Winter 2015-16

[nrgjeff]

Colder the better, rather than playing boundary layer games. Original question to me:

You think the cold is over done by the euro? I liked the pattern we are in. Like we know extreme cold does nothing but send dry air in our parts

 

I like the pattern too. Agree with bolded 1,000 times, esp if a sneaky inverted trough helps the Valley:

The Euro was just amazing. It vastly under performed it's precip shield and had the moisture south of us, but I'll take a 999 mb low near Panama City with cold air in place every single time.

 

Has another huge snow event on the heels of the first one, once again a northern GOM low with a much smaller precip shield than would actually be the case with the track it shows. 

 

If that run came to pass I believe most of the valley would be under 6-16 inches of snow.

 

Overall the snow picture improved a bit overnight runs. Euro parallel still not as on board with the Euro Op but it is mainly timing of waves in both streams, as usual. Parallel is better at discerning both streams, but that does not necessarily mean it is right. A week out timing can change.

 

GFS is confused about boundary layer temps late next week 00/06Z all over the place. Are we shocked? Nope! GFS 00/06 Z runs both have a favorable 11-15 pattern. See what the 12Z does with both issues. I am less concerned with the bombs than the gorgeous west-east thickness lines that say Texas slider.

[Carvers Gap]

In between basketball games.  Just took a look at the 12zGFS...better hope the GEFS looks better, because the operational had nothing but passing chances through day 14.  Again, I think the models are struggling, but if one is looking for a more consolidated look...not happening w/ the GFS today.  Plenty of potential...the phrase for the winter.   Will check back later after game 2. 

[1234snow]

The CMC 12z has a similar idea to last nights Euro. It has 2 storms back to back but it is too warm for the 1st storm. 2nd storm is mostly warm too but the valley gets some good wraparound moisture.

[1234snow]

12z Euro out to 114. 1016 low pressure south of Louisiana. Precip shield is small in Louisiana.

[1234snow]

1st wave is going to be a miss on the Euro. Out to hour 126 and the precip shield isn't much above the Florida panhandle. Looking at 500mb the energy is just too positive tilt on this run. Let's see what the next wave brings.

[1234snow]

2nd wave looks like a mess similar to the GFS. Hour 192 main low is around Joplin, MO. Some overrunning is going into the cold air in East Tn. Then it warms too much after that.

This is a double barrel low solution. By 210 there are 2 lows. 1 is in the middle of KY. The other low is off the coast of NC. Most of Virginia looks to do okay with this setup as it looks like a wedge has set up there.

Then the main coastal low takes over giving the Northeast a good storm. It is down to 970 off Cape Cod.

[jaxjagman]

The CMC 12z has a similar idea to last nights Euro. It has 2 storms back to back but it is too warm for the 1st storm. 2nd storm is mostly warm too but the valley gets some good wraparound moisture.

Yeah that looks good.Euro tries,GFS is a split flow

 

Edit:actually the GFS isn't horrible

[Carvers Gap]

Well after a great 12z run yesterday...back to reality.  I think it wise to remember not to get frustrated w/ model runs.   They are just predictions and change w/ varying data input.  Indeed they are a computer program based on 1s and 0s.  That said...on w/ the 12z discussion.

 

1.  Thanks to 1234 for the discussion earlier.  Read through it in between games.  The EPS is basically WxSouth's winter forecast on a wx model.  Blocking over the top.  Lower heights in the SE w/ marginal temps.

 

2.  The GFS as mentioned before shows basically nothing for 16 days.  Now, the timing will actually change on many of those pieces of energy over the coming days.  My bet is something pops up sooner than later.

 

3.  Euro Deterministic.  Suppressed threat at 120.  Another threat a t 210.  Hybrid.

 

4.  CMC.  Clipper at 84.  Weak disturbance from GOM at 156.  Another at 192.  Like the look of both - but warm.  Then cold. 

 

5.  JMA for fun has a weak disturbance moving out of the GOM at 192. 

 

6.  GEFS.  Just go look at WxSouth's seasonal forecast for temps.  Looks remarkably similar to the EPS. 

 

7.  CPC ensembles.  NAO trends to neutral.   AO tries to come up for air, but doesn't quite get there.  PNA is forecast to strengthen even more.

 

Summary.  This weekend's system that produced rain was originally forecast at ten days to be on the EC.  It went to Michigan.  I maintain the models are really struggling with the high latitude blocking.  Seems it takes only a slight difference in the placement of the block, timing of energy, or just back-eddies in the jet to produce massive differences in outcomes on each wx model.  Super Nino continues to be the trump card.  Let's see if the strong blocking as it matures can produces a couple of strong systems before backing into the Hudson and connecting w/ the PNA ridge.  I feel certain the 0z is going to be very different.  No sure if good or bad...but different.  Theme for 12z...suppressed chances or warm-up and rain.   Most models really like the 1/17-1/18 time frame for the East.

