January 18th Winter Storm Looms

billg315 wrote:Here are my Sudden Thoughts and Second Thoughts (RIP Bill Lyon):
A. The temperature profiles on the GFS have trended colder over the past 72 hours for Saturday. A couple days ago I was forecast to approach 40 degrees by Saturday evening. Now I am unlikely to get above 35 degrees (and even that only very briefly at the end of the storm Saturday night). This indicates the strength of the High Pressure and how difficult it will be to scour out the cold air. This bodes well for prolonged front-end thump snows most of the day Saturday.
B. The NAM is still out of range but the 12z has Friday evening temperatures in the low 20s in SNJ and the teens in CNJ/NNJ. If true, temps could be in the teens almost statewide by Saturday morning which would be consistent with what I mentioned in Point A. It will take a long time to warm those temps up.
C. Most of the state is at or below freezing up until almost the end of the storm Saturday evening. The exception is the coast. The 850 freezing line is southeast of most of the state for most of the event. While most areas probably do change to rain before ending -- I think for areas away from the immediate coast that will be "after the damage is done" so to speak in terms of snow accumulations.
D. Frank's 3-6" sounds like a solid guess for most of the state at this point, but with delayed changeover I wouldn't be surprised if areas further North and West hit 7 or 8" out of this.
E. Timing has shifted a bit. Originally looked to start Friday night. Now looks more like snow spreading into the area late morning Saturday and getting heavier during the afternoon and evening before winding down/changing to rain Saturday night. This means Saturday morning may start just cloudy, but most of Saturday afternoon and evening may be very snowy across the area.
Those are my impressions for now.

heehaw453 wrote:

billg315 wrote:Here are my Sudden Thoughts and Second Thoughts (RIP Bill Lyon):
A. The temperature profiles on the GFS have trended colder over the past 72 hours for Saturday. A couple days ago I was forecast to approach 40 degrees by Saturday evening. Now I am unlikely to get above 35 degrees (and even that only very briefly at the end of the storm Saturday night). This indicates the strength of the High Pressure and how difficult it will be to scour out the cold air. This bodes well for prolonged front-end thump snows most of the day Saturday.
B. The NAM is still out of range but the 12z has Friday evening temperatures in the low 20s in SNJ and the teens in CNJ/NNJ. If true, temps could be in the teens almost statewide by Saturday morning which would be consistent with what I mentioned in Point A. It will take a long time to warm those temps up.
C. Most of the state is at or below freezing up until almost the end of the storm Saturday evening. The exception is the coast. The 850 freezing line is southeast of most of the state for most of the event. While most areas probably do change to rain before ending -- I think for areas away from the immediate coast that will be "after the damage is done" so to speak in terms of snow accumulations.
D. Frank's 3-6" sounds like a solid guess for most of the state at this point, but with delayed changeover I wouldn't be surprised if areas further North and West hit 7 or 8" out of this.
E. Timing has shifted a bit. Originally looked to start Friday night. Now looks more like snow spreading into the area late morning Saturday and getting heavier during the afternoon and evening before winding down/changing to rain Saturday night. This means Saturday morning may start just cloudy, but most of Saturday afternoon and evening may be very snowy across the area.
Those are my impressions for now.

Nice write up.  I think though just as important as temps will be where the best forcing occurs.  The H7 strong jet stream winds (70 knots+) will cause lift and where that sets up determines who gets 6".  If that sets up further west then we will struggle to get 3 inches even NW of 95.  That is a rather fine detail that we just don't know yet.  All IMHO of course.

sroc4 wrote:Frank and CP kind of beat me to it.   Again with the MJO in such an amplified state in phase 6, our final soln favors a much more amplified wave, which unfort raises heights out ahead.  Unfort the low will follow the path of least resistance.  As you can clearly see in the images below(GFS then Euro) while there is a very potent arctic/polar HP parked to our North the delay in the timing of the system, combine with the lack of blocking in the Atlantic, the HP has little resistance to continue sliding east leaving a weakness on the western flank for which the primary LP, who's 500mb energy conts to trend stronger as does the resultant primary MSLP, can move/cut into.  As Frank mentions with a stronger primary the further N&W it gets before any possibility of a transfer off the coast.  The stronger it is and the further N&W it gets means the mid levels will warm faster.  Dont get me wrong I think we all start as snow(including the coast), but I think overall my confidence is mod-high that a trend will persist that sees snow totals slowly drop as we get in tight.  That said things that could still surprise us is the actual level of cold we are dealing with.  Ive been fooled before with how stubborn the cold can be.   Obv like Heehaw said N&W has the best chance to hold on the longest.  Not 100% sold yet but getting there.      

sroc4 wrote:Mugs I forgot to mention it but you did, the maps Im looking at the LLJ is screaming in from the SW from 900mb-925-850mb levels on both GFS and euro as the precip moves in.  I hate the LLJ.  Me and the LLJ are not cool with each other.  Last time me and the LLJ ran into one another it got ugly.  This is what I looked like after our last encounter.  

(disclaimer: thats not really me lol)

sroc4 wrote:Mugs I forgot to mention it but you did, the maps Im looking at the LLJ is screaming in from the SW from 900mb-925-850mb levels on both GFS and euro as the precip moves in.  I hate the LLJ.  Me and the LLJ are not cool with each other.  Last time me and the LLJ ran into one another it got ugly.  This is what I looked like after our last encounter.  

(disclaimer: thats not really me lol)

sroc4 wrote:Mugs I forgot to mention it but you did, the maps Im looking at the LLJ is screaming in from the SW from 900mb-925-850mb levels on both GFS and euro as the precip moves in.  I hate the LLJ.  Me and the LLJ are not cool with each other.  Last time me and the LLJ ran into one another it got ugly.  This is what I looked like after our last encounter.  

(disclaimer: thats not really me lol)

heehaw453 wrote:3 days+ out now and I'd say models are telling us that storm moves north and is bit more amped.  This does two things: erodes the cold air mass more quickly and allows forcing to be much further west.  We won't get the really good thump as modeled.

This could still trend either way, but it's not like models pulled the rug out from under us 2 days out.  So if trends the other way that'll be great.

Thoughts as of today
2-4" NW of 95 (lots more 2's & 3's)
1-2" Along and near 95
C-1" SE of 95

heehaw453 wrote:3 days+ out now and I'd say models are telling us that storm moves north and is bit more amped.  This does two things: erodes the cold air mass more quickly and allows forcing to be much further west.  We won't get the really good thump as modeled.

This could still trend either way, but it's not like models pulled the rug out from under us 2 days out.  So if trends the other way that'll be great.

Thoughts as of today
2-4" NW of 95 (lots more 2's & 3's)
1-2" Along and near 95
C-1" SE of 95