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Winter 2015-16

Mr Bob

By Mr Bob,
in Tennessee Valley

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Carvers Gap

Carvers Gap

Posted
Posted

So do tell, what is depicted?

Just one run on one model...but fun to watch. Looks like the GL arrives late which allows the slp to develop along the SE coast and then the GL pulls the low back into the coast w some interaction between the two. Wild look to that run.

Gem and GFS at 12z are cold throughout. Waiting to check the ensembles. Have to think the GEM might be out on a limb.

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weathertree4u

weathertree4u

Posted
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Just one run on one model...but fun to watch. Looks like the GL arrives late which allows the slp to develop along the SE coast and then the GL pulls the low back into the coast w some interaction between the two. Wild look to that run.

Gem and GFS at 12z are cold throughout. Waiting to check the ensembles. Have to think the GEM might be out on a limb.

At what point do we start wondering whether the MJO is out on a limb? I mean, we have now had a few runs of the GFS that has been consistently cold throughout, after a while, it gets a little harder to discount.

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ShawnEastTN

ShawnEastTN

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Just one run on one model...but fun to watch. Looks like the GL arrives late which allows the slp to develop along the SE coast and then the GL pulls the low back into the coast w some interaction between the two. Wild look to that run.

Gem and GFS at 12z are cold throughout. Waiting to check the ensembles. Have to think the GEM might be out on a limb.

Yeah the storm is like i'm going OTS, then the low in the Great Lakes is like no you aren't and pulls it back to the coast.   Then lots of low level moisture left over us in the wake with bits of energy associated for some lift.  Would be really awesome just to see something like that happen just out of how strange it appears.  CMC though also seems to want to keep the trough over the east a little deeper without a brief ridge the GFS shows for around the 12th.

 

Loop of CMC end of page 18.

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Carvers Gap

Carvers Gap

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At what point do we start wondering whether the MJO is out on a limb? I mean, we have now had a few runs of the GFS that has been consistently cold throughout, after a while, it gets a little harder to discount.

While the 6z GFS op was cold, its ensemble was warm. The MJO is real, just hoping we can steal some cold so the warmup after next week is shorter. The biggest thing I notice is how the cold has been pushed back and dampened. IMO that is MJO influence. Phase 4 will want to flood the US with warmth. Let's see where the Euro goes and its ensembles. Also, want to see the Canadian ensembles as its 12z run was pretty remarkable end to end. Still a ton of support for warm. But...climo for this time of year is favorable for the Plateau eastward and it will have a say.

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tnweathernut

tnweathernut

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Posted

12z GEFS ensembles are warm in the LR. The Euro goes OTS with our storm next week. The low over the Lakes is late. GEM looks like it is on its own.

I guess the good news is..................the 12z Canadian ensembles are also cold throughout its run, showing an eastern trough all the way through 384.  I am probably going down with the ship, but not without a fight.  lol

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Carvers Gap

Carvers Gap

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What might be interesting and this might need to be considered...Are the models breaking down the blocking too quickly? Was a problem in January. The Ops had some nice trends at 12z. But the ensembles have more weight IMO at this point. This is going to be a real battle. Blocking vs MJO. How long can the blocking hold out? Would be nice to see the EPS trend cooler like the OP.

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John1122

John1122

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I've been reading up on the MJO today. From what I can gather it's effects are muted during DJF and more pronounced during transitional seasons. It's main effects on the east also occur during phases 8,1 and 5,6.  Also, as the MJO moves into 5,6 it takes 12 days for the effects to reach the United States. During that timeframe the East Coast is usually under a trough with colder than average temperatures. Currently the MJO is weak and is in 4 and is predicted to remain there as there is not much eastward progression on models. In the study I read 4 did send warmth to the east in winter, but only in one instance out of all the events they looked at. 5 is much more likely to send warmth into the east. But once again, with a 12 day lag time, during which there is usually a trough in the East.

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John1122

John1122

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18z GFS is also snow showery/upslope, wringing out every bit of moisture and slowly piling up snow over several days from a couple of systems dropping in from the NW. 

