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Dec 24-25 Snowstorm part 2

jhamps10

By jhamps10,
in Central/Western States

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jhamps10

jhamps10

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ILX AFD, WWA coming down the tube

]AREA FORECAST DISCUSSIONNATIONAL WEATHER SERVICE LINCOLN IL230 PM CST THU DEC 23 2010.DISCUSSION...ISSUED 115 PM CST THU DEC 23 2010MAIN CONCERN IS THE STORM SYSTEM FOR LATE TONIGHT THROUGH CHRISTMASEVE. SEVERAL OF THE SHORT TERM MODELS HAVE SHOWN LARGE SWINGS IN THEIRINDIVIDUAL SOLUTIONS OVER THE LAST COUPLE OF DAYS. HOWEVER...WITHTHE 12Z GUID VARIATIONS BETWEEN THE MODELS IS A BIT LESS DRAMATIC.DIFFS STILL EXIST...WHICH IS UNDERSTANDABLE DUE TO THE FORCINGMECHANISMS IN PLAY FOR THIS TYPE OF SPLIT FLOW-INVERTED TROUGHEVENT. OVERALL...THE FORECAST PACKAGE WAS NOT CHANGEDSIGNIFICANTLY...AND WE CONTINUE TO EXPECT 2-4" OF SNOW OVER AMAJORITY OF CENTRAL ILLINOIS. SHORT TERM...TONIGHT THROUGH SUNDAY.ENOUGH AGREEMENT CONTINUES FOR THE ONSET OF SNOW NORTH OF CANTONTO PEORIA TO BLOOMINGTON BETWEEN MIDNIGHT AND 6 AM TONIGHT...AS ANARM OF SNOW DEVELOPS AHEAD OF THE MAIN BAND OF SNOW. DRY AIR INTHE LOWER LAYERS WILL DELAY THE START OF SNOW...BUT THE ATMOSPHEREIS ALREADY BECOMING SATURATED THIS AFTERNOON BASED ON RADARRETURNS OF THE MID LEVEL CLOUDS. THE POSITION AND LONGEVITY OF THE INITIAL BAND OF SNOW WILL HAVE AMAJOR AFFECT ON SNOW AMOUNTS CREEPING UP OVER 4 INCHES IN ANYLOCATION FOR THE EVENT. THIS BAND MAY EVENTUALLY EXTEND ALL THEWAY TO CHAMPAIGN AND DANVILLE DURING THE DAY ON FRIDAY. CROSSSECTION ANALYSIS OF FRONTOGENESIS/FN CONVERGENCE/EPV SUPPORTS THEPOTENTIAL FOR BANDED STRUCTURE TO THE SNOWFALL ON FRIDAY...ESPECIALLY ACROSS THE NORTHERN CWA. BANDED POTENTIAL DIMINISHES BYFRIDAY EVENING.DUE TO THE DRY AIR IN THE LOWER LEVELS...THE SOUTHERN TWO THIRDSOF THE CWA WILL FINALLY SEE SNOWFALL BEGIN AFTER 12Z...ANDPOSSIBLY AS LATE AT 18Z FOR AREAS SOUTH OF SPI TO MATTOON. THEREAPPEARS TO BE ENOUGH LONGEVITY TO THE LIGHT SNOWFALL TO PRODUCE2-3 INCHES OF SNOW IN THE SOUTHERN HALF OF THE CWA...WITH THE FARSOUTHEAST MOST LIKELY IN THE LOWER AMOUNTS.WINDS AND BLOWING SNOW SHOULD NOT BE A MAJOR CONTRIBUTOR TO THEHAZARDOUS TRAVEL ON FRIDAY. EASTERLY WINDS WILL BE MAINLY 10 MPHOR LESS FOR MOST OF THE EVENT.EVEN THOUGH SOME AREAS MAY ONLY BE BORDERLINE WITH RESPECT TOADVISORY AMOUNTS OF SNOW...WE DECIDED TO GO WITH A WINTER WEATHERADVISORY FOR THE ENTIRE CWA. TO KEEP THINGS SIMPLE...WE DECIDEDTO USE ONE HEADLINE FOR THE ENTIRE CWA...STARTING AT 12Z FRIDAYAND GOING THROUGH 12Z SATURDAY. WE WILL INCLUDE DETAILED WORDINGON AMOUNTS AND TIMING WITHIN THE PRODUCT.AN EXTENDED PERIOD OF FLURRIES LOOKS LIKELY AFTER THE MAIN SNOWEVENT...TO CONTINUE THROUGH CHRISTMAS DAY AND INTO SUNDAY. THIS ISMAINLY DUE TO THE SLOW PROGRESS OF THE UPPER TROUGH...SO VARIOUSSHORTWAVES WILL ROTATE SOUTH INTO ILLINOIS. SURFACE WINDSFