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February Mid/long Range Winter Discussion


TARHEELPROGRAMMER

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FFC is growing confidence in a winter storm next week.

SUNDAY AND MONDAY...CONFIDENCE IS INCREASING THAT A WINTRY EVENT

WILL UNFOLD ACROSS THE SOUTHEASTERN STATES DURING THIS TIMEFRAME.

THE BASIS IS THE STRONG ARCTIC SURFACE RIDGE WHICH SLIDES INTO THE

OHIO VALLEY WHICH ALL OF THE EXTENDED MODELS AND EVEN THE

ENSEMBLE MEMBERS ARE PROGGING. BOTH THE GFS...ECMWF AND THEIR

MEMBERS ARE PROGGING A STRONG CAD EVENT SETTING UP LATE SUNDAY

INTO MONDAY AS STRONG SHORT WAVE DIVES SOUTHEAST ON THE BACKSIDE

OF THE LONG WAVE TROF AND TAPPING A BIT OF GULF MOISTURE. THE

BIGGEST QUESTION AND LOWEST CONFIDENCE EXISTS IN DETERMINING ANY

PRECIPITATION TYPE AT THIS POINT WHICH COULD RANGE EVERYTHING FROM

AN ALL VERY COLD RAIN TO FREEZING RAIN TO SNOW AND SLEET...WHICH

ALL DEPENDS ON THE TIMING...DEPTH OF THE COLD AIR...AND THE WARM

NOSE. NONETHELESS. FOR NOW...LEFT EVERYTHING IN THE FORECAST AS A

RAIN OR SNOW. KEEP IN MIND THAT IT LIKELY WILL CHANGE AND IS SOMETHING

TO WATCH AS THE EVENT DRAWS NEARER.

Full Discussion below

http://forecast.weather.gov/product.php?site=FFC&issuedby=FFC&product=AFD&format=CI&version=1&glossary=1

This is the Forecast for Valentines Day night/President's Day for Atlanta right now...

Sunday NightA 30 percent chance of snow. Mostly cloudy, with a low around 27.
Washington's BirthdayA chance of rain and snow. Cloudy, with a high near 36. Chance of precipitation is 50%.

This one may be ours man.

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Para Euro drops a couple inches of snow over northeast Georgia/Upstate then an inch+ of freezing rain on top.

Para Euro snow maps match up closely with the OP Euro. More snow for the mountains. The difference lies in the surface temps. The para is keeping NE GA and Upstate SC sub-freezing when the heaviest axis of precip pivots through on Monday evening.

Edit: From Gwinnett through Athens/Anderson/Greenville is still subfreezing at 7pm Monday evening where 1.25 to 1.75 inches of liquid has fallen up and down this line.

Also, precip doesnt really make it to Raleigh until midnight, when the wedge has been busted and surface temps have risen to the mid 50's there! (It does this b/c it's plowing the strengthening surface low up through Central, NC)

This has got to be one of the wetter solutions! I mean 1.25-1.75 QPF ! Would be awesome, but all the other models look like a very weak system.

Have also seen a storm as you described here, with temps in the upper 20s and sleet and freezing rain and RAH in the 50s

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I know, just always seems to be a fly in the ointment here. Just seems we should be far enough north and west for it not to be so hard to get snow here more often instead of a cold rain.

 

Welcome to the central Midlands club.  Tracks are always just close enough to ruin everything for us down this way.  The best run for this area was the 12z Para Euro from yesterday.  But, on the flip-side it screwed a lot of people outside the deeper South because it ended up too far South.  The track was perfect climo for CAE, Macon, Savannah (possibly) though.

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I know, just always seems to be a fly in the ointment here. Just seems we should be far enough north and west for it not to be so hard to get snow here more often instead of a cold rain.

 

You better hope the track is not correct on the euro op or para because that is a the kiss of death for our area.  Strong storm but the inland track does not work for us.  Good for the NC mountains though.  My daughter is at App State so it might be time for a dad visit.  I know she'd love that. 

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I know, just always seems to be a fly in the ointment here. Just seems we should be far enough north and west for it not to be so hard to get snow here more often instead of a cold rain.

A lot of models want to take the low more inland and push the high out before precipitation sets in. Perhaps it's the weenie inside speaking, but I don't buy this solution.

Take this last storm in late January as an example. The GFS wanted to take the low pressure track for that storm further north into the high pressure that was providing our CAD event- just like some aforementioned models are doing with this storm. The Euro began to pick up on this being too far north about 100-120 hours out, and began shifting the track further south. That storm had a much stronger low pressure system and a much weaker high pressure system (around the mid-1020's, if I remember right, versus the mid-to-upper-1030's) than this system. That just begs the question: "If it happened then, why can't it happen now?"

It should be noted that one thing that we had with that storm that we don't have with this one was a (retreating) -NAO. That probably helped the high pressure stay in place some with that storm, but again this high pressure is more robust than the 1/22-1/23 storm, so I would think it would have more staying power than what models are showing.

Watch tomorrow's 12z and 00z model runs (especially the Euro) for any hints of the storm taking a track further south. If we don't see any models at least hinting at this sort of thing by 12z Thursday, I'd start being skeptical of any significant snow/wintery precipitation falling in the triangle area.

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It is frustrating.  Other parts of the country have low pressure snows...but it doesn't bring the warm with it like they do here.

 

 

Well, I mean, low pressure systems down here tend to draw their moisture from the gulf so of course, it's bringing the warmer, moist air with it...how else do low pressure systems form and strengthen without both cold and warm air meeting?

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WxSouth, Had a nice write this evening for a lot of the SE! Just hope he's got the right Idea..........  :snowing:

 have a technical, in depth review of the factors leading up to and through the upcoming Winter Storm in the MidSouth and East Coast on Sunday night and Monday at my site (wxsouth.com). The storm shown on European and Canadian models is one that is jet-streak driven (think Jan 1988) where the upper level jet enhances precip amounts in the face of such entrenched cold air firmly in place. The only questions are how much moisture, the angle of the moisture field, and where the 850 freezing line is to start the event in Alabama and Georgia, South Carolina. Already I see an error on the European model low level temps...the storm begins with dewpoints sub zero in Virginia, teens to Atlanta--that is major wetbubl cooling (evaporative cooling) and the model brings temps up to 33 at the end of the event for most of upstate SC and western NC, western VA region but that would be an error thanks to the Pseudo high parked inland for the bulk of the storm. We know how hard it is to dislodge low level cold air, and in this storm, there's plenty of low level cold in place Sunday night and Monday. Check out the discussion and preliminary maps I have. Lots to talk about.

Animation is from tropicaltidbits.com and portrays the Canadian model run

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Well, I mean, low pressure systems down here tend to draw their moisture from the gulf so of course, it's bringing the warmer, moist air with it...how else do low pressure systems form and strengthen without both cold and warm air meeting?

Also, this issue isn't unique to the southeast.  There are plenty of midwest blizzards where Chicago gets rain

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Uncertainty is what we have here, ladies and gentlemen. Big track envelope. What makes the least sense? Seems like a runner to me, at this point.

Agree CR.  I tell you what, this cold vortex over the northeast and the associated high pressure that drops down from Canada have been modeled very consistently.  I haven't seen the northern stream / PV low movement over Canada be modeled well at all this winter...but for this one, it has.  The more inconsistent modeling in this setup is with how the Pacific waves and central U.S. trough evolve.  The GFS and UKMet, for example, are quite drastically different at the moment.  We aren't going to have a clear picture until we have a better handle on how the Pac troughing evolves.

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