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January 2016 Discussion


IWXwx

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Just looking at a couple of soundings off of the 0z NAM for Monday when the band would be trying to push into SE WI/NE IL, moisture depth isn't great, but you have a saturated layer with absolutely unstable lapse rates up to about 5k feet and through a good chunk of the DGZ. I think the marginal inversion heights/moisture depth would keep things from getting out of hand, but the 18z soundings from under the band look similar, so I could see a band that produces nice, very high ratio dendrites that add up relatively fast. I still like my 3" number max for the west side of the lake given the short duration and marginal moisture depth/inversion heights, but I'm never against bumping up if needed.

 

 

Any thoughts on the southern and eastern side of the lake?  Earlier I was thinking 3-6" somewhere but not ready to commit on placement.

 

Will be nice to get more hi-res runs.  Sort of feel like I'm flying in the blind without them.

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Any thoughts on the southern and eastern side of the lake?  Earlier I was thinking 3-6" somewhere but not ready to commit on placement.

 

Will be nice to get more hi-res runs.  Sort of feel like I'm flying in the blind without them.

As of right now I like 3-6" amounts for parts of NW IN and western MI in the favored NW flow Snowbelts. My main concern as I believe you also mentioned earlier was the winds shifting quite a bit during the event. It looks like winds could be fairly steady NW for a decent period of time Sunday into Sunday night which could allow light to locally moderate snow to be fairly persistent where it's favored in a NW wind. The inversions/moisture/instability all really come up Sunday night into very early Monday for a few hours, but then the winds go NNE and the atmosphere starts drying...so still a short window of heavy snow downwind of the lake on the southern and east side...but longer than on the west side and with some light stuff starting Sunday. Ratios should be pretty good so I could see somewhere locally squeezing out 6". I agree, it'll be interesting once the hi-res stuff starts getting into range.

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Alot of the NWS offices seem to be downplaying the LES threat, especially IWX who mentioned they don't think forcing will be enough for any thing other than snow showers.

Here's IWX

 

POTENT NRN STREAM SW TROF OVR WRN NWT THIS AFTN WILL

AMPLIFY SEWD THROUGH THE NRN LAKES BY SUN AS LARGER SCALE ERN CONUS

HGTS BUCKLE SIGLY ALLOWING FOR THE COLDEST AIRMASS OF THIS WINTER TO

SETTLE SWD ACRS THE ERN US. BRIEF BUT VIGOROUS LK RESPONSE XPCD SUN

NIGHT-EARLY MON TIMED W/SWD INFLUX OF LL CAA AND FVRBL LL FLW

TRAJECTORIES OFF LK MI. SLUG OF ACCOMPANYING MID LVL MSTR ASSOCD/W

SW TROF SHLD SERVE TO ENHANCE -SHSN FURTHER INLAND AND IN LIGHT OF

GROSS CONSENSUS SIGNALS BUMPED POPS APPRECIABLY.

 

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Yeah they sounded more bullish in the afternoon afd.

The GFS and NAM have trended farther west with the core of the upper level trough compared to even a day or two ago and bring colder air and deeper moisture farther west too, so it's not surprising that LOT and IWX for example have both bumped up the wording some in their most recent AFDs. The Euro has consistently looked better for LES for the last couple of days so if that holds another run or two I'd definitely feel good about some "brief but vigorous" LES...brief but vigorous is fun if you're in the right spot, but definitely makes the margin for error smaller than a drawn out event. Definitely good trends today though.

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Geos, why does the precip map from the 0z NAM show nothing along the Lakeside areas of the western shore?

 

 

Was just going to point that out...

 

It's definitely on these maps.

 

namconus_ref_ncus_22.png

 

namconus_ref_ncus_23.png

 

4km NAM resolution shows the LES even better, but that's not in range quite yet.

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The GFS and NAM have trended farther west with the core of the upper level trough compared to even a day or two ago and bring colder air and deeper moisture farther west too, so it's not surprising that LOT and IWX for example have both bumped up the wording some in their most recent AFDs. The Euro has consistently looked better for LES for the last couple of days so if that holds another run or two I'd definitely feel good about some "brief but vigorous" LES...brief but vigorous is fun if you're in the right spot, but definitely makes the margin for error smaller than a drawn out event. Definitely good trends today though.

 

Good trends indeed.  I guess we can hope the band manages to get hung up somewhere (how about over my house :D) and results in more impressive totals.  I'm sure you've seen it with Erie where bands end up less transient than predicted. 

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Good trends indeed.  I guess we can hope the band manages to get hung up somewhere (how about over my house :D) and results in more impressive totals.  I'm sure you've seen it with Erie where bands end up less transient than predicted. 

Ha, just a few times ;)

 

It really would only take a few hours of being under the band when conditions are most favorable for LES to get a pretty good total...we'll see if someone can pull that off.

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That's so strange...this is from WxBell and NCEP has the same...

 

attachicon.gifNAM.png

 

Maybe TT is using different calculations for the LES? Seeing a different dry layer height - higher up in the column instead of just above 850mb? If we can get the dry layer to lift up above 800mb or so, we're in better business.

We need more high resolution models to get within range.

 

That does look pretty sweet for N IN.

 

gem_mslp_pcpn_frzn_ncus_10.png

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A benign week of weather coming up for those of us outside of the belts.  Looks like the next synoptic op for precip comes along about Friday.  GFS lays some more snow down for the MSP peeps.  The next system after that looks to arrive in the Mon-Tue time frame.  Will be nice to have something else to track after this short break in activity.