[jaxjagman]

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1058 AM EST SAT JAN 09 2016

VALID 12Z TUE JAN 12 2016 - 12Z SAT JAN 16 2016

...MODEL PREFERENCES...
THROUGH DAY 4 (14/00Z-14/06Z)...THE 9/00Z GFS/ECMWF/CANADIAN AND
UKMET WERE CERTAINLY DEEPER THAN THE ENSEMBLE MEANS WITH THE
SURFACE CYCLONE IN THE GULF OF MAINE---BUT EVERYTHING SEEMS
REASONABLE AT THIS TIME SCALE FROM WEST TO EAST TO INCORPORATE
SOME 9/00Z DETERMINISTIC ECMWF/GFS INTO THE NATIONAL FORECAST.
ALONG WITH THE 9/00Z NAEFS AND/OR GEFS MEANS AT/BEYOND
14/12Z---THE ECENS MEANS WERE UTILIZED TO HANDLE THE REMAINDER OF
THE MEDIUM RANGE FORECAST.

ALTHOUGH THE PATTERN CHANGE ACROSS THE EASTERN HALF OF NORTH
AMERICA LOOKS TO BE ON TRACK---WHAT ACTUALLY TRANSPIRES DURING THE
TRANSITION HAS QUITE A BIT OF UNCERTAINTY 'HANGING IN THE
BALANCE'. THE FORECAST PHILOSOPHY FOLLOWS A 'SOUTHERN STREAM
DOMINANCE' THIS MEDIUM RANGE PERIOD---WITH SEPARATION FROM THE
NORTHERN STREAM --- BETWEEN THE CONTINENTAL DIVIDE AND DELMARVA
ALONG 40N LATITUDE.

BETWEEN DAYS 4 AND 6...THE DETERMINISTIC GUIDANCE BEGINS TO DIFFER
WITH RESPECT TO THE CHARACTER OF THE PACIFIC FLOW...ITS SHORTWAVE
DETAILS ENTERING THE WEST COAST ... CONTINENTAL DIVIDE AND
SOUTHERN ROCKIES. EAST OF THE DIVIDE AND ACROSS SOUTHEAST
CANADA...THE DETERMINISTIC GUIDANCE OFFERS A MYRIAD OF SOLUTIONS
FOR THE UPPER-LEVEL TROUGH AND FLOW TRANSITION FOR THE GREAT
LAKES...GULF COAST AND NORTHEAST. AND THE 9/00Z ECMWF OFFERS THE
BIGGEST RUN-TO-RUN 'CHANGE' OF THE 4 PRIMARY MODEL GUIDANCE
PACKAGES (GFS/CANADIAN/UKMET INCLUDED).

FOR NOW...BEST WAY TO DESCRIBE THE DIFFERENCES AND
IMPLICATIONS/CONCERNS HEADING INTO DAY 6--- PHASING OR
LACK-THERE-OF --- BETWEEN UPPER-LEVEL NORTHERN AND SOUTHERN JET
AXES. THE 9/00Z DETERMINISTIC GFS/CANADIAN/ECMWF DO A DECENT JOB
WITH THE NATURE OF THE SOUTHERN STREAM FLOW (THE SUBTROPICAL JET)
IN THE WESTERN GULF OF MEXICO AND NORTHERN CENTRAL MEXICO---BUT
THE 9/00Z ECMWF ESPECIALLY...MAINTAINS A MUCH WEAKER NORTHERN
STREAM WESTERLY 250MB SOLUTION ALONG THE ENTIRE STRETCH OF
CANADIAN BORDER. AND ALTHOUGH --- THE NORTHERN STREAM APPEARS TO
HOLD THE KEY TO THE LATTER HALF OF THIS MEDIUM RANGE PERIOD---WITH
PHASED JET OR SPLIT-FLOW (SEPARATED JET STREAMS)--- DETERMINING
THE OUTCOME OF BROAD AND DEEP COLD ADVECTION AND SENSIBLE WEATHER
EAST OF THE DIVIDE AND DOWNSTREAM OF THE MISSISSIPPI RIVER---USING
THE 9/00Z ECMWF DETERMINISTIC SOLUTION FOR DETAILS (CERTAINLY
BEYOND DAY 4) SEEMS TO BE THE MORE QUESTIONABLE OUTCOME DURING
THIS WEST-TO-EAST MID-LEVEL FLOW TRANSITION.

IF THERE IS A 'RENEWED' EL NINO APPROACH TO THE FLOW (MY OPINION)
AND HAS GOOD ENSEMBLE SUPPORT (AT THE MOMENT) --- IT IS WITH THE
CONSENSUS-DRIVEN SOUTHERN STREAM WESTERLY FLOW PATTERN ALONG 30N
LATITUDE FROM COAST TO COAST. AND WHAT MID-LEVEL ENERGY 'SPINS
OUT' OF THE SOUTHERN ROCKIES SHOULD BE --- WHERE TO WATCH AND
MONITOR AS IT WILL ORIGINATE --- BE THE SOURCE REGION FOR --- MUCH
OF THE MEDIUM RANGE AND DAY7+ SENSIBLE WEATHER.

