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WidreMann told us it was gonna snow thread

LithiaWx

By LithiaWx,
in Southeastern States

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LithiaWx

LithiaWx

Posted
Posted

Actually, we a working toward a (hybrid) 4D-Ensemble-Var system (not exactly the same as 4DVAR, since it uses a 4D ensemble in stead of linearized model and its adjoint in the minimization process). Lack of resources (computing AND manpower) is a huge issue (I think there are other threads on this and I have made various comments/replies along the way).

The 4D-ensemble-var type development is something also being embraced/pursued by the Canadians and UKMet Office.

I am feeling the mojo. There is lots of time left to go but I feel a one stop shop for discussion is appropriate at this time.

Monday February 11th 18Z GFS Run

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Jon

Jon

Posted
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Ah, the 18z...glad to have you. I'll go ahead and assume this solution will be gone come the 0z run, but it's fun to look at that's for sure. 18z Ensembles are rolling, it will be interesting to see the individual members and see what the 0z run says.

 

Looks like the high pressure keeps this baby suppressed longer, 1026mb over great lakes/NY....slightly colder into the gulf, 18z bombs but way off the coast because of it. I want to say this is best case unless the low gets stronger earlier with the gulf tap....like at hour 126 say that's 1004mb instead of 1008 over SC that thing would dig off the coast in that setup.

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pcbjr

pcbjr

Posted
Posted

Tallahassee NWS sums it up pretty well:

 

.LONG TERM [Thursday through Monday]...Quieter weather arrives with surface high pressure and increasingsubsidence in the wake of the cold front on Thursday and Friday.An amplifying longwave trough in the eastern CONUS on the weekendmay provide a shot of colder air, although details still vary frommodel-to-model, and run-to-run.
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burgertime

burgertime

Posted
Posted

since its all from the norther stream the energy is out over the n Pacific where there is very limited data. Thats why we keep seeing the run to run changes

 

We probably will not know anything concrete until Thursday night as it's diving down. That being said I'm sure if the models keep showing this solution than they will send a recon flight in probably Tues night or Wed. night. 

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NCSNOW

NCSNOW

Posted
Posted

Good call Marietta. It'S not like we got anything to loose. Will this be when the rubberband snaps. Pattern has been crap for 2 straight years since Feb 2011 winter weather wise for the SE. The only exception being the MTNS / east TN where IMO it's been coming back around to normal the past few weeks. I have to admit I'd be shocked if the GFS having MBY in the bullseye 5 days out verified.

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GaWx

GaWx

Posted
Posted

 For the ATL-AHN corridor based on longterm (130+ years that I've researched) climo, this (no Gulf low) is the type of setup that typically results in less than 1" of accumulation and often only a fraction of an inch to a dusting due to it being too dry at lower levels despite a decent (moist WSW flow) look at 500 mb. Besides the lack of low level Gulf moisture, there tends to be a bit of a shadowing effect from the mountains to our N and W at the lower levels. In the extreme scenario, this area could get as much as a widespread ~1-2" in this non-Gulf low mainly upper level type of setup. The Lincoln's Birthday event of Feb. 1985 is an example of an extreme event of this kind in that it was caused by a very strong (530 dm) closed low that traversed just to our north and produced a pretty widespread ~1.5".

 

  Keep in mind that based on data back to 1890, the ATL median total seasonal S/IP is only ~1" (mean is ~2"). So, assuming this doesn't produce a Miller A GOM sfc low, I'd certainly consider getting our total seasonal median (~1") in the ATL-AHN corridor from just this one event from a far from ideal setup a significant victory. Even ~0.5" would be very nice to see. Assuming no classic Miller A, expectations need to be kept reasonable so as to avoid a high likelihood of disappointment imo. The odds of getting, say, a widespread 2-3"+ in the ATL-AHN corridor are quite low as long as the Miller A scenario doesn't occur. N GA is not NC, which usually does a good bit better in these situations. Don't let the models that show 2-4"+ of snow there lead to false expectations at ATL/AHN. The 18Z GFS giving much of NC much more than ATL-AHN is no accident. NC getting much more would be very likely with no Miller A.

 

 In summary, assuming there is even going to be sticking snow (still very iffy, of course), the most likely amount for ATL-AHN based on climo for these types of systems (mainly upper level based with no Miller A GOM low) would be less than 1". If the upper levels get really favorable (strong closed upper low like Feb. 1985 but still no Miller A), then we could reasonably hope for ~1-2". Now, in the unlikely event of a classic Miller A GOM low forming, only then can a widespread major snow (say 3.5"+) be considered a reasonable possibility. The important thing is that we have a shot at getting something this weekend here in ATL-AHN. Keeping expectations in check may be vital to both prevent disappointment and allow for the greatest chance for satisfaction. Personally, I haven't seen a single flake fall since 3/2010! So, just seeing some fall would be very nice to see. Any accumulation would be a bonus to me.

