janetjanet998

TN valley heavy rain/flooding week of whenever

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No kidding!

 

My non-educated review of GFS 12Z run says bulls eye of 7-8" around central valley over the next 156 hours. Entire valley is 4"+

 

EURO 12Z says 1-3" in valley, heavier numbers more middle/west TN

 

I work as a Geotechnical Consultant and we have enough land slides and sinkholes as it is... come on, give us a break lol!!! 

 

Doing this job for over 10 years now, I have never seen the amount of massive deep seated on-going slope failures we have at this point (really beginning since last March 2019). Check your bedding planes, soil properties, vegetation growth patterns, and slope inclinations before you buy a home or property!!! My heart has been broken countless times helping poor folks trying to repair geotechnical issues costing 5-10 times what the home costs.

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No doubt the boundary stalls out over the Valley somewhere,wouldnt pin point any area this far out

BNA

ECMWF Deterministic FORECAST FOR: BNA    LAT=  36.12 LON=  -86.68 ELE=   591

                                            12Z FEB27
                6 HR    6 HR    FROZN   TOTAL    SFC     2 M    1000    1000 
                 QPF     CVP     PCP     QPF     PCP     TMP     500     850 
                (IN)    (IN)    (IN)    (IN)    TYPES    (C)     THK     THK 
SUN 12Z 01-MAR  0.00    0.00    0.00    0.08             1.2     545     133    
SUN 18Z 01-MAR  0.00    0.00    0.00    0.08            15.3     546     135    
MON 00Z 02-MAR  0.00    0.00    0.00    0.08            12.9     548     135    
MON 06Z 02-MAR  0.00    0.00    0.00    0.08            10.2     549     134    
MON 12Z 02-MAR  0.29    0.24    0.00    0.38             8.4     550     134    
MON 18Z 02-MAR  0.08    0.07    0.00    0.46            13.3     552     135    
TUE 00Z 03-MAR  0.01    0.00    0.00    0.47            13.7     554     136    
TUE 06Z 03-MAR  0.07    0.05    0.00    0.53            13.6     557     137    
TUE 12Z 03-MAR  0.30    0.09    0.00    0.83            15.0     559     137    
TUE 18Z 03-MAR  0.44    0.12    0.00    1.27            16.1     560     137    
WED 00Z 04-MAR  0.60    0.16    0.00    1.88            16.3     564     138    
WED 06Z 04-MAR  0.75    0.24    0.00    2.63            17.3     566     138    
WED 12Z 04-MAR  1.62    0.35    0.00    4.25            12.7     563     137    
WED 18Z 04-MAR  2.49    0.33    0.00    6.74            11.2     563     135    
THU 00Z 05-MAR  0.39    0.05    0.00    7.13             5.8     541     131    
THU 06Z 05-MAR  0.01    0.00    0.00    7.14             3.4     530     131    
THU 12Z 05-MAR  0.00    0.00    0.00    7.14             1.2     536     131    
THU 18Z 05-MAR  0.00    0.00    0.00    7.14            13.5     543     133    
FRI 00Z 06-MAR  0.00    0.00    0.00    7.14            11.1     547     135    
FRI 06Z 06-MAR  0.00    0.00    0.00    7.14             8.0     547     135    
FRI 12Z 06-MAR  0.00    0.00    0.00    7.14             4.5     548     134    

 

