1/5-1/6 clipper system

[snowlover2]

ILN goes watch for I-70 north. 

[Hoosier]

Encouraging to see the NAM continuing to spit out these higher precip amounts.  It should be able to resolve the banding potential better than the lower res globals but I think I'd rather wait until tomorrow's runs to go all in with it lol.

[Whitelakeroy]

Today's trends suggest maybe 1 to 2 inches

P&C:

Monday Night Snow after 1am. Low around 6. Wind chill values as low as -6. Southwest wind 5 to 7 mph. Chance of precipitation is 90%. New snow accumulation of 1 to 2 inches possible.

 

Correct!!  

[buckeye]

ILN goes watch for I-70 north. 

 

included Pickaway and Fairfield, so actually south of I-70 as well

[snowlover2]

ILN with a very detailed reasoning for the watch placement with mention that south adjustment could still be needed.

 

 

 

.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
WE GO FROM 50S/60S AND BEING CONCERNED ABOUT FLOODING AND QLCS
WIND GUSTS SUNDAY MORNING...TO A VERY COLD AND SNOWY FORECAST IN
THIS TIME PERIOD AS BIG PATTERN CHANGE CONTINUES TO EVOLVE.

ALL THE FOCUS IN THIS TIME PERIOD OF SHORTWAVE TROUGH DIGGING
THROUGH LONGWAVE TROUGH FROM BRITISH COLUMBIA SUNDAY
EVENING...QUICKLY SOUTHEAST INTO AND THROUGH THE GREAT LAKES
TUESDAY MORNING. THIS SYSTEM BRINGS MODERATE TO STRONG KINEMATIC
FORCING IN BRIEF FASHION MONDAY NIGHT AND TUESDAY
MORNING...PROMISING A SWATH OF FLUFFY ACCUMULATING SNOW TO MUCH OF
THE FORECAST AREA.

GOT VERY CLOSE...TO ISSUING A WINTER STORM WATCH WITH THIS
FORECAST ISSUANCE FOR MUCH OF CENTRAL OHIO...MAINLY NORTHERN THREE
TIERS OF THE WFO ILN CWA...BUT CONFIDENCE IN 6" AMOUNTS JUST NOT
QUITE THERE...THOUGH THERE IS PLENTY TO BE CONCERNED ABOUT. AS IT
STANDS...THIS FORECAST DID TWO THINGS: 1) INCREASED AMOUNTS ALL
AREAS FROM PREVIOUS FORECAST AND 2) SPREAD ACCUMULATIONS FURTHER
SOUTH...EVEN AS FAR SOUTH AS OHIO RIVER/CINCINNATI AREA.

