Tn Valley March 4-6 Storm OBS

[Stovepipe]

0z GFS clown:

 

 

QPF:

 

[tnweathernut]

My maps are hung up at hr 19 and 27 on American and Weatherbell, respectively. My guess is its old 0z

[Stovepipe]

My maps are hung up at hr 19 and 27 on American and Weatherbell, respectively. My guess is its old 0z

 

Weird, my American maps appear to have updated for 0z Wed, and they don't match that text data.  Weatherbell is currently on hour 33 but totals are healthy.  Strange data is about hehe.

[jaxjagman]

thats a big difference on the temps,the text on the GFS has BNA -2.6c AT OZ,IT'S 36.2F on the NAM the same time

 

Edit that:i had it on MEM,IT'S 1.5C for BNA,but every degree counts..lol

[1234snow]

I'm starting to take notice now. That's a pretty powerful high dropping down behind the front. Should make easy progress to the Plateau. After that who knows. Jax hang on its going to be a wild ride.

[jaxjagman]

I'm starting to take notice now. That's a pretty powerful high dropping down behind the front. Should make easy progress to the Plateau. After that who knows. Jax hang on its going to be a wild ride.

Still has a warm nose around 800mb 2c, 6z thursday,not sure there will be much snow

[jaxjagman]

GFS 0.5 Degree FORECAST FOR: MEM    LAT=  35.05 LON=  -90.00 ELE=   285

                                            00Z MAR04   * - APPROXIMATED
                 2 M     850    1000    FZING    SFC     SFC    6 HR    SNCVR
                 TMP     TMP     850     HGT     WIND    PCP     QPF     LIQ
                 ©     ©     THK    (FT)    (KTS)   TYPES   (IN)    (IN)
WED 00Z 04-MAR  13.6    12.3     138   12904    19005                   0.00   
WED 06Z 04-MAR  16.1    12.7     138   13144    20011           0.00    0.00   
WED 12Z 04-MAR  12.1    10.6     137   12151    34007     RA    0.13    0.00   
WED 18Z 04-MAR   4.2     8.8     133   12054    02017     RA    0.16    0.00   
THU 00Z 05-MAR  -2.6     5.3     130   11803    02018     ZR    0.25    0.11   
THU 06Z 05-MAR  -5.2     0.1     127    8751    01017     IP    0.63    0.72   
THU 12Z 05-MAR  -6.8    -2.6     127    6657    02017     IP    0.40    1.10   
THU 18Z 05-MAR  -5.4    -8.2     126       0    02014     SN    0.02    1.10   
FRI 00Z 06-MAR  -8.6    -6.5     126       0    01009           0.00    1.07   
FRI 06Z 06-MAR -12.8    -5.2     126       0    02008           0.00    1.07   
FRI 12Z 06-MAR -17.6    -3.2     127       0    04006           0.00    1.07   
FRI 18Z 06-MAR  -7.9    -0.4     128       0    01003           0.00    1.07   
SAT 00Z 07-MAR -18.1     2.6     130    7738    28001           0.00    1.03

[John1122]

I guess we'll have to see how well the models are handling the cold air. This is incoming cold air rather than retreating cold, it may help change this stuff over to more snow than sleet or zr. 

[John1122]

00z RGEM has a real mixed bag, almost statewide. Far east doesn't get as much, but the western 2/3rds of the area gets at least .3 qpf snow, .4 qpf sleet, and .3-.4 qpf freezing rain. Western areas get much more than that.

[Stovepipe]

00z RGEM has a real mixed bag, almost statewide. Far east doesn't get as much, but the western 2/3rds of the area gets at least .3 qpf snow, .4 qpf sleet, and .3-.4 qpf freezing rain. Western areas get much more than that.

 

 

No kiddin:

 

 

 

[1234snow]

00z RGEM has a real mixed bag, almost statewide. Far east doesn't get as much, but the western 2/3rds of the area gets at least .3 qpf snow, .4 qpf sleet, and .3-.4 qpf freezing rain. Western areas get much more than that.

Looks to be 3-5 inches of rain in middle TN on the 0z RGEM. Rivers are full here. Won't take much to send them over.

[John1122]

I fully expect flooding here, flash flooding if the rain is as heavy as they say it's going to be. The creeks are very full already, there's still snow and ice melting into them and add another 2 inches or more of rain in a short time and they will be rampaging. I get localized flooding in extreme events. I am in an area where 3 creeks drain into a large creek. One of the three gets out of it's banks in these situations and the road in front of my house becomes a river. 

[jaxjagman]

I fully expect flooding here, flash flooding if the rain is as heavy as they say it's going to be. The creeks are very full already, there's still snow and ice melting into them and add another 2 inches or more of rain in a short time and they will be rampaging. I get localized flooding in extreme events. I am in an area where 3 creeks drain into a large creek. One of the three gets out of it's banks in these situations and the road in front of my house becomes a river. 

you must be in this area?

http://www.hpc.ncep.noaa.gov/nationalfloodoutlook/index.html

[Stovepipe]

Looks to be 3-5 inches of rain in middle TN on the 0z RGEM. Rivers are full here. Won't take much to send them over.

 

I'd like to be a fly on the wall at the TVA river operations place, I'm sure it would be fascinating to see the strategies they use to adjust the dams at times like these, knowing there are huge consequences if something is off.  Tough job, lots of respect.

[Stovepipe]

FWIW the 0z GGEM amplified the sleet, expanding the heavier stuff eastward and beefing up middle and west, compared to 0z RGEM.

[John1122]

you must be in this area?

http://www.hpc.ncep.noaa.gov/nationalfloodoutlook/index.html

Yep, in the yellow and about 5-10 miles from the orange.

[John1122]

Don't have the clown, but the Euro looked pretty good for a lot of us on the panels I could see. Of course really lets West and Middle have it, but looked like 2-4 or maybe even 3-5 in the Eastern parts of the Valley.

[John1122]

MRX upgraded my area to a Winter Storm Warning. Not terribly clear on my forecast as the zone forecast, point forecast and winter storm warning text are all pretty vastly different.

[Stovepipe]

Don't have the clown, but the Euro looked pretty good for a lot of us on the panels I could see. Of course really lets West and Middle have it, but looked like 2-4 or maybe even 3-5 in the Eastern parts of the Valley.

 

That is a noticeable improvement over the 12z run for sure:

 

 

MRX upgraded my area to a Winter Storm Warning. Not terribly clear on my forecast as the zone forecast, point forecast and winter storm warning text are all pretty vastly different.

 

This has been killing me the last few storms.  Why even have the point forecast if it regularly results in wild variations within a county compared to the zone.  I honestly don't know what to expect here based on MRX, could be virtually nothing or could be school buses in ditches.

[Stovepipe]

6z hi-res NAM:

 

[Stovepipe]

The SREF has made a late shift towards more frozen here, now up to 3 inches (with decent clustering support) verses the half inch or so it was showing.

[John1122]

All the models seem to be shifting the cold/frozen pretty far East now. It's a tough forecast for MRX, if they miss by 20 miles on the progress of the cold it could have a massive impact on close to a million people.

[jaxjagman]

PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
347 AM EST WED MAR 04 2015

VALID 12Z WED MAR 04 2015 - 12Z SAT MAR 07 2015

DAYS 1 THROUGH 3...

...SOUTHERN PLAINS/LOWER AND MID MS VALLEY/GULF COAST...