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Mem

CMWF Deterministic FORECAST FOR: MEM    LAT=  35.05 LON=  -90.00 ELE=   285

                                            12Z FEB27
                6 HR    6 HR    FROZN   TOTAL    SFC     2 M    1000    1000 
                 QPF     CVP     PCP     QPF     PCP     TMP     500     850 
                (IN)    (IN)    (IN)    (IN)    TYPES    (C)     THK     THK 
SUN 12Z 01-MAR  0.00    0.00    0.00    0.06             7.7     548     135    
SUN 18Z 01-MAR  0.00    0.00    0.00    0.06            15.8     548     135    
MON 00Z 02-MAR  0.02    0.02    0.00    0.08            15.3     552     136    
MON 06Z 02-MAR  0.24    0.24    0.00    0.32            12.6     552     135    
MON 12Z 02-MAR  0.26    0.25    0.00    0.58            11.7     554     136    
MON 18Z 02-MAR  0.01    0.00    0.00    0.59            18.2     556     137    
TUE 00Z 03-MAR  0.01    0.00    0.00    0.60            17.9     559     138    
TUE 06Z 03-MAR  0.11    0.02    0.00    0.71            17.0     561     138    
TUE 12Z 03-MAR  0.56    0.38    0.00    1.27            16.3     560     137    
TUE 18Z 03-MAR  0.60    0.26    0.00    1.88            17.6     562     138    
WED 00Z 04-MAR  0.95    0.58    0.00    2.82            17.2     566     138    
WED 06Z 04-MAR  2.21    1.13    0.00    5.03            13.9     564     137    
WED 12Z 04-MAR  0.48    0.12    0.00    5.50            12.9     560     136    
WED 18Z 04-MAR  0.44    0.11    0.00    5.94             9.3     549     133    
THU 00Z 05-MAR  0.09    0.01    0.00    6.03             7.6     537     133    
THU 06Z 05-MAR  0.00    0.00    0.00    6.03             7.1     539     132    
THU 12Z 05-MAR  0.00    0.00    0.00    6.03             2.4     544     133    
THU 18Z 05-MAR  0.00    0.00    0.00    6.03            15.7     548     134    
FRI 00Z 06-MAR  0.00    0.00    0.00    6.03            13.2     551     135    
FRI 06Z 06-MAR  0.00    0.00    0.00    6.03            10.1     552     136    
FRI 12Z 06-MAR  0.00    0.00    0.00    6.03             6.9     553     135    

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12 hours ago, jaxjagman said:

Mem

CMWF Deterministic FORECAST FOR: MEM    LAT=  35.05 LON=  -90.00 ELE=   285

                                            12Z FEB27
                6 HR    6 HR    FROZN   TOTAL    SFC     2 M    1000    1000 
                 QPF     CVP     PCP     QPF     PCP     TMP     500     850 
                (IN)    (IN)    (IN)    (IN)    TYPES    (C)     THK     THK 
SUN 12Z 01-MAR  0.00    0.00    0.00    0.06             7.7     548     135    
SUN 18Z 01-MAR  0.00    0.00    0.00    0.06            15.8     548     135    
MON 00Z 02-MAR  0.02    0.02    0.00    0.08            15.3     552     136    
MON 06Z 02-MAR  0.24    0.24    0.00    0.32            12.6     552     135    
MON 12Z 02-MAR  0.26    0.25    0.00    0.58            11.7     554     136    
MON 18Z 02-MAR  0.01    0.00    0.00    0.59            18.2     556     137    
TUE 00Z 03-MAR  0.01    0.00    0.00    0.60            17.9     559     138    
TUE 06Z 03-MAR  0.11    0.02    0.00    0.71            17.0     561     138    
TUE 12Z 03-MAR  0.56    0.38    0.00    1.27            16.3     560     137    
TUE 18Z 03-MAR  0.60    0.26    0.00    1.88            17.6     562     138    
WED 00Z 04-MAR  0.95    0.58    0.00    2.82            17.2     566     138    
WED 06Z 04-MAR  2.21    1.13    0.00    5.03            13.9     564     137    
WED 12Z 04-MAR  0.48    0.12    0.00    5.50            12.9     560     136    
WED 18Z 04-MAR  0.44    0.11    0.00    5.94             9.3     549     133    
THU 00Z 05-MAR  0.09    0.01    0.00    6.03             7.6     537     133    
THU 06Z 05-MAR  0.00    0.00    0.00    6.03             7.1     539     132    
THU 12Z 05-MAR  0.00    0.00    0.00    6.03             2.4     544     133    
THU 18Z 05-MAR  0.00    0.00    0.00    6.03            15.7     548     134    
FRI 00Z 06-MAR  0.00    0.00    0.00    6.03            13.2     551     135    
FRI 06Z 06-MAR  0.00    0.00    0.00    6.03            10.1     552     136    
FRI 12Z 06-MAR  0.00    0.00    0.00    6.03             6.9     553     135    

