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February 2019 Winter Speculation

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The 06z NAM stepped up the winter threat for northern areas of the forum region. Lots of ice and some areas of moderate to heavy snow, parts of SWVA see .25+ freezing rain and 3-5 inches of snow. Parts of southern Kentucky also see 1-2 inches of snow and some ice. NW Tennessee gets heavy ice, over .50. The ice threat got heavier and further south and if the NAM verified there could be decent icing even in NW Davidson. The NAM actually stepped towards the FV3 solution and really stepped up with the streak of snow across Kentucky into SWVA. It wasn't there at all on 0z. The models showed something similar a few days ago but it went away. Hopefully the snowline can start to be seen on more models and trend further south. 

The 0z Euro puts the Southern 1/3rd of Kentucky on the edge of moderate snow, but that represents a 75-100 mile shift south with the snow axis from 12z today. As I said, models a few days ago had that snow streak running along the TN/KY line down to nearly I-40 with ice below it. Not going to hold my breath, but hopefully the southern trend continues. The Low tracks south of us, but not quite far enough yet. We need it to go another 100 miles to 150 miles south.

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Hate to beat a dead horse...but MRX is getting out in front of the heavy rain and flooding potential.  Here is their graphic and a snippet from their morning disco....

.LONG TERM (Friday through Wednesday)...The main focus of this
part of the forecast will be the precip amounts falling over
already moist soils. Looks like three waves of precip--Friday/Fri
night; Sunday; then the big show Monday night through the end of
the forecast. The first couple of events should each stay below 1
inch in general, but the big event will likely produce very heavy
rains over part of the area, and possibly repeatedly for some
areas. The mid-range ensembles show an axis of heaviest rains over
N GA/N AL/SE TN/W NC/W SC and staying over the same areas, but
the deterministic GFS/Euro show more active north or south
movement of the axis over time, so there may well be some lulls in
the precip, but some areas should definitely get some very heavy
rains and possible flooding. Between now and when this big event
starts, it will be important to watch for changes in the placement
of this axis and the placement of the associated frontal
boundary. Looking at the contributing components for heavy rains,
things are a little more progressive than it might seem at first
glance--looks like the heaviest rain rates and flash flooding
threats will generally be confined to one 24-hour period--like
Tuesday and Tuesday night -or- Tuesday night and Wednesday, etc.
However, the river (non-flashy) threat probably will continue
through the end of next week for the places under that heaviest
precip axis--once again the forecast for this axis may drift north
or south in the coming days--still 5-6 days away. Pretty cool
airmass over southwest VA some of these nights, but looks like
almost all precip will be in the form of rain.

2142927839_ScreenShot2019-02-14at10_26_32AM.png.1477ad8664abc45cae6885b98dbd636c.png

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@Carvers Gap 6z GEFS. Bullseye of 8.5" over Fall Creek Falls State Park. Higher totals across SW North Carolina. Does not bode well for spring tourism in the area. DuPont, in particular, may be looking at a significant stretch of time with popular trails closed.

qpf_acc.conus.png

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53 minutes ago, Blue Ridge said:

@Carvers Gap 6z GEFS. Bullseye of 8.5" over Fall Creek Falls State Park. Higher totals across SW North Carolina. Does not bode well for spring tourism in the area. DuPont, in particular, may be looking at a significant stretch of time with popular trails closed.

Both the 12z CMC and GFS operationals have incredible amounts of precip.  Really hoping those totals have some feedback in them.  

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The thing that's worrying to me is that all this isn't based on a particular system like most of the stuff we look for is, but that the TN/ OH valley is basically under the right rear quadrant of jet streak after jet streak for 10 - 15 days.  That jet is coming. Every system has over performed this year, why should this one be any different? Believe me, I don't want that at all. 

The precipitable water anomalies are 250 - 300% on GFS and Euro. The jet will provide the lift with occasional embedded shortwaves providing more.  The whole set up just screams big time rain.  I think some area gets wholloped, but exactly who remains unknown. 

giphy.gif 

I guess we can hope the SE ridge trends stronger (it has been a little bit at a time), but then that just screws over the OH valley. 

:( 

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35 minutes ago, Holston_River_Rambler said:

Every system has over performed this year, why should this one be any different?

Every system over performed except the one that brought Knoxville a little bit of snow. I agree almost every other system has over performed and the upcoming pattern is very concerning for flooding. I'm ready for Spring and longer and warmer days so we can attempt to dry out since this Winter has been a huge bust for most of us.

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1 hour ago, Holston_River_Rambler said:

 

I guess we can hope the SE ridge trends stronger (it has been a little bit at a time), but then that just screws over the OH valley. 

:( 

not looking good..trends are more NW again...instead of TN valley and Northern gulf coast states ...now trending towards TN and OH valley

 

looks the firehouse starts south about day 5 and works its way north..I suspect convection might slow the north push so perhaps the SE older model runs may be correct but the wrong reasons?

 

the Euro is more NW then the GFS in the LATER PART OF 10 day range with surface features...anyone have the precip map for the EURO

 

yikes GFS op run

gfs_apcpn_us_52.png

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4 minutes ago, janetjanet998 said:

anyone have the precip map for the EURO

Heavy rain still moving through East TN at 240, so those totals would likely go up if extended 6 hours.

