3/6 - 3/7 Event is it this seasons last gasp?

[packbacker]

RGEM showing snow in western NC along with ice too, this is through 6z Friday.

http://meteocentre.com/models/get_accum.php?mod=gemreg&run=06&type=SN&hi=000&hf=048〈=en&map=na

[Hvward]

Looking back at the past nam runs, it has the freezing line never making past WV for this morning but here I sit in Asheville at 29 degrees.  Two or three degrees difference could be a big deal for my area.

[NCSNOW]

...A WINTRY MIX POSSIBLE...MAINLY OVER THE WESTERN PIEDMONT THURSDAY

NIGHT...

WEST COAST RIDGING WILL ALLOW A SHORTWAVE MOVING FROM THE ROCKIES

TOWARD THE SOUTHEAST US TO AMPLIFY OVER THE SOUTHEAST ON THURSDAY.

CYCLOGENESIS IS EXPECTED OVER THE EASTERN GOMEX BY THURSDAY

AFTERNOON...WITH A MILLER-A TYPE SURFACE LOW TRACK ALONG THE

CAROLINA COAST FRIDAY. UPPER DIFLUENCE AHEAD OF THE TROUGH WILL

OVERSPREAD THE REGION DURING THE THE DAY ON THURSDAY...THOUGH MODELS

KEEP DEEPER MOISTURE AND PRECIP JUST TO OUR SOUTH THROUGH

MIDDAY...REACHING THE SOUTHERN CWA BY MID-LATE AFTERNOON.

MEANWHILE...A CANADIAN SURFACE HIGH IS EXPECTED TO EXTEND DOWN THE

EASTERN SEABOARD INTO THE CAROLINAS. WHILE THE HIGH IS

PROGRESSIVE...THE HIGH DOES SHIFT INTO A FAVORABLE POSITION OVER NEW

ENGLAND LATE THURSDAY AND THURSDAY NIGHT. AS THE HIGH NOSES INTO

THE AREA...DEWPOINTS ARE FORECAST TO DROP INTO THE MID 20S IN THE

WESTERN PIEDMONT AND THE WETBULB FREEZING LINE PUSHES SOUTH TO THE

NC/SC BORDER. DURING THIS TIME...PARTIAL THICKNESSES ARE FORECAST

TO HOVER NEAR 1300/1550...WHICH SUGGESTS THERE MAY BE A FEW HOURS

OVERNIGHT WHERE A RAIN/SNOW MIX TRANSITIONING TO FREEZING RAIN WILL

BE POSSIBLE. FORECAST SOUNDINGS SUPPORT THIS...WITH A WARM NOSE AS

FAR WEST ARE THE TRIAD AND MORE PROMINENT THAN IN PAST MODEL RUNS.

WE EXPECT TO LOSE THE SUPPLY OF COLD AIR BY FRIDAY MORNING AS THE

HIGH SHIFTS EAST... AND FORECAST SOUNDINGS SHOW JUST ENOUGH RISE IN

SURFACE TEMPS TO MITIGATE ADDITIONAL ICING.

ONE OF THE BIGGER UNCERTAINTIES IS IN QPF. THE SURFACE LOW

TRACK...WHICH THE GFS AND ECMWF AGREE FAIRLY WELL ON BEING EAST OF

CHARLESTON FRIDAY MORNING...AND STRONGEST WARM ADVECTION/LOW-LEVEL

CONVERGENCE KEEP MOST OF THE PRECIP FOCUSED OVER EASTERN NC.

HOWEVER...MODELS HINT AT SOME MID-LEVEL FGEN BACK TO THE

WEST...WHERE MODELS HAVE VARIED TREMENDOUSLY WITH QPF FROM RUN TO

RUN...WITH THE LAST FEW RUNS OF THE ECMWF GOING FROM AROUND AN INCH

OVER WESTERN NC TO NEARLY NOTHING...BACK TO AN INCH AGAIN ON THE

MOST RECENT RUN.