FORCING FOR ASCENT WILL SPREAD QUICKLY DOWNSTREAM OF THE
APPROACHING WAVE ON MONDAY EVENING AND SNOW SHOULD MOVE/DEVELOP
INTO THE FORECAST AREA AROUND MIDNIGHT OR PERHAPS A LITTLE BEFORE.
IT SHOULD QUICKLY BECOME MODERATE OR EVEN HEAVY GIVEN STRONG
FORCING/VERTICAL MOTION SIGNALS IN MODEL CROSS-SECTIONS NORMAL TO
THICKNESS CONTOURS. VERY STRONG Q/G COMPONENT TO FORCING PIVOTS
RIGHT ACROSS CENTRAL OHIO...AND 1.5 PV /DYNAMIC TROPOPAUSE/ MAPS
SHOW RIGHT ENTRANCE REGION COMPONENT AIDING AGEOSTROPHIC VERTICAL
CIRCULATION WITH 150KT JETLET ORIENTED ACROSS NRN OH/LAKE ERIE
MIGRATING QUICKLY EAST. FORECAST BUFR SOUNDINGS /ANY OF
C25...KCMH..KDAY/ SHOWS AN EVOLVING VERY DEEP DENDRITIC GROWTH
ZONE NEAR THE MIDDLE/END OF THE SNOW EVENT...AND THIS CAUSES ME
THE GREATEST PAUSE/CONCERN THAT WARNING-CRITERIA SNOWS MAY BE
REALIZED ACROSS PORTIONS OF OUR FORECAST AREA. HAVE SEEN...TIME
AND TIME AGAIN...EXTREME SNOW RATIO EVENTS REALLY GET BIG RATES
VIA DENDRITIC GROWTH PROCESSES AND VERTICAL MOTION/DGZ OVERLAP IS
PRIME IN THIS EVENT. HOWEVER...A CON...THE TEMPORAL NATURE OF THIS
OVERLAP IS BRIEF...ON THE ORDER OF 3-4 HOURS IT SEEMS PER THE
HOURLY SOUNDING DATA...SO NOT SURE IF ENOUGH IS GOING TO BE THERE
TO GET WARNING SNOWS. SO FOR RIGHT NOW HAVE TAKEN A LARGE PART OF
CENTRAL OHIO/ECNTL IND INTO 3-5" RANGE WITH OPEN ACKNOWLEDGMENT
THAT SOME 6" AMOUNTS COULD BE REALIZED IF THERMODYNAMIC ASPECTS OF
ENVIRONMENT COME TOGETHER. THERE ARE SOME SREF MEMBERS IN THE
6-7" RANGE FROM AOH TO CMH BUT THE BULK RESIDE BELOW...SO WILL
HOLD ON A WATCH FOR NOW.

OTHER CONS FOR A WATCH IS LATITUDINAL VARIATION OF BAND OF
STRONGEST FORCING. HI-RES WINDOWS...NAM CONUS NEST...GFS...ARE
AMONG SOME OF THE DATA SETS THAT SPILLED SOUTH WITH 04.12Z RUNS IN
TERMS OF ACCUMULATING SNOW FURTHER SOUTH...AND THIS FORECAST
ACKNOWLEDGES THIS WITH INCREASING SNOW CHANCES ALL THE WAY TO OHIO
RIVER WITH LIGHT ACCUMULATIONS. WE NEED TO WATCH THESE TRENDS AS
IF ONE WERE TO TAKE THIS DATA AT FACE VALUE...POTENTIAL WATCH
WOULD BE SITUATED A GOOD DEAL SOUTH THAN WHAT SREF/NAM/ECMWF
SUGGEST...MORE CENTERED THROUGH WILMINGTON/MIDDLETOWN. I DON/T
THINK WE KNOW ENOUGH YET TO SAY THIS COULDN/T OCCUR GIVEN THE LOW
AMPLITUDE NATURE OF THE SYSTEM AND IT BEING SEVERAL THOUSAND MILES
AWAY AT THIS HOUR. WHERE THE HIGHER RES WINDOW RUNS ARE SITTING
AND MARGINAL CONFIDENCE OF HITTING 6 INCHES...RIGHT NOW IT ADDS ENOUGH
UNCERTAINTY THAT A WATCH PLACEMENT IN OUR AREA IS PREMATURE.

BOTTOM LINE...HIGH CONFIDENCE THE ILN CWA RECEIVES A SWATH OF
ACCUMULATING...FLUFFY SNOW MONDAY NIGHT AND TUESDAY MORNING. THIS
SWATH WILL LIKELY BE 3-5" AND CENTRED IN THE NORTHERN HALF OF THE
FORECAST AREA...LOCALLY HIGHER CONSIDERING DENDRITIC CONTRIBUTIONS.
THERE WILL BE A TIGHT SOUTHERN GRADIENT AS PER USUAL WITH THESE
EVENTS...AND THERE/S SOME FARTHER SOUTH RUNS THAT WE NEED TO
RESOLVE IN THE NEXT 6-12 HOURS. A QUICK HITTING SYSTEM...BUT THE
TUESDAY MORNING COMMUTE WILL DEFINITELY BE AFFECTED.

