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Winter 2014-2015 Pattern Discussion Thread III


BIG FROSTY

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Thanks Bob!  Yeah, lot of members showing wintery (ice/snow) hits.  But, the Euro hasn't had 2 runs in a row that have been consistent yet.

 

The EPS is sure trying to bring the cold back in a hurry.  Just after day 10 you see it trying to build a trough in the east and with his propensity for leaving cold in the west it actually get's stuck in central US.  The ridging in the west with -EPO is showing up really strong and it's building it across the pole.  Also, no SE ridge on there either.    

 

The +NAO is never going away, the Greenland low is a staple of this winter, ugghh.

 

Euro was a notable step towards the 12z gefs. I think the "relax" is going to end up being nothing more than a 3-4 day typical spell before a cutter/cold front. Then game back on. NAO is a royal PITA but at least all guidance is pointing towards a neutral or negative ao in the future. 

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Euro was a notable step towards the 12z gefs. I think the "relax" is going to end up being nothing more than a 3-4 day typical spell before a cutter/cold front. Then game back on. NAO is a royal PITA but at least all guidance is pointing towards a neutral or negative ao in the future. 

 

Going to be very difficult to get +climo snow without a -NAO.  Maybe you guys can get away it during the 2nd half of winter but we will need a stout -AO in Feb to even hit climo, IMO.

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I don't have a lot of hope on this Jan 15 storm.  Next week or two looks rather ho hum. I see the last week or 10 days of January being the time when things really kick up and finally get some real blocking setting up.

I am not giving up that something can pop for the 15th.  Southern branch stuff can often throw forecasting for a loop and even though temps are borderline for many I think it should be watched.

I agree that we see late blocking this year, although admittedly seeing vortex after vortex sit and spin in Greenland, I am not confident AT ALL that will be correct.  What do you see that gives you confidence, a gut feeling...... or are you just going on past analogs for a weak Nino mostly having late season blocking episodes?

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I don't have a lot of hope on this Jan 15 storm.  Next week or two looks rather ho hum. I see the last week or 10 days of January being the time when things really kick up and finally get some real blocking setting up.

 

When you've been alone in Mom's basement for awhile you're willing to accept that date to the prom that mind end up being a giant prank. Just the risk you take.  :weenie:

 

As for the bolded I am hoping against hope that this is the case. Starting to get late in the game now. 

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Going to be very difficult to get +climo snow without a -NAO. Maybe you guys can get away it during the 2nd half of winter but we will need a stout -AO in Feb to even hit climo, IMO.

Heh, I stopped worrying about climo+ once late Dec/early Jan failed. One event at a time is all I care about.

I don't think the nao plays nearly as much of a role as the ao/pna does for standard modest events. A big +nao causes all kinds of issues but inside of +1/-1 is serviceable and I'm pretty sure that's the case for you guys.

Get some heights building around the pole and a +pna and the pv itself will act as a block to keep things from cutting. If the gefs has the right idea then things will get busy around here in a hurry.

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I am not giving up that something can pop for the 15th. Southern branch stuff can often throw forecasting for a loop and even though temps are borderline for many I think it should be watched.

I agree that we see late blocking this year, although admittedly seeing vortex after vortex sit and spin in Greenland, I am not confident AT ALL that will be correct. What do you see that gives you confidence, a gut feeling...... or are you just going on past analogs for a weak Nino mostly having late season blocking episodes?

A bit of all of the above plus the models seem to be in a general agreement with above normal Hts over the arctic. This relax period may be the spark to set it up.

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Hell, I am going to enjoy my 35-38 degree day on Sunday with some light rain and drizzle!!  wooohoooo.  The NAM wants to really drop it down to sub 35...ewwwwwww

The nam is suggesting the potential for some actual ice accumulation. here is the nam soundings for my location starting at hour 48. Plenty of room for evaporational cooling with wetbulbs solidly below freezing

NAM Text Sounding | 18 UTC Sun 11 Jan 2015 |
PRES	HGHT	TEMP	DWPT	RELH	MIXR	DRCT	SKNT	TWTB	TVRT	THTA	THTE	THTV
1006.2	228	0.9	-6.6	57	2.3	42	5	-1.5	1.3	273.6	280.1	274.0
1000.0	278	0.1	-7.9	55	2.1	42	5	-2.4	0.4	273.2	279.3	273.6
975.0	479	-1.9	-9.3	57	2.0	55	8	-4.0	-1.6	273.2	278.8	273.6
950.0	687	1.4	-2.7	74	3.3	108	13	-0.1	2.0	278.6	288.0	279.2
925.0	905	6.5	6.4	99	6.6	172	10	6.5	7.6	286.0	304.5	287.1
900.0	1130	7.3	7.2	99	7.1	191	18	7.3	8.5	289.0	309.3	290.3
875.0	1362	8.0	7.7	98	7.6	189	32	7.9	9.3	292.1	314.0	

By 54 hours/0z monday notice the nam does not show much cooling despite precip. Logic dictates there would be more than 0.3c cooling with dewpoints jumping 4c