One thing is for sure though, I bet that TVA/Corps of Engineers is stepping up the flows from the area holding facilities in advance of this system next week. 

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ECMWF backed off severe a touch, but seems to have shifted the highest QPF into the heart of TVA. Only good news is that high QPF isn't as high as shown 12 hours ago elsewhere.

On the severe side, several EPS ensemble members are more like the previous runs. Low press into the Midwest and severe here. EC Op is frontal overrunning.

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Slow Euro or faster GFS ?Who will win? Euro dont show much of any flooding as it crashed the 300mb jet through the Valley while the GFS is into the OV.Could be the Euro doing its typical thing holding back energy to the west,who knows

AccuWeather com® Professional - Forecast Models (14).png

AccuWeather com® Professional - Forecast Models (13).png

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Another 4 inch week of rain would probably out us back into areal flooding. The ground is like a full sponge right now.  I had a flat earlier and had the worst time changing it. Due to the nature of where I live there are sections of paved road and sections of gravel. My flat happened in gravel. It was like soup, my jack kept sinking into the ground. Soil is soaked at every level.  

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There are a couple of islands in the Holston that we only see when TVA has the generators off.  That summer with the drought(where G-burg burned) those islands had grass growing on them.  LOL.  They rarely had water over them as the feeder streams were so low - even generation schedules rarely flooded them.  Past two years, I rarely see those islands at all now.   If anything, I have seen some high water marks in those areas that I have never seen before, usually just after big thunderstorms.  Might be an adventure today!  We got hammered with heavy rain yesterday.

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Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
426 PM EDT Mon Jun 29 2020
 
Day 2
Valid 12Z Tue Jun 30 2020 - 12Z Wed Jul 01 2020 

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF 
THE TENNESSEE AND MID MISSISSIPPI VALLEYS...AS WELL AS THE 
NORTHERN PLAINS...

...2030 UTC Excessive Rainfall Outlook Discussion...

Spaghetti plots from the GEFS and SREF point to the potential for 
rainfall amounts to exceed 3 inches from parts of Iowa into 
western Kentucky into eastern Tennessee...predominantly from ARW 
cores.  The on-going Slight Risk was pretty well aligned in this 
corridor, so only changes were made to expand the western boundary 
based on antecedent conditions from the past week or so as well as 
anticipated rainfall amounts from today to the beginning of the 
Day 2 period.  Also made some minor adjustments to the southern 
periphery based on latest model runs.  These are fairly modest 
moves considering the run to run and model to model run 
consistency...but the numerical guidance tended to be in broad 
agreement with respect to the magnitude of instability and the 
amount of precipitable water available and the presence of the 
dynamics to help force and focus the activity.  Not many changes 
elsewhere. 

Bann

 

 

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ational Weather Service Nashville TN
156 PM CST Wed Feb 24 2021

.DISCUSSION...

It`s a warm one out there this afternoon, but worry not; we`re
nowhere near record values. The record high for today`s date is 81
set waaay back in 2017. Somebody will have to tilt the earth a
little more for that to occur today. Other than the warmth, it`s
a little breezy and clouds are starting to build in from the
northwest. These are associated with the light rain that is
expected this evening. Again, not much to get excited about as
latest guidance would suggest some will get none and a few will
only see a couple hundredths by sunrise.

The big story with this forecast package continues to be the heavy
rainfall expected this weekend. If there`s any good news, it comes
in the form of confidence because models continue to zero in on a
4 to 6 inch solution from Friday until Monday morning. All of this
is due to what looks to be a stationary boundary that sets up
Friday night and hangs around through the weekend. Multiple
shortwaves traverse the boundary as it sits over the mid-state and
because of this, we very well could be looking at widespread flooding
issues as early as noon on Sunday. PWs continue to be anomalously
high for this time of the year (forecast soundings are showing
record numbers Saturday night into Sunday) and an impending low-
level jet will only work to enhance rainfall rates both Saturday
and Sunday. Included in all of this, I`ve maintained a slight
chance of thunder starting Friday night and while this will give
some a rumble of thunder, any convective enhancement will only
fuel rainfall efficiency. I wouldn`t be surprised if we`re talking
Flood Watches at this time tomorrow for the weekend.

What could end up being a bigger issue is the runoff. Grounds
likely won`t absorb all of this rainfall, which will cause quick
rises on area rivers and creeks. Forecast ensembles run by our
River Forecast Centers are suggesting minor and *possibly* even
moderate flooding on a few rivers in Middle TN by Monday. You will
need to monitor this closely if you have interests near Middle TN
rivers that flood regularly.

All of this should come to an end on Monday, however, the Euro
continues to show yet another system moving into the area on
Tuesday. While the GFS isn`t currently showing this same system,
if the Euro verifies, additional flooding could be a concern.

For now, enjoy the beautiful day and check back with us over the
next 24-48 hours for the latest information regarding this
weekend`s heavy rainfall forecast.

NWS-Significant-Flood-Outlook.png

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12z models still look on track for 3-6 inches of rain over the next few days. I just had a bunch of water drainage issues fixed around my house a few weeks ago, so this should be a good test for all that work.

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National Weather Service Nashville TN
157 PM CST Thu Feb 25 2021

.DISCUSSION...

A little cooler today, but all-in-all, not a half bad day. The sun
is out and there`s a little breeze. Can`t complain. However,
starting tonight? Let the complaining begin. Light to moderate
rains will move into our southern zones around midnight and while
they`ll likely garner less than a half inch of rain south of I-40
tonight and tomorrow morning, it`ll be a prelude to what`s coming
over the weekend.

Models continue to be surprisingly consistent regarding the rainfall
potential this weekend. 3 to 5 inch totals have been maintained for
several days now. I would argue that with the parameters as they are
(anomalously high PW values and some convective potential, along
with a stationary boundary across the mid-state), 4 to 6 inches is
likely with a few spots getting more than that. Of note, models have
shifted the axis of these heavier rains slightly further south, with
a focus along and south of I-40 and on the Plateau. This is an
expected development as models tend to shift northward or southward
with time, but what it means is the exact locations that will get
the highest amounts is still yet to be determined. That said, I
do believe these numbers are legit. In coordination with
surrounding WFOs, with flooding concerns not expected to begin
until Sunday, we`ll hold off on issuing any Watch headlines at
this time, but the likelihood of them being issued on this shift
tomorrow is pretty high. Bottom line, look for periods of heavy
rainfall, especially Friday night through Monday morning.

Speaking of Friday night, there is some indication that we could
have a couple of strong storms across the south. However, I`m not
wholly sold on this idea as forecast soundings are completely
saturated and CAPE is scarce at best, but there is plenty of shear
with which to work and mid-level lapse rates aren`t shabby (6.5-7
deg C). I`ll mention it in the updated HWO this afternoon, but in
the grand scheme of things, it`s not the biggest concern this
weekend.

So, overall flooding concerns? Check. Meager strong storms Friday
evening? Check. What`s next? Rivers...

