Feb 13-14 - valentines southern slider

[bugalou]

LOL...very true. I have before and will again sacrifice sleep for a snow event much more than anything else (Feb 2010 'surprise' event most exemplifies that)

Ugh... Dont remind me.  I slept through it. 

[Coach B]

I'm a lowly high school math teacher, so what do I know?

I know you want to use a snow day.  

I right there with you, I'm a lowly high school finance/econ teacher with 9 snow days to burn.  

[bugalou]

I honestly don't know. You almost never know what goes into any snowfall output map and there are so many variables that can create wildly different totals. It's interesting to note for sure...and will want to see how it verifies no matter which way it turns out.

I found a youtube video that explains a similar process that is likely the same as to how these maps are created:
http://www.youtube.com/watch?v=IPEYycCRKXo&feature=related

[Milodog2]

 

In situations where the temps are borderline it is almost impossible to know what is going to happen with great confidence even a few hours before the event.

[Thundersnow]

OHX not impressed:

THE NEXT SYSTEM TO BE WATCHED WILL ARRIVE MONDAY AFTERNOON INTO
MONDAY NIGHT. THIS SYSTEM DOES NOT LOOK LIKE A MAJOR WINTER WX
EVENT AT THIS TIME...BUT THERE COULD ENOUGH COLD AND DRY AT THE
ONSET OF PRECIPITATION FOR SOME EVAPORATIVE COOLING...RESULTING IN
A SNOW...SLEET AND RAIN MIX. WIDESPREAD WAA AND DEEP SW FLOW FAVOR
A MAINLY LIQUID EVENT LATE MONDAY NIGHT INTO TUESDAY. STILL
SEVERAL DAYS AHEAD...SO LOTS CAN CHANGE BY THAT TIME.

Though they concede that "lots can change" between now and then, the forecast shows mid 40s on Monday, not even making it down to freezing on Monday night (34 for Nashville grids), with upper 40s on Tuesday and pushing 60 by Wednesday.

[jmundie]

OHX not impressed:

Though they concede that "lots can change" between now and then, the forecast shows mid 40s on Monday, not even making it down to freezing on Monday night (34 for Nashville grids), with upper 40s on Tuesday and pushing 60 by Wednesday.

OHX is full of crap. They have been horrible this past week. No discussion of possible events. Blanket statements of transient cold. Just yesterday they had saturday's high in the 40s... now all of the sudden we might not get out of the 20s.

They are still negative nancy on Monday's event, even though trends are for the cold lingering, and there's no possible way we get 60s on wednesday with the pv rotating in.

Its freaking amatuer hour. Why can't we get a forecast office that looks at anything other than the OP GFS?

[jmundie]

from Monday

PREV DISCUSSION... /ISSUED 316 PM CST MON FEB 6 2012/

DISCUSSION...CLOUD COVER IS PULLING EWD AND SHOULD CONTINUE TO
CLEAR THE AREA OVERNIGHT. RADIATIONAL COOLING WILL LIKELY RENDER A
BIT OF GROUND FOG LATE TONIGHT. SHOULD REMAIN DRY THROUGH TUE AS
THE WEAK SFC RIDGE MOVES ACROSS THE AREA.

THE WEAK LOW THAT IS CURRENTLY OVER THE CNTRL ROCKIES IS EXPECTED
TO MOVE EWD INTO THE PLAINS ON TUE. LIFT ASSOCIATED WITH THIS FEATURE
WILL GENERATE A FEW SHOWERS MAINLY TUE NGT. I DID INCLUDE A
RAIN/SNOW MIX FOR LATE TUE NGT DUE TO LOW LEVEL TEMPS DROPPING
INTO THE MID 30S. SCATTERED SHOWERS SHOULD PULL OUT OF THE PLATEAU
AREA WED MORNING AS THE SFC RIDGE...CENTERED OVER THE PLAINS...PUSHES
EWD ACROSS THE AREA WED NGT TO THU NGT.

BOTH THE GFS AND ECM BRING VERY COLD AIR SEWD OUT OF THE NRN
PLAINS ON FRI WITH THE COLD FRONT REACHING THE MIDSTATE ON FRI NGT.
THUS IT APPEARS WE`LL HAVE A STRETCH OF BELOW NORMAL TEMPS BEGINNING
SAT AND CONTINUING THROUGH THE WEEKEND. SOME RECOVERY IS POSSIBLE...
BEGINNING PROBABLY TUE AS WINDS BECOME MORE SOUTHERLY. VERY LITTLE
SIGNIFICANT WEATHER WITH THIS FRONT AS MOISTURE RETURN BEFORE THE
FRONT IS MINIMAL.

and tuesday

MODELS CONTINUE TO PUSH A STRONG CANADIAN FRONT SOUTHWARD INTO
MIDDLE TENNESSEE FRIDAY NIGHT, WITH A SLIGHT CHANCE OF SHOWERS SOUTH
OF THE FRONT, ACROSS SOUTHERN MIDDLE TENNESSEE AND SOME SCATTERED
FLURRIES POSSIBLE IN THE SHALLOW MOIST LAYER BEHIND IT. TEMPERATURES
WILL STRUGGLE TO REACH THE UPPER 30S OVER THE EXTREME NORTH AND
CUMBERLAND PLATEAU ON SATURDAY, AND LOWS SATURDAY NIGHT WILL
LIKELY DROP INTO THE UPPER TEENS AND LOWER 20S.

LONG TERM...AIR MASS STARTS TO MODIFY SUNDAY, WITH HIGHS PUSHING
INTO THE MIDDLE AND UPPER 40S MOST AREAS WEST OF THE CUMBERLAND
PLATEAU, AND READINGS RETURNING TO THE 50S MONDAY AND TUESDAY. IN
ADDITION TO WARMER TEMPERATURES, ANOTHER LOW PRESSURE SYSTEM
WILL PROBABLY WORKS ITS WAY IN EARLY NEXT WEEK AND BRING ALONG AN
INCREASED CHANCE OF SHOWERS.