...SENSIBLE WEATHER HIGHLIGHTS...
NEW ENGLAND WILL BE IN A FAVORABLE REGION OF MID-LEVEL
FRONTOGENESIS AND BRIEF WARM ADVECTION UP GLIDE --- FOR WINTER
CONDITIONS --- AS EXITING SURFACE CYCLONE MIGRATES ACROSS THE GULF
OF MAINE BETWEEN DAY 3-5.

THE GULF COAST APPEARS TO BE THE WETTEST PORTION OF THE NATION
THIS MEDIUM RANGE PERIOD---WITH THE WEST COAST A SECONDARY AREA OF
ORGANIZED SYNOPTIC-SCALE PRECIPITATION.

TEMPERATURES ACROSS THE GREAT LAKES AND NORTHERN PLAINS WILL ROUND
OUT THE TEMPERATURE HIGHLIGHTS ACROSS THE LOWER 48---AND BELOW
NORMALS READING FOR MID-JANUARY --- BOTH HIGHS AND LOWS.

VOJTESAK

[Carvers Gap]

EXTENDED FORECAST DISCUSSION

NWS WEATHER PREDICTION CENTER COLLEGE PARK MD

1058 AM EST SAT JAN 09 2016

VALID 12Z TUE JAN 12 2016 - 12Z SAT JAN 16 2016

...MODEL PREFERENCES...

THROUGH DAY 4 (14/00Z-14/06Z)...THE 9/00Z GFS/ECMWF/CANADIAN AND

UKMET WERE CERTAINLY DEEPER THAN THE ENSEMBLE MEANS WITH THE

SURFACE CYCLONE IN THE GULF OF MAINE---BUT EVERYTHING SEEMS

REASONABLE AT THIS TIME SCALE FROM WEST TO EAST TO INCORPORATE

SOME 9/00Z DETERMINISTIC ECMWF/GFS INTO THE NATIONAL FORECAST.

ALONG WITH THE 9/00Z NAEFS AND/OR GEFS MEANS AT/BEYOND

14/12Z---THE ECENS MEANS WERE UTILIZED TO HANDLE THE REMAINDER OF

THE MEDIUM RANGE FORECAST.

ALTHOUGH THE PATTERN CHANGE ACROSS THE EASTERN HALF OF NORTH

AMERICA LOOKS TO BE ON TRACK---WHAT ACTUALLY TRANSPIRES DURING THE

TRANSITION HAS QUITE A BIT OF UNCERTAINTY 'HANGING IN THE

BALANCE'. THE FORECAST PHILOSOPHY FOLLOWS A 'SOUTHERN STREAM

DOMINANCE' THIS MEDIUM RANGE PERIOD---WITH SEPARATION FROM THE

NORTHERN STREAM --- BETWEEN THE CONTINENTAL DIVIDE AND DELMARVA

ALONG 40N LATITUDE.

BETWEEN DAYS 4 AND 6...THE DETERMINISTIC GUIDANCE BEGINS TO DIFFER

WITH RESPECT TO THE CHARACTER OF THE PACIFIC FLOW...ITS SHORTWAVE

DETAILS ENTERING THE WEST COAST ... CONTINENTAL DIVIDE AND

SOUTHERN ROCKIES. EAST OF THE DIVIDE AND ACROSS SOUTHEAST

CANADA...THE DETERMINISTIC GUIDANCE OFFERS A MYRIAD OF SOLUTIONS

FOR THE UPPER-LEVEL TROUGH AND FLOW TRANSITION FOR THE GREAT

LAKES...GULF COAST AND NORTHEAST. AND THE 9/00Z ECMWF OFFERS THE

BIGGEST RUN-TO-RUN 'CHANGE' OF THE 4 PRIMARY MODEL GUIDANCE

PACKAGES (GFS/CANADIAN/UKMET INCLUDED).

