New Years' Weekend Snow Potential

[Hoosier]

looks to me like the EE rule is in effect…GFS setting up for another fail?

 

Bad sign for the Euro.  You rarely want to resemble the NAM at 72-84 hours. 

[buckeye]

did michsnowfreak just post the Norwegian? Buckeye would be proud.

 

attaboy Mich!!!!!  

 

let me know if you need a link to the ensemble package

[Rainman]

looks to me like the EE rule is in effect…GFS setting up for another fail?

 

The 12z GFS changed its tune wildly today compared to yesterday's 00z.  So yes, probably.

[snowstormcanuck]

did michsnowfreak just post the Norwegian? Buckeye would be proud.

 

I think that page is giving EURO QPF output.

[A-L-E-K]

I think that page is giving EURO QPF output.

 

you're probably right and i'm mostly just teasing

[snowstormcanuck]

you're probably right and i'm mostly just teasing

 

I woosh'ed.

[Gilbertfly]

snippet from IWX....

 

 

NATIONAL WEATHER SERVICE NORTHERN INDIANA
344 PM EST WED DEC 31 2014


A TOUGH FORECAST MOVING INTO THIS WEEKEND AS SIGNIFICANT UNCERTAINTY
STILL EXISTS REGARDING THE EXACT TRACK OF THE SURFACE LOW AND THE
CONSEQUENT THERMAL PROFILE. CONFIDENCE IS INCREASING THAT THE WARM
LAYER ALOFT WILL OVERSPREAD OUR ENTIRE AREA BY THE LATE AFTERNOON ON
SATURDAY WHICH WILL ELIMINATE THE CHANCE FOR ANY SNOW...BUT BOTH THE
GFS AND ECMWF KEEP SURFACE TEMPS AT OR SLIGHTLY BELOW FREEZING FOR A
MAJORITY OF THE EVENT ACROSS OUR NORTHWESTERN HALF. THE INHIBITING
FACTORS FOR FREEZING RAIN ARE THE LACK OF SNOWCOVER...THE LACK OF A
STRONG HIGH NORTH OF THE SYSTEM...AND PRECIPITATION ONSET DURING THE
DAYTIME HOURS. THESE INHIBITING FACTORS SHOULD KEEP SIGNIFICANT
ICING POTENTIAL QUITE LOW...ALTHOUGH IF THIS STORM SYSTEM SLOWS EVEN
FURTHER..THE ICING POTENTIAL MAY INCREASE AS DIURNAL TEMPERATURE
FALLS WILL ASSIST IN KEEPING TEMPERATURES BELOW FREEZING.

CURRENT THINKING IS THAT A BRIEF PERIOD OF FREEZING RAIN WILL LIFT
THROUGH THE AREA WITH ACCUMULATION LESS THAN A TENTH OF AN INCH
BEFORE PRECIPITATION CHANGES OVER TO ALL RAIN FOR A MAJORITY OF THE
FORECAST AREA AND THEN CHANGES TO A BRIEF PERIOD OF SNOW ON THE BACK
SIDE. KEPT CATEGORICAL POPS LIMITED TO THE SE ON SATURDAY NIGHT DUE
TO THE UNCERTAINTY WRT TIMING AND THE POTENTIAL FOR THIS SYSTEM TO
SLOW EVEN FURTHER.

[Gilbertfly]

Freezing rain likely and snow likely added for Saturday and Saturday night for MBY via LOT....

 

AFD should be an interesting read with those probs being put in place

[Chicago Storm]

Freezing rain likely and snow likely added for Saturday and Saturday night for MBY via LOT....

 

AFD should be an interesting read with those probs being put in place

SATURDAY THROUGH WEDNESDAY...  

 

307 PM...MULTIPLE FORECAST CONCERNS AND CHALLENGES INCLUDING...A  

WINTRY MIX OF PRECIP SATURDAY CHANGING TO POSSIBLE ACCUMULATING  

SNOW SATURDAY NIGHT...TURNING MUCH COLDER AND WINDY SUNDAY...THEN  

ANOTHER POSSIBLE ACCUMULATING SNOW MONDAY NIGHT WITH A FAST MOVING  

CLIPPER SYSTEM...THEN EVEN COLDER INTO MID NEXT WEEK.  

