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New Years' Weekend Snow Potential


Rainman

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0z NCEP Ensembles messy here, but heavy majority southeast of the model itself.

http://www.emc.ncep.noaa.gov/gmb/tpm/emchurr/tcgen/tcgif/track.aeperts.2015010100.east_coast.single.png

I think part of the issue with the op run of the GFS is that it takes the storm NNE initially before shifting NE, where as the ensembles look to just move NE. That will be something to watch into Friday, we should know by then if it is going to be on the north or south side of the envelope.

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I think part of the issue with the op run of the GFS is that it takes the storm NNE initially before shifting NE, where as the ensembles look to just move NE. That will be something to watch into Friday, we should know by then if it is going to be on the north or south side of the envelope.

Yeah, rather wide spread with the 0z Canadian ensembles doesn't help either. With the Grinch storm, the storm never really stopped shifting until the ensembles were compact; If I recall correctly, the final westward shift on Dec 23 had some ensemble support, but still a noticeable spread prior to that evening's final eastward haul.

CMC Ensembles

http://meteocentre.com/tracking/cmc_geps_amer_00/pres_short.gif

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00z GGEM freezing rain clown map.  Halving this would produce a strip of warning criteria ice.  1 or 2 degrees going to make a big difference in the transition zone.

 

 

attachicon.gifZR_000-096_0000.gif

 

That did shift a bit south. Earlier run had some heavy ice accumulation around here and in southern WI.

 

0z EURO.

 

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Good argument against any significant icing in Northern IN by the morning forecaster at IWX:

 

IT IS IMPORTANT TO REMEMBER
THAT FREEZING RAIN IS A SELF-LIMITING PROCESS. A CONTINUAL FEED OF
COLD/DRY AIR IS NEEDED TO OFFSET THE LATENT HEAT RELEASE DUE TO
FREEZING. THIS IS DEFINITELY NOT AN IDEAL FREEZING RAIN SETUP WITH
SURFACE HIGH DISPLACED WELL TO OUR EAST.
INITIALLY...EASTERLY FLOW
MAY HELP MAINTAIN FREEZING PRECIP FOR A FEW HOURS SATURDAY
MORNING...ESPECIALLY IN OUR NORTHERN COUNTIES...BUT SUSPECT THERE
WILL BE A FAIRLY QUICK CHANGEOVER TO JUST PLAIN RAIN GIVEN SLOWLY
VEERING SURFACE WINDS...LATENT HEAT RELEASE...AND A VERY STRONG WARM
LAYER JUST ABOVE THE SURFACE. NOT TO MENTION SURFACE TEMPS ARE VERY
MARGINAL TO BEGIN WITH AND DIURNAL TIMING IS HIGHLY UNFAVORABLE.

 

Looks like another forecasting nightmare for LOT.

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Good argument against any significant icing in Northern IN by the morning forecaster at IWX:

 

IT IS IMPORTANT TO REMEMBER

THAT FREEZING RAIN IS A SELF-LIMITING PROCESS. A CONTINUAL FEED OF

COLD/DRY AIR IS NEEDED TO OFFSET THE LATENT HEAT RELEASE DUE TO

FREEZING. THIS IS DEFINITELY NOT AN IDEAL FREEZING RAIN SETUP WITH

SURFACE HIGH DISPLACED WELL TO OUR EAST. INITIALLY...EASTERLY FLOW

MAY HELP MAINTAIN FREEZING PRECIP FOR A FEW HOURS SATURDAY

MORNING...ESPECIALLY IN OUR NORTHERN COUNTIES...BUT SUSPECT THERE

WILL BE A FAIRLY QUICK CHANGEOVER TO JUST PLAIN RAIN GIVEN SLOWLY

VEERING SURFACE WINDS...LATENT HEAT RELEASE...AND A VERY STRONG WARM

LAYER JUST ABOVE THE SURFACE. NOT TO MENTION SURFACE TEMPS ARE VERY

MARGINAL TO BEGIN WITH AND DIURNAL TIMING IS HIGHLY UNFAVORABLE.

 

Looks like another forecasting nightmare for LOT.

 

 

Indeed about LOT.  Though at this point it seems like some type of winter weather headline is a decent bet. 

 

All of IN and most of IL looks like it will change to plain rain at this point.  I suspect the best chance of not getting above freezing (though certainly not a slam dunk) will be in parts of NW IL. 

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It sure got quiet in here once the models took Chicago and Detroit out of the snowstorm potential.  Eastern Iowa through Wisconsin are still in good shape, although even here the GFS/pGFS have above-zero at 850mb through Saturday evening, which would make it tough to accumulate snow during the first surge of moisture.  A 3-6 inch defo band overnight Saturday night appears most likely for Iowa.  It's at night, as usual, and it's no huge storm, but I'll take it.

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It sure got quiet in here once the models took Chicago and Detroit out of the snowstorm potential.  Eastern Iowa through Wisconsin are still in good shape, although even here the GFS/pGFS have above-zero at 850mb through Saturday evening, which would make it tough to accumulate snow during the first surge of moisture.

 

Makes me wish there were more Iowa posters here besides me and Hawkeye_wx. :(

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It sure got quiet in here once the models took Chicago and Detroit out of the snowstorm potential.  Eastern Iowa through Wisconsin are still in good shape, although even here the GFS/pGFS have above-zero at 850mb through Saturday evening, which would make it tough to accumulate snow during the first surge of moisture.  A 3-6 inch defo band overnight Saturday night appears most likely for Iowa.  It's at night, as usual, and it's no huge storm, but I'll take it.

I don't think any chicago folks looked at this as a snowstorm. Maybe a low level advisory storm which may still pan out.

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Considering what this airmass looks like right now, the NAM seems ambitious with low level moistening on Saturday.  It looks a little too fast imo, and this would also play in to its surface temp progs.  In reality I think dewpoints will be lower near onset, creating a more favorable window for evaporational cooling to try to temporarily offset the waa.  So basically I believe the NAM is currently underplaying the ice potential to some degree.  The negative factors (less than favorable high position, marginal temps, precip rates possibly becoming too heavy) have been touched on and can't be ignored...with that being said, my early guess is a corridor of a tenth to two tenths of an inch of ice in southern/eastern IA, northern IL, northern IN and over into parts of southern/central MI.  Subject to change of course.

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It sure got quiet in here once the models took Chicago and Detroit out of the snowstorm potential.  Eastern Iowa through Wisconsin are still in good shape, although even here the GFS/pGFS have above-zero at 850mb through Saturday evening, which would make it tough to accumulate snow during the first surge of moisture.  A 3-6 inch defo band overnight Saturday night appears most likely for Iowa.  It's at night, as usual, and it's no huge storm, but I'll take it.

Well to be fair there is a much bigger Chicago/Detroit contingent here than Iowa :P

 

I dont mind Iowa seeing snow, as you guys have not had near the fun we have had in recent years snow-wise, not to mention youve been even colder, but even this doesnt look to be a big storm (need to get a cyclone a 6"er). Just havent been able to spin up a significant snowstorm in the region...yet.

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