FOR NOW...BEST WAY TO DESCRIBE THE DIFFERENCES AND

IMPLICATIONS/CONCERNS HEADING INTO DAY 6--- PHASING OR

LACK-THERE-OF --- BETWEEN UPPER-LEVEL NORTHERN AND SOUTHERN JET

AXES. THE 9/00Z DETERMINISTIC GFS/CANADIAN/ECMWF DO A DECENT JOB

WITH THE NATURE OF THE SOUTHERN STREAM FLOW (THE SUBTROPICAL JET)

IN THE WESTERN GULF OF MEXICO AND NORTHERN CENTRAL MEXICO---BUT

THE 9/00Z ECMWF ESPECIALLY...MAINTAINS A MUCH WEAKER NORTHERN

STREAM WESTERLY 250MB SOLUTION ALONG THE ENTIRE STRETCH OF

CANADIAN BORDER. AND ALTHOUGH --- THE NORTHERN STREAM APPEARS TO

HOLD THE KEY TO THE LATTER HALF OF THIS MEDIUM RANGE PERIOD---WITH

PHASED JET OR SPLIT-FLOW (SEPARATED JET STREAMS)--- DETERMINING

THE OUTCOME OF BROAD AND DEEP COLD ADVECTION AND SENSIBLE WEATHER

EAST OF THE DIVIDE AND DOWNSTREAM OF THE MISSISSIPPI RIVER---USING

THE 9/00Z ECMWF DETERMINISTIC SOLUTION FOR DETAILS (CERTAINLY

BEYOND DAY 4) SEEMS TO BE THE MORE QUESTIONABLE OUTCOME DURING

THIS WEST-TO-EAST MID-LEVEL FLOW TRANSITION.

IF THERE IS A 'RENEWED' EL NINO APPROACH TO THE FLOW (MY OPINION)

AND HAS GOOD ENSEMBLE SUPPORT (AT THE MOMENT) --- IT IS WITH THE

CONSENSUS-DRIVEN SOUTHERN STREAM WESTERLY FLOW PATTERN ALONG 30N

LATITUDE FROM COAST TO COAST. AND WHAT MID-LEVEL ENERGY 'SPINS

OUT' OF THE SOUTHERN ROCKIES SHOULD BE --- WHERE TO WATCH AND

MONITOR AS IT WILL ORIGINATE --- BE THE SOURCE REGION FOR --- MUCH

OF THE MEDIUM RANGE AND DAY7+ SENSIBLE WEATHER.

...SENSIBLE WEATHER HIGHLIGHTS...

NEW ENGLAND WILL BE IN A FAVORABLE REGION OF MID-LEVEL

FRONTOGENESIS AND BRIEF WARM ADVECTION UP GLIDE --- FOR WINTER

CONDITIONS --- AS EXITING SURFACE CYCLONE MIGRATES ACROSS THE GULF

OF MAINE BETWEEN DAY 3-5.

THE GULF COAST APPEARS TO BE THE WETTEST PORTION OF THE NATION

THIS MEDIUM RANGE PERIOD---WITH THE WEST COAST A SECONDARY AREA OF

ORGANIZED SYNOPTIC-SCALE PRECIPITATION.

TEMPERATURES ACROSS THE GREAT LAKES AND NORTHERN PLAINS WILL ROUND

OUT THE TEMPERATURE HIGHLIGHTS ACROSS THE LOWER 48---AND BELOW

NORMALS READING FOR MID-JANUARY --- BOTH HIGHS AND LOWS.

VOJTESAK

At first glance, that sounds pretty good.  We will see.    Nice info.  I always forget to read their discussion.  Usually is very good.

[jaxjagman]

Larry C.

 

I smell a major winter storm coming. And I strongly suspect that an area from the lower Great Plains through the Old South, Appalachia and the Eastern Seaboard will be involved. Timing and track sequence is everything here, and it does not help one bit that some of the most widely used forecast models are not handling the risk of intense cyclogenesis very well, If at all! The GFS and ECMWF series have been wildly inconsistent with the prospect of energy from the subtropical jet stream phasing with a shortwave rotating around a cAk vortex near James Bay in the January 17-21 time frame.

But if you follow a blend of the GGEM model suite and the European ensemble group, which for the most part have been consistent with both the formation mechanism and pressure/precipitation trajectory of this prospective system. That is important for the main reason that many living east of the Mississippi River and below Interstate 80 have seen no appreciable snow this winter. And if these schemes are correct, that is all about to change.

There will likely be a warm-up of sorts late week across the eastern and southern portions of the U.S. The cold dome over Ontario and Quebec may contract somewhat in response to warm advection associated with the subtropical jet stream and its impulse as it moves into Texas from Mexico. But the lower-latitude track (this time along the Gulf Coast and into North Carolina) looks to start pulling in colder air. The path idea that I am currently following calls for the low pressure center to make a jump to offshore of the Delmarva Peninsula on the morning of January 18, then intensify passing over Nantucket MA toward an eventual destination near Halifax NS on January 19. I cannot say for sure that the snowfall prediction of the Canadian model will verify. But I am inclined to think that the advance of cA values will be strong enough to offset warmer than normal oceanic temperatures, and that accumulations of snow may make it over or at least near to the Interstate 95 cities at and above Washington DC.

And you know what else? Read the EXTENDED OUTLOOK below about another important storm threat to the same geographic area in the last third of January.