 

ONE AREA OF LOW PRESSURE WILL BE MOVING EAST FROM THE ROCKIES TO  

THE NORTHERN PLAINS FRIDAY NIGHT INTO SATURDAY AS A SECOND LOW  

DEVELOPS NEAR THE ARKLATEX FRIDAY NIGHT. THE NORTHERN PLAINS LOW  

WEAKENS AND ELONGATES THE SURFACE TROUGH OF THE LOW MOVING NORTH  

FROM THE SOUTH DURING THE DAY SATURDAY. THIS MAIN LOW IS THEN  

PROGGED TO MOVE ACROSS INDIANA SATURDAY EVENING TO THE EASTERN  

LAKES SUNDAY MORNING AS IT STRENGTHENS. WHILE THIS GENERAL TRACK  

HAS BEEN FAIRLY CONSISTENT FOR THE PAST FEW DAYS AND TRENDS ARE  

EMERGING WITH THIS OVERALL SPEED...THERE STILL REMAINS SOME  

UNCERTAINTY REGARDING THE EXACT TRACK AND MORE IMPORTANTLY PRECIP  

TYPE OVER THE CWA.  

 

GIVEN THE THERMAL PROFILES FROM THE FORECAST SOUNDINGS...IT WOULD  

APPEAR THAT A WINTRY MIX OF PRECIP IS LIKELY. THIS TRACK WOULD  

SUGGEST MORE SNOW/SLEET ACROSS THE NORTH...TO A MIX OF FREEZING  

RAIN/SLEET ACROSS THE CENTRAL CWA TO A FREEZING RAIN CHANGING TO  

RAIN ACROSS THE SOUTH/SOUTHEAST. WHILE SMALL CHANGES TO THE  

TRACK/THERMAL PROFILES WILL RESULT IN LARGE CHANGES TO THE  

FORECAST...FELT IT WAS PRUDENT AT THIS POINT TO INCLUDE A WINTRY  

MIX BASED ON THE CURRENT CONSENSUS TRACK OF THE LOW. HOWEVER...  

THE LONG WEAK TROUGH OVER THE WESTERN LAKES DURING THE DAY ON  

SATURDAY ADDS UNCERTAINTY TO SURFACE TEMPS...WHICH COULD END UP  

BEING ABOVE FREEZING. OPTED TO ADD FREEZING RAIN TO THIS FORECAST  

WHICH ALSO MATCHES WITH WPC THOUGHTS OF A POSSIBLE SWATH OF LIGHT  

ICE ACCUMULATION ACROSS PORTIONS OF THE SOUTHERN GREAT LAKES.  

CONFIDENCE OF A WINTRY MIX IS INCREASING BUT AGAIN ITS IMPORTANT  

TO STRESS SMALL CHANGES COULD HAVE LARGE IMPACTS TO THE FORECAST.  

 

BY SATURDAY NIGHT...AS THE LOW BEGINS TO DEPART...THERE IS GROWING  

CONSENSUS OF A BAND OF SNOW DEVELOPING FROM NORTHERN MISSOURI TO  

SOUTHERN WISCONSIN WITH THE ECMWF FURTHEST TO THE SOUTHEAST. BY  

THIS TIME...THERMAL PROFILES SUGGEST PRECIP TYPE WILL BE SNOW OR  

QUICKLY CHANGING TO SNOW LATE SATURDAY AFTERNOON/EARLY SATURDAY  

EVENING. IF THIS WERE TO DEVELOP...A FEW INCHES OF SNOW WOULD BE  

POSSIBLE BUT CONFIDENCE REGARDING THE AREAS THIS IS MOST LIKELY TO  

OCCUR IS LOW AT THIS TIME.  