THE BOTTOM LINE AT THIS POINT IS THAT WE ARE CONFIDENT THAT THE

WESTERN PIEDMONT HAS THE BEST CHANCE OF A WINTRY MIX...WITH LESSER

CHANCES CLOSER TO THE TRIANGLE AND POINTS EAST. MODELS HAVE TRENDED

TOWARD A BETTER CHANCE OF FREEZING RAIN...BUT CONFIDENCE IN THE

PREDOMINATE PRECIP TYPE AND POSSIBLE ACCUMULATIONS IS STILL LOW

GIVEN SOME OF THE SMALL DIFFERENCES IN THE SURFACE/850MB LOW TRACK

AND WESTERN EXTENT/STRENGTHEN OF THE WARM NOSE

[NCSNOW]

Amazing that now the NAM is closing off but there is just no cold air to work with. For me this one is pretty much cooked but the Euro was intriguing. If you could get the Euro temps with the NAM energy we would be in business.

We need a little more Northern Stream interaction IMO. This may be the limiting factor in keeping our temps up top (850's) just a smidge to warm. This is a perfect Miller A track with stout HP sitting in the prime spot. Can't believe someone isn't gonna get a heavy wet thump of snow as opposed to ice/cold rain the predominant ptype.

[GaWx]

Greenville,SC gets down to 31.5 on the GFS at 1am Friday morning during the heaviest precip.  It is also very close to a snow sounding as all levels are below freezing except it’s 1.5C at 850mb.

 

I just don’t know what to think with this system.  It’s hard to believe we won’t get freezing rain with one of the strongest CAD set ups I have ever seen on Thursday.  It’s a shame that precip is not moving in earlier.

 

 Yep, I have a lot of respect for this CAD, one of the strongest in early March in decades, and the threat for sig. ZR/IP is certainly there! The 6Z now has the high at 1042 mb as of 12Z on 3/6, the strongest yet! I still think there's too much rain vs. snow thinking here as this isn't typical early March setup!

[Hvward]

RGEM showing snow in western NC along with ice too, this is through 6z Friday.

http://meteocentre.com/models/get_accum.php?mod=gemreg&run=06&type=SN&hi=000&hf=048〈=en&map=na

 

Wow zooming in on that map on Americanwx it looks like 7" in downtown Asheville and 1" in Eastern Henderson Co.  What a crazy gradient.  

[mackerel_sky]

I know the wedge is strong, but the timing is very poor. If you have the wedge set up Thur.,but the precip does not arrive until Thursday night, you may lose half the precip waiting on the temps to wet bulb? The wedge may be stout , but so is the higher march sun angle.

[packbacker]

Wow zooming in on that map on Americanwx it looks like 7" in downtown Asheville and 1" in Eastern Henderson Co. What a crazy gradient.

RGEM does run a little warm but this is what I expect to happen, primarily west of 77 snow/sleet. Hopefully RGEM holds.

[tarheelwx]

Yep. Would really like to see the precip speed up and/or the hp slow down. One thing we should keep in mind is the tendency for models to move the hp out a little too quickly and to erode the wedge a bit too quickly.

TW

[burgertime]

RGEM showing snow in western NC along with ice too, this is through 6z Friday.

http://meteocentre.com/models/get_accum.php?mod=gemreg&run=06&type=SN&hi=000&hf=048〈=en&map=na

 

It must be struggling with the temp profiles. It shows ZR southeast and east of CLT...snow west of CLT and rain in CLT. 

[burgertime]

SREF looks like it came in colder with the wedge on the 9z run though it's still only cold enough verbatim in WNC. It has a 1032 high floating around which quickly scours out. 

[burgertime]

12z NAM has a 1036 high sitting in PA out to 21 hours. Noticeably colder at 850's in NC compared to the 6z run. I'm sure it will scoot that high out as soon as it's go time but another little step. 

[Tacoma]

We need a little more Northern Stream interaction IMO. This may be the limiting factor in keeping our temps up top (850's) just a smidge to warm. This is a perfect Miller A track with stout HP sitting in the prime spot. Can't believe someone isn't gonna get a heavy wet thump of snow as opposed to ice/cold rain the predominant ptype.

I'm with you on someone getting a heavy snow on the northwest side of the storm.  I would think mtns. and foothills would have a good chance but boy GSP won't bite yet.  