[jaxjagman]

The recent expansion of convection over the Indian Ocean gave pause to many forecasters who support the colder JFM portion of the winter forecast. As it turns out, however, the broad area of tropical forcing near and to the right of the International Dateline is holding steady. With the continued promise of both amplifying the northern branch jet stream into a complex blocking pattern (+PNA/-AO/-NAO) and enhancing the subtropical wind field, our thoughts turn to what sections of the nation will be coldest over the rest of January. And where the storm track will set up.

I made a small alteration in my analog list, discarding one insertion of 1998 and adding 1958. The similarities of the winter 40 years ago are impressive, from the +PDO signature, the weakening but still strong El Nino, and the development of cold intrusions under formative blocking ridges at high latitudes. While no season is an exact match for the present day, the evolution of the current winter has some strong parallels that cannot be ignored.

The snow cover is expected to expand south and east over the next ten days. At the same time, the "triple block" at 500MB seems destined to continue, and trash some of the expectations for a "winter cancel" that flowed from both media and scientific sources since last summer. I suspect that the atmosphere is going to try and "right itself", as both atmospheric and oceanic temperatures have been unusually high since late last summer.

If you run the revised analogs for 500MB and temperature forecasts, you come up with these conclusions. One, that any "January Thaw" will be brief; we have already had a warm response for so long, it makes no sense in climatology to revert existing upper air patterns so quickly again. Another is the storm threat. As you can see by my hemispheric plots between January 20 - 29, the risk for a true monster disturbance, and follow-up cold advection, is very high. The model ensemble forecasts are supportive of a energy digging through California, then proceeding through Texas and Dixie before moving just off of the East Coast. I suspect the time frame is a little slow. But you get the picture that something impressive could happen if the comparison mean is correct. This system in theory would produce abundant snow cover well to the south and east of what is expected with the January 17 - 20 system. Also, the potential for widespread and likely long-lasting cold must be mentioned.

The blended projection for February calls for a warm/dry West vs. cold and stormy East, but with a slight difference. Note the extensive dry anomaly over the Midwest and Mississippi Valley, while a higher precipitation risk is present along the Gulf Coast and Eastern Seaboard. This speaks of an Arctic air mass presence which keeps the base storm track offshore from the South and Coastal Plain.

Wonder what could result from that arrangement in the Interstate 10, 20 and 95 corridors? But for now, that is just speculation. Get set for an active, and wintry, January 2016 forecast.

Prepared by Meteorologist LARRY COSGROVE on

[Carvers Gap]

Very active pattern found in the 0z model suite. Some very different solutions, but much more like one would think that a strong Nino and strong blocking would produce. Heading off to church or would comment more.

[JayCee]

Wind is howling here this morning.  I'm thankful we've had some time to dry out a bit since the saturating rains of December.  Otherwise, we'd probably be having some trees uprooted if the soil was still as wet as it was a few weeks ago.

[John1122]

Not sure what to make of any model run right now, they change so massively from run to run, even in the 6-8 day range. I guess we will have to wait until inside of 3 days to get any handle on what will actually happen.

[John1122]

06z features some clippers riding through the area, giving the 40 corridor and points north 2-4 inches of snow over the next 10 days, then follows that up with a major Miller A snow storm on day 11, followed by bone chilling cold.  

 

This is progressing very similarly to 1966 still. The pattern flipped by January 6th or so that year. It stayed below normal with a few rain and light snow events (<2 inches each) over the next few weeks until the large snowstorm hit January 29th and brought Arctic cold with it for a brief visit. 

 

It's currently 9 degrees as I type this, we had snow showers for the second time in the past few days today. We will have them again tomorrow afternoon most likely. I like where we're at and where we could be going pretty well over the next few weeks.

 

In my case, I am not holding as much hope out for February as everyone else seems to be, but I could be wrong.

[JayCee]

MRX isn't sounding optimistic about snow chances tomorrow.   

 

 

LONG TERM...(TUESDAY THROUGH SUNDAY)...FAST MOVING CLIPPER MOVES
THROUGH THE SOUTHERN APPALACHIAN REGION ON TUESDAY INTO TUESDAY
NIGHT BUT VERY LITTLE MOIST AIR WILL BE AVAILABLE AHEAD OF THE NEXT
SURGE OF COLD CANADIAN AIR. IT DOESN`T EVEN LOOK LIKE THERE WILL BE
ANY PRECIP SOUTH OF I-40. HAVE BEEN TRIMMING BACK AREAL PRESENTATION
OF PREDICTED SNOWFALL AS WELL AS AMOUNTS FOR THE PAST THREE DAYS AND
THE TREND CONTINUES WITH TODAY`S FORECAST. SNOWFALL ACCUMULATION
WILL BE LIMITED TO THE HIGHER TERRAIN MAINLY ACROSS SOUTHWEST
VIRGINIA AND THE MOUNTAINS ACROSS EXTREME NORTHWEST TENNESSEE WHERE
AMOUNTS WILL BE IN THE NEIGHBORHOOD OF A HALF TO ONE INCH OF SNOW.
 

