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Feb 16th/17th/18th Winter Wx


burgertime

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Brad Panovich has been putting out quite a few interesting tweets.  I won't post them all here, but they are about how bad the models are busting on the dewpoints.

 

Also, both the nam and hi-res nam are sleet fests for the Triad. Over .8" to fall as sleet!  Looks like models are trending colder and wetter. Fingers crossed!  #keepmypoweron

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NAM and HRRR really having trouble with the surface temps...they are TOO WARM, rather significantly, this also includes dewpts, which in turn will affect the wet bulbs. I haven't looked at the upper levels, yet, though.

We'll just have to see how all of this plays out now.

 

This is interesting because our local NWS office has downgraded us to a WWA due to their belief the NAM is too cold with its temp profiles.

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http://www.srh.noaa.gov/epz/?n=wxcalc

Does anyone have a good formula/calculator for evaporational cooling? It's going to take a while for the column to become saturated, and I'm wondering how much that may affect temps.

 

DPs aren't going to be below zero when the precip arrives, but let's say they sit around 10, with air temps of around 30. I'm assuming DPs would rise much more than temp drops, but am unsure of the ratio. Can't find any calculations for this around, so I figured I'd ask. Apologies if this is not the time in Storm Mode, but it seemed relevant.

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Wow -- if you toggle between 6z GFS at 9 hours and 12z at 3 hours, you'll see a big difference with 850 temps. Pretty big shift for first frame in the run. #Colder

did it initialize right that's the question...

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NAM and HRRR really having trouble with the surface temps...they are TOO WARM, rather significantly, this also includes dewpts, which in turn will affect the wet bulbs. I haven't looked at the upper levels, yet, though.

We'll just have to see how all of this plays out now.

The models may not be that far off. Sunshine has been out all morning long here in the mountains and temps have risen into the mid and upper 30s. Still dry, but much warmer than any forecast I saw.

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Hey southeast crew... I've updated my HRRR page so that it covers the snow/ice event in the southeast.

 

http://www.atmos.albany.edu/student/ppapin/hrrr.php#flt

 

KGSO.gif

 

I also have HRRR soundings for select locations. I am willing to add more locations so let me know! Good luck with the even everyone!

 

KGSO

KAVL

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The NAM is 8 degrees higher on the dew point at CLT at 15z than reported conditions.

 

I don't recall off the top of thy head an incoming storm that had dewpoints below zero (F) here.  Even the cold Jan 2011 wasn't that cold.  Of course, warming aloft will win out.  I think the NWS forecasts are good for this area.  Up to an inch of snow/sleet, then something like 0.2-0.4 of ice.  Euro/Euro Ens Mean are locked in around 0.6 of total QPF...looks like a good number to me

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LOL..  some folks saying models coming in colder.  Then some folks saying warmer... 

 

Which is it?  Let's just blend it all and things stay the same.

 

 

Looking at a profile of the atmosphere, at my specific location the GFS has been pretty steady with 850 temps...

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You look to be OK, but the triangle get's precip holed...

Yeah the precip minimum in central NC is exactly what you'd expect to see from a Miller B. It definitely looks to me like the RGEM has the best handle on the situation. The relatively equal blanket of precipitation shown by some models just doesn't seem likely.

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Interesting the GFS is picking up the precip hole over the triangle, similar to the RGEM.

 

The GFS is very cold, as is the RGEM, with temps in low 20's for most of precip with it bottoming at 19F for the triangle.

 

I would agree w/ the precip hole the gfs and rgem are showing.  With this being a Miller B I believe the transfer is really going to kill our overall qpf.  I definitely don't trust the nam.

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Yeah the precip minimum in central NC is exactly what you'd expect to see from a Miller B. It definitely looks to me like the RGEM has the best handle on the situation. The relatively equal blanket of precipitation shown by some models just doesn't seem likely.

 

Looks like all the models have the big slug of precip rolling right on up I-85 now, which is nice for us.  Probably heavy pingers after a good shot of snow.  We rock at late-winter sleet these days.

 

 

Looking at GFS temps (850/700/925) it looks to be a lot of snow for GSO up to about 3z, per GFS. Looks to be a solid 3-4" of snow.

 

Seems to match up decently with the 12z RGEM, as well.  The NAM was a little warmer, I think, but probably still a couple inches.

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