 

THE GRADIENT QUICKLY TIGHTENS SUNDAY MORNING AS THE SNOW IS ENDING  

WITH MUCH COLDER AIR SPREADING ACROSS THE AREA. COULD BE A RATHER  

WINDY PERIOD WITH FALLING TEMPERATURES AND WHERE ANY SNOW DOES  

FALL...BLOWING SNOW. TEMPERATURES CONTINUE TO FALL SUNDAY NIGHT  

INTO MONDAY MORNING WITH LOW SINGLE DIGITS ON TRACK...AND POSSIBLY  

COLDER WHEREVER A SNOW PACK EXISTS.  

[michsnowfreak]

I think that page is giving EURO QPF output.

Thats what it is. I dont even know where to get the Norweigan lol. Its the closest thing I have to text data for Euro output

[Gilbertfly]

SATURDAY THROUGH WEDNESDAY...  

 

 

Thanks Joe....I'm always late to get the updates there for some reason....

 

nothing too earth shattering in the update I suppose...but at least trending towards possibilities of wintery weather to get the ball rolling

[Stebo]

 

THE AREA OF INTEREST FOR THIS WEEKEND`S SYSTEM HAS NARROWED

TO THE SECTOR BETWEEN 160W-140W IN THE NORTHERN GULF OF ALASKA

BETWEEN NOW AND ABOUT 00Z FRIDAY. SUNY STONY BROOK NCEP/CMC ENSEMBLE

SENSITIVITY ANALYSIS (VALID 00Z) REVEALS A MAJORITY OF SPREAD WITHIN

THE GREAT LAKES SECTOR BY THIS WEEKEND IS DIRECTLY ATTRIBUTABLE TO

THE EVOLUTION OF THE NORTHERN STREAM/GOA WAVE OVER THE NEXT 24 HOURS

OR SO. IN PARTICULAR, THE SPREAD LOOKS TO BE TIED TO THE BRIEF

DEVELOPMENT SEQUENCE THAT WILL BE TAKING PLACE OVER THE NEXT DAY

DURING WHICH TIME IT WILL UNDERGO DEEPENING BEFORE COMING ONSHORE IN

BRITISH COLUMBIA THURS NIGHT INTO EARLY FRIDAY. THIS WILL IMPACT

BOTH THE INTENSITY OF THE NORTHERN WAVE ITSELF AND THE SUBSEQUENT

DOWNSTREAM SHORTWAVE RIDGING RESPONSE. BOTH OF THESE WILL IN TURN

HAVE IMPLICATIONS FOR THE NATURE OF ITS ENTRAINMENT INTO THE MEAN

FLOW AND SUBSEQUENT EVOLUTION OF ITS INTERACTION WITH THE SW U.S.

CUTOFF LOW.

IN ADDITION, RATHER SUBTLE ENERGY ORIGINATING IN THE SUBTROPICS

LOOKS TO BE DRAWN AROUND THE CLOSED LOW AND ACROSS MEXICO FRIDAY

NIGHT INTO SATURDAY MORNING AND REPRESENTS A POTENTIAL KEY PLAYER IN

EXACT STRENGTH/PLACEMENT OF A JET THAT IS PROGGED TO RAPIDLY BLOW UP

TO 190-200KTS WHILE THE LOW IS LIFTING ACROSS THE GREAT LAKES. IN

SHORT, A LOT OF SENSITIVE ASPECTS OF THE FORECAST THAT WILL TAKE

SOME TIME TO COMPLETELY SORT OUT.