MOISTURE TRANSPORTED NORTHEAST FROM THE PACIFIC AND WESTERN GULF
OF MEXICO IS FUNNELED ALONG A FRONTAL BOUNDARY EXTENDING FROM THE
SOUTHERN PLAINS THROUGH THE NORTHERN MID ATLANTIC STATES ON DAY 1.
THE FRONT DROPS SOUTH ACROSS THE GULF COAST STATES ON DAY 2...AS
COLD AIR POURS SOUTH FROM THE MIDWEST. THE COMBINATION OF MOISTURE
AND COLD AIR PRODUCES SNOW...SLEET AND FREEZING RAIN ACROSS THE
REGION...MAINLY ON DAYS 2 AND 3. FOR THE MOST PART...THERE WAS
GOOD MODEL AGREEMENT WITH RESPECT TO THE OVERALL SYNOPTIC
SETUP...THOUGH THERE WERE SOME DIFFERENCES CONCERNING THERMAL
FIELDS. THE 00Z GFS APPEARED TO BE TOO FAST WITH LONG WAVE TROUGH
DROPPING OUT OF THE NORTHERN PLAINS...WHICH DRIVES THE LOW LEVEL
COLD AIR FASTER TO THE SOUTH. THE 00Z NAM/12Z ECMWF WERE CLOSER
WITH THE MID LEVEL SOLUTION...AS WELL AS A SLOWER RATE OF COOLING.
THUS...THE THERMAL PORTION OF THE FORECAST WAS BASED ON A BLEND OF
THE 00Z NAM/12Z ECMWF...AND THE QPF PORTION OF THE FORECAST WAS
BASED ON THE LATEST WPC QPF.

DAY 1...
AS THE DEVELOPING LONG WAVE TROUGH CROSSES THE NORTHERN PLAINS AND
GREAT LAKES...IT DRIVES LOW LEVEL COLD AIR SOUTH ACROSS THE
SOUTHERN PLAINS AND THE LOWER AND MID MS VALLEY DURING THE FIRST
HALF OF DAY 1. THE MID LEVELS ARE SLOWER TO RESPOND...AS THE FLOW
BACKS SLOWLY. THIS SCENARIO PROMOTES FREEZING RAIN ACROSS THE
SOUTHERN PLAINS FROM CENTRAL TX AND SOUTHEAST OK INTO AR INTO
NORTHERN AND CENTRAL LA. THE BEST LIFT ASSOCIATED WITH THE
MOISTURE FEED OCCURS ACROSS AR AND NORTHERN LA...WHERE A LARGE
AREA OF 0.10 TO 0.25 INCHES OF QPF IS EXPECTED (WHICH WAS
SUPPORTED WELL BY THE 00Z NAM). THERE IS A MULTI MODEL SIGNAL FOR
0.25+ INCH ICE AMOUNTS ACROSS EAST CENTRAL AR INTO NORTHWEST MS
AND EXTREME SOUTHWEST TN.

AS THE MID LEVEL HEIGHTS DROP...THE COLUMN BECOMES COLD ENOUGH TO
SUPPORT SNOW FIRST ACROSS CENTRAL TX AND SOUTHEAST OK. IN THIS
AREA...QPF SUPPORTS 2 TO 4 INCHES OF SNOWFALL AS THE LAST MID
LEVEL IMPULSE TRACKS TO THE NORTHEAST. THE CHANGEOVER OCCURS MORE
QUICKLY ACROSS NORTHERN AR AND WESTERN TN...WHERE THE DEEP
MOISTURE AND LIFT IN THE DENDRITIC GROWTH ZONE PRODUCES AN AREA OF
4 TO 8 INCHES OF SNOWFALL. THESE AMOUNTS ARE WELL SUPPORTED BY
BOTH THE 21Z SREF AND THE LATEST ECMWF ENSEMBLE OUTPUT.

DAY 2...
SHALLOW COLD AIR DRIVES SOUTH TO THE LOWER MS VALLEY AND GULF
COAST DURING DAY 2. THE MID LEVELS REMAIN TOO WARM TO SUPPORT MUCH
IN THE WAY OF SLEET ACROSS LA/MS/AL/NORTH GA...BUT THE QPF COULD
SUPPORT LOCAL 0.10 INCH ICE AMOUNTS STRETCHING FROM PORTIONS
CENTRAL MS ACROSS THE MOUNTAINS OF NORTH GA.

...OH VALLEY/MID ATLANTIC/SOUTHERN NEW ENGLAND...