 

The 10:1 map underestimates what would actually fall in a situation like this as 850s suggest 20:1 if not 25:1 for what would fall. So you can basically double this clown. It also gets very very cold and pops some -20s over the mountains with 0-5 type lows and highs in the 10s and low 20s.

 

gfs_asnow_seus_36.png

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Carvers Gap

Carvers Gap

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18z GFS is also snow showery/upslope, wringing out every bit of moisture and slowly piling up snow over several days from a couple of systems dropping in from the NW. 

 

The 10:1 map underestimates what would actually fall in a situation like this as 850s suggest 20:1 if not 25:1 for what would fall. So you can basically double this clown. It also gets very very cold and pops some -20s over the mountains with 0-5 type lows and highs in the 10s and low 20s.

 

 

 

Very true.  The GFS has been showing a pretty good upslope event for the past several runs.  Definitely helps to be on a west facing slope.  Probably not something Kingsport scores w/ but is definitely a great set-up for communities nearer the Apps like Johnson City, Bristol, Erwin, Unicoi, Mountain City, southwest Virginia, and southeast KY.  John, you guys do well on the Plateau w/ these types of events as well don't you?  I think the tops of the Apps could easily go 1' plus.

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John1122

John1122

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Posted

Gfs and Canadian are showing a bit more than just upslope with several vorts dropping across the area. That's why it snows over most of the state at tiles. I can do well with upslope. I've gotten 6-10 inches before when the flow was hooked up with Lake Michigan in the past.

Very true.  The GFS has been showing a pretty good upslope event for the past several runs.  Definitely helps to be on a west facing slope.  Probably not something Kingsport scores w/ but is definitely a great set-up for communities nearer the Apps like Johnson City, Bristol, Erwin, Unicoi, Mountain City, southwest Virginia, and southeast KY.  John, you guys do well on the Plateau w/ these types of events as well don't you?  I think the tops of the Apps could easily go 1' plus.

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Carvers Gap

Carvers Gap

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Posted

Gfs and Canadian are showing a bit more than just upslope with several vorts dropping across the area. That's why it snows over most of the state at tiles. I can do well with upslope. I've gotten 6-10 inches before when the flow was hooked up with Lake Michigan in the past.

Yeah, I group the northwest flow events and clipper in the same boat which I prob shouldn't. We usually get the same result here in KPT no matter the origin of the precip. If it is on a northwest wind, we get downsloped.

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Carvers Gap

Carvers Gap

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Posted

Gfs and Canadian are showing a bit more than just upslope with several vorts dropping across the area. That's why it snows over most of the state at tiles. I can do well with upslope. I've gotten 6-10 inches before when the flow was hooked up with Lake Michigan in the past.

And yes, I would be licking my chops to see that on the models if I was in your area. I would think 6+" would be within the realm of expectation over that three day period.
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Daniel Boone

Daniel Boone

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While the 6z GFS op wad, its ensemble was warm. The MJO is real, just hoping we can steal some cold so the warmup after next week is shorter. The biggest thing I notice is how the cold has been pushed back and dampened. IMO that is MJO influence. Phase 4 will want to flood the US with warmth. Let's see where the Euro goes and its ensembles. Also, want to see the Canadian ensembles as its 12z run was pretty remarkable end to end. Still a ton of support for warm. But...climo for this time of year is favorable for the Plateau eastward and it will have a say.

Good points! Mjo is hard to override when it's healthy for sure. If there's no strong blocking or all other indices working against it, u could forecast warm or cold anomalies by it with high accuracy. 

    If strong enough effects from blocking along with a+pna mute the Mjo enough, I guess it could be possible that our snow chances would be higher as a battleground may setup within our area and suppression wouldn't be an issue.

 

   I wonder if there's any analogue to such occurrence/time , where that scenario happened.?

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jaxjagman

jaxjagman

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And for whatever reason the GFS on the precip type map spits out some rain with temps between 35 and 40 as one clipper moves into the area, The 528 line is under the rain and the 850 0 line is along the gulf coast and 850s under the rain it's showing are around -5.

