Jan 25th Winter Weather Discussion Thread

[GaWx]

 Unless model guidance changes significantly before Friday, which is getting more doubtful now, and considering the lack of moist 500 mb flow, I'm going with a few hours of a light glaze for much of the ATL-AHN areas, especially northern burbs where the higher moisture is showing on the models. I'm thinking 0.01"-0.10" of liquid precip. falling during the CAD, itself, and leaning toward the lower side of this for most. This could certainly cause some roads and especially bridges to become very slippery for a couple of hours. I don't know if any ZR will get down as far south as the ATL airport due to a modeled lack of precip. while it is still cold.

[SnowGoose69]

My opinion, but I see this as a trap that some (myself included) fall into...when we get into the range of the higher resolution, short term models (throw the NAM in that bucket), they always seem to be amped up and end up overdoing the precip. I've seen that a lot over the years. Maybe folks have seen them pan out, but I really haven't.

I don't know, would be curious as to what others think.

 

Overrunning events are tricky, they tend to be the one scenario where models underdo the precipitation but its tough to tell which ones are going to be the ones where thats the case.  I find usually you want to look for either an area where you see high 700mb RHs but no precip being generated to know the spot thats going to surprise you with alot of stuff breaking out thats not forecast.  Also you want to see tight packing of the 700mb height lines here too.

[tnweathernut]

Overrunning events are tricky, they tend to be the one scenario where models underdo the precipitation but its tough to tell which ones are going to be the ones where thats the case. I find usually you want to look for either an area where you see high 700mb RHs but no precip being generated to know the spot thats going to surprise you with alot of stuff breaking out thats not forecast. Also you want to see tight packing of the 700mb height lines here too.

I agree. A lot of times with an overrunning situation I have noticed precip will break out ahead of where modeling depicts it, causing an earlier onset of hazardous conditions than anticipated.

[Shawn]

00z RGEM, NAM, GFS, Hi-Res NAM have all let go of anything to note Wintry for CAE now.  The darned 21 SREF won't budge though, it may have been getting progressively more impressive.

 

Barring something amazing, I no longer need to update this thread for fellow CAE readers.  Expect wintry weather to be removed from the forecast/greatly reduced and temps increased soon from KCAE.

[Buddy1987]

Hey guys if it makes anybody feel better here is the model initialization from HPC

 

...TROF ENERGY AMPLIFYING ACRS THE UPR MIDWEST BY EARLY
FRI/ASSOCIATED SFC LOW...
...COASTAL CYCLOGENESIS OFFSHORE THE DELMARVA ON FRI NIGHT...

PRELIMINARY PREFERENCE/FCST CONFIDENCE: MODEL BLEND OF THE 00Z
NAM/12Z ECMWF (MEDIUM CONFIDENCE)

A SYSTEM ORIGINATING FROM THE WA/BC BORDER IS EXPECTED TO QUICKLY
TRACK EWRD REACHING THE SRN MANITOBA BY ROUGHLY 24 TO 30 HRS FROM
NOW. ACCOMPANYING THIS UPR TROF WILL BE A GENERAL AREA OF LOW
PRESSURE WITH ONLY MODEST STRENGTHENING EXPECTED BY FRI MORNING.
IT IS THEN FCST TO NOSE S AND E IN RESPONDING TO AN UPR LOW
DROPPING DOWN FROM HUDSON BAY. THEREAFTER...IT APPEARS THE 00Z NAM
HAS REVERTED BACK TO THE 12Z VERSION WITH THE STRENGTH OF THE UPR
TROF WHEN CROSSING THE MID-ATLC LATE FRI. ON THE OTHER HAND...THE
00Z GFS HAS CONTINUED ITS TREND OF BEING MORE SUPPRESSED WITH HGT
FALLS SPREADING TOWARD THE EAST COAST. COASTAL CYCLOGENESIS IS
FCST TO TAKE PLACE OFFSHORE OF SRN VA BY 26/0600Z WITH THE 00Z NAM
TRENDING STRONGER AND A BIT FURTHER W WHILE FLATTER GFS HAS
SHIFTED WEAKER AND MORE TOWARD THE E. RELATIVE TO OTHER
GUIDANCE...THE NCEP MODELS SEEM TO BE THE STRONGEST WITH THE
INITIAL WAVE CROSSING INTO THE UPR GRT LAKES. LATER ON...THE 12Z
UKMET IS ON THE SLOWER SIDE WITH THE TROF AXIS CROSSING THE EAST
COAST WHILE THE 00Z GFS IS NOW FLATTER THAN ANY OTHER PIECE OF
GUIDANCE. SPREAD AT THE SFC SEEMS TO INC IN TIME BY 26/1200Z AS
THE WAVE STRENGTHENS WHILE EXITING TOWARD THE CANADIAN MARITIMES.
AT THIS PT...THE GFS/UKMET SOLNS WILL BE RULED OUT AS THEY DIFFER
FROM THE MORE STABLE ENS MEANS. GENERAL AGREEMENT BETWEEN THE 00Z
NAM/12Z ECMWF WILL MAINTAIN THIS COMBO AS A FCST BLEND.