AS IT STANDS, 12Z MODEL TRENDS WERE NOT TERRIBLY DIFFERENT AT THE

SURFACE, BUT TRENDS ALOFT WERE DECIDEDLY TOWARD THE ECMWF. THE GEM

MAINTAINED ITS STRONGER AND MORE PHASED SOLUTION, BUT UPPER LEVEL PV

ANALYSIS REVEALS INCREASED WAVE SEPARATION BETWEEN THE NORTHERN WAVE

AND THE EJECTING CLOSED LOW COMPARED TO PRIOR RUNS, PERHAPS

INDICATIVE OF A TREND TOWARD SOMETHING SLIGHTLY LESS PHASED AND MORE

IN AGREEMENT WITH MANY OF THE CMC ENSEMBLE MEMBERS. ALSO WORTH

NOTING IS THE LACK OF SHORTWAVE RIDGING BETWEEN THE WAVES IN THE CMC

APPEARS RATHER SUSPECT. MEANWHILE, THE GFS HAS COMPLETELY CHANGED

COURSE. THE MODEL THAT WAS ONCE SHOWING ZERO INTERACTION BETWEEN THE

TWO WAVES AS THE LOW WAS KICKED OUT OF THE SOUTH NOW SHOWS A

DEFINITIVE OVERLAPPING OF ROSSBY RADII AND NOD TOWARD THE PARTIAL

PHASING SUGGESTED BY THE ECMWF. AFTER A FEW BAD CYCLES EARLIER IN

THE WEEK, THE EURO APPEARS TO NOW POSSESS BOTH THE MODEL "MIDDLE

GROUND" IN TERMS OF WAVE PLACEMENT/INTERACTION ALOFT AS WELL AS THE

BEST CONTINUITY OVER THE LAST COUPLE OF RUNS.

REGARDLESS OF DETAILS A GENERAL COLD-WARM-COLD SCENARIO LOOKS TO BE

IN PLAY FOR SE MICHIGAN, ESPECIALLY ACROSS THE FAR SOUTHEAST, WITH

THE SYSTEM STARTING AND ENDING WITH FROZEN PRECIP AT ALL LOCATIONS.

THE PRIMARY CHANGE TO THE FORECAST TODAY WAS TO ADD A CHANCE OF

FREEZING RAIN TO THE FORECAST, ESPECIALLY ALONG/WEST OF THE GLACIAL

RIDGE, WHERE A MORE PROGRESSIVE GFS/EC TYPE OF SOLUTION SUGGESTS

THAT THE COLD RESIDENT AIRMASS WILL BE DIFFICULT TO SCOUR OUT.

DTX looks to be leaning toward the Euro and toward a snow to ice to snow event at this junction. They are tossing the GEM as being suspect.

[Stebo]

 

THE MODELS ARE CONTINUING TO COME INTO BETTER AGREEMENT ON THE

WEEKEND SYSTEM. SURFACE LOW TRACK APPEARS TO BE FROM NEAR ST. LOUIS

SATURDAY EVENING TO SOUTHERN LAKE HURON BY SUNDAY MORNING. THIS

WILL CAUSE PCPN TYPE ISSUES AS A WARM LAYER ALOFT SHOULD RIDE ALONG

THE H8 LOW TRACK. THIS APPEARS TO TRACK FROM ABOUT GRAND HAVEN TO

MT. PLEASANT. SOUTH OF THIS LINE A WINTRY MIX WILL BE IN THE

FORECAST...WITH ALL SNOW NORTH OF THE LINE. ITS POSSIBLE SOME AREAS

END UP SEEING MORE FREEZING RAIN THAN SNOW...PARTICULARLY SOUTH OF

I-96 WHERE A QUARTER INCH OF ICE COULD BE POSSIBLE. WHERE IT SHOULD

REMAIN ALL SNOW...ACROSS CENTRAL LOWER...IT APPEARS TO BE ABOUT A

3-5 INCH ACCUMULATION. SLIGHT VARIATIONS IN THE TRACK IS STILL

POSSIBLE AND COULD RESULT IN FORECAST TWEAKING.

GRR also leaning toward a snow-ice-snow scenario for the storm.

[Gilbertfly]

DTX looks to be leaning toward the Euro and toward a snow to ice to snow event at this junction. They are tossing the GEM as being suspect.

 

That is an awesome write up...love the players on the field analysis there....

[Stebo]

That is an awesome write up...love the players on the field analysis there....

Yeah that really was a nice and thorough write up, they certainly explained their take on everything as it stands right now.

[Hoosier]

Stebo, what are your early thoughts on SE MI?  To me it looks like some plain rain could enter the picture unless the system goes farther south, especially around Detroit proper.

[Powerball]

Stebo, what are your early thoughts on SE MI?  To me it looks like some plain rain could enter the picture unless the system goes farther south, especially around Detroit proper.