Looks odd doesnt it even at the 5h

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Daniel Boone

Daniel Boone

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And for whatever reason the GFS on the precip type map spits out some rain with temps between 35 and 40 as one clipper moves into the area, The 528 line is under the rain and the 850 0 line is along the gulf coast and 850s under the rain it's showing are around -5.

I've noticed that since the upgrade. Possibly basing it on expected 2m 0c temps. Of which if so, is just childish in a sense, IMO, as with cold air aloft snow can fall several degrees above freezing. Also, what about elevated areas above 2 meter ?..

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Carvers Gap

Carvers Gap

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Posted

6z GEFS and 0z EPS depict very warm temps in the LR. Additionally, the 0z Euro OP shows the warm-up inside of 10 days. Once the warm-up begins on the the most recent ensembles around d10, it continues to the end of the run w very little weakening. Minus one or two runs, this warm-up has been locked onto by the ensembles for several days.

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JayCee

JayCee

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Posted

MRX seeing some interesting mischief for next week:

 

LONG TERM...(THURSDAY THROUGH TUESDAY)...

THE BEGINNING OF THE LONG-TERM FORECAST WILL FEATURE COLD AIR
ADVECTION MOVING IN BEHIND THE FRONT. MOSTLY SUNNY SKIES WILL RETURN
BUT TEMPERATURES WILL BE NEAR NORMAL VALUES WITH HIGHS IN THE 40S
ACROSS MOST OF THE AREA. ANOTHER UPPER LEVEL TROUGH MOVES IN LATE
THURSDAY INTO EARLY FRIDAY BUT THE PW VALUES WILL BE AROUND 0.1-0.2
INCHES...WHICH IS NEAR THE MINIMAL VALUE FOR EARLY FEBRUARY.
THEREFORE...NOT EXPECTING ANY PRECIPITATION FROM THIS UPPER LEVEL
SYSTEM. WITH THIS DRY AIR IN PLACE...THURSDAY NIGHT SHOULD BE MOSTLY
CLEAR WITH LIGHT WINDS AS SURFACE HIGH PRESSURE MOVES OVER THE AREA.
THIS WILL ALLOW FOR IDEAL RADIATIONAL COOLING CONDITIONS WITH
TEMPERATURES DROPPING DOWN INTO THE 20S AREAWIDE. HIGH PRESSURE AT
THE SURFACE AND ABNORMALLY LOW PW VALUES WILL KEEP THINGS DRY INTO
THE WEEKEND. MODELS INDICATE A DEEP CLOSED LOW PIVOTING ACROSS THE
SOUTHEASTERN U.S. SATURDAY INTO SUNDAY. A LOW PRESSURE DEVELOPS OFF
THE CAROLINA COAST AND THE PRECIPITATION FROM THIS SYSTEM WILL
REMAIN WELL OFF TO THE EAST.