 

[Jon]

00z Euro much drier for majority of areas, especially in NC where the precip was sliced by 50% in central NC including the foothills and Piedmont, even coastal regions. Much of SC has no moisture at all this run.

[GaWx]

Folks,

 A look at MeteoStar output shows that ~0.02" of  ZR is actually being generated by the 0Z THU GFS at the Atlanta airport between 9 and 11 AM on FRI 1/25 with the temp. as low as 31 F. This is the first GFS run generating any measurable ZR there since the 6 Z run of Wed. Intuitively, it is back because of an earlier start to the precip.

 The 0Z THU GFS gives Marietta ~0.07" of ZR with the temp. as low as 29 F. This is a very slight uptick from the two prior runs, which had 0.04-0.06", but is still well below the 0.20-0.25" of the three runs before those two.

 This confirms to me that there is a risk of very slippery travel for a couple of hours in some spots, especially bridges and elevated roadways, in the Atlanta area on Friday due to a thin glaze.

 

 ***Edit: The 0Z GFS, which has a cold bias, is currently 6 F too cold at KATL and 5 F too cold at Marietta as of 2 AM. I've been assuming that with a fresh cold airmass and CAD that the GFS' cold bias is not making it too cold during the CAD on Friday. However, should the cold bias happen to be playing tricks, then it is possible that no ZR may occur even with the light precip. Right now, I'm not expecting that but I'm aware it is possible with only very light precip.

[Bozart]

00z Euro much drier for majority of areas, especially in NC where the precip was sliced by 50% in central NC including the foothills and Piedmont, even coastal regions. Much of SC has no moisture at all this run.

 

Then for the moment, WidreMann rulz, as he very often does.

 

Note to the person who asked: that's how we put up with him.

[DixieBlizzard]

Then for the moment, WidreMann rulz, as he very often does.

 

Note to the person who asked: that's how we put up with him.

 

Betting against winter weather in the south is often a good bet.

[Shawn]

I've got this kid msging me saying "it still says .04 ZR!" getting all upset because I said CAE is outta the threat per new models.  Let me be real.  0.04 of ice won't cause any issues what so ever even on slick tires if you follow speed limits.  0.10+ would though.  Don't forget, we haven't been as cold as areas further North.

 

Disclaimer:  Don't take this literally.  Just 0.04 is very little if it would even be able to stay frozen more than an hour.

[SN_Lover]

for charlotte: 

yes everyone the models are showing .0X amount of precip. does that mean ALL of that will make it to the ground? No. We are dealing with a arctic air-mass with VERY dry air. It will take TIME for the column to saturate and by the time it does, the precip might already be gone. 

[dsaur]

Folks,

 A look at MeteoStar output shows that ~0.02" of  ZR is actually being generated by the 0Z THU GFS at the Atlanta airport between 9 and 11 AM on FRI 1/25 with the temp. as low as 31 F. This is the first GFS run generating any measurable ZR there since the 6 Z run of Wed. Intuitively, it is back because of an earlier start to the precip.

 The 0Z THU GFS gives Marietta ~0.07" of ZR with the temp. as low as 29 F. This is a very slight uptick from the two prior runs, which had 0.04-0.06", but is still well below the 0.20-0.25" of the three runs before those two.

 This confirms to me that there is a risk of very slippery travel for a couple of hours in some spots, especially bridges and elevated roadways, in the Atlanta area on Friday due to a thin glaze.

 

 ***Edit: The 0Z GFS, which has a cold bias, is currently 6 F too warm at KATL and 5 F too warm at Marietta as of 2 AM. I've been assuming that with a fresh cold airmass and CAD that the GFS' cold bias is not making it too cold during the CAD on Friday. However, should the cold bias happen to be playing tricks, then it is possible that no ZR may occur even with the light precip. Right now, I'm not expecting that but I'm aware it is possible with only very light precip.

I've picked up .02 on the 0z over the 18, and, .02 when the temps are in the range. Not holding my breath for zrain though,  even if it was only .25, or .5.  The trees sure need a half inch of ice to shred them out some, but I can will myself to wait further, lol.   T

[Bozart]

Betting against winter weather in the south is often a good bet.

 

He did more than that. He presented reasons. People can disagree with his reasoning, but if he turns out to be right, their disagreement doesn't really make any difference, does it?

 

Wishcasting makes some of us lurkers break out in hives. It isn't what we come here for.

 

I also agree with arwx: ATL and CAE are boring to tears. If I cared one bit less about .03" of IP falling down there, I'd turn into a black hole.