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Ha, just a few times ;)

 

It really would only take a few hours of being under the band when conditions are most favorable for LES to get a pretty good total...we'll see if someone can pull that off.

 

 

Agree...doesn't take long when it's ripping.

 

There was an event here in January 2014 that dumped like 11" in under 3 hours (I hadn't moved here yet)...there was some enhancement with a s/w moving through but even after moisture/inversion heights started to dip, the band remained intense for a while.  Was also supposed to move east quicker but that didn't happen.  I love and hate the unpredictability at the same time. 

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Agree...doesn't take long when it's ripping.

 

There was an event here in January 2014 that dumped like 11" in under 3 hours (I hadn't moved here yet)...there was some enhancement with a s/w moving through but even after moisture/inversion heights started to dip, the band remained intense for a while.  Was also supposed to move east quicker but that didn't happen.  I love and hate the unpredictability at the same time. 

It's probably safe to say that the best LES often occurs immediately ahead of an approaching shortwave due to increased mid-level moisture and also large scale ascent. I'd guess that if you have a well-established band and the winds don't become too sheared behind the shortwave that uplift within the band can locally cause moisture/inversion heights to remain a bit higher longer than models indicate ahead of time. We'll see if that can help out the west side of the lake at all, as although moisture/inversion heights become marginal pretty quickly behind the shortwave, low level lapse rates could remain very steep which could keep a good band going and allow locally better conditions to persist into Monday afternoon.

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It's probably safe to say that the best LES often occurs immediately ahead of an approaching shortwave due to increased mid-level moisture and also large scale ascent. I'd guess that if you have a well-established band and the winds don't become too sheared behind the shortwave that uplift within the band can locally cause moisture/inversion heights to remain a bit higher longer than models indicate ahead of time. We'll see if that can help out the west side of the lake at all, as although moisture/inversion heights become marginal pretty quickly behind the shortwave, low level lapse rates could remain very steep which could keep a good band going and allow locally better conditions to persist into Monday afternoon.

 

 

LOT has mentioned before that studies have shown that meteorological conditions inside a well developed band sometimes aren't handled well by the models...i.e. the thermodynamics can be altered compared to surrounding environment.  So basically what you said. 

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IWX really upped there wording in the morning AFD:

 

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 440 AM EST SAT JAN 2 2016

THE SECOND IN A SERIES OF SHORT WAVE TROFS WAS DISTANT UPSTREAM
EARLY THIS MORNING AND WAS STILL OVER THE ARCTIC REGIONS OF
NORTHERN CANADA. THIS SYSTEM WILL RACE SOUTHEAST TODAY AND SUNDAY
AND IS EXPECTED TO BRING A QUICK ROUND OF MAINLY LAKE EFFECT SNOW
SHOWERS LATE SUNDAY INTO EARLY MONDAY. THE EDGE OF A FRESH SURGE
OF ARCTIC AIR WILL ACCOMPANY THIS SYSTEM WITH A BRIEF INTRUSION OF
ARCTIC AIR. AS HAS BEEN THE PATTERN FOR THE PAST SEVERAL
WEEKS...THE DOME OF ARCTIC AIR WILL MOVE EAST AND OUT OF THE AREA
QUICKLY ALLOWING TEMPERATURES TO RISE ABOVE NORMAL FOR MOST OF
THIS UPCOMING WEEK. IN THE INTERIM..A BRIEF WINDOW FOR FAVORABLE
LAKE EFFECT SNOW SHOWERS SUNDAY NIGHT WILL EXIST. GIVEN FAVORABLE
UPSTREAM PRECONDITIONING FROM LAKE SUPERIOR AND THE MILD WATERS OF
LAKE MICHIGAN THAT ARE ABOUT 4 DEGREES ABOVE NORMAL FOR THIS TIME
OF YEAR...INCREASED SNOW SHOWER CHANCES FOR FAR SOUTHWEST LOWER
MICHIGAN INTO NORTHWEST INDIANA. CURRENT THINKING IS THE HIGHEST
SNOW AMOUNTS WILL BE OVER BERRIEN COUNTY AND RANGE FROM 2 TO 4
INCHES. LESSER AMOUNTS ARE EXPECT FURTHER INLAND.

OTHERWISE...TEMPERATURES WILL RISE ABOVE NORMAL BY THE MIDDLE OF
THIS UPCOMING WEEK WITH DRY CONDITIONS TUESDAY THROUGH THURSDAY.

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It's amazing how a inch or two of fresh snow can change the perception of the season. Picked up roughly 1.5" yesterday. Looks like a sharp north to south cutoff.

Agreed on all fronts. Drove yesterday evening from AA where there was just a dusting on the grass to West Bloomfield where there's about an inch and a half.
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Agreed on all fronts. Drove yesterday evening from AA where there was just a dusting on the grass to West Bloomfield where there's about an inch and a half.

And yet people "cancel" winter every day on the boards, a fresh inch of snow and their tune changes :lol:

 

Winter is such a long season but people always think of whats going on right now. On Thanksgiving (a week removed from a big snowstorm) I had to field questions "omg are we in for ANOTHER hard winter" then on Christmas (torch) I had to answer "will we have any winter?". Weather...always talked about, never understood.

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