NAM Text Sounding | 00 UTC Mon 12 Jan 2015 | 
PRES	HGHT	TEMP	DWPT	RELH	MIXR	DRCT	SKNT	TWTB	TVRT	THTA	THTE	THTV
1004.7	228	0.4	-2.3	82	3.2	25	7	-0.6	0.9	273.2	282.1	273.7
1000.0	265	0.0	-2.7	82	3.1	25	7	-0.9	0.5	273.2	281.9	273.7
975.0	467	0.2	-2.9	80	3.2	43	17	-0.9	0.7	275.3	284.2	275.8
950.0	679	7.2	6.0	92	6.2	106	18	6.6	8.2	284.5	301.9	285.5
925.0	899	8.1	7.0	93	6.8	130	28	7.5	9.2	287.5	307.0	288.7
900.0	1127	9.7	9.6	99	8.4	149	35	9.7	11.2	291.5	315.6	293.0
875.0	1361	9.6	9.5	99	8.6	163	40	9.6	11.1	293.8	318.6	295.3
850.0	1602	9.2	9.1	99	8.6	185	38	9.2	10.7	295.8	320.9	297.3
825.0	1849	7.7	7.4	98	7.9	203	29	7.6	9.1	296.7	320.0	298.1
800.0	2103	5.9	5.7	99	7.3	211	23	5.8	7.1	297.4	318.8	

By hour 57, it's 0.1c at the surface LOL :arrowhead:

 

 

 

By 60 hours, we see the nam with temps barely above freezing and dewpoints above freezing as well.

NAM Text Sounding | 06 UTC Mon 12 Jan 2015 | 
PRES	HGHT	TEMP	DWPT	RELH	MIXR	DRCT	SKNT	TWTB	TVRT	THTA	THTE	THTV
1002.0	228	0.7	0.1	96	3.9	37	3	0.5	1.3	273.7	284.3	274.3
1000.0	244	0.5	-0.0	96	3.8	42	3	0.3	1.2	273.7	284.2	274.3
975.0	446	-0.2	-0.5	98	3.8	71	12	-0.3	0.4	274.9	285.4	275.5
950.0	655	6.1	6.1	100	6.3	142	23	6.1	7.2	283.4	300.9	284.4
925.0	878	13.5	13.3	99	10.5	184	36	13.4	15.3	293.1	323.2	294.9
900.0	1109	12.3	12.1	99	10.0	201	34	12.2	14.0	294.1	322.8

There is very strong waa above 950mb so the temps will warm to above freezing even if we manage to drop below it. However, by the time it does so I think there could be some advisory/ nuisance level ice accumulation over north and parts of central ga/south carolina (eventually parts of nc) IF there is enough precip before going to all rain pretty quickly.

 

The  biggest negative against it, assuming  there is appreciable precip falling, is the depth or lack thereof of the near surface cold layer. Normally you want it to be at least 50mb deep  But as you can see, it only goes up to below 950mb. That is narrow enough that indeed temps might not drop as much as one would think because that is an awful deep warm layer that rain is falling through and there is no CAA. So the rain itself could be warm enough to keep temps from dropping below freezing, despite having subfreezing wetbulbs initially. Combined with latent heat release/no CAA, It certainly would mean it would rise above freezing fairly quickly if we manage to drop below it.

 

It should be noted though the gfs is much drier during this time frame and no where near cold enough.

 

At least it's something to watch for though, even if it doesn't amount to much.

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The nam is suggesting the potential for some actual ice accumulation. here is the nam soundings for my location starting at hour 48. Plenty of room for evaporational cooling with wetbulbs solidly below freezing

NAM Text Sounding | 18 UTC Sun 11 Jan 2015 |
PRES	HGHT	TEMP	DWPT	RELH	MIXR	DRCT	SKNT	TWTB	TVRT	THTA	THTE	THTV
1006.2	228	0.9	-6.6	57	2.3	42	5	-1.5	1.3	273.6	280.1	274.0
1000.0	278	0.1	-7.9	55	2.1	42	5	-2.4	0.4	273.2	279.3	273.6
975.0	479	-1.9	-9.3	57	2.0	55	8	-4.0	-1.6	273.2	278.8	273.6
950.0	687	1.4	-2.7	74	3.3	108	13	-0.1	2.0	278.6	288.0	279.2
925.0	905	6.5	6.4	99	6.6	172	10	6.5	7.6	286.0	304.5	287.1
900.0	1130	7.3	7.2	99	7.1	191	18	7.3	8.5	289.0	309.3	290.3
875.0	1362	8.0	7.7	98	7.6	189	32	7.9	9.3	292.1	314.0	

By 54 hours/0z monday notice the nam does not show much cooling despite precip. Logic dictates there would be more than 0.3c cooling with dewpoints jumping 4c

