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December 24-25 Snowstorm

Jim Martin

By Jim Martin,
in Central/Western States

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dilly84

dilly84

Posted
Posted

Also stated that it had stronger northern energy that would absorb the s/w energy. Wouldn't this mean a more northern track?

it also says in there: WINTER WEATHER SHOULD SPREAD FROM THE CENTRAL PLAINS

EASTWARD ACROSS THE TENNESSEE VALLEY THROUGH THE MID-ATLANTIC

STATES...AS WELL AS SNOW SHOWERS UNDER THE BASE OF THE UPPER LEVEL

LOW ACROSS THE GREAT LAKES AND NORTHEAST.

So woohoo they are giving us some snow showers lol. White Christmas odds are dwindling fast here, the temps today have already eaten away a lot of the snow here. down to maye 1/4 inch now.

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Stevo6899

Stevo6899

Posted
Posted

All the models are to the south currently. During the last big storm, the Euro was consistently north, now it is consistently south. Doesn't look good for you all. But it's still 5 or so days away and a lot can change.

Yea I know they are to the south but trying to find out the reasons. Perhaps a track further south is due

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JoMo

JoMo

Posted
Posted

That is to beautiful to come true.

Yeah some kind of snow band sits over you for hours up that way (GGEM), heh.

This is overall a very volatile situation (could easily change) because a lot depends on what happens to the N Stream energy and the position of the energy over the south.

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The_Global_Warmer

The_Global_Warmer

Posted
Posted

Yeah some kind of snow band sits over you for hours up that way (GGEM), heh.

This is overall a very volatile situation (could easily change) because a lot depends on what happens to the N Stream energy and the position of the energy over the south.

right now the euro low end: 4-5 inches here.

GEM high end with 8-10 and GFS.

the only thing that is really good is that the far south solutions can come north and still get us good...and they can stay there and get us good with an inverted trough.

these are the typical major snow storms for STL

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michsnowfreak

michsnowfreak

Posted
Posted

So does it all come down to whether the ec storm departs fast enough that it doesn't block this storm from going further north? Or is the high up in canada keeping this thing from going north? Is there another low it could phase with? Really confused.

I have no clue to any of those questions. All I know is whenever there is a storm, I keep an eye on it. Look at the Dec 12th snowstorm, we did so well because another L popped out of nowhere on Lake Erie, not because of the original storm we were actually tracking. All the models are south now? So what, 5 days ago every single model had this current clipper south of us, and now it ends up north/northwest of us.

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dilly84

dilly84

Posted
Posted

May be a newb question, but oh well. I'll ask anyways

How much impact does this current storm have on the Christmas day storm. Basically the clipper looks to be moving almost due east with the precip shield expanding south instead of getting eaten up like models showed.. But the thing I find peculiar is the fact it is moving east instead of SE? Just wondering your thoughts on what impact this could have for Christmas.

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baroclinic_instability

baroclinic_instability

Posted
Posted

May be a newb question, but oh well. I'll ask anyways

How much impact does this current storm have on the Christmas day storm. Basically the clipper looks to be moving almost due east with the precip shield expanding south instead of getting eaten up like models showed.. But the thing I find peculiar is the fact it is moving east instead of SE? Just wondering your thoughts on what impact this could have for Christmas.

This is a horribly and crudely drawn map, but the kinematic flow field often has regions of deformation. Shearing and stretching deformation flow fields are common with developing weather systems, and deformation also plays a significant role in frontogenesis. You can see here the crude deformation zone I drew with air "stretching" from Wisconsin and into Iowa. The precip shield is therefore propagating SE even though the main system is heading eastward. Also note the thermal gradient south of the deformation zone is strong WAA. This is acting in a frontogenetic manner, hence the heavy and sharp snow band currently over parts of N IL and Iowa.

Frontogenesis itself only means "birth of a front" and is characterized by an increasing thermal gradient in the horizontal with respect to time. This can be accomplished a number of ways including differential heating, tilting of the front, convergence, and deformation.

post-999-0-76619600-1292877521.png

As modeled now, this system will play little eventual role in potential changes of the Christmas storm.

