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Feb 25-26 Discussion/pbp


Wow

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Gradient is going to set up over I-20 in the ATL metro.. County on big numbers north side of the metro, little to nothing on the south side.

 

I've been told by more than a few people that they do not recall a snow/rain event where the gradient setup over downtown ATL like this, it usually sets up south of the airport between Macon or well north between the north perimeter and Rome...it makes you wonder if in the end one of those scenarios ultimately pans out and this jumps 50 miles either way of where it is now....the tendency is for those favored gradients to occur over and over, there can be exceptions but they are rare.

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Closed off (albeit barely) over C TN valid 0z 2/26.  That's the first time it's shown this.  Thus, the precip building back west.

 

18z GFS almost does it too!  .. and also finally starting to look like the rest of the models.  I think W NC is going to look better with qpf amounts as this ULL is better defined and stronger.

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I wouldn't Fishel bash too much just yet.  The NWS shares some of his concerns and they're pretty smart people.  Let's try not to weenie too hard.

 

I agree...If his forecast ends up being correct, you say that's why he's a professional meteorologist and I'm not... :D

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Just a heads up...the RPM model is usually horrible, it's just a marketing tool and I believe it just runs off the Hi-Res NAM with a few tweaks...those tweaks tend to make it bad. I would guess it is seeing the thickness the NAM is and not properly accounting for cooling. Either way moisture moves in by 7pm if by 10pm we're turning to snow we might loose an inch. I'm not worried. This is the best look we've had in a long time. There will be surprises, winners and losers. We won't know until it starts falling. If GA overperforms early then it's going to be good for us. 

Something that I always look at are recent trends. The last few storms have trended wetter and SFC temps have been cooler than models predicted even 24 hours out due to the cold air hanging around longer. That has to account for something here. I doubt many of us break 40 tomorrow. Just a non scientific guess. 

Ya, I think yalls area is ok...but, I have very HIGH concerns for GA.  The warming trend is enough to push that to at least N metro now.   not that it concerns me, I am going to need a boat!!

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You and your homeboy Fishel need to go pitch a tent together Wed night and take your little umbrellas with you too.

Seriously, I can't believe you'd listen to anything out of that clowns mouth, he's about as bad as DT but on the other side of the fence. WRAL should be sued for public endangerment, what a joke that station is.

 

That's funny that the guy said they were hesitant to post a WSW when there is one issued now. I think WRAL and WTVD is out to lunch on this idea it's going to be rain mostly. The NWS briefing said they are pretty confident in 2-4 in the Triangle.

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I've been told by more than a few people that they do not recall a snow/rain event where the gradient setup over downtown ATL like this, it usually sets up south of the airport between Macon or well north between the north perimeter and Rome...it makes you wonder if in the end one of those scenarios ultimately pans out and this jumps 50 miles either way of where it is now....the tendency is for those favored gradients to occur over and over, there can be exceptions but they are rare.

 

One exception I can think of is the March '09 event where the northern suburbs got nothing with 3"+ 10 miles south. I have a bad feeling that the northern metro will be right on the edge in this event given model trends...as much as we want to throw out the NAM/GFS/etc the closer we get to the evemt the more accurate the models will be.

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Great point. Today's event was different and shouldn't have a tremendous impact on the next storm. This one started as snow after full night of tremendous cooling. The next event will start at 9 PM after a full complement of late Feb sunshine in NC. Smart move for WRAL, not to jump on the bandwagon. Even if they have "egg on their faces" right now. They were pretty much right with this event. The main issue was that it occurred right around rush hour, and temps were COLD.

They were not right with this event. They said this developed last night and it was more than they thought, even though models were showing up to 2 inches of snow yesterday. And we have had snow for hours today. Even if the sun comes out tomorrow that doesn't mean it is going to be warm. This concern about the temps is out of proportion.

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That's funny that the guy said they were hesitant to post a WSW when there is one issued now. I think WRAL and WTVD is out to lunch on this idea it's going to be rain mostly. The NWS briefing said they are pretty confident in 2-4 in the Triangle.