[HurricaneTracker]

I'm with you on someone getting a heavy snow on the northwest side of the storm.  I would think mtns. and foothills would have a good chance but boy GSP won't bite yet.  

 

That's because there's nothing to "bite" at.  The GFS shows just about no precip, while the NAM shows 1-2" of liquid equivalent, and the Euro is somewhere inbetween.  There's no consistency between the models or their individual runs.

 

That being said, the 850 temps are very warm (+3 to +5), so snow should not be the predominant ptype in AVL.  It looks like a case of freezing rain transitioning to all rain.  It appears the cold pool with the H5 low just isn't that potent to cool the whole column for a big snow event.

 

So I definitely see this as a ZR event for the mountains, little to no snow, and eventually all rain.

[burgertime]

Would love to know how we have a 1040 high staying longer on the 12z NAM in NY....yet somehow it's warmer at the surface than the 6z which ships it off. 

[deltadog03]

wedge pretty stout...mid to upper 30's for NGA and CGA by 18z thur

[Tacoma]

That's because there's nothing to "bite" at.  The GFS shows just about no precip, while the NAM shows 1-2" of liquid equivalent, and the Euro is somewhere inbetween.  There's no consistency between the models or their individual runs.

 

That being said, the 850 temps are very warm (+3 to +5), so snow should not be the predominant ptype in AVL.  It looks like a case of freezing rain transitioning to all rain.  It appears the cold pool with the H5 low just isn't that potent to cool the whole column for a big snow event.

 

So I definitely see this as a ZR event for the mountains, little to no snow, and eventually all rain.

you would think a perfect set-up even with the 1040 HP up north.  so what gives on the cold air at least at the start of the event.  you also have a snow pack just north of us, so I guess I don't quite understand this setup it looks perfect on the track and there is some cold air to the north. 

[HurricaneTracker]

you would think a perfect set-up even with the 1040 HP up north.  so what gives on the cold air at least at the start of the event.  you also have a snow pack just north of us, so I guess I don't quite understand this setup it looks perfect on the track and there is some cold air to the north. 

 

Yes, this is all true, but the arctic air is incredibly shallow this time.  So surface temperatures reflect a CAD but the mid- and upper-levels do not (at least on Euro/GFS).  The NAM solution is tempting to buy into, but it's the NAM and has proven to be garbage beyond 12 hours out, as we have seen and documented many times this winter.

[burgertime]

Yes, this is all true, but the arctic air is incredibly shallow this time.  So surface temperatures reflect a CAD but the mid- and upper-levels do not (at least on Euro/GFS).  The NAM solution is tempting to buy into, but it's the NAM and has proven to be garbage beyond 12 hours out, as we have seen and documented many times this winter.

 

At least this go round the NAM is showing some cold air associated with the ULL although it's a very tiny amount....but yes the NAM has been hot garbage lately. 

[burgertime]

Finally the NAM is giving that ULL a cold core @51. If the NAM can somehow be right about this then it's game on. 

[deltadog03]

it really sucks that we have a very nice looking upper low and we be stuck in the mid 30's at 2m.  NAM now has an area of below 0c at 850, but back over AL through hour 48.

[burgertime]

it really sucks that we have a very nice looking upper low and we be stuck in the mid 30's at 2m.  NAM now has an area of below 0c at 850, but back over AL through hour 48.

 

This my reaction to this run of the NAM...it was a baby step in the right direction but it's temp profiles at the SFC were just confusing 

[Cold Rain]

All of the guidance is showing pretty much above freezing surface temps for the bulk of the event.  Looking at the upper level and surface features, that makes sense to me.  Is there any meteorological reason at this point to expect a big winter storm hit outside maybe the mountains?  I don't mean a little brief rain/snow mix, a few sleet pellets, or a spot of freezing rain at the onset.

 

Is there any meteorological reason that a big area outside the mountains will see any significant winter weather out of this, the way the features are forecast, by virtually all of the models, to evolve?

[burgertime]

All of the guidance is showing pretty much above freezing surface temps for the bulk of the event.  Looking at the upper level and surface features, that makes sense to me.  Is there any meteorological reason at this point to expect a big winter storm hit outside maybe the mountains?  I don't mean a little brief rain/snow mix, a few sleet pellets, or a spot of freezing rain at the onset.

 

Is there any meteorological reason that a big area outside the mountains will see any significant winter weather out of this, the way the features are forecast, by virtually all of the models, to evolve?

 

The only thing I am hoping on...and it's about 5% hope is that the ULL can keep getting stronger. If it does then it should have enough dynamic energy to cool the column. You can see on the Hi-Res NAM at 850 is' making it a two contour closed low and 850's are crashing on the backside of it. What confuses me about the SFC temps is how the CAD is not stronger especially when a 1040 high is sitting in NY for longer than the 6z had yet it's somehow warmer? Granted it's not around when we need it but still you would think if we can get a good wedge entrenched early that could help down the line. 

[tarheelwx]

All of the guidance is showing pretty much above freezing surface temps for the bulk of the event. Looking at the upper level and surface features, that makes sense to me. Is there any meteorological reason at this point to expect a big winter storm hit outside maybe the mountains? I don't mean a little brief rain/snow mix, a few sleet pellets, or a spot of freezing rain at the onset.

Is there any meteorological reason that a big area outside the mountains will see any significant winter weather out of this, the way the features are forecast, by virtually all of the models, to evolve?

I think it is entirely possible that the cad regions of nc get warning criteria zr Thursday night/ early Friday morning before going over to plain rain. Also, is that lp around hr 48 on the Wisconsin/Canada border what's shoving our hp off the coast?

TW

[packfan98]

12z 4k nam gives Greensboro .67 inches of freezing rain.  Yuck!

[calculus1]

As always, Robert has a good writeup on the upcoming system.  It's hot off the presses, but you need a membership to read it.  Generally speaking, he still believes that wintry precipitation is a possibility for the western parts of NC and northward.

[Cold Rain]

I think it is entirely possible that the cad regions of nc get warning criteria zr Thursday night/ early Friday morning before going over to plain rain. Also, is that lp around hr 48 on the Wisconsin/Canada border what's shoving our hp off the coast?

TW

 

 

Behind the shortwave moving northeast through Maine is where the best convergence is, which is where the high pressure is located.  That sw is moving rapidly north east, not slowly east.  Slowly east would keep the convergence zone in the NE US longer and thus keep high pressure anchored in a favorable position longer.  The next wave coming in, helps kick the initial one out, not to mention that it ultimately kills the convergence.  The fast flow means high pressure is transitory as opposed to stationary.

 

Last week, a few models were showing the initial wave being very strong and heading due east slowly, as opposed to quickly northeast.  If I recall, there was just enough -NAO ridging to allow this to happen.  But I noted that time and again this season, we've seen those waves translate more northeast than east and do so more quickly.  And if that were to happen this time, we'd get a situation where high pressure moves out and is weaker than was modeled.

 

And here we are.  High pressure is not going to be as strong as was modeled, and it's moving out more quickly than was modeled.  And the fact that the storm is now coming in a bit later is a bigger deal.  Had it moved in earier (or if it does move in earlier, I should say), there would be much more chance of a more widespread winter storm.  As it stands now, we're all in, hoping for an inside straight on the River.

[Cold Rain]

The only thing I am hoping on...and it's about 5% hope is that the ULL can keep getting stronger. If it does then it should have enough dynamic energy to cool the column. You can see on the Hi-Res NAM at 850 is' making it a two contour closed low and 850's are crashing on the backside of it. What confuses me about the SFC temps is how the CAD is not stronger especially when a 1040 high is sitting in NY for longer than the 6z had yet it's somehow warmer? Granted it's not around when we need it but still you would think if we can get a good wedge entrenched early that could help down the line. 

 

I made a post about this.  Then I looked at the board again, and it showed my post twice.  I deleted one of them and both went away.   Anyway, the gist was, I guess we have to hope that the ULL is significantly undermodeled at this point.  But we're running out of time and need to see some big changes with it in a hurry.

[tarheelwx]

I've given up on the ull. Just hoping precip is a bit quicker and hp holds a little longer for good zr in the triad.

TW