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dilly84

dilly84

Posted
Posted

where did you see this information on INDY?

FOCUS OF THE EXTENDED REMAINS ON POTENTIAL STORMS SYSTEM TO IMPACT

THE OHIO AND TENNESSEE VALLEYS CHRISTMAS EVE INTO EARLY CHRISTMAS

DAY. MODEL CONSENSUS AFTER A CONSISTENT TRACK THROUGH THE TENNESSEE

VALLEY FOR SEVERAL RUNS HAS TRENDED STEADILY SOUTH AND SOMEWHAT MORE

CHAOTIC AS THE INFLUENCE OF THE UPPER TROUGH SLIDING SOUTH THROUGH

CANADA LATE WEEK IS KEEPING NORTHERN AND SOUTHERN STREAM SEPARATE

AND OUT OF PHASE TO VARYING DEGREES AND ESSENTIALLY BLOCKING ANY

NORTHERN MOVEMENT TO THE SYSTEM UNTIL NEAR/OFF THE EAST COAST.

THE 12Z SUITE OF RUNS THIS AFTERNOON ARE OFFERING TRACKS ANYWHERE

FROM THE LOWER TENNESSEE VALLEY TO THE GULF COAST FRIDAY INTO EARLY

SATURDAY. THE GGEM HAS ABRUPTLY SHIFTED TO THE FURTHEST TRACK SOUTH

COINCIDENT WITH THE ECMWF ALONG THE GULF COAST...AND CLOSER ANALYSIS

SHOWS THAT THIS IS DUE TO A PIECE OF UPPER LEVEL ENERGY ASSOCIATED

WITH THE POLAR VORTEX BEING DISPLACED SOUTH AND WEST OF VIRTUALLY

ALL OF THE OTHER AVAILABLE MODEL DATA ON FRIDAY. AM HIGHLY SKEPTICAL

OF THE GGEM SOLUTION FOR THIS VERY REASON AND HAVE LARGELY

DISCOUNTED ITS 12Z RUN OF KEEPING ANY PRECIPITATION CONFINED TO I-70

AND POINTS SOUTH FOR THE DURATION OF THE EVENT. WHILE THE ECMWF IS

ALSO SOUTH WITH THE SURFACE LOW...ITS NOT NEARLY AS ROBUST WITH THE

BLOCKING ALOFT OVER THE GREAT LAKES AS THE GGEM IS AND

CONSEQUENTLY...MOISTURE IS FUNNELED INTO THE REGION AHEAD OF THE

APPROACHING UPPER LOW ALBEIT IN A MUCH DIMINISHED CAPACITY. THE 12Z

OP GFS AND MAJORITY OF THE GFS ENSEMBLE MEMBERS CONTINUE TO

ADVERTISE A FURTHER NORTH TRACK THROUGH THE MID SOUTH WITH THE MOST

APPRECIABLE MOISTURE RETURN NORTH INTO THE OHIO VALLEY AS BLOCKING

FEATURE REMAIN NORTH OF THE GREAT LAKES.

THE IMPACT OF THE BLOCKING TO THE NORTH AND SUBSEQUENT SHIFT SOUTH

BY MAJORITY OF THE MODEL GUIDANCE IN RESPONSE TO IT CANNOT BE

DISCOUNTED...BUT IT WOULD BE FAR TOO PREMATURE TO HOP ONTO THE IDEA

THAT THE ECMWF AND ESPECIALLY THE GGEM SUGGEST IN PUSHING BULK OF

THE MOISTURE TO THE SOUTH OF THE AREA. THERE ARE STILL SEVERAL

VARIABLES AT PLAY INCLUDING EVENTUAL DEGREE OF THE INFLUENCE AND

LOCATION OF THE BLOCK AND TIMING OF THE TRACK OF THE LOW AND ITS

PRECIP SHIELD. MUCH BETTER SAMPLING OF THE UPPER LEVEL FEATURE WILL

TAKE PLACE BY MIDWEEK AS IT ARRIVES ON THE CALIFORNIA COAST AND

CURRENT SYSTEM IMPACTING THE MIDWEST HAS MOVED OFF TO THE EAST. WILL

CONTINUE TO FINE-TUNE AND ADJUST BASED ON MODEL TRENDS OVER THE NEXT

COUPLE DAYS.