FRIGID AIR POURS IN BEHIND THIS SYSTEM...AND IT APPEARS MORE
BORDERLINE ADVISORY-LEVEL WIND CHILLS ARE LIKELY BY TUESDAY NIGHT.

[CoachLB]

NWS

[buckeye]

ILN with a very detailed reasoning for the watch placement with mention that south adjustment could still be needed.

 

but they DID issue watches....  that discussion sounds like they are holding off

[ILSNOW]

chicago nws

 

SNOWFALL DISCUSSION...THE MID/UPPER TROUGH WILL BE STRONG ENOUGH TO
FORCE COMPACTING OF THE MID LEVEL BAROCLINIC ZONE LEADING TO STRONG
FRONTOGENETICAL FORCING. CROSS SECTIONS SHOW A VERY UPRIGHT
AGEOSTROPHIC VERTICAL CIRCULATION DURING THE EVENING OCCURRING IN
CONJUNCTION WITH THE PASSAGE OF A POTENTIAL VORTICITY MAX SUPPORTIVE
OF REDUCED STABILITY. THIS POINTS TO VERY STRONG ASCENT WITHIN A
VERY COLD AIRMASS AND POTENTIAL FOR ENHANCED BANDING WITHIN THE
LARGER AREA OF SNOWFALL. GUIDANCE CONTINUES TO VARY ON LIQUID
EQUIVALENT PRECIP WITH SOME OF THE GUIDANCE WHICH HAD BEEN
INDICATING 0.4-0.5 LIQUID OUTPUT NOW BACKING OFF TO THE 0.3-0.4
RANGE. CLIPPERS ARE TYPICALLY ON THE DRY SIDE BUT WITH THIS ONE
ORIGINATING OVER THE PACIFIC BETTER THAN TYPICAL MOISTURE CAN BE
EXPECTED. THE ECMWF REMAINS LIGHTEST WITH LIQUID WITH PEAK VALUES
AROUND 0.25. GIVEN THIS TREND AND CONSIDERING THE DOWNWARD
TREND IN OTHER GUIDANCE WILL SETTLE ON LIQUID VALUES AROUND 0.3 IN
WHICH COMBINED WITH SNOW RATIOS OF 15-20:1 CONTINUE TO SUPPORT 3
TO 6 INCH AMOUNTS...WITH BANDING SUPPORTIVE OF AMOUNTS OVER 6
INCHES. SNOWFALL RATES WILL ALSO BE VERY INTENSE...LIKELY BETWEEN 1
AND 2 INCHES AT TIMES FOR SOME AREAS WHICH WILL CONTRIBUTE TO THE
IMPACT. COVERAGE OF SNOW LOOKS TO BE WIDESPREAD ACROSS THE AREA SO
MOST AREAS LOOK TO ACHIEVE THE LOWER TO MID END OF THE RANGE. BEST
OR MOST PROLONGED BANDED POTENTIAL IS FAVORED GENERALLY ALONG AND
SOUTH OF A MENDOTA TO SOUTH CHICAGO METRO TO RENSSELAER LINE AND AM
WONDERING IF MAY IT END UP BEING FOCUSED A LITTLE FURTHER SOUTH THAN
THAT. HAVE NOT TWEAKED TIMING MUCH WITH START TIME 00-03Z FROM WEST
TO EAST AND THE THE PEAK INTENSITY WINDOW IN THE 3-6 HRS AFTER
ONSET...BUT AGAIN THIS MAY NEED TO BE SPED UP SLIGHTLY.