[jaxjagman]

 

[nrgjeff]

Weather pattern should stay colder than normal but variable. This weekend into early next week looks similar to a repeat maybe 12 hours faster. Assuming snow is again deposited from MO to West KY low temps early next week should verify very cold again.

 

Weekend system could also be a repeat. Northern stream partner is almost always bad. No high press north with a sfc low instead; 850 line dragged north; and, boundary layer issues Valley. This is no big disappointment though because it has been shown that way for a while. 7-14 day still looks promising. Hey, we moved it forward from 11-15 so we're making progress!

 

General note about my northern stream preaching: Forecasting rule says with a vort max north do not forecast snow. Now if high press is anchoring cold air, one might forecast ice. However it is very hard to get a full snow profile that way. Weak/no high press, and certainly low press north, forecast rain.

 

Next week the GFS wants to slide clipper-like systems through. Euro wants to absolutely bury everything in the southern stream. Oh John and I should be careful what we wish for, per the 999 Florida low agreement, lol. At the same time I kind of share his optimism about at least possibilities.

 

One could just blend the two and get a perfect track, but that's wish-casting. More importantly as the pattern builds one could forecast a little better cooperation, or maybe less influence overall, from the northern stream. We need a system to dig into Texas and then shoot east. Don't keep digging into Cuba and don't cut through the MO Bootheel. If we can get just one to dig into the Plains/Texas instead of pivoting too soon from the southern Rockies, maybe... 

 

DT WxRisk explains another general forecasting rule in his SECS MECS thread - also valid here, esp Tenn Valley. System must pivot at the right time. Too late and it is cold and dry. Too early and it is rain. The posts linked are a gold mine of simple yet extremely effective forecasting methodology, and an example. 

 

http://www.americanwx.com/bb/index.php/topic/47565-on-the-jan-17-18-secs-mecs-threat/?p=3844395

 

http://www.americanwx.com/bb/index.php/topic/47565-on-the-jan-17-18-secs-mecs-threat/?p=3844404

[Carvers Gap]

Weather pattern should stay colder than normal but variable. This weekend into early next week looks similar to a repeat maybe 12 hours faster. Assuming snow is again deposited from MO to West KY low temps early next week should verify very cold again.

Weekend system could also be a repeat. Northern stream partner is almost always bad. No high press north with a sfc low instead; 850 line dragged north; and, boundary layer issues Valley. This is no big disappointment though because it has been shown that way for a while. 7-14 day still looks promising. Hey, we moved it forward from 11-15 so we're making progress!

General note about my northern stream preaching: Forecasting rule says with a vort max north do not forecast snow. Now if high press is anchoring cold air, one might forecast ice. However it is very hard to get a full snow profile that way. Weak/no high press, and certainly low press north, forecast rain.

Next week the GFS wants to slide clipper-like systems through. Euro wants to absolutely bury everything in the southern stream. Oh John and I should be careful what we wish for, per the 999 Florida low agreement, lol. At the same time I kind of share his optimism about at least possibilities.

One could just blend the two and get a perfect track, but that's wish-casting. More importantly as the pattern builds one could forecast a little better cooperation, or maybe less influence overall, from the northern stream. We need a system to dig into Texas and then shoot east. Don't keep digging into Cuba and don't cut through the MO Bootheel. If we can get just one to dig into the Plains/Texas instead of pivoting too soon from the southern Rockies, maybe...

DT WxRisk explains another general forecasting rule in his SECS MECS thread - also valid here, esp Tenn Valley. System must pivot at the right time. Too late and it is cold and dry. Too early and it is rain. You do not have to agree with the original post forecast. The posts linked are a gold mine of simple yet extremely effective forecasting methodology, and an example.

http://www.americanwx.com/bb/index.php/topic/47565-on-the-jan-17-18-secs-mecs-threat/?p=3844395

http://www.americanwx.com/bb/index.php/topic/47565-on-the-jan-17-18-secs-mecs-threat/?p=3844404

Jeff, what do you make of the 12z Euro in the LR. Some support w other models, not much. But a big switch...it has hinted af this for a couple of days. Mr. Bob feel free to jump in as well.

[Carvers Gap]

Just dropping in before heading off to help coach basketball. Big changes the past couple of days on the Euro in that the -NAO and -AO vanish in about a week. Rapid switch to positive for each. The 12z GFS is more steady with the -NAO and -AO throughout its run. At some point have to wonder if the GFS is going to cave to the Euro...but the Euro did struggle with last year's cold pattern constantly trying to break it down. However, w a Nino in place this year it is plausible. The 12z Euro after a big cold shot flips warm. Has been hinting at this for a couple of days...so this is not really a post about one run. Just that the trend on the Euro is growing stronger w each run. I did look at each of the EPS members for days 13&15. They did not overwhelming support the flip, but at least half did.