 

Personally, I'm thinking a quick 1-2" rally of mod-heavy snow at the onset, then flipping over to a cold 33*F to 35*F rain in the city proper.

 

We then flip back to a dusting or an 1" of light snow at the end...

[Gilbertfly]

DVN's thoughts....

 

 

NATIONAL WEATHER SERVICE QUAD CITIES IA IL
310 PM CST WED DEC 31 2014


.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 305 PM CST WED DEC 31 2014

SATURDAY...MODELS HAVE SLOWLY BEEN COMING INTO BETTER AGREEMENT OVER
THE PAST FEW DAYS IN THAT A WIDESPREAD PRECIPITATION EVENT WILL
IMPACT THE MIDWEST INCLUDING THE DVN CWA ON SAT OR SAT NIGHT.

SINCE THE LEAD VORT. MAX WILL NOT FULLY PHASE WITH AN UPSTREAM
SHORTWAVE TROUGH THAT WILL REMAIN OVER N MN/WI..UPPER DIVERGENCE AND
THE SFC LOW WILL NOT BE THAT STRONG. THE SFC LOW WILL BE A FAST
MOVER WITH A CENTRAL PRESSURE ABOVE 1000 MB INTO INDIANA.
HOWEVER...THE SUB-TROPICAL JET ON THE EASTERN SIDE OF THE LONGWAVE
TROUGH WILL PHASE WITH THE POLAR JET TO THE NORTH CAUSING THE
LOWER-LEVEL MASS FIELDS TO RESPOND. AN INITIAL INVERTED SFC TROUGH
OVER W IOWA INTO MINNESOTA WILL EVENTUALLY CONGEAL INTO ONE
ORGANIZED SFC LOW ACROSS CENTRAL ILLINOIS/N INDIANA.

MODEL DISCREPANCIES...THE GFS/GEM/ECMWF ALL BRING A MID-LEVEL VORT.
MAX FROM NEW MEXICO ON FRI NIGHT THROUGH CENTRAL ILLINOIS SAT NIGHT
TO LOWER MICHIGAN BY SUN MORNING. THE REASON FOR THIS MORE NORTHERN
TRACK IS THAT A 300 MB JET STREAK WILL DEVELOP OVER BRITISH COLUMBIA
ON FRIDAY...THE SOUTHERN EDGE OF WHICH WILL DIG INTO THE FOUR
CORNERS REGION. AN ASSOCIATED SECONDARY VORT. MAX WILL MOVE INTO N
NEW MEXICO...KICKING THE LEAD VORT. MAX TO THE NE. THE NAEFS AND
GEFS MEANS HAVE AN ORGANIZED SFC LOW TRACKING ACROSS CENTRAL
ILLINOIS/N INDIANA DURING THIS TIME.

CONFIDENCE...IS HIGH THAT WIDESPREAD PRECIP WILL AFFECT THE AREA BUT
LOW WITH REGARDS TO EXACTLY WHERE THE RAIN/SNOW OR RAIN/FREEZING
RAIN LINE WILL SET UP. REGARDLESS...PRECIP SHOULD CHANGE TO ALL SNOW
SAT NIGHT...RIGHT AS NW WINDS RAMP UP WITH GUSTS OVER 25 MPH LIKELY
LEADING TO BLOWING/DRIFTING SNOW.

PRECIPITATION AMOUNTS...MODELS HAVE DEFORMATION ZONE PRECIP
IMPACTING THE REGION SAT EVENING/NIGHT. THE GFS HAS WIDESPREAD
AMOUNTS BETWEEN 0.25 TO 0.35 INCHES AND IS A COMPROMISE BETWEEN THE
MORE ROBUST/WARMER GEM...AND THE WEAKER/COLDER ECMWF. CURRENT
FORECAST SIDES WITH THE LOWER END OF THE GFS.

[Hoosier]

12z ECMWF ensemble mean seems to be north of the op run.

 

 

[Jonger]

I'm going to be riding this one out in the U.P, hoping for some enhanced banding.