IMPACTS DISCUSSION...WITH SUCH STRONG FORCING AND A DEEP SNOW GROWTH
ZONE VERY INTENSE SNOWFALL RATES ARE FAVORED. EXPECT THAT MUCH OF
THE SNOW WILL FALL INSIDE A 6 HR PERIOD. WITH CURRENT TIMING START
TIME SHOULD BE AT THE TAIL END OF THE EVENING RUSH IN ROCKFORD AND
JUST AFTER IN CHICAGO BUT TIMING MAY NEED TO BE SPED UP SLIGHTLY.
WITH SNOW ENDING QUICKLY OVERNIGHT ACCUMULATION WILL WRAP UP BEFORE
THE TUESDAY MORNING RUSH BUT WINDS WEST TO NORTHWEST WINDS WILL
INCREASE THROUGH THE DAY TUESDAY. WITH VERY DRY/FLUFFY
SNOW...BLOWING AND DRIFTING IS LIKELY...WITH NORTH-SOUTH ROADWAYS
THE MOST AFFECTED. THIS MAY MEAN THAT WINTER HEADLINES WILL NEED TO
CONTINUE THROUGH THE DAY TUESDAY.

HEADLINE DISCUSSION...THE ONLY CHANGE TO HEADLINES RIGHT NOW WILL BE
TO EXPAND THE WINTER STORM WATCH ACROSS FORD...IROQUOIS AND BENTON
COUNTIES. ANTICIPATE THAT NORTHERN AREAS WILL END UP NEEDING AN
ADVISORY WHICH MAY NEED TO EXTEND THROUGH THE DAY TUESDAY DUE TO
BLOWING SNOW. STILL FEEL THAT WARNING CRITERIA SNOWS MAY OCCUR IN
THE FORECAST AREA BUT AM NOT YET CLEAR ON WHERE TO DIFFERENTIATE A
WARNING VS. ADVISORY GIVEN THE FACTORS DISCUSSED ABOVE. HOWEVER...DO
HAVE GREATER CONFIDENCE IN THAT AREA BEING ALONG AND SOUTH OF THE
MENDOTA TO SOUTH CHICAGO METRO TO RENSSELAER LINE BUT A FURTHER
SOUTH SHIFT COULD PUT IT FURTHER SOUTH YET. BETTER SAMPLING OF THE

NOW DEVELOPING WAVE WILL HOPEFULLY HELP WITH REFINEMENT.

[Gilbertfly]

Fairly large cluster at 6 inches for this event on the 15Z plumer @ JOT...Mean is up close to 7 inches...but the cluster at 6 inch looks more believable at this juncture

[A-L-E-K]

LOT has this under control

[Central Illinois]

ILX doesn't even go with a WSW or Advisory for their northern counties 

[Harry]

Need a Jan 05 miracle..

[michsnowfreak]

Need a Jan 05 miracle..

The SREFs and GEFS have definitely drifted south over the last few days, but they both remain north of the OPs run after run.

[cyclone77]

DVN has upgraded to a warning and calls for 5-8" and 20-25:1 LSRs.

 

MONDAY NIGHT...QUICK HITTING ALBERTA CLIPPER TO BRING A WARNING
CRITERIA (EVENT TOTAL 5-8 INCHES) FLUFFY SNOW TO AREAS ALONG AND
NORTH OF I-80...AND ADVISORY CRITERIA (EVENT TOTAL 2-5 INCHES) FROM
SOUTH OF I-80 TO HIGHWAY 34. LESS THAN 2 INCHES EXPECTED IN EXTREME
NORTHEAST MO. OPERATIONAL MODELS PRETTY CONSISTENT (ONLY A SLIGHT
SOUTHWARD SHIFT) OVER THE PAST SEVERAL RUNS AND CONFIDENCE IS HIGH.
WILL USE SNOW RATIOS WHICH FOR NOW WILL BE 20:1 TO 25:1. THERE IS
MODERATE TO STRONG FORCING AND 300 MB DEPTH OF DENDRITIC GROWTH ZONE
WHICH SHOULD SUPPORT MODERATE TO HEAVY SNOWFALL. THE GOOD NEWS IS
THE WIND WILL BE RATHER LIGHT DURING THE SNOWFALL. THE SNOW WILL BE
ENDING FROM WEST TO EAST BEFORE SUNRISE.

[Harry]

The SREFs and GEFS have definitely drifted south over the last few days, but they both remain north of the OPs run after run.