MOISTURE FUNNELED ALONG A FRONTAL BOUNDARY STREAKING THROUGH THE
OH VALLEY INTO THE MID ATLANTIC AND SOUTHERN NEW ENGLAND AS COLD
AIR DROPS INTO PLACE LATE ON DAY 1 AND DURING DAY 2. THE
COMBINATION OF MOISTURE AND COLD AIR DRIVING SOUTH RESULTS IN THE
POTENTIAL FOR HEAVY SNOW ACROSS THE OH VALLEY AND MID ATLANTIC
STATES DURING THIS TIME PERIOD. WHILE THERE WAS GENERALLY GOOD
MODEL AGREEMENT WITH RESPECT TO THE OVERALL SYNOPTIC SETUP...THERE
WERE SOME SUBTLE BUT IMPORTANT THERMAL FIELD DIFFERENCES LATE ON
DAY 1 AND EARLY ON DAY 2...ESPECIALLY ACROSS THE MID ATLANTIC. THE
00Z GFS IS A BIT FASTER WITH THE COLD AIR IN THE LOWER AND MID
LEVELS...RESULTING IN FASTER PRECIPITATION CHANGE TO SNOW IN THE
MID ATLANTIC. THE 00Z NAM/12Z ECMWF SOLUTION IS A TAD
SLOWER...WHICH SLOWS THE TRANSITION FROM SLEET TO SNOW ACROSS THE
MID ATLANTIC LATE ON DAY 1. THEREFORE...THE THERMAL PORTION OF THE
FORECAST WAS BASED ON THE 00Z NAM/12Z ECMWF...WHILE THE QPF
PORTION OF THE FORECAST WAS BASED ON THE LATEST WPC QPF.

DAY 1...
MOISTURE STREAMING ACROSS THE TN VALLEY PRODUCES RAIN ACROSS THIS
REGION DURING THE FIRST PART OF DAY 1...AS THE COLUMN IS NOT YET
COLD ENOUGH FOR SNOW AND SLEET. LOW LEVEL COLD AIR DRIVING SOUTH
PRODUCES A FREEZING RAIN PROFILE ACROSS PORTIONS OF WESTERN TN AND
SOUTHWEST KY AFTER 05/00Z...AS TEMPERATURE CHANGES IN THE MID
LEVEL LAG. THERE IS MULTI MODEL SUPPORT FOR 0.10 TO 0.25 INCHES OF
ICE BETWEEN 05/00Z AND 05/06Z...AFTER WHICH TIME THE MID LEVEL
COOL ENOUGH FOR A CHANGE TO SLEET.

FURTHER NORTH...LOWERING MID LEVEL HEIGHTS ASSOCIATED WITH THE
LONG WAVE TROUGH DEVELOPING OVER THE NORTHERN PLAINS AND GREAT
LAKES STARTS COOLING THE MID LEVELS FROM NORTH TO SOUTH ACROSS THE
OH VALLEY. USING THE BLEND OF THE 00Z NAM/12Z ECMWF AS A
BASIS...THE CHANGE FROM SLEET TO SNOW OCCURS ACROSS THE OH VALLEY
BEFORE 05/06Z...AS THE BEST MID LEVEL FRONTOGENETIC LIFT OCCURS
FROM KY INT NORTHERN WV. MODEL SOUNDINGS ALONG THIS AXIS ALSO SHOW
MOISTURE AND LIFT IN THE DENDRITIC GROWTH ZONE...WHICH SHOULD
RESULT IN HEAVY SNOW BETWEEN 05/06Z AND 15/12Z IN THIS AREA. THERE
IS SUPPORT FROM BOTH THE LATEST ECMWF ENSEMBLE OUTPUT AND THE 21Z
SREF FOR 12+ INCH AMOUNTS STRETCHING FROM NORTHERN KY INTO
NORTHERN WV AND SOUTHWEST PA. THESE AMOUNTS ARE PART OF A LONGER
AXIS OF LIFT AND MOISTURE OF WHICH SUPPORTS 6 TO 10 INCHES OF SNOW
EXTENDING FROM SOUTHEAST MO THROUGH NORTHWEST TN...MUCH OF
KY...SOUTHERN OH AND NORTHERN WV.