Funny, they are looking at the same data. Its called educated opinions, experience, etc. Dont dismiss one or the other unless you have a foundation of experience that tells you to. Lighten up folks.

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That's funny that the guy said they were hesitant to post a WSW when there is one issued now. I think WRAL and WTVD is out to lunch on this idea it's going to be rain mostly. The NWS briefing said they are pretty confident in 2-4 in the Triangle.

RAH also said 6 for Raleigh. And all the mets outside the Triangle are calling for at least 6 in the Triangle.

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GFS is pretty warm at the surface, folks. The rain concerns for central and southern NC are not at all unreasonable.

 

Only storm I can remember with this much bust potential (and it did bust hard) was that ULL in Feb. of 2013. Had us under heavy snow warnings and it ended up being all rain for the most part with a little bit of sleet....but in that case the ULL just made a last second turn and ended up slamming parts of the MA and OV IRRC. So it went overhead and we never got the advantage of the dynamics. 

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Only storm I can remember with this much bust potential (and it did bust hard) was that ULL in Feb. of 2013. Had us under heavy snow warnings and it ended up being all rain for the most part with a little bit of sleet....but in that case the ULL just made a last second turn and ended up slamming parts of the MA and OV IRRC. So it went overhead and we never got the advantage of the dynamics.

Was that one of those isothermal storms? Those never work out.
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This was evident even yesterday with the thickness values being above 540 in some models. For example, the 540 lines is not even in NC at the height of the storm according to the NAM. My 5-7 snow accumulation was if it was all snow, but that is clearly not going to happen. Should have stuck with my inch or two forecast from 2 days ago lol

 

cld33.gif

 

the 540 lthickness line is

 

This was evident even yesterday with the thickness values being above 540 in some models. For example, the 540 lines is not even in NC at the height of the storm according to the NAM. My 5-7 snow accumulation was if it was all snow, but that is clearly not going to happen. Should have stuck with my inch or two forecast from 2 days ago lol

 

cld33.gif

 

The 540 thickness line is not as valuable in this part of the country as is 1000-850mb and 850-700mb thickness values

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Only storm I can remember with this much bust potential (and it did bust hard) was that ULL in Feb. of 2013. Had us under heavy snow warnings and it ended up being all rain for the most part with a little bit of sleet....but in that case the ULL just made a last second turn and ended up slamming parts of the MA and OV IRRC. So it went overhead and we never got the advantage of the dynamics. 

 

Burger, are you talking about the January 2013 ULL?

 

accum.20130117.gif

 

The majority of NC and probably upstate SC were under WSWs for that one, IIRC, but most places never changed over from rain until the very end, aside from the Triad area (where we got a heavy wet snowfall at 33-34 degrees that evening with like 5:1 ratios... knocked out power here, too.).

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RAH also said 6 for Raleigh. And all the mets outside the Triangle are calling for at least 6 in the Triangle.

 

Brick, Here was their language regarding the map that had the 4-6.

 

"This map shows a less likely, but a possible scenario if the amounts end up higher."

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WSW from GSP

 

Interesting... they changed accumulations from 3-5" (from this morning) to 3-7". 

 

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
AS OF 230 PM TUESDAY...THE MAIN FOCUS OF COURSE FOR THE SHORT TERM
IS THE IMPENDING WINTER EVENT WHICH BEGINS WED. AFTERNOON AND THEN
UNFOLDS ACROSS THE ENTIRE AREA WED NIGHT. THERE IS GOOD MODEL
CONSENSUS THAT THE SOUTHERN STREAM UPPER WAVE OVER THE 4 CORNERS
THIS MORNING WILL MOVE RAPIDLY EASTWARD AND INDUCE CYCLOGENESIS OVER
THE GOM EARLY WED. THE GULF LOW IS THEN FORECAST TO MOVE QUICKLY
EASTWARD ACROSS THE DEEP SOUTH WED NIGHT. THE MAIN CONCERN FOR THIS
FORECAST IS WHERE THE BEST BANDING WILL SET UP AND THE SUBSEQUENT
QPF RESPONSE.
ALSO FOR THE PIEDMONT AREA...THE QUESTION OF QUICKLY
THE BOUNDARY LAYER COOLS IS A BIG PLAYER IN SNOW ACCUMS. BASED ON
SURFACE WET BULBS...IT LOOKS INITIALLY ALONG AND SOUTH OF I-85
PRECIP WILL BEGIN AS RAIN WHICH WILL USE UP SOME QPF.

