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BretWx

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    2018/2019 Mountains and Foothills Fall/Winter Thread

    in Southeastern States

    Posted

    4 minutes ago, HurricaneTracker said:

    Good evening everyone.  I wanted to take a moment and give y’all an update in light of the disastrous communications issue that is unfolding before our eyes.

    1. Overall things have NOT changed that much since this time yesterday.  Euro came in with a swath of 20”+ from KAVL to KTNB and consistent liquid equivalents around 2.50”.  Duly noted is that the Euro was NOT mentioned in the afternoon discussion by GSP.   It has been absolutely rock solid on this storm system since last Saturday!  To boot, we added the CMC model today with a lot of liquid equivalent, too.  And now the 18Z FV3 (which we should all be looking at since it IS our future!), comes in with at least 2.00” of liquid (minimum QPF in Bristol, TN but that is expected given the setup).

    2. 12Z NAM was a dumpster fire and has since corrected itself at 18Z (more corrections coming too, I suspect).  12Z GFS was a dumpster fire (just ridiculously low QPF) and p-type issues abound.  Yet, this is the model of choice today by GSP.  Oh but wait there’s more!  18Z GFS self-corrected and came in with more QPF and colder wedging solution.  You want to hang your hat on the GFS?  Better be ready to make more changes to the snowfall forecast as the GFS shifts.

    3. Let’s talk warm nose.  Does it exist?  YES.  Someone in the main thread said NE Georgia was out of the snow.  I agree.  This is climatology.  Even parts of the favored escarpment areas will see sleet for a time being Sunday morning.  What is confusing the models is the isothermal layer in the soundings. My eye sees the isothermal layer as a deep layer of snow, since dendrites will be falling into this isothermal layer. ALL MODELS say that even at 850mb temperature of 0.1 deg F this melts the flakes.  I just completely and utterly disagree.  In all my years of forecasting, deep isothermal layers that hover on the 0 deg isotherm (and are below freezing either side of this layer) tend to run as all snow. Watch for this in the next 24 hours.

    4. Do we need to cut down snow amounts?  Maybe. But don’t forget we are using a 7:1 ratio anyway to start with (see my post from yesterday).  So instead of 2.50” of liquid coming out to 17.5” of cement, maybe we go 2.00” of liquid and 14” of snow.   I’m currently most comfortable going with a range of 8-12” for KAVL and the eastern escarpment.  Boone will see slightly more sleet because they are actually *too high* in elevation and above the wedge into the warm nose.  So instead of 17” there, I think 8-12” also applies to them.

    Hang in there folks.  Watch the 00Z trends.  Can’t ignore the intense dynamics and the fire hose that is our deep tropical moisture connection!

    Supposedly I’m out of reactions for the day, but THANK YOU! 

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    2018/2019 Mountains and Foothills Fall/Winter Thread

    in Southeastern States

    Posted

    When the Euro is showing 20-30 inches less than 48 hours out... I listen. 

    Edit: Sorry, just really annoyed that the triad mentions getting 10 inches and we... well, lol.  

    * WHAT...Significant accumulations of snow combined with sleet and
  freezing rain is expected. Total snow accumulations of 4 to 8
  inches combined with ice accumulations of up to one tenth of an
  inch are possible. The greatest snow amounts are likely to be in
  the Triad, where amounts could approach 10 inches.
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