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Late December Discussion and Christmas um Event


Cold Rain

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So much for Ice threat on that map!!! Hope it's to warm?

Could be....almost always is with CAD situations.

HOWEVER, this is not an ideal CAD setup, as it's currently modeled. Position of the high, amount of available cold air, and strength of the high are all less impressive than you'd like to see to get a huge, model number-busting CAD, at least in my opinion.

Again, will SFC temps wind up colder than model projections? Probably. But not a perfect setup as is.

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Could be....almost always is with CAD situations.

HOWEVER, this is not an ideal CAD setup, as it's currently modeled. Position of the high, amount of available cold air, and strength of the high are all less impressive that you'd like to see to get a huge, model number busting CAD, at least in my opinion.

Again, will SFC temps wind up colder than model projections? Probably. But not a perfect setup as is.

I pretty much lost any hope of something wintry with this storm, but I always hang on till last second if (and it's a big if this time) there's the slightest chance models are too warm. But what you pointed out I need to throw in the towel! But I think I'll wait another run or two! lol

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I pretty much lost any hope of something wintry with this storm, but I always hang on till last second if (and it's a big if this time) there's the slightest chance models are too warm. But what you pointed out I need to throw in the towel! But I think I'll wait another run or two! lol

Well, I wouldn't completely toss any towels yet for NW NC, but I've seen far better setups at this stage of the game.

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Hey stranger...lol

Its on the MS river about to move through central MS.

Hello and thanks. :)

a moderate risk of severe weather on Christmas does not make me feel holly jolly. The Euro has shown a dangerous severe setup for several runs now. If that track verifies, we have a tornado outbreak on our hands.

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Storm on the 29-30 has gone from nothing to something.3 or 4 days ago it wasn't even showing,believe the GGEM picked up on it first.Might surprise you E/COAST folks if it keeps trending stronger,but the problem would most definite be WAA,good luck

EDIT:Looks to form a secondaryoff the coast,never know

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18z GFS still holding firm with the Dec 30th system...right now its a weak low with 850's just cold enough West of I-77 in North Carolina at 162-168. Good advisory criteria snows along I-40...definitely plenty of time for this to ramp up. And at least its not in fantasy range on the model.

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18z GFS still holding firm with the Dec 30th system...right now its a weak low with 850's just cold enough West of I-77 in North Carolina at 162-168. Good advisory criteria snows along I-40...definitely plenty of time for this to ramp up. And at least its not in fantasy range on the model.

Agreed, 850's look to warm up towards the middle of the event, but if we could stay cold enough it could reach warning criteria.

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Something to note:

The model wants to put a good band of snow almost exactly parallel to the heavy snow pack that's already down.

This is a very good sign - and very typical of a progressively cold pattern.

Also look at the next storm which puts down snowpack right next to that one.

I think anything after 180h for the GFS will be fairly useless until the new years storm is over and done, frankly. It can't handle progressive patterns very well because with each storm there is more and more variability, and more feedback.

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If the Euro/GFS don't come back east some this will be some poor modeling by the CMC.

yep..

Even though it's likely not happening, this track loosely corresponds to the day-4 surface map HPC put out last night (forecaster Cisco). It looked as if they were riding CMC and UKMET guidance on their products last night. Although, HPC's map had the parent low near Statesboro/Savannah, GA and even an occluded low over north GA which would be a wild solution. HPC amended it back this morning, but this still looks like an easter outlier.

It is interesting to note that the UKmet has been right up there with the Euro on verification scores.

In looking at the GFS, it won't surprise me at all when we get closer to the event when each model run will probably recognize a slightly taller ridge out west leading to more of a bundled energy look with slightly more dig to the trof in the Mississippi Valley on the 25th. In the end this may lead to a tad more intense of a system pulling inland with a more dynamic core on the northwestern side with a stout squall line of storms in GA and midlands of SC. I will say that I don't see the base of this trough being strung out to allow a weaker wave to roll from Jackson, MS to Charleston, SC and OTS

Speaking of sharpening the trof as it gets closer, I made it a point to check that exact thing (whether the GFS was sharpening it or stringing it out) back on Thursday night's midwest storm compared to past 0z runs. Thursday night was when the 5H closed low was fully negative allowing for the blizzard in the upper Midwest. Sure enough. When comparing the 6-hr chart on Friday's 0z with the 30hr chart on Thursday's 0z and the 54hr chart on Wednesday's 0z... the trof has sharpened on every subsequent run.