THE CHANGE FROM SNOW TO SLEET OCCURS BETWEEN 15/06Z AND 15/12Z
ACROSS THE SOUTHERN AND CENTRAL PA...NORTHERN MD AND NORTHERN
VA...MUCH OF NJ AND SOUTHERN NEW ENGLAND (FROM NORTH TO SOUTH).
THE 00Z GFS IS A BIT FASTER THAN THE 00Z NAM/12Z ECMWF BRINGING
THE LOW LEVEL BOUNDARY (AND LOWER AND MID LEVEL COOLING)...WHICH
ACCELERATES THE PROCESS INTO NORTHERN MD/DE. AT THIS POINT...THAT
LOOKS TOO FAST...AND THE 4 TO 6 INCH AXIS WAS PLACED OVER
PA/NJ. THIS TREND IS BETTER DEPICTED BY THE ECMWF ENSEMBLE OUTPUT
THAN THE 21Z SREF OUTPUT.

DAY 2...
THE BEST MID LEVEL FRONTOGENETIC FORCING NORTH OF THE SURFACE
BOUNDARY STRETCHES FROM NORTHERN VA THROUGH CENTRAL AND SOUTHERN
NJ TO A POSITION SOUTH OF LONG ISLAND. ALONG THIS AXIS...MODEL
SOUNDINGS SHOWED THE LIFT AND MOISTURE CONTINUING TO STREAM
NORTHEAST ALONG THE BOUNDARY FROM THE WESTERN GULF OF MEXICO IN
THE DENDRITIC GROWTH ZONE BETWEEN 0612Z AND 06/18Z. THIS SUPPORTS
A LONG AXIS OF 6 TO 8 INCHES OF SNOW IN THIS CORRIDOR...WHICH
INCLUDED KDCA/KBWI THROUGH KILG/KACY. THESE AMOUNTS ARE SUPPORTED
BY THE LATEST ECMWF ENSEMBLE OUTPUT...WHICH SHOWED AN 8+ INCH
STRIPE ALONG THIS AXIS. THE 21Z SREF AXIS WAS A TAD FURTHER
NORTH...BUT SHOWED SIMILAR AMOUNTS.

FURTHER SOUTH...THE COLD AIR DRIVES SOUTH WITH THE LOW LEVEL
BOUNDARY...BUT THE SLOWLY BACKING MID LEVEL KEEPS THE LEVEL
BETWEEN 800 MB AND 70 MB TOO WARM FOR SNOW. THE TRANSITION FROM
FREEZING RAIN TO SLEET OCCURS ACROSS SOUTHEAST VA ACROSS MUCH OF
NC. MUCH OF THE QPF DURING THE SUBFREEZING PORTION OF DAY 2 OCCURS
AS FREEZING RAIN...WITH LOCAL 0.10 TO 0.25 INCH ICE AMOUNTS
POSSIBLE OVER EAST CENTRAL AND FAR WESTERN NC.

DAY 3...
AS THE MOISTURE PULLS AWAY FROM THE MID ATLANTIC COAST AT THE
START OF DAY 3...LOW LEVEL COLD AIR REMAINS WEDGED IN ALONG
EASTERN NC. THE MID LEVEL REMAINS WARM...SO THERE IS NO ICE IN THE
DENDRITIC GROWTH ZONE FOR SNOW OR EVEN SLEET. ICE AMOUNTS BETWEEN
0.01 AND 0.05 INCHES ARE EXPECTED ALONG COASTAL NC.

HAYES

[jaxjagman]

[jaxjagman]

Still seeing a warm nose at 750mb at 1c.not as bad but still there at 6z tomorrow for BNA.Memphis is 2C same time,after that it's gone hopefully it goes away quicker

[Stovepipe]

I misspoke earlier about the SREF mean at TYS, I was looking at BNA, which has jumped an inch from 3 to 4 now.  TYS still at half an inch.

[jaxjagman]

More qpf's looking at the NAM,you're probably gonna see a bigger warm nose,i'll check in a few

[Stovepipe]

12z NAM:

 

[Stovepipe]

Road trip to Union City?

[weathertree4u]

Road trip to Union City?

If you look at the last four runs of the NAM you can see the southward movement. My question is, what are your thoughts on this continuing say for example, into the Nashville area?