12z Euro Precip Map.png

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The Euro slipped another 25-50 miles south with the frozen precip again for this weekend. NWTn still looks favorable for ice, Kentucky/SWVA looks like they could gets snow, heavy snow right across central Kentucky, could effect travel to the Kentucky game if anyone tries to go up Friday as I-75 sees heavy snow from around London Ky and north overnight Friday, the Euro now has snow/rain down into northern East Tennessee. Getting close, will have to see if the South trend continues any or if it's about as far south as it's going to get.

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1 hour ago, Holston_River_Rambler said:

The thing that's worrying to me is that all this isn't based on a particular system like most of the stuff we look for is, but that the TN/ OH valley is basically under the right rear quadrant of jet streak after jet streak for 10 - 15 days.  That jet is coming. Every system has over performed this year, why should this one be any different? Believe me, I don't want that at all. 

The precipitable water anomalies are 250 - 300% on GFS and Euro. The jet will provide the lift with occasional embedded shortwaves providing more.  The whole set up just screams big time rain.  I think some area gets wholloped, but exactly who remains unknown. 

giphy.gif 

I guess we can hope the SE ridge trends stronger (it has been a little bit at a time), but then that just screws over the OH valley. 

:( 

That’s a good point.  I usually don’t pay much attention to specific 10 day model output, but in this case it seems to be a fairly stable solution due to the features you mentioned.

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5 minutes ago, Math/Met said:

Heavy rain still moving through East TN at 240, so those totals would likely go up if extended 6 hours.

 

Yikes. Nightmare scenario. 

I checked flash flood guidance and...it's pretty low. image.png.196f3272ea21198e160b74000047358d.png

 

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8 minutes ago, Math/Met said:

it seems to be a fairly stable solution

I was just thinking too, that the whole awful pattern looks stable. I bet the Euro control will just keep bringing it when I can look at it in an hour or two. 

MJO in phase 8 and aimlessly wandering around as of now (hopefully that will change) and tanking SOI would usually = STJ amp, right? La Nina overall pattern in N. America with a juicy El Nino STJ tossed in, aimed at us. 

That latest Euro solution is not only hurting TN valley watershed, but OH Valley at the same time. I think we've all probably seen set ups like this before, just not as long lived. Firehose sets up rather WSW - ENE, shortwave rides through and pulls the firehose NW for a bit, then once it passes, the hose aims more W - E again. Somebody may get stuck in a situation where both firehose orientations intersect over and over again as the shortwaves cruise through and that area would be the one to get hammered. 

Right now I would speculate that would be on the plateau just W of Chattanooga where Euro is showing 10+ inches. Upslope probably won't help much.

W and S areas would seem to be more at risk for the overlapping firehoses than N and E areas

 

And then mountain run off.... 

:facepalm:

 

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Desert Southwest regional radar mosaic and local radars are very impressive today Thursday. GOES-17 shows a massive plume of moisture back to Hawaii (actually farther south to the ITCZ). Big time atmospheric river is teeing up on the STJ. Rain and flooding will be the weather story next week.

Agree parts of West Kentucky (maybe northwest Tenn) should see some light ice Saturday morning. Could be light snow into higher elevations of East Kentucky over toward the VA/WV border Saturday.

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Control actually brings us more rain past day 10 then a snowfall to end it all. Wouldn't it be something if we finally got a regional snowfall after flooding? Normally wouldn't post one run of the control at 360, but hey, I'll take a pick me up right now:

 

eps_snow_by5_c01_conus_360.png

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8 minutes ago, nrgjeff said:

Big time atmospheric river is teeing up on the STJ.

It's not even the pineapple express at this point, it's the Polynesian express.

giphy.gif 

@EastKnox remember Maui's hook? 

It connects to the MJO wave. Incredible. Looking at the movement and orientation of the trough digging west of Hawaii, it almost looks like it would help kick some of that deep, deep tropical moisture NE. 

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MRX on top of next week....

Continued high rain chances throughout the extended forecast over
already soggy soils will lead to an increased risk of flooding next
week. Still looks like the next round or wave of rainfall begins
Saturday night and through Sunday night. Higher pressure with drier
airmass moves in early Saturday evening temporarily behind latest
frontal system. However moisture begins to pool to the south ahead
of developing low pressure along the gulf coast that then moves
northeast towards the Tennessee Valley Sunday. As air is lifted over
old frontal system boundary increasing rainfall possible Sunday into
Sunday night. This next developing system will move through by early
Monday. ECMWF model shows no break but GFS does show about a 12 hour
dry period before the front moves back north and then stays near the
southern border of Tennessee as a couple of low pressure areas move
along the front Tuesday through Wednesday night. Rainfall amounts
Saturday night through Sunday night are about one half inch
northeast to 1.5 inches in the southwest which is not expected to
produce flooding. The latter system is now showing much more
rainfall from about 2 inches northeast to as much as 5 inches in the
extreme southeast through Thursday morning. The models try to bring
the system farther south and east but another wave may bring in more
rain at the end of the extended. With the extended period of
moderate to possibly heavy rainfall several rivers will likely rise
to near or above flood stage by mid of next week.
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18z GFS just doubled down..cant remember an event quite like what's being shown. Scary part, as some have said already, is modeling lately at this range is underperforming vs realtime. 

gfs_tprecip_nc_37.png

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11 minutes ago, Holston_River_Rambler said:

For any watching for the possible KY snowfall tomorrow night, 18z Euro ever so slightly south of 12z. 

The Euro keeps edging frozen south. I think @Kentucky could see something out of this. Blunderstorm may as well. 

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