FOR NOW...FEEL COMFORTABLE IN SHIFTING TRACK OF THE LOW SOUTH INTO

THE MID-SOUTH AND SLOWING DOWN ITS FORWARD PROGRESSION A BIT. WILL

BRING INITIAL POPS INTO FORECAST AREA LATE THURSDAY NIGHT BUT HOLD

OFF ON HIGH CHANCE/LIKELY POPS UNTIL FRIDAY/FRIDAY NIGHT...WITH

HIGHEST POPS FOCUSED SOUTH OF I-70. ANY MENTION OF MIXING PRECIP

WILL BE REMOVED AS LOW LEVEL THERMALS REMAIN STRONGLY SUPPORTIVE OF

ALL SNOW FOR DURATION OF THE EVENT. SNOWFALL AMOUNTS REMAIN HIGHLY

IN QUESTION...ALTHOUGH OVERALL AMOUNT POTENTIAL LOOKS LOWER THAN IT

DID ON SAT/SUN. THE POSSIBILITY REMAINS FOR THIS STORM TO CAUSE

SIGNIFICANT WINTER WEATHER ACROSS THE OHIO VALLEY FRIDAY AND FRIDAY

NIGHT. WILL CONTINUE TO MONITOR CLOSELY WITH FURTHER ADJUSTMENTS AND

MORE DETAIL TO COME AS MODEL GUIDANCE ALIGNS OVER THE NEXT FEW DAYS.

COLDER AIR RETURNS WITH POTENTIAL FOR SCATTERED SNOW SHOWERS TO

CONTINUE THROUGH THE WEEKEND AS UPPER TROUGH AMPLIFIES OVER THE MID

ATLANTIC. HIGH PRESSURE WILL THEN SLOWLY BUILD IN FOR EARLY NEXT

WEEK.

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L.B. LaForce

L.B. LaForce

Posted
Posted

This is a horribly and crudely drawn map, but the kinematic flow field often has regions of deformation. Shearing and stretching deformation flow fields are common with developing weather systems, and deformation also plays a significant role in frontogenesis. You can see here the crude deformation zone I drew with air "stretching" from Wisconsin and into Iowa. The precip shield is therefore propagating SE even though the main system is heading eastward. Also note the thermal gradient south of the deformation zone is strong WAA. This is acting in a frontogenetic manner, hence the heavy and sharp snow band currently over parts of N IL and Iowa.

Frontogenesis itself only means "birth of a front" and is characterized by an increasing thermal gradient in the horizontal with respect to time. This can be accomplished a number of ways including differential heating, tilting of the front, convergence, and deformation.

post-999-0-76619600-1292877521.png

As modeled now, this system will play little eventual role in potential changes of the Christmas storm.

Greta explanation there Baro, really helps understand what is going on, and how. :thumbsup:

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JoMo

JoMo

Posted
Posted

18z nam would end up rolling right threw us with a major winter storm..much stronger with the vort then the gfs.