BIG CHANGES ARE IN STORE FOR THE BEGINNING OF THE WORK WEEK AS A
TROUGH RACES QUICKLY OUT OF THE NORTHERN PLAINS INTO THE TENNESSEE
VALLEY. COLD AIR WILL SPILL DOWN FROM CANADA WITH THIS SYSTEM. UPPER
LEVEL HEIGHTS WILL DECREASE SIGNIFICANTLY AS THE LOW CLOSES OFF
ACROSS THE AREA WITH MULTIPLE SHORTWAVE TROUGHS ROTATING THROUGH THE
MAIN LOW EARLY NEXT WEEK. MODELS INDICATE A SURFACE LOW MOVING
THROUGH THE AREA ON MONDAY AS TEMPERATURES BEGIN TO COOL DOWN WITH
THE COLDER AIR ALOFT. MOISTURE WILL SPREAD FROM WEST TO EAST DURING
THE DAY WITH TEMPERATURES COOLING. FOR NOW...IT APPEARS IT WILL
MAINLY BE A MIX OF RAIN/SNOW IN THE VALLEY THROUGHOUT MUCH OF THE
DAY WITH SNOW IN THE HIGHER TERRAIN. THE FREEZING LEVEL WILL BE
AROUND 2-3 KFT AND THIS IS WHY THERE WILL BE A MIXTURE OF RAIN/SNOW
IN THE VALLEY. BASED ON CURRENT MODEL SOUNDINGS...NOT SEEING ANY
INDICATION OF ANY OTHER PRECIP. TYPE OTHER THAN RAIN OR SNOW. THE
ATMOSPHERE CONTINUES TO COOL MONDAY AFTERNOON AND BASED ON CURRENT
GUIDANCE EXPECT THIS IS WHEN ALL LOCATIONS WILL TRANSITIONS TO SNOW.
THE GFS IS SHOWING SOME RATHER IMPRESSIVE LAPSE RATES MONDAY
AFTERNOON INTO TUESDAY MORNING WITH 850-500 MB LAPSE RATES OF 6.5-
7.5 C/KM. IS THIS WHERE TO VERIFY...THERE WOULD BE SOME HEAVIER
BURST OF SNOW. MODELS INDICATE ANOTHER SHORTWAVE TROUGH MOVING
THROUGH TUESDAY THAT COULD BRING ANOTHER ROUND OF SNOW AS A SURFACE
LOW TRACKS UP THE EAST COAST. IT IS STILL TOO EARLY TO GET SPECIFIC
BUT BASED ON THE LATEST MODELS...IT APPEARS A GOOD 2-4 INCH SNOWFALL
ACROSS THE AREA WITH HIGHER AMOUNTS IN THE MOUNTAINS. SNOW BEGINS TO
TAPER OFF FROM SOUTHWEST TO NORTHEAST TUESDAY NIGHT INTO WEDNESDAY.
PLEASE STAY TUNED TO THE LATEST FORECAST AS THERE ARE STILL MANY
MODEL RUNS TO COME BETWEEN NOW AND MONDAY.
 

 

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weathertree4u

weathertree4u

Posted
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I'm certainly digging the ratios that would be, dare I say some possibly see up to 30-1...  Probably not the valley but Plateau and Mountains.  

I am certainly not a meteorologist but seems like those arctic fronts are known for squeezing out all the moisture. I remember the arctic front that accompanied the outbreak January 1985 they were predicting flurries or snow showers we got about 6" of fluffy airy snow - do not misunderstand, I am not comparing the two in severity just simply saying that it usually snows with those fronts and they usually underestimate them.

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tnweathernut

tnweathernut

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Posted

GFS 12Z Clown assuming 10-1 ratio.  I think for most its safe to double this as John was mentioning earlier, and I think some triple.  As is this map at 10-1 basically Nashville and east 1-3" plateau and mountains 3"-6".  So probably safe to say 2"-6" and wouldn't be surprised to for up to a foot in the Mountains by the time all is said and done and some spots on the plateau could approach that with the ratios that would be with these.  We are talking 522 to down as low as 500mb swinging through the region during the the snow. 

Shawn,

Thanks for all the posts!  Start throwing these in the other thread dedicated to this time period.....

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Carvers Gap

Carvers Gap

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Posted

The Para EPS weeklies show Feb 15-25th as being above normal.  Then sometime during the last week of February the weeklies deepen a trough over eastern NA and maintain that for roughly ten days.  Then, it is slightly below normal temps at 850 for the rest of the period.  Massive, massive PNA ridge in late Feb.  The trough axis is not exactly perfect for storms, but the warmth off the SE coast may correct that trough westward a bit.  Anyway, a bit of good news.  Now, what would be nice is for the models to be incorrect in breaking down the block too quickly and creating just a 5-7 day window of above normal temps.  Anyway, looks like we have at least one more time frame where we have a chance to score some cold and snow.   So, roughly the last week in Feb to the first week in March is that window.  But that is a long way off, so things can easily change.  Just relaying what the model showed.  Also, precip is shown to be below normal for that period as well.  Snow was minimal w/ the NE getting absolutely hammered.

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