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RaleighWx

RaleighWx

Posted
Posted

Personally I didn't like the looks of the 18z ensemble mean run.  Imo it had a very 12z euro look.  By all means I hope I'm wrong.

 

It actually looks good in the 120-144 time frame. Click through the hours. Of the 11 non op graphics (top left) I count 3 that are essentially non-events, and quite a few that are big dogs.

 

http://raleighwx.americanwx.com/models/gfsensemble/members/18zf120.html

 

As you can see from the 72 hour precip at 144, many are pretty moist

http://raleighwx.americanwx.com/models/gfsensemble/members/18zp72f144.html

 

And quite a few have a good snow event for the upper SE.

 

http://raleighwx.americanwx.com/models/gfsensemble/members/18zsnowf144.html

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rduwx

rduwx

Posted
Posted

It actually looks good in the 120-144 time frame. Click through the hours. Of the 11 non op graphics (top left) I count 3 that are essentially non-events, and quite a few that are big dogs.

 

http://raleighwx.americanwx.com/models/gfsensemble/members/18zf120.html

 

As you can see from the 72 hour precip at 144, many are pretty moist

http://raleighwx.americanwx.com/models/gfsensemble/members/18zp72f144.html

 

And quite a few have a good snow event for the upper SE.

 

http://raleighwx.americanwx.com/models/gfsensemble/members/18zsnowf144.html

 

 

Thanks Allan!  Honestly I just looked at the loop of the mean on SV.  Looking through the links you provided look better.

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Jon

Jon

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It actually looks good in the 120-144 time frame. Click through the hours. Of the 11 non op graphics (top left) I count 3 that are essentially non-events, and quite a few that are big dogs.

 

http://raleighwx.americanwx.com/models/gfsensemble/members/18zf120.html

 

As you can see from the 72 hour precip at 144, many are pretty moist

http://raleighwx.americanwx.com/models/gfsensemble/members/18zp72f144.html

 

And quite a few have a good snow event for the upper SE.

 

http://raleighwx.americanwx.com/models/gfsensemble/members/18zsnowf144.html

I agree Allan. This looks about as good as you can get this far out and with the 18z, this thing shouldn't be tossed given the ensemble members. Though I like member 10 it has about a 1% chance of verifying, 0c line almost to cuba...one can dream though.

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GaWx

GaWx

Posted
Posted

It actually looks good in the 120-144 time frame. Click through the hours. Of the 11 non op graphics (top left) I count 3 that are essentially non-events, and quite a few that are big dogs.

 

http://raleighwx.americanwx.com/models/gfsensemble/members/18zf120.html

 

As you can see from the 72 hour precip at 144, many are pretty moist

http://raleighwx.americanwx.com/models/gfsensemble/members/18zp72f144.html

 

And quite a few have a good snow event for the upper SE.

 

http://raleighwx.americanwx.com/models/gfsensemble/members/18zsnowf144.html

 

I'm curious. Is there any semblance of a GOM sfc low from members P08 and P10? Why is the precip. so sig. for these two members?

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WeatherNC

WeatherNC

Posted
Posted

This is probably our best look inside day 5 for a larger scale event this winter. Funny how Friday night everyone was excited about the 0z's, then over the weekend we were all worried about the cold and lack of moisture. Now it would appear we may have a surface wave developing and riding up the artic front. Cold seems like an almost lock at this point, storm not so much. Scenarios where we are dependent on a phase always show the greatest variability in solutions. One could argue against this point, but we are going to have to rely on energy phasing into the trough as it moves east, like the GFS is showing around 114 over IA/IL, this shaperns and tilts it. Pin pointing where and if this takes place at 5 days out is impossible, hence varying solutions from the Apps to half way to Bermuda.

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WeatherNC

WeatherNC

Posted
Posted
I'm curious. Is there any semblance of a GOM sfc low from members P08 and P10? Why is the precip. so sig. for these two members?

Not that I can tell, a weak disturbance moving through the northern Gulf Coast, interacts with an area of lp off the EC of Florida, development starts off the SE coast, crazy panels though, I have seen a few members doing this for the last couple days, they basically occlude the low in to the negatively tilting trough. Low gets captured for a period and is pulled back towards the coast, hence the higher qpf output.

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dsaur

dsaur

Posted
Posted

My gut has said all along a low would form given all the activity in the stream this week, and leaving some sagging down in Fla. as the rain train departs...so I'm not surprised to see the 18 trying to form something up.  YOu need that cold energy though, and I think that's the big key here, not the maybe rain.  If the cold actually shows up, then I think something else will respond to that boundry of cold.  If the big two both show cold still, come Wed., then I'll be feeling good about a gom low. Heck, things are juiced up down here.  I've picked up another .6 since about 5, giving me 2.85 in 24 hours.  Add to that the .95 from a few days back..and, tonights rain has only just commenced.  I haven't been seeing this kind of rain in a system, much less a string of systems, for years.  Usually Tenn. is getting this, and we get a tenth.  But not this winter.  T

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