[jmundie]

And here's their AFD from Sunday

PREV DISCUSSION... /ISSUED 331 PM CST SUN FEB 5 2012/

DISCUSSION...REMAINS OF THE FRONTAL SYSTEM ARE LOCATED OVER THE
EXTREME SOUTHEASTERN US WITH A WEAK SFC TROUGH EXTENDING WWD
ACROSS TN/AR. SFC RIDGE IS CENTERED OVER THE PLAINS.

THE RIDGE WILL MOVE EWD ACROSS THE MIDSTATE ON MONDAY AS ANOTHER
FRONTAL SYSTEM SWEEPS SEWD ACROSS THE OH/TN VALLEYS LATE TUE/TUE NGT.
MOISTURE ASSOCIATED WITH THIS FRONT WILL YIELD A CHANCE OF RAIN
FOR TUE NGT AND WED.

DRY AIR TAKES HOLD FOR THE NEXT FEW DAYS AS A STRONG SFC RIDGE
CENTERED OVER THE CENTRAL PLAINS ON WED EVE MOVES EWD ACROSS THE
AREA ON THU/THU NGT.

AT THIS POINT THE GFS AND ECM SOLUTIONS DIVERGE. THE GFS DEVELOPS
A LOW PRESSURE SYSTEM OVER THE GULF OF MEXICO AND SOUTH TX. THE
GFS SPREADS THE ASSOCIATED MOISTURE NEWD ACROSS THE DEEP
SOUTH...INCLUDING THE MIDSTATE. THE GFS MOVES THIS LARGE BLOB OF
MOISTURE ACROSS THE SERN STATES ON FRI NGT THROUGH SUN.
IN THE MEANTIME...THE ECM PUSHES A LARGE COLD HIGH PRESSURE AREA
SEWD FROM THE GREAT PLAINS ON FRI WITH THE RIDGE SITTING OVER THE
OH VALLEY LATE SAT.

THE CONSENSUS SEEMS TO BE WITH THE ECM ON THIS ONE. THATS FINE
WITH ME...SINCE THE ECM HAS A BETTER RECORD IN THE 4-7 DAY RANGE
AND SEEMS ALSO TO HANDLE THESE SRN STREAM FEATURES BETTER THAN THE GFS.
THUS THE FORECAST IS DRY AFTER WED.

So - the ECMWF is the best in the 4-7 day range when its not showing anything, but when its been showing large snow/winter event starting day four, andhas been showing it since day 8, you completely dismiss it and go with the GFS.

I know folks at OHX read this. I'd really like to know what you guys are doing. Other forecast offices have been on top of things with the friday system as well as the monday system. You guys are dismissing the threat of anything that's not warm or dry.

Weird.

[Clarksville Snowman]

I suspect that because of the mild winter they simply do not want to get onboard with a prediction to early. If by tommorow the models are still looking cold with precip I suspect they will change. I have no other explanation.

[Kevin]

FYI - EP and I are keeping winter precip out of the forecast for Memphis metro as of now (MEG added in a sleet/freezing rain mention this afternoon) until we get a better handle of temperatures and precip timing in the models. Perhaps depending on the 0z models tonight he may throw something in tomorrow morning.

[MrOysterhead]

I'll just plan on a cold cold rain here 

[ams30721us]

18z GFS seems to have come in more like the Euro around the Chattanooga/SE Tenn area. Not really talking about accums obviously now but looks like we will have a 6-8 hour window of time from around Midnight through Tuesday Morning to see some wintry precip before WAA takes over.




Uploaded with ImageShack.us

[Milodog2]

Wow 5-6 inches painted across the southern valley.


Sent from my iPhone using Tapatalk

[jmundie]

From Foothills at Americanwx and wxsouth.com

I agree with you on the surface winds, and thats the number one problem going on right now with the surface high progged to go offshore. But that just might be a little bit erroneous on the models as there's stilla good bit of confluence in the northeast at the time before precip begins, and a lot of times the models fail to put a high there, and also one develops in central Va or northern NC during a weak in-situ CAD event. I've seen several do that and sometimes the models still miss a meso high right up until the event begins. There's a lot of details that will be ironed out over the weekend, and a lot actually depends on the currently developing system that bombs out eastern Maine. We definitely need the timing and location of the southern system to not be delayed at all, there's a few ways this can shake out, either good or bad. Also the GFS has dewpoints to start well into the lower 20's with surface temps near freezing, so evap. cooling can help the first few hours of the event, but any strong sw winds at the surface will hinder areas esp. east of the mountains. Right now the models are both honing in on the western Carolinas and Georgia to keep a cool layer from the mtns and just next to the mountains as in-situ cad holds on, probably for the whole event, but it still might not be enough to keep as snow (but I do think it starts as snow from just north of Atlanta up interstate 85 to RDU and points west. Looks like Tennessee is mostly snow as they utilize all the precip as snow from warm advection before any strong sw or se winds occur for that area. Its an usual setup overall, and I don't like south winds usually for snow events in lower elevations...I recall one two years ago that managed to rain around here at -4 at 850. A lot of different things can happen locally though and each situation is slighly different. For the mountains , so long as the low doesn't pull north this could be a good event....just depends on how much moisture there is, and if any dryslotting occurs quickly, as some areas in NC are prone to. Also a thing to watch is how quickly moisture blossoms eastward before winds turn southerly....could be a couple quick inches anywhere that has snow to start, but as you stated many would go over to rain.

[connerconner]

Knoxville TV mets not even mentioning a chance for snownext week... whats up with that?