HurricaneTracker

Heads up! High pressure centered in Illinois is 1039.2mb! This is the strongest it has been and bests all model expectations from the last several runs. Something to watch as the day unfolds. Edit - note the temperatures BELOW ZERO in Wisconsin. Teens in central Illinois. GFS was too warm by 10-15 degrees in this area of Wisconsin, but NAM not too far off. NAM and GFS about 1 mb too low on the strength of the high though.

Always nice to confirm upstream obs. Fire hose is primed!

This includes heavy rain next Friday. And that’s a whole other issue. Flooding concerns go up dramatically next week as heavy rain falls on a deep and high liquid water content snowpack.

Not necessarily too soon. It can happen upright if it lines up just right

How are you determining this? What parameters/fields? Thunder snow is not usually done by upright convection (summer storms) but rather by slant wise convection which is hard to get model output on.

Lines up perfectly with Euro and FV3. All models in excellent agreement.

00Z NAM looks great for AVL to Boone! Much better wedge this run and substantial liquid QPF over 2.25". Mixing with sleet, if it happens, would be mid morning Sunday near tail end of the event....based on soundings analysis and not some silly colored algorithm

Yea. Boone liquid mean is 2.27" with 15.8" of snow

New 21Z SREF is in. Wet! Mean up to 2.63" with 8 members over 3.00" of liquid. Snowfall mean 11.45". Few members over 30" and under 2". Lol. My bet is 00Z NAM comes in wetter

Gulf temperatures have zero impact on our storm. If anything, warmer temperatures support more evaporation and thus more added water vapor / moisture availability.

We do need to watch this. But seems that given the moisture transport mechanism off of the Gulf and Atlantic, perhaps this won't be too big an issue.

Nah. Looks fine to me. All systems go.

Looking super promising at the moment. 12Z NAM soundings are surprisingly supportive of all snow (no mixing at all during the event). So then snowfall will be determined by ratios and compaction.

NAM is HUGE!!!! ALL SNOW SOUNDINGS for just about the entire event. Closing in on 20-25" across Henderson, Transylvania, Buncombe, and McDowell counties.

This is probably correct. Intense warm nose by deep southerly fetch of moisture riding north on 50kt LLJ and you guys are almost always tucked away from the wedge.

And substantially colder. Now aligns perfectly with Euro, FV3, and CMC. What worries me greatly is 55 knot winds at 850mb Sunday morning in the mountains. Exceptionally dangerous situation may be unfolding!

00Z NAM trending his direction. Starts precip MUCH earlier (mid morning Saturday) and thus wedges us in much sooner.

SREF plumes for AVL have really skyrocketed today. The scale now goes to 40"! Three members over 30". Three members near zero. 00Z NAM should be telling.

Ha ha ha. For now.....yes

Finally looks like Euro

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!

and they gave no nod to the FV3 (which has liquid to > 2").

They based it off of the lower QPF values from the GFS. Didn't even look at or mention the Euro.

This is a big deal given the horrid 12Z NAM run we saw. Just verifies to me that the 12Z run was junk. EDIT: also suggests the NAM will correct itself at 18Z