[dsaur]

Dang, man, we are sure sorry to clutter up you important thread   We are so appreciative you let us come in here.  Wow, can you tell us when it's ok to say something?  We figured late at night you folks wouldn't mind sharing a little band width.  Please, please accept this humble apology for us boring you so.  I hope it isn't too painful, lol.  T

[Bozart]

Dang, man, we are sure sorry to clutter up you important thread   We are so appreciative you let us come in here.  Wow, can you tell us when it's ok to say something?  We figured late at night you folks wouldn't mind sharing a little band width.  Please, please accept this humble apology for us boring you so.  I hope it isn't too painful, lol.  T

 

-lol-

I reckon at 3 a.m. a certain amount of griping and moaning is acceptable from anyone. I was really just hoping I could get one of you ladies to expound on how stupid and insufferable you think the nearly always correct WidreMann is!

[lilj4425]

We must wait on Brick Tamland first dsaur. 2:55am isn't late. It's early. You can now delete my post buckeye fan.

kind of annoying that random places like ATL and CAE keep gettign mentioned (especially ATL) where they are going to receive barely anything more than a slight glaze tht wil barely affect traffic...what about AVL, GSO, ROA, RDU, CLT and FAY? cities that are actually in the firing line?

I believe in Harvey Dent.

[dsaur]

-lol-

I reckon at 3 a.m. a certain amount of griping and moaning is acceptable from anyone. I was really just hoping I could get one of you ladies to expound on how stupid and insufferable you think the nearly always correct WidreMann is!

Hell, I'm still trying to figure out how you can ignore all the innumerable posts from Wilks and Brick, and hone right in on me and Michelle, lol.    T

[valkhorn]

Two things:

1) How did RGEM do with the last event?

2) You have to ask yourself what would result in significant precip for this area. You can't just look at precip maps verbatim. Is there flow from the gulf? Is there a strong low? No. There's very little to generate precipitation except some upper level energy that will squeeze every last drop out of the atmosphere, but there aren't many drops to start with. So be skeptical of models that generate significant precip.

They were right in the last storm for East TN. Sorry you lost in that one. Enjoy your margins of betting the safe bet.

[LovingGulfLows]

People are really wishing for a large ice storm to happen in Atlanta? Seriously? I'm all for snow and even some sleet, but ice is too dangerous in a large metro like this. Lives will be lost if there is a huge ice event. It also causes major traffic issues. I'm glad we are modeled too not get much. Not everyone here is hoping for work and school off in exchange for dangerous conditions.

[valkhorn]

-lol-

I reckon at 3 a.m. a certain amount of griping and moaning is acceptable from anyone. I was really just hoping I could get one of you ladies to expound on how stupid and insufferable you think the nearly always correct WidreMann is!

It's like betting for heat in the desert. He's never around when he's wrong, and it does happen.

[valkhorn]

People are really wishing for a large ice storm to happen in Atlanta? Seriously? I'm all for snow and even some sleet, but ice is too dangerous in a large metro like this. Lives will be lost if there is a huge ice event. It also causes major traffic issues. I'm glad we are modeled too not get much. Not everyone here is hoping for work and school off in exchange for dangerous conditions.

It wont be pretty in Knoxville if we get an inch of snow then ice on top. The last storm snarled everything up, and I had to straighten out a tree.

[lilj4425]

It's like betting for heat in the desert. He's never around when he's wrong, and it does happen.

It can get cold at night in the desert.

[Buddy1987]

Well the NAM continues to show a nice precipitation maxima over the same areas as the oz did with .50 QPF extending from KY,TN and heading into southern VA on the 36 hr map. Hope it is right. The GFS and EURO really squashed hopes for Friday but the NAM seems to like to pull some tricks

[Bozart]

It can get cold at night in the desert.

And it can snow in the desert. It wish it snowed in the Southeast as regularly!

 

Well, all this exhaustive play-by-play of the 00Z Euro has made me sleepy. Good night, everyone!

[Buddy1987]

Out to 42 hrs, it has a nice swath of precip (.25) extending from central PA through MD, DC and down to SC

[Buddy1987]

Keeps the vort practically in the same spot on the 0z with it traveling down through WV and swinging out through central VA

[Poimen]

6Z GFS came in even drier than previous runs. This event is quickly becoming a non-starter for me. However, RAH says "low precipitation and high impact" still possible.

[FallsLake]

Maybe not that bad; if you look at the 72 hours total, it still puts our area in the >.25 range:

 

[DaculaWeather]

kind of annoying that random places like ATL and CAE keep gettign mentioned (especially ATL) where they are going to receive barely anything more than a slight glaze tht wil barely affect traffic...what about AVL, GSO, ROA, RDU, CLT and FAY? cities that are actually in the firing line?

You know what? Screw you. What a pissy, little child comment. Go start your own thread if you don't like it. There are PLENTY of NC posters here, if they had something to say, they would say it. You on the other hand need to close your mouth and read more.  Can't believe the mods let your stupid post stay up over night. 

 

Random place? We have more than 5-6 million people that would be affected by this. Random place?

[Poimen]

Maybe not that bad; if you look at the 72 hours total, it still puts our area in the >.25 range:

 

 

one of us has the wrong map. The qpf map I see from the 6Z GFS has most of central NC, including us, in the .01-.10 qpf...with only .10 amounts east toward the coast.