Grounds are still relatively saturated after the snow/ice melt from
last week. We`ll get them primed more tonight and tomorrow night and
then the heavier stuff comes in Saturday night into Sunday. With
this progression, I think rivers are going to start becoming a
problem Sunday afternoon at the earliest as run-off starts
occurring. River Forecast Centers are already indicating that
several rivers in Middle TN will be an issue as late as Monday and
that`ll likely run into the middle of next week. That said, if you
have interests near rivers that are well-known flooders, you`ll want
to begin taking necessary precautions soon.

In the extended part of the forecast, the Euro continues to show two
more systems next week (Tue and Thu) and the GFS is maintaining a
dry solution next week. Obviously, this doesn`t lead to much
confidence in the extended, but if we do end up with more rain on
top of what we get this weekend, we could be looking at prolonged
river issues.

&&

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CFS cume cuts us a little slack in Lincoln County and overall, looking at 4-4 1/2" tops through Tuesday anywhere in TN, with central state the highest. Of course, it disagrees with the NAM (through Monday) about the area to be hit heaviest and extent. I dunno, I have just heard so much that has not come true regarding rains in forecasts this winter. This is like the fifth heavy rain warning for my area, and the other four petered out by quite a margin. In one, we got none! Still, I have been away from the site because I am designing my arc, just in case. How long is a cubit, again? :lol:

Barometer in southern Lincoln County, 7 miles above Alabama, is a strong 30.02 inHg so far. Skies slightly overcast and 63 degrees with winds NNE at 3 mph. Rain forecast to start tonight at around 11 p.m. Looking all the way west to the West Memphis, Ark. Police Department's PWS, it is sunny there, 53, and barometer at 30.32.

Screen Shot 2021-02-25 at 4.23.17 PM.png

Screen Shot 2021-02-25 at 4.30.55 PM.png

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Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
325 AM EST Fri Feb 26 2021

Day 1
Valid 12Z Fri Feb 26 2021 - 12Z Sat Feb 27 2021

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE TENNESSEE VALLEY AND ADJACENT AREAS...

We will maintain a Marginal risk across portions of northern
MS/AL/GA into central and eastern TN. Total rainfall amounts, from
earlier Thur evening through today, should end up around 2-3"
across portions of northern MA/AL/GA. Rainfall rates will never
get all that high, given limited instability and quick cell
motions. However elevated convective cells will continue to track
across the region through the morning hours, with hourly totals
locally exceeding 0.5". It is the persistence of these elevated
heavy cells moving over the same area that will eventually result
in some rainfall totals approaching 3". Overall it looks like
rainfall should stay below the 1,3 and 6 hr FFG...thus this mainly
just looks to be a soaking rain without much in the way of flood
impacts. However, can not rule out some localized, mainly minor,
flooding through the morning hours where brief training of the
aforementioned elevated convective cells overlaps the increasingly
saturated soil conditions. Thus will maintain the Marginal risk
across this region.

The focus for later tonight into early Saturday shifts northward
into central and eastern TN. Model forecasts show a corridor of
strong 850mb moisture transport pushing into this region...likely
helping expand/intensify shower activity. This intensification of
low level inflow also pushes PWs up above the climatological 90th
percentile. The main question mark here will be instability. The
current model consensus is only a couple hundred J/KG at
most...which is likely not enough to get get rates over 0.5" in an
hour. However moisture convergence will be quite strong, so it
will not take much more instability to start getting rates towards
0.75" in an hour, and the orientation of the moisture convergence
axis with the mean flow would support some training. Thus while
the most likely solution would suggest rates too low for a flash
flood risk, there is at least a small threat of the event
overachieving and beginning to approach or locally exceed
FFG...which is a bit lower over eastern TN compared to areas
upstream to the southwest. We will carry a Marginal risk over this
region to account for this threat later tonight into early
Saturday.

Chenard


Day 2
Valid 12Z Sat Feb 27 2021 - 12Z Sun Feb 28 2021

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE MIDDLE MISSISSIPPI VALLEY INTO THE OHIO VALLEY...