St. Louis AFD

THE IMPENDING WINTER STORM (THURSDAY - FRIDAY)...MODELS CONTINUE TO
HAVE A SOMEWHAT LARGE SPREAD ON THE TIMING OF THE STORM...WITH THE
ECMWF THE SLOWEST TRANSLATING IT EWD AND BRINGING IT THRU MAINLY
FRIDAY AND FRIDAY NIGHT...WHILE THE OTHERS BRING IT THRU MAINLY
THURSDAY NIGHT AND FRIDAY. THE GENERAL FLOW WHICH IS RATHER FLAT
ACROSS THE CONUS DURING THIS TIME WOULD ENCOURAGE A FASTER EWD
TRANSLATION AND SO STILL PREFER THE THURSDAY NIGHT-FRIDAY TIMEFRAME
FOR THE MAIN IMPACT. HOWEVER...ANOTHER TREND OBSERVED FROM THE
MODELS 24HRS AGO IS THE TRACK OF THE STORM HAS TRENDED A BIT MORE S
IN ALL OF THEM. THIS WILL SERVE THE EFFECT OF LESSENING THE
MAGNITUDE OF THE WARM WEDGE OF AIR ALOFT AND SHOULD RESULT IN MORE
SNOW AND LESS ICE. I DO NOT WANT TO OVERESTIMATE THE COLDER
TREND...HOWEVER...GIVEN MANY MODEL SOLNS STILL TRACK THE H850 LO
JUST S OF THE I-70 CORRIDOR AND THE MODELS HISTORICAL TENDENCY TO
UNDERDO THE MAGNITUDE OF THE WARM WEDGE OF AIR ALOFT. SO ALL OF THAT
TAKEN INTO CONSIDERATION...HAVE TRENDED COLDER WITH P-TYPES...ADDING
SNOW INTO MORE PLACES WHERE WE DID NOT HAVE IT BEFORE...BUT HELD ON
TO FZRA IN MOST PLACES AS WELL...AS IT APPEARS WE WILL SEE A
TRANSITION OF P-TYPES ON THURSDAY NIGHT HEADING INTO ALL SNOW. BY
FRIDAY...THE MODELS HAVE A GOOD CONSENSUS THAT OUR DOMINANT P-TYPE
WILL BE ALL SNOW. PUTTING IT ALL TOGETHER...FORECAST LIQUID
EQUIVALENT PCPN IS STILL OF A LARGE ENOUGH MAGNITUDE THAT WE ARE
STILL FCSTG A MAJOR WINTER STORM WITH THE POTENTIAL FOR SEVERAL
INCHES OF SNOW WITH SOME ICE AND SLEET THROWN INTO THE MIX AS WELL.
THE REASON DECENT QPF STILL EXISTS DESPITE THE FARTHER SWD TRACK IS
ELEVATED FRONTOGENESIS OF SUFFICIENT STRENGTH TO INTERACT WITH THE
NRN STREAM SYSTEM. THE ODDS FOR A WHITE CHRISTMAS ARE LOOKING
BETTER...BUT GIVEN HOW WE ARE STILL EXAMINING WHAT IS FOR ALL
INTENTS AND PURPOSES A MOVING TARGET...ADDITIONAL SHIFTS IN THE
TRACK AND FORECAST ARE LIKELY GOING TO OCCUR TO SOME DEGREE. WILL
ISSUE A SPECIAL WX STATEMENT FOR ADDITIONAL FORECAST DETAILS.

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Stevo6899

Stevo6899

Posted
Posted

Keep hearing about this block in quebec that could will make this storm move more west to east and not more NW. The NAO is weakening and todays storm is tracking well further north of where the xmas storm is displayed on the models. Granted todays storm is weakening (maybe because of the block or the ec storm), but nonetheless it is well north. The models 2 days ago had todays storm moving more SE and now its moving NW. The xmas storm looks to be stronger but somehow it's going to be forced south but this current weaker storm is able to move NW? Perhaps I am missing something or maybe I should just accept that every storm is diferent and reacts to the atmosphere differently.

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hoosierwx

hoosierwx

Posted
Posted

LMK:

LATEST SUITE OF MED/LONG RANGE DETERMINISTIC AND ENSEMBLE MODEL RUNS

CONTINUE TO AGREE THAT A MID-LEVEL WAVE WILL EJECT OUT OF THE

SOUTHERN ROCKIES AND INTO THE SOUTHERN PLAINS THURSDAY EVENING.