Something to watch during the next few days...

Edit: 18z GFS joins the Euro in quickly breaking down the NAO in the LR... Super Nino taking over is the trend today.

[Stovepipe]

My takeaway from recent modeling is that the clipper this week will be mostly a non-event, maybe a little action for northern plateau and mountains.  There seems to be very little in the way of ensemble support for anything other than a cutter with rain for next weekend although obviously things can still change (maybe a backside dusting?).  What has me mildly encouraged for next week is the EPS (as opposed to Euro OP).  Today's 12z was the 5th run in a row that had most of the great valley in 2+ inches mean snow with parts of the area at 4 inches.  Not only snow maps, but the locations of the lows moving through seem to suggest we could avoid another cutter or Cuba squash.  Oh and decently cold air seems to be somewhat abundant during the period.  We'll see.  There is so much flip-flopping in the operational runs it's not even banter-worthy to post fantasies.  Hoping to keep some consistency for a shot next week.  Beyond that it seems nearly impossible to speculate. 

 

I will say it is refreshing to look out and see the sun reflecting off what little snow the mountains got.  That has been a rare sight this winter!  Also, I got down to 16 degrees this morning, it was the final blow to the mustard greens haha.  Not complaining.

 

[jaxjagman]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NASHVILLE TN
255 PM CST MON JAN 11 2016

.DISCUSSION...

SUNNY AND COOL IS THE STORY FOR TODAY.  HIGH PRESSURE HAS TAKEN OVER
AND WINTER-ISH TEMPERATURES ABOUND.  HIGHS TODAY WILL STRUGGLE TO
MAKE 40 IN MOST PLACES TODAY...WHICH IS A GOOD 6 TO 8 DEGREES BELOW
NORMAL. AS THE SURFACE LOW CURRENTLY OVER IOWA PUSHES EASTWARD
TONIGHT AND AN UPPER LEVEL JET-MAX DIGS THE ASSOCIATED TROUGH INTO
THE OHIO AND TENNESSEE VALLEYS...A VERY WEAK PRE-FRONTAL SURFACE
TROUGH WILL MOVE INTO THE MID-STATE.  MODELS CONTINUE TO BE QPF-FREE
ACROSS OUR COUNTIES BUT TONIGHT WILL BE AN INTERESTING STUDY IN HOW
THESE CLIPPER SYSTEMS AFFECT MIDDLE TN.  FORECAST SOUNDINGS HAVE
BEEN PERSISTENT IN PROVIDING SUFFICIENT DEEP-LAYER MOISTURE...DEEP
ENOUGH FOR CRYSTAL FORMATION.  TYPICALLY...YOU WOULD THINK THAT
WITHOUT ANY QPF WE WON`T GET ANY SNOW...BUT ODDLY ENOUGH WE
USUALLY DO. WITH A LITTLE BIT OF SYNOPTIC AND OROGRAPHIC LIFT
THROWN IN...SOME SNOWFLAKES COULD REACH THE GROUND. IF THERE`S ANY
GOOD NEWS...IT`S THAT NO ACCUMULATIONS ARE EXPECTED BECAUSE THERE
JUST ISN`T ENOUGH OVERALL MOISTURE AND THE AIR DRIES OUT QUICKLY
AS THE ACTUAL FRONT MOVES IN BEHIND THIS FEATURE. SO...SOME LIGHT
SNOW AND FLURRIES AS FAR SOUTH AS THE METRO AREA ARE POSSIBLE BY
DAYBREAK TOMORROW BUT BY NOON...THE DRY AIR SHOULD INTRUDE QUICK
ENOUGH TO END THE FLAKES. HOWEVER...THAT DRY AIR IS ALSO VERY
COLD. TEMPERATURES VERY SIMILAR TO WHAT WE SAW THIS MORNING ARE
LIKELY WEDNESDAY MORNING.

THE SURFACE RIDGE RESPONSIBLE FOR THE COLD AIR WEDNESDAY WILL PUSH
SOUTH AND EAST OF US THURSDAY.  THIS WILL PUT US INTO A WEAK RETURN
FLOW ALLOWING FOR TEMPERATURES TO CLIMB INTO THE LOW TO MIDDLE 50S
THURSDAY AND FRIDAY.  UNFORTUNATELY...RETURN FLOW MEANS EVENTUAL
RAIN AND THIS IS NO DIFFERENT.  RAIN CHANCES INCREASE ON FRIDAY AS A
WARM FRONT LIFTS NORTHWARD THROUGH THE STATE.  I DON`T SEE ANY
THUNDER INVOLVED AS MID-LEVEL LAPSE RATES ARE POOR.  WILL MAINTAIN
RAIN ONLY THROUGH FRIDAY EVENING.