 

With Jan 05 the old ETA ( Now known as the NAM for those who were not around )  went north at like 24/36hrs before storm time and then all the rest followed suit. You remember that?

[Gilbertfly]

rippin'....

 

[buckeye]

Need a Jan 05 miracle..

 

wasn't that the bowling ball from hell/ manitoba mauler?   That was a crazy bust here.  I think we were under a warning for 5-8", it was suppose to hit late friday night into Saturday.   We ended up with drizzle, a couple of claps of thunder and about a 15 minute snowshower that dusted the ground.

 

thankfully that was a totally different animal then this thing coming up.

[Powerball]

Need a Jan 05 miracle..

 

That would be a miracle indeed...

[Harry]

wasn't that the bowling ball from hell/ manitoba mauler?   That was a crazy bust here.  I think we were under a warning for 5-8", it was suppose to hit late friday night into Saturday.   We ended up with drizzle, a couple of claps of thunder and about a 15 minute snowshower that dusted the ground.

 

thankfully that was a totally different animal then this thing coming up.

 

It was more of a manitoba mauler. It's origins ( like this clipper ) was of the pacific though. What the models missed was the blocking ( a sort of 50/50 low ) ahead of it which wasn't as robust or in the location as the models had shown and allowed it to go further north. The good ole ETA was first to show it. Yep it even beat the euro but that joined in next behind the eta.

[mimillman]

GFS a baby step south. I see the 00z guidance coming north a tad.

[buckeye]

It was more of a manitoba mauler. It's origins ( like this clipper ) was of the pacific though. What the models missed was the blocking ( a sort of 50/50 low ) ahead of it which wasn't as robust or in the location as the models had shown and allowed it to go further north. The good ole ETA was first to show it. Yep it even beat the euro but that joined in next behind the eta.

 

yea those closed ULL digging in from the nw are infamous screw jobs for central OH.  They often model as a big deal, but we end up with too much ridging out ahead and either get warm tongued...or more commonly...dry-slotted.

 

sorry for the threadjack....back to the clipper

[michsnowfreak]

With Jan 05 the old ETA ( Now known as the NAM for those who were not around )  went north at like 24/36hrs before storm time and then all the rest followed suit. You remember that?

I dont remember the models, I just remember being shocked we got that much snow

[snowlord81]

_{18Z RGEM in line with the GFS. NAM still a bit north (leaving me on the edge) but a blend would do just fine here. I'd say Im looking at 4-7.}

[Harry]

yea those closed ULL digging in from the nw are infamous screw jobs for central OH.  They often model as a big deal, but we end up with too much ridging out ahead and either get warm tongued...or more commonly...dry-slotted.

 

sorry for the threadjack....back to the clipper

 

 

Got a foot from it here but i would have loved to have gotten what southern New England did with that. THAT BTW also had a system a day or so ahead of it. That was what was supposed to help with the blocking.

 

Some similarities but meh.. Back to the present. Good luck with it. Highly doubtful ( know better then to say 0 though )  this comes back north.

 

Wherever this goes it should deposit some decent amounts of snow as these Pacific origin clippers do unlike the counter parts that drop in due south from Canada..

[buckeye]

Got a foot from it here but i would have loved to have gotten what southern New England did with that. THAT BTW also had a system a day or so ahead of it. That was what was supposed to help with the blocking.

 

Some similarities but meh.. Back to the present. Good luck with it. Highly doubtful ( know better then to say 0 though )  this comes back north.

 

Wherever this goes it should deposit some decent amounts of snow as these Pacific origin clippers do unlike the counter parts that drop in due south from Canada..

 

i would imagine you guys would be cashing in with some LES with this cold shot this week....regardless of what happens synoptically

[Harry]

i would imagine you guys would be cashing in with some LES with this cold shot this week....regardless of what happens synoptically

 

All depends on the flow.. Could look great today and gone tomorrow or look bad today and great tomorrow. For now it looks ok. GRR is more pumped with it then i am.

[michsnowfreak]

Got a foot from it here but i would have loved to have gotten what southern New England did with that. THAT BTW also had a system a day or so ahead of it. That was what was supposed to help with the blocking.

 

Some similarities but meh.. Back to the present. Good luck with it. Highly doubtful ( know better then to say 0 though )  this comes back north.

 

Wherever this goes it should deposit some decent amounts of snow as these Pacific origin clippers do unlike the counter parts that drop in due south from Canada..

my gut says it will come north slightly, but not nearly enough to put us in the heavy band.

[Harry]

my gut says it will come north slightly, but not nearly enough to put us in the heavy band.

 

I'll feel more confident once this thing is fully sampled which it should be by the 12z runs tomorrow and perhaps as early as tonights 00z.

[Powerball]

And remember the talk about ratios being good? 

 

Well here it is from DTX...

 

000
FXUS63 KDTX 042044
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
344 PM EST SUN JAN 4 2015

 

TIMING OF THE CLIPPER SYSTEM EXPECTED TO BRING SNOW TO THE AREA
MONDAY NIGHT DID NOT CHANGE WITH THE ARRIVAL OF THE 12Z MODEL
RUNS...BUT THE SYSTEM DOES LOOK DIFFERENT REGARDING SNOW AMOUNTS FOR
SOUTHEAST MICHIGAN. ENERGY CURRENTLY OVER THE GULF OF ALASKA SHOULD
DIVE THROUGH THE OHIO VALLEY AND CENTRAL GREAT LAKES MONDAY NIGHT
AND TUESDAY. THIS IS A SLIGHT SHIFT TO THE SOUTH...AND DID RESULT IN
A TRIMMING OF SNOWFALL TOTALS OVER THE NORTHERN PORTION OF THE
FORECAST AREA. 850-925MB FRONTAL BOUNDARY WILL LIFT NORTHWARD INTO
SOUTHERN LOWER MICHIGAN OVERNIGHT. ISENTROPIC ASCENT ALONG THIS
BOUNDARY DOES LOOK STRONG ENOUGH TO OVERCOME THE PRECEDING DRY
AIRMASS IN THE VERY LATE EVENING...WITH MOST OF THE SNOW THEN
EXPECTED OVERNIGHT AND THROUGH SUNRISE. THIS SYSTEM DOES NOT LOOK TO
TAP INTO AN INFLUX OF MOISTURE...AND SPECIFIC HUMIDITY VALUES LOOK
TO REMAIN LIMITED TO ABOUT 1 G/KG. LATEST MODEL CROSS SECTIONS AND
FORECAST SOUNDINGS FROM THE GFS AND NAM SHOW THE BEST INSTABILITY
AND LIFT CENTERED IN A THERMAL REGION OF ABOUT -24 TO -26C FOR MUCH
OF SOUTHEAST MICHIGAN. THIS WOULD FAVOR COLUMNS AND PLATES AS
OPPOSED TO DENDRITES...CHIPPING INTO SNOWFALL TOTALS AS DRY AND
SMALL FLAKES COMPACT NICELY. SNOWFALL TOTALS WERE LOWERED TO ROUGHLY
1 TO 2 INCHES FROM M-59 NORTHWARD (LOWER OVER NORTHERN THUMB)...AND
BETWEEN 2 AND 3 INCHES FOR WAYNE/WASHTENAW/LENAWEE/MONROE COUNTIES
WHERE LIFT WILL BE CENTERED SLIGHTLY MORE IN THE DENDRITIC GROWTH
ZONE (A LITTLE LOWER IN THE ATMOSPHERE) AND SLIGHTLY BETTER MOISTURE
WILL SEEP UP INTO THE AREA.

[Hoosier]

And remember the talk about ratios being good? 

 

Well here it is from DTX...

 

 

 

You're actually too far north/east with a colder column/less deep dgz, so I could buy that (ratios not being as high as in the main band).