Shortwaves rounding a mid-level trough axis situated across the
central U.S. will interact with a residual surface boundary draped
across the region.  As a result, moderate to heavy rain will
develop along and just north of the boundary which will eventually
lift north as a warm front ahead of a developing system to the
west.  Anticipate this to occur during the latter half of the
forecast period as the shortwave approaches Saturday evening
coincident with the upper level jet strengthening helping to
promote strong divergence aloft.  With return flow increasing
through the forecast period, precipitable water values will climb
to around 1.25-1.5 inches aided by 35-45 knot low level
southwesterly flow by 28/06Z.  This is 2.5 standard deviations
above the mean.  With isentropic ascent along/north of the warm
front with modest elevated instability (on average 500 J/kg
MUCAPE), rain rates will likely exceed 0.75 inches per hour in
some locations.  In addition, training may occur based on the deep
southwesterly mean wind aligning briefly with the propagation
vector.  This could result in 3 hourly rainfall totals in
exceeding of 1.5 inches. 

While antecedent conditions may illustrate fairly dry conditions
as of late, with recent snow melt, soil moisture is slightly above
average. Therefore, the aforementioned rain rates may exceed flash
flood guidance resulting runoff and thus scattered flash flooding
in some locations.  As a result, a Slight Risk was introduced
along a narrow corridor where the heavy rain rates overlap with
higher soil moisture.  The inherited Marginal Risk was modified
based on the latest model guidance and resultant WPC QPF.

Pagano

Day 3
Valid 12Z Sun Feb 28 2021 - 12Z Mon Mar 01 2021

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS A PORTION
OF THE TENNESSEE VALLEY...

A trough axis situated across the eastern half of the country will
advance south and east through the forecast period.  Mid-level
shortwaves will continue to round the trough, moving atop a
surface boundary/cold front which will act as the focus for
multiple rounds of showers and thunderstorms across portions of
the Deep South and TN Valley.  Within the warm sector, strong
moisture feed and return flow from the Gulf of Mexico will mean a
surge in precipitation water values to over 1.5 inches which is
around 2.5 standard deviations above the mean.  This moisture
transport will be aided by 35-45 knot low level southwesterly
winds into a strengthening frontogenetic zone within the right
entrance region of an upper level jet streak. Therefore, large
scale lift and deep layer moisture will not be limited; though
instability does appear modest.

So, while key ingredients for heavy rainfall clearly exists, it is
the training and back building of moderate to heavy rain along the
aforementioned front that could lead to rain rates exceeding flash
flood guidance over 1 to 3 hours in some locations.  If this
occurs over fairly saturated soils, especially given the
additional rainfall on Day 1-2, then localized to scattered flash
flooding may occur. This signal is also supported by ensemble
probabilities and looks to occur Sunday afternoon through the
overnight before the front eventually sinks south.  Therefore, a
broad Marginal Risk area was introduced with a focused Slight Risk
area across the TN Valley where heavy rain/rates will overlap with
wetter antecedent conditions.  

Given some lingering model uncertainty, anticipate there will be
modifications made to the extent and position of the Slight Risk
area.  We will continue to monitor the latest model trends and
modify accordingly. 

Pagano

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Ha guys I have been looking at this website for over 15 years now.  Decide to post.  I love weather but don’t have near the knowledge you guys do.  I loving reading your post and keeping up with your weather analysis. I work with the United States Geological Survey and I am a Hydrologist Technician I measure the flow and maintain the River gages in East TN.  I am out of Knoxville office and live in Farragut.

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1 hour ago, BobbyB said:

Ha guys I have been looking at this website for over 15 years now.  Decide to post.  I love weather but don’t have near the knowledge you guys do.  I loving reading your post and keeping up with your weather analysis. I work with the United States Geological Survey and I am a Hydrologist Technician I measure the flow and maintain the River gages in East TN.  I am out of Knoxville office and live in Farragut.

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