AS QUICKLY AS WE WARM UP...THE COLD AIR WILL RETURN...AND IT LOOKS
LIKE THERE WILL BE A LITTLE MOISTURE WITH WHICH TO WORK.  SO...BY
MIDDAY SATURDAY...CAA SHOULD BE SUFFICIENTLY STRONG ENOUGH TO ALLOW
FOR SOME MORE FLURRIES/LIGHT SNOW AND MOISTURE COULD LINGER LONG
ENOUGH TO ALLOW FOR THE WHITE WINTRY STUFF TO PERSIST INTO
SATURDAY NIGHT AND SUNDAY. STILL THOUGH...NO ACCUMULATIONS ARE
EXPECTED.

BEYOND SUNDAY...THERE IS ONE THING MODELS AGREE ON.  IT`S GONNA BE
COLD.  THE EURO IS THE COLDER AND DRIER OF THE TWO SOLUTIONS WITH A
1040MB CP RIDGE DIGGING INTO THE EASTERN HALF OF THE COUNTRY.  THE
GFS ISN`T QUITE AS COLD...BUT IT DOES PROVIDE ADDITIONAL
OPPORTUNITIES FOR THAT WHITE WINTRY STUFF MONDAY AND MONDAY NIGHT.
FOR NOW...WILL LEAVE THE FORECAST DRY AFTER SUNDAY AND WORK THE
KINKS OUT OF THE EXTENDED FORECAST AS WE GO THROUGH THE WEEK.

&&

[John1122]

GFS keeps showing a suppressed Gulf storm Sunday. 18z had it leaving central Mexico and moving towards Cuba. 00z and 06z Pops a LP off the LA coast and tracks it ESE towards Florida then up the coast a bit before going out to sea. The 06z moved it about 50-100 miles north of where it was on the 00z after the 00z moved it about 300 miles north of where it was on the 18z. Hopefully the threat is real, I'll be shocked if the storm doesn't have a N/NW trend as it gets closer if it can stick around. I just hope it doesn't trend into a GLC.

[John1122]

As for the clipper today, SE Kentucky and SW Virginia look to be in line for some pretty good snow showers. Hopefully some sneak their way across the border, looks like the best chance for that is Johnson County and that area. Jackson WFO mentions heavy squalls possible with isolated 2 inch amounts for areas that get under one. Pretty much the pop up thunderstorm equivalent snow showers.

[Carvers Gap]

GFS keeps showing a suppressed Gulf storm Sunday. 18z had it leaving central Mexico and moving towards Cuba. 00z and 06z Pops a LP off the LA coast and tracks it ESE towards Florida then up the coast a bit before going out to sea. The 06z moved it about 50-100 miles north of where it was on the 00z after the 00z moved it about 300 miles north of where it was on the 18z. Hopefully the threat is real, I'll be shocked if the storm doesn't have a N/NW trend as it gets closer if it can stick around. I just hope it doesn't trend into a GLC.

6z GFS reduces the strength of the Lakes cutter this weekend almost until it gets to Canada. That really changes the sensible wx that follows. It and the 0z Euro are very different in the LR. Euro has a torch and the GFS holds onto normal temps in the SE for much of its run if not below. Canadian is very warm at 240. Both the Euro and Canadian show +20 temps moving in after 240. What is your take on the differences?

[Carvers Gap]

12z GFS continues the trend this weekend...weakens the cutter and strengthens the EC surface low. Sets the stage for the trailing event. 84 NAM(I know...h84) shows in its sim radar a much bigger surface reflection for the first low even thought the pressure is deeper for the cutter. Again sets the stage for what follows. Will wait for other models before commenting more... But at 120, this is no longer fantasy.

Edit...just looking at low position, not temps. Also, anyone think we need a short range thread and turn this into the medium/LR thread?

[JayCee]

From radar appearances, it looks like the bulk of the precip with today's event is staying in KY.  I'd say John stands the best chance of seeing much, thanks to his location & elevation.  Other than that, probably a quit hitting light rain or light rain/snow mix for the rest of us.  Of course, the mountains will probably see more due to elevation and upslope. 

 

A ho-hum event

[lugnuts]

From radar appearances, it looks like the bulk of the precip with today's event is staying in KY.  I'd say John stands the best chance of seeing much, thanks to his location & elevation.  Other than that, probably a quit hitting light rain or light rain/snow mix for the rest of us.  Of course, the mountains will probably see more due to elevation and upslope. 

 

A ho-hum event

Finally got under a decent band here in SE Ky..Maybe will get a deck coating before everything moves out..Was hoping for at least an inch but it is what it is..Anyways hopefully something will develop this weekend for the Tenn. valley..If Sunday's system can start to trend inland some maybe there's hope.

[John1122]

Have limited Internet due to power being out and bad signal here. But getting light snow and strong winds right now. Not been able to look at any 12z suite models.