HENCE...SNOWFALL ACCUMS WILL FALL OFF TO THE SOUTH WITH THE
RAIN/SNOW LINE MOST LIKELY SETTING UP SOMEWHERE ACROSS THE SOUTHERN
FRINGS OF NE GA AND THE SOUTHERN UPSTATE...FROM ELBERT COUNTY GA
EAST THROUGH ABBEVILLE AND GREENWOOD COUNTIES. THE SREF PLUMES CATCH
THIS SCENARIO WITH THE HIGHEST TOTALS OUTSIDE THE MOUTAINS ALONG AND
NORTH OF I-85 WHERE 4-6 INCHES OF SNOW IS THE MEAN FORECAST. THE
PLUMES INDICATE THAT ACTUALLY THE SW MOUNTAINS MAY ACHIEVE THE MOST
SNOW OF 6-8 INCHES WHICH IS PLAUSIBLE BASED ON UPSLOPE. THE WPC WWD
PAINTS A SWATH OF 4-6 INCH SNOW FROM THE GA MOUNTAINS EASTWARD
THROUGH CLT.
HAVE FOLLOWED THIS GENERAL IDEA WITH SNOW GRIDS...
EXCEPT WENT HIGHER IN THE SW MOUNTAINS (6-8 INCHES SOME AREAS). 12Z
MODEL QPF HAS A LITTLE BETTER AGREEMENT WITH THE GFS NOW WETTER BUT
STILL NOT QUITE AS WET AS THE NAM. THE UPSHOT IS THAT CONFIDENCE IS
HIGHEST TO GO AHEAD AND PULL THE TRIGGER ON A WINTER STORM WARNING
FOR MOST OF THE AREA BEGINNING WED LATE AFTERNOON.
THE EXCEPTION IS
THE SOUTHERN TIER OF COUNTIES OF ELBERT...ABBEVILLE...GREENWOOD
WHERE WILL A WINTER STORM WATCH WILL BE MAINTAINED AS RAIN/SNOW LINE
WILL BE IN VICINITY.

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Burger, are you talking about the January 2013 ULL?

 

accum.20130117.gif

 

The majority of NC and probably upstate SC were under WSWs for that one, IIRC, but most places never changed over from rain until the very end, aside from the Triad area (where we got a heavy wet snowfall at 33-34 degrees that evening with like 5:1 ratios).

...and that 1" for Cary was a wet stretch.  Just a lot of big flakes with not much on the ground.

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Just a heads up...the RPM model is usually horrible, it's just a marketing tool and I believe it just runs off the Hi-Res NAM with a few tweaks...those tweaks tend to make it bad. I would guess it is seeing the thickness the NAM is and not properly accounting for cooling. Either way moisture moves in by 7pm if by 10pm we're turning to snow we might loose an inch. I'm not worried. This is the best look we've had in a long time. There will be surprises, winners and losers. We won't know until it starts falling. If GA overperforms early then it's going to be good for us. 

Something that I always look at are recent trends. The last few storms have trended wetter and SFC temps have been cooler than models predicted even 24 hours out due to the cold air hanging around longer. That has to account for something here. I doubt many of us break 40 tomorrow. Just a non scientific guess. 

 

That actually makes a lot of sense because the track Glenn Burns showed earlier definitely looked NAM-like.

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