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News from the potential bullseye:

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE PADUCAH KY

335 PM CST SAT DEC 22 2012

.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)

ISSUED AT 335 PM CST SAT DEC 22 2012

RELATIVELY QUIET WEATHER IS EXPECTED IN THE SHORT TERM. INCREASING

SOUTHWEST LOW LEVEL FLOW WILL BRING MILDER TEMPS TONIGHT THROUGH

SUNDAY NIGHT. LOWS TONIGHT WILL LIKELY BE IN THE 00Z TO 06Z TIME

FRAME...BEFORE HIGH CLOUDS AND LOW LEVEL WINDS INCREASE FROM THE

SOUTHWEST. CLOUDS WILL CONTINUE TO LOWER AND THICKEN ON SUNDAY AS

MOISTURE INCREASES AT LOWER LEVELS. FOR HIGH TEMPS...FOLLOWED THE

MILDER NAM MOS GUIDANCE FOR HIGHS...BASED ON UPSTREAM READINGS IN

THE 60S ACROSS ARKANSAS THIS AFTERNOON.

ON SUNDAY NIGHT...A WEAK SURFACE LOW WILL MOVE NORTHEAST ACROSS THE

LOWER OHIO VALLEY IN ASSOCIATION WITH A FAST MOVING/LOW AMPLITUDE

SHORTWAVE TROUGH. MODEL QPF AND MOISTURE FIELDS INDICATE HIGHEST

POTENTIAL FOR MEASURABLE PRECIP WILL BE ACROSS WESTERN KY...WHERE

THE COMBINATION OF FORCING AND MOISTURE WILL BE MOST FAVORABLE.

FOLLOWED HPC QPF GUIDANCE AND RAISED POPS INTO THE LIKELY CATEGORY

IN PARTS OF WESTERN KY. PRECIP TYPE SHOULD BE ALMOST EXCLUSIVELY

RAIN...DUE TO A PERSISTENT WARM LAYER AROUND 850 MB.

CHRISTMAS EVE WILL BE THE CALM BEFORE THE STORM. SEASONABLY COLD AIR

WILL FILTER SOUTHWARD ACROSS THE FORECAST AREA IN THE WAKE OF THE

DEPARTING LOW PRESSURE SYSTEM. AFTER SOME LINGERING SHOWERS MONDAY

MORNING...DRY CONDITIONS ARE EXPECTED THROUGH MONDAY NIGHT.

.LONG TERM...(TUESDAY THROUGH SATURDAY)

ISSUED AT 335 PM CST SAT DEC 22 2012

LATEST GFS AND ECMWF ARE IN GOOD AGREEMENT ON THE TRACK OF THE

SURFACE LOW CHRISTMAS DAY INTO WEDNESDAY...TAKING IT FROM

NORTHEAST MISSISSIPPI TO JUST EAST OF THE PAH FORECAST AREA. THE

MAIN DIFFERENCE IS THE ECMWF IS ABOUT 6 HOURS SLOWER THAN THE

GFS...WITH ECMWF SHOWING THE LOW OVER SOUTH CENTRAL KENTUCKY AT

12Z WEDNESDAY...AND GFS AT THE SAME LOCATION AT 06Z WEDNESDAY.

BOTH MODELS PRODUCE SOME IMPRESSIVE QPF AMOUNTS WITH THIS

SYSTEM...AND SOUNDINGS INDICATE THE MAJORITY OF THE PRECIP WILL

FALL AS SNOW.

THE PRECIP WILL MOVE NORTH INTO WEST KENTUCKY AND SOUTHEAST

MISSOURI CHRISTMAS AFTERNOON...WITH SNOW WEST AND A

RAIN/SLEET/SNOW MIX MORE LIKELY EAST OF THE MISSISSIPPI RIVER.

SNOW WILL SPREAD NORTH ACROSS THE REST OF THE PAH FA CHRISTMAS

EVENING...WITH A RAIN/SNOW MIX MORE LIKELY ACROSS THE PENNYRILE

REGION OF WEST KENTUCKY. FORECAST SOUNDINGS SHOW THIS AREA WILL

BECOME ALL SNOW AFTER MIDNIGHT. ACCUMULATING SNOW MAY CONTINUE

INTO WEDNESDAY MORNING...MAINLY ACROSS THE EASTERN THIRD OF OUR

COUNTIES. ALL IN ALL...SIGNIFICANT SNOW AMOUNTS ARE POSSIBLE WITH

THIS SCENARIO.