NAM Text Sounding | 00 UTC Mon 12 Jan 2015 | 
PRES	HGHT	TEMP	DWPT	RELH	MIXR	DRCT	SKNT	TWTB	TVRT	THTA	THTE	THTV
1004.7	228	0.4	-2.3	82	3.2	25	7	-0.6	0.9	273.2	282.1	273.7
1000.0	265	0.0	-2.7	82	3.1	25	7	-0.9	0.5	273.2	281.9	273.7
975.0	467	0.2	-2.9	80	3.2	43	17	-0.9	0.7	275.3	284.2	275.8
950.0	679	7.2	6.0	92	6.2	106	18	6.6	8.2	284.5	301.9	285.5
925.0	899	8.1	7.0	93	6.8	130	28	7.5	9.2	287.5	307.0	288.7
900.0	1127	9.7	9.6	99	8.4	149	35	9.7	11.2	291.5	315.6	293.0
875.0	1361	9.6	9.5	99	8.6	163	40	9.6	11.1	293.8	318.6	295.3
850.0	1602	9.2	9.1	99	8.6	185	38	9.2	10.7	295.8	320.9	297.3
825.0	1849	7.7	7.4	98	7.9	203	29	7.6	9.1	296.7	320.0	298.1
800.0	2103	5.9	5.7	99	7.3	211	23	5.8	7.1	297.4	318.8	

By hour 57, it's 0.1c at the surface LOL :arrowhead:

 

 

 

By 60 hours, we see the nam with temps barely above freezing and dewpoints above freezing as well.

NAM Text Sounding | 06 UTC Mon 12 Jan 2015 | 
PRES	HGHT	TEMP	DWPT	RELH	MIXR	DRCT	SKNT	TWTB	TVRT	THTA	THTE	THTV
1002.0	228	0.7	0.1	96	3.9	37	3	0.5	1.3	273.7	284.3	274.3
1000.0	244	0.5	-0.0	96	3.8	42	3	0.3	1.2	273.7	284.2	274.3
975.0	446	-0.2	-0.5	98	3.8	71	12	-0.3	0.4	274.9	285.4	275.5
950.0	655	6.1	6.1	100	6.3	142	23	6.1	7.2	283.4	300.9	284.4
925.0	878	13.5	13.3	99	10.5	184	36	13.4	15.3	293.1	323.2	294.9
900.0	1109	12.3	12.1	99	10.0	201	34	12.2	14.0	294.1	322.8

There is very strong waa above 950mb so the temps will warm to above freezing even if we manage to drop below it. However, by the time it does so I think there could be some advisory/ nuisance level ice accumulation over north and parts of central ga/south carolina (eventually parts of nc) IF there is enough precip before going to all rain pretty quickly.

 

The  biggest negative against it, assuming  there is appreciable precip falling, is the depth or lack thereof of the near surface cold layer. Normally you want it to be at least 50mb deep  But as you can see, it only goes up to below 950mb. That is narrow enough that indeed temps might not drop as much as one would think because that is an awful deep warm layer that rain is falling through and there is no CAA. So the rain itself could be warm enough to keep temps from dropping below freezing, despite having subfreezing wetbulbs initially. Combined with latent heat release/no CAA, It certainly would mean it would rise above freezing fairly quickly if we manage to drop below it.

 

It should be noted though the gfs is much drier during this time frame and no where near cold enough.

 

At least it's something to watch for though, even if it doesn't amount to much.

I agree, I think there is a VERY small window that could make something very interesting around parts of GA.  Depends on when the precip arrives.. your right, the depth of the layer of cold is very shallow, but man, the NAM should do the BEST with this setup.  The 4KM shows the same thing, as you would expect.  I also agree with you that there is some potential IF** anything can reach the ground.  

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The EPS is impressive. Only two members doesn't show wintry precip at GSO and the mean is over 2.25" of "snow."

The mean at RDU is 1.8" while it's 1.3" in CLT.

 

If it shows that at tomorrow's 12z run, which will be right at day 5, it will be a miracle.  It's seems like the models have had a tough time getting things inside day 5 for other winter storms in east/central this winter.  Last week the clipper start trending south around day 5 was the latest example.  Plus, Euro has great skill at day 5.

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If it shows that at tomorrow's 12z run, which will be right at day 5, it will be a miracle.  It's seems like the models have had a tough time getting things inside day 5 for other winter storms in east/central this winter.  Last week the clipper start trending south around day 5 was the latest example.  Plus, Euro has great skill at day 5.

 

3-5 is wheel for euro, correct? Let's see a few runs beginning with 12z tomorrow.

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I agree, I think there is a VERY small window that could make something very interesting around parts of GA.  Depends on when the precip arrives.. your right, the depth of the layer of cold is very shallow, but man, the NAM should do the BEST with this setup.  The 4KM shows the same thing, as you would expect.  I also agree with you that there is some potential IF** anything can reach the ground.  

Anytime the train is running just to the south, with super cold on top of us, there's chances.  I love this pattern.  I hope it goes the rest of the winter :)  I've had several virga bursts, and like with smoke and fire, where there's virga, there's moisture, lol.  I think we'll get some ice, or something down here on the southside with that rain running under us like this.  Just need the wet part to move up a bit higher, and it will if the precip increases :) Just need that cold to erode slowly.  Tony

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