cwa.  It's still close enough that a bump back north would mean a largely mix/rain event after a short period of snow.  The 12z RGEM is still a hold out, and keeps the precip mostly rain for the QCA.  All I can say for sure is it looks like around 1/2" of precip in some form will fall tomorrow night lol.

Now about 6-8hrs from the start of the event and it's still a little muddled as to what to expect.  The GFS has consistently been showing an all snow event for the QCA, and other guidance seems to be trending in that direction.  HRRR/RAP/NAM3 still bring the snow/mix line up to this area by mid evening.  RGEM still gets us into all rain for a period, but it has trended south as Chicago Storm pointed out.  Compared to yesterday the period of mixing is substantially less.  It would still appear the northern/western DVN cwa has the best shot at the most snow, but if trends continue the QC may end up doing quite well out of this yet again.  Apparently it's just one of those seasons when everything seems to trend in our favor in the final 24-48hrs.  

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1 hour ago, CheeselandSkies said:

Wow, big time wallop looking likely for central WI. That map above has Madison flirting with double digit totals, although we whiffed on our previous opportunity to hit that single-storm benchmark earlier this winter.

Still, what a turnaround from the bare ground of December and most of the first half of January, although the two thaws were annoying especially the second coming on the heels of the historic polar vortex.

This looks like a big storm for Madison with most models showing .75" QPF or more, and should be the biggest snowfall of the winter. I'm approaching it with more skepticism though, because the last storm 8" seemed like a lock, but we ended up with extremely small flake size and 10:1 ratios even with temps in the teens and only 5-6".

This storm my list of things to watch include:

- possible delay of heavy snow onset this evening due to dry air, suggested by HRRR and RAP

- flake size, ratios (thinking ~12:1 with temp of 27?)

- how soon will dry slot push in (4am or will heavy snow hold on longer), also will there be any heavier snow during the day Tuesday

The way it looks right now I think we're good for the 6-9" that NWS is forecasting.

 

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33 minutes ago, cyclone77 said:

Now about 6-8hrs from the start of the event and it's still a little muddled as to what to expect.  The GFS has consistently been showing an all snow event for the QCA, and other guidance seems to be trending in that direction.  HRRR/RAP/NAM3 still bring the snow/mix line up to this area by mid evening.  RGEM still gets us into all rain for a period, but it has trended south as Chicago Storm pointed out.  Compared to yesterday the period of mixing is substantially less.  It would still appear the northern/western DVN cwa has the best shot at the most snow, but if trends continue the QC may end up doing quite well out of this yet again.  Apparently it's just one of those seasons when everything seems to trend in our favor in the final 24-48hrs.  

You can bet the Quad Cities will report at least 6 inches again.  Over here we have a decent shot at our first 6" snowfall of the season.

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1 hour ago, snowcaine said:

I have no idea what to expect here in Toronto. There are so many possible outcomes

I was looking at the soundings off the NAM. The warm layer aloft is pencil thin. Could see + rates keeping us snow.

I think it's pretty safe to pencil in 4-8" of snow and sleet. How much sleet we get will determine where in that range we end up. If we do stay all snow, could see us going north of 8" (but I'd say the chances of *no* changeover whatsoever is pretty small).

Also gotta watch that dry slot. 850/700 low pass well to our west so there's that threat to amounts too (although same scenario didn't remotely hurt us during the January 29 event).

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5 minutes ago, hawkeye_wx said:

You can bet the Quad Cities will report at least 6 inches again.  Over here we have a decent shot at our first 6" snowfall of the season.

Haha maybe.  I hope you guys get at least 6-8".  Everything seems to point that way for you guys, but I know you've had some bad luck this season at the last second.  Hope this storm more than makes up for it.  As for here, the HRRR/RAP bring the sleet in an hour earlier than the previous run, so the trend actually reversed at least for this run.  The HRRR/RAP would equate to a few inches of snow followed by a sleet-fest verbatim.  It's so close though it could go either way.  It's about time to say screw the guidance and just watch it come in, but I know I won't be able to help but check on each run that comes in lol.  

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34 minutes ago, cyclone77 said:

Now about 6-8hrs from the start of the event and it's still a little muddled as to what to expect.  The GFS has consistently been showing an all snow event for the QCA, and other guidance seems to be trending in that direction.  HRRR/RAP/NAM3 still bring the snow/mix line up to this area by mid evening.  RGEM still gets us into all rain for a period, but it has trended south as Chicago Storm pointed out.  Compared to yesterday the period of mixing is substantially less.  It would still appear the northern/western DVN cwa has the best shot at the most snow, but if trends continue the QC may end up doing quite well out of this yet again.  Apparently it's just one of those seasons when everything seems to trend in our favor in the final 24-48hrs.  

4

We know what you're gonna end up with ;)

Trying to break my event high of 4" with this storm.

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Definitely a tricky call around here.  My expectation is still for several hours of freezing rain.  Trying to pin down the ending time is probably the hardest part.  I am studying the 2m temp progs of course but you can get carried away with when the models show you getting to 32.1.  Looking at dews and wet bulb temps are also helpful.  

In any case, I expect to spend an inordinate amount of hours between 31 and 33 degrees.

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4 minutes ago, Hoosier said:

Definitely a tricky call around here.  My expectation is still for several hours of freezing rain.  Trying to pin down the ending time is probably the hardest part.  I am studying the 2m temp progs of course but you can get carried away with when the models show you getting to 32.1.  Looking at dews and wet bulb temps are also helpful.  

In any case, I expect to spend an inordinate amount of hours between 31 and 33 degrees.

Does being so close to the freezing mark help keep accretion down at all?

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Interesting to see the RAP and HRRR trying to flip to sleet all the way down through I-80 after midnight.  I can see why they are doing it as there is better lift then and an isothermal layer straddling 0C on forecast soundings.  Whether that is right is another matter.