[RCNYILWX]

18z GFS would suggest a ZR problem in the southeast LOT CWA, western IWX and NW IND CWA's on Saturday. Never get southerly winds at the surface so the low level cold locks in better. Most of the precip Saturday and Sat night would be snow along/west of I-55.

Sent from my SM-G900V using Tapatalk

[blizzardof96]

18z GFS notably colder in the low levels when compared to 12z... at least initially.

[Stebo]

Stebo, what are your early thoughts on SE MI?  To me it looks like some plain rain could enter the picture unless the system goes farther south, especially around Detroit proper.

I think the models are warming the surface a bit too quickly especially north of the city, I would not be shocked to see this stay predominantly wintry precip especially north of the city. The room for error is razor thin though, and we could use a shift to the south a hair, otherwise the city and points south could be looking at some cold rain.

[Thundersnow12]

18z GFS would suggest a ZR problem in the southeast LOT CWA, western IWX and NW IND CWA's on Saturday. Never get southerly winds at the surface so the low level cold locks in better. Most of the precip Saturday and Sat night would be snow along/west of I-55.

Sent from my SM-G900V

 

It's really close though and I'd even argue it's snow out here at the onset looking at 18z fcst soundings. 

 

Here are DPA at 18z and 21z Sat. ORD and MDW both look to be all snow at least from a fcst sounding perspective as well at these times. Down near IKK though as you said is a different story and has a more ZR look. 

 

They do have that classic WAA/big veering wind profile you see with ZR around here

 

 

[Thundersnow12]

18z GFS notably colder in the low levels when compared to 12z... at least initially.

 

I was thinking the same thing as well along with overall it looks a bit colder/SE as well. 

 

Here are the 850mb and 925mb temp progs off the 12/18z op GFS valid 3z Sunday (first images are the 18z run)

 

 

 

 

[Hoosier]

18z GFS would suggest a ZR problem in the southeast LOT CWA, western IWX and NW IND CWA's on Saturday. Never get southerly winds at the surface so the low level cold locks in better. Most of the precip Saturday and Sat night would be snow along/west of I-55.

Sent from my SM-G900V

 

 

Indeed.   Winds eventually flip more southerly (especially in IN) but only when the low is passing by.

 

 

[Minnesota Meso]

I haven't got a good look at the gem H7 maps as of yet today, but my first guess is that it develops a weak disturbance at that level between the southern energy and the northern energy around hour 72, causing earlier phase of the two systems, other models are trying to hint at that, but don't quite get there.  If the TC metro gets into play on the phase this is how its going to happen.

 

As for the gem and the H7 pattern, I was mistaken.  What it was showing was the result of surface reflection phasing, and the 18z op GFS agrees.

[IWXwx]

When Hoosier talks about it not being a complete shutout on "wintry" precip, I'm sure that he's alluding to a zr front end thump and some mood flakes at the end.

 

Guess I'll look forward to my 2" from the clipper next Tuesday.

 

Gonna nail it for MBY (IWX)....

 

"CURRENT THINKING IS THAT A BRIEF PERIOD OF FREEZING RAIN WILL LIFT

THROUGH THE AREA WITH ACCUMULATION LESS THAN A TENTH OF AN INCH

BEFORE PRECIPITATION CHANGES OVER TO ALL RAIN FOR A MAJORITY OF THE

FORECAST AREA AND THEN CHANGES TO A BRIEF PERIOD OF SNOW ON THE BACK

SIDE."

[Hoosier]

To RC's point, the NAM also locks in easterly low level flow for much of Saturday in the areas he mentioned but is a little warmer at the surface.  The question is which one is right.  I'm inclined to lean a bit on the pessimistic side (quicker warmup) in these situations with a retreating cold airmass, but having that easterly low level flow is definitely preferable to something more southerly and would keep an icier outcome on the table.

[Ottawa Blizzard]

Still looks like a couple of inches of front-end stuff for YYZ on the 12z GFS. I'll take it.

Remember it was last year around the same time that we had front end snows and we expected it to turn to steady rain, only for this to not happen. You never know. As long as we can get an inch of snow on the ground, I'll be happy. Not expecting too much from this.