HOWEVER...GFS ENSEMBLES AND THE LATEST NAM SHOW THE LOW TAKING A

TRACK A LITTLE FARTHER SOUTHEAST AND EAST OF THE PAH FA...WHICH

WOULD INDICATE A COLDER BUT LOWER QPF SOLUTION. THIS CAUSES SOME

HESITATION IN GETTING TOO ROBUST WITH ANY SNOW AMOUNTS. IN EITHER

CASE...ANOTHER CONCERN WITH THIS WEATHER SYSTEM IS WIND. THE

PRESSURE GRADIENT TIGHTENS UP QUITE A BIT CHRISTMAS DAY AND

ESPECIALLY CHRISTMAS NIGHT AND WEDNESDAY MORNING. FORECAST

SOUNDINGS SHOW 40 TO 50 KT WINDS JUST OFF THE SURFACE AS THE LOW

MOVES SOUTHEAST OF THE REGION. EVEN IF SNOW AMOUNTS ARE NOT TOO

IMPRESSIVE...WINDS WOULD MAKE ANY DETERIORATING ROAD AND DRIVING

CONDITIONS EVEN WORSE FOR HOLIDAY TRAVELERS.

AFTER SOME LINGERING SNOW INTO WEDNESDAY AFTERNOON...WEAK HIGH

PRESSURE WILL SLIDE NORTHEAST ACROSS OUR AREA. THIS WILL KEEP US

DRY AND COLD INTO THURSDAY NIGHT. ECMWF AND GFS SHOW ANOTHER

LOW PRESSURE SYSTEM DRAGGING A COLD FRONT ACROSS THE MIDDLE

MISSISSIPPI AND LOWER OHIO VALLEYS. SOME LIGHT RAN AND/OR SNOW IS

POSSIBLE BY FRIDAY AFTERNOON...WITH A CHANCE OF LIGHT SNOW FRIDAY

NIGHT ACROSS THE ENTIRE AREA. QPF AMOUNTS ARE NOTHING LIKE OUR MID

WEEK SYSTEM...BUT WITH COLD AIR ALREADY IN PLACE...SOME LIGHT

ACCUMULATIONS ARE POSSIBLE.

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Hello and thanks. :)

a moderate risk of severe weather on Christmas does not make me feel holly jolly. The Euro has shown a dangerous severe setup for several runs now. If that track verifies, we have a tornado outbreak on our hands.

Given that the last few runs of the GFS, and the GFS and ECMWF ensembles are starting to converge on such a low track, this seems to be the direction we're heading in. A broad based trough with an intense jet streak like that certainly raises some eyebrows.

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Given that the last few runs of the GFS, and the GFS and ECMWF ensembles are starting to converge on such a low track, this seems to be the direction we're heading in. A broad based trough with an intense jet streak like that certainly raises some eyebrows.

Already seeing an ominous signal from the SREF.

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00z GFS is coming in. It looks like Memphis may get some snow out of this too, and it may accumulate all the way to Southaven, MS. The cumberland plateau gets a little accumulation too - but nobody else does further east except the highest elevations.

The cutoff is pretty sharp. Dyersburg to Paducah does really well. Murray, KY is right near the edge. Clarksville and Nashville get nothing from this run.

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00z GFS is coming in. It looks like Memphis may get some snow out of this too, and it may accumulate all the way to Southaven, MS. The cumberland plateau gets a little accumulation too - but nobody else does further east except the highest elevations.

The cutoff is pretty sharp. Dyersburg to Paducah does really well. Murray, KY is right near the edge. Clarksville and Nashville get nothing from this run.

Southaven is a southern suburb of Memphis....it looks like some light accumulations would be possible down to just south of Clarksdale in the MS delta, however. It's very difficult to tell without having the Buffkit data in hand yet. In analyzing the run verbatim, it looks like 4-6" for Memphis proper but the gradient is very tight so it's not like anyone's gonna feel like it's a likely scenario. Certainly, it was an vast improvement from the 12z for us. Of course, Dr. No will be out shortly and hopefully he'll have a yes this time.

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00Z UK finally makes the big shift - tracks deepening surface low through WC MS and N AL to an eventually weaken into NC as new development occurs over the Tidewater Wed evening.

Unless something crazy happens, this seems to put the severe threat as the big issue for most of the SE. What makes me particularly nervous about the severe potential with this setup is that the lead wave moving through Monday will pull up quite a bit of moisture which will just be left behind as that wave moves off and everything waits for the big system Tuesday/Tuesday night. This will result in an unusually moist and unstable airmass (especially for late December) for an extremely potent weather system to work with.

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