HRRRFLT2_prec_ptype_017.png.ef4f2a0e0bfe69dc5034c56ad0142eff.png

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15 minutes ago, Hoosier said:

Interesting to see the RAP and HRRR trying to flip to sleet all the way down through I-80 after midnight.  I can see why they are doing it as there is better lift then and an isothermal layer straddling 0C on forecast soundings.  Whether that is right is another matter.

HRRRFLT2_prec_ptype_017.png.ef4f2a0e0bfe69dc5034c56ad0142eff.png

If it were moving more easterly it would be a great snow track. Certainly a good positon for NIL

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3 hours ago, RCNYILWX said:

Unless the short range guidance 2m and sfc wet bulb temps are too cold this evening into tonight, would think we have to extend headlines south at least to I-80 corridor counties. With brisk east-northeast surface winds coming from the cool dry high pressure to the east, doesn't look good for temps warming rapidly above freezing.

 

NAM12 verbatim has warning criteria ice all the way to 2 tiers south of the current advisory. Even if that's too far south and overdone with the ice accums, latest HRRR has headline worthy ice accums in the I-80 counties not currently in the advisory.

 

The other challenging aspect is exact p-type. Most recent RAP/HRRR are colder and have mainly sleet for I-88 counties and snow for WI border counties. From what I recall, RAP/HRRR did a good job picking up on the more stout low level cold wedge for our pinger fest on 12/28/2015.

 

Sent from my SM-G965U using Tapatalk

 

 

 

 

 

 

LOT did expand the advisory southward through the I-80 counties.

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1 hour ago, snowstormcanuck said:

I was looking at the soundings off the NAM. The warm layer aloft is pencil thin. Could see + rates keeping us snow.

I think it's pretty safe to pencil in 4-8" of snow and sleet. How much sleet we get will determine where in that range we end up. If we do stay all snow, could see us going north of 8" (but I'd say the chances of *no* changeover whatsoever is pretty small).

Also gotta watch that dry slot. 850/700 low pass well to our west so there's that threat to amounts too (although same scenario didn't remotely hurt us during the January 29 event).

I'd be shocked if we got less than 6". I'd go more for 7-11" come Wednesday morning

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1 minute ago, HillsdaleMIWeather said:

IWX, GRR, DTX, and CLE considering Ice Storm Warning upgrades

Here's the latest update form GRR

.UPDATE...
Issued at 110 PM EST Mon Feb 11 2019

The forecast is generally on track, but we will make a couple
changes to the WSW. We will upgrade the northern zones to a Winter
Storm Warning for the expected impacts of 6 or more inches of
snow combined with winds gusting 35 to 40 mph at times. Expect
significant impacts to travel from blowing and drifting with near
whiteouts in open country roads beginning late tonight.

We will also move the start time of the advisory across the
southern zones to 7 pm this evening, as snow and mixed precip is
expected to be arriving there this evening.
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10 minutes ago, HillsdaleMIWeather said:

IWX, GRR, DTX, and CLE considering Ice Storm Warning upgrades

From IWX... 

While no upgrade in headlines was done in the NE areas, potential
does still exist for a quarter inch or more of ice. Per discussion
with GRR/DTX/CLE have held off for the time being. Will look at
closer for afternoon package, but most likely will pass off to the
evening shift to monitor trends.

 

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25 minutes ago, Michigander said:

Here's the latest update form GRR


.UPDATE...
Issued at 110 PM EST Mon Feb 11 2019

The forecast is generally on track, but we will make a couple
changes to the WSW. We will upgrade the northern zones to a Winter
Storm Warning for the expected impacts of 6 or more inches of
snow combined with winds gusting 35 to 40 mph at times. Expect
significant impacts to travel from blowing and drifting with near
whiteouts in open country roads beginning late tonight.

We will also move the start time of the advisory across the
southern zones to 7 pm this evening, as snow and mixed precip is
expected to be arriving there this evening.

I am in GRR and I agree they should upgrade to WSW. All models point to 6-8" of heavy snow and some ice possible. Right now they are calling for 2-4" which I think is too low

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5 minutes ago, Aleksey said:

I am in GRR and I agree they should upgrade to WSW. All models point to 6-8" of heavy snow and some ice possible. Right now they are calling for 2-4" which I think is too low

They have been very stingy with their WSWs this year, except of course having them for a week straight during the vortex. IMO they totally blew it last week, when we had ice storms close down the city and force a state of emergency.

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This is a very tough ptype forecast, especially between the I-80 and I-88 corridors and about 10-15 miles either side. Despite what I posted earlier, having looked more at the soundings, I'm not buying sleet being much of an issue other than mixing in at times.

 

It should be primarily either snow or freezing rain. The big question is the northern extent of the warm nose and if it's enough to get full melting or do heavier rates keep it more as snow. The NAM and RGEM are by far more aggressive with the magnitude and northern extent of the warm nose around 850 mb, with the other guidance much more muted and farther south.

 

Given lack of stout low level cold wedge around 925 mb, it doesn't appear there will be enough refreezing energy for widespread full freezing of melted hydrometeors into sleet, except maybe far north for a time if warm nose does get that far north.

 

The pivotal weather soundings show this better with the temperature and wet bulb profile positive and negative energies. A modified version of the wet bulb is what we're using for ptype derivation in our grids, rule of thumb is negative energy of 100 j/kg or more gives 100% sleet probability and less than 50 gives 0% sleet, while for positive energy, I believe 20 j/kg gives full melting. So the big thing to watch on mesoanalysis this evening is the 850 mb zero line. Within the vicinity of that will be transition zone likely driven by rates to go over to all snow and far enough south will be solidly freezing rain.

 

 

 

 

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