OVERALL...THE MAJORITY OF THE MODEL GUIDANCE HAS DONE TWO

THINGS...FIRST...THEY HAVE ALL SLOWED DOWN THE EASTWARD PROGRESSION

OF THE SYSTEM A BIT...AND SECOND...THE OVERALL TRACK OF THE SYSTEM

HAS COME IN A BIT MORE SOUTH. SINCE THE CONSENSUS OF THE MODELS

HAVE TRENDED A BIT FURTHER SOUTH...THEIR OVERALL THERMAL PROFILES

ACROSS OUR AREA ARE A BIT COLDER IN TODAY RUNS.

THERE REMAINS CONSIDERABLE SPREAD AMONG THE DETERMINISTIC GUIDANCE

AND THE ENSEMBLE SOLUTIONS FROM BOTH THE GFS AND EURO ALSO EXHIBIT A

BIT OF SPREAD IN THEIR SURFACE LOW TRACK SOLUTIONS. CURRENTLY THE

GFS AND ITS ENSEMBLES ARE ON THE NORTH SIDE OF THE GUIDANCE WHILE

THE EURO AND CANADIAN GEM RUNS ARE ON THE SOUTHERN EDGE OF THE

GUIDANCE ENVELOPE. CURRENTLY...THE ENSEMBLE SOLUTIONS FROM BOTH THE

GFS AND EURO DO NOT FULLY SUPPORT THE CAN GEM AND EURO FAR SOUTHERN

SOLUTIONS. IN ADDITION...LOOKING AT THE GLOBAL PATTERN...IT APPEARS

THAT THE NORTHERN STREAM OF THE JET SHOULD REMAIN A BIT STRONGER

THAN THE SOUTHERN STREAM. THUS...FEEL THAT THE GEM/EURO SOLUTION IS

TOO FAR SOUTH AND HAVE GONE MORE THE 12Z GFS ENSEMBLE MEAN FOR A

TRACK SOLUTION AT THIS TIME. WITH THAT SAID...WILL NEED TO MAKE A

FEW ADJUSTMENTS TO THE FCST.

FOR THU NIGHT...CLOUDS WILL CONTINUE TO STREAM IN FROM THE WEST AS

THE STORM DEVELOPS OVER THE SOUTHERN PLAINS AND HEADS EAST.

PRECIPITATION WILL BREAK OUT ACROSS THE REGION LATE THURSDAY

NIGHT...BUT PROBABLY MORE LIKELY FRIDAY MORNING IN THE WEST AND THEN

SPREAD EAST DURING THE DAY. BOUNDARY LAYER TEMPERATURES HAVE COOLED

IN THE MOST RECENT RUNS...BUT FEEL THAT A RAIN/SNOW MIX IS STILL

LIKELY ON FRIDAY DURING THE DAY. MUCH COLDER AIR WILL DUMP INTO THE

REGION EARLY CHRISTMAS TRANSITIONING THE PRECIPITATION FROM

RAIN/SNOW OVER TO PLAIN SNOW WHICH SHOULD CONTINUE OVERNIGHT AND

INTO CHRISTMAS DAY. SO A WHITE CHRISTMAS LOOKS VERY LIKELY AT THIS

TIME. IN ADDITION...THE INCREASING PRESSURE GRADIENT WILL RESULT IN

WINDY CONDITIONS WHICH MAY RESULT IN SOME BLOWING SNOW AT TIMES.

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dilly84

dilly84

Posted
Posted

Keep hearing about this block in quebec that could will make this storm move more west to east and not more NW. The NAO is weakening and todays storm is tracking well further north of where the xmas storm is displayed on the models. Granted todays storm is weakening (maybe because of the block or the ec storm), but nonetheless it is well north. The models 2 days ago had todays storm moving more SE and now its moving NW. The xmas storm looks to be stronger but somehow it's going to be forced south but this current weaker storm is able to move NW? Perhaps I am missing something or maybe I should just accept that every storm is diferent and reacts to the atmosphere differently.

you mean NE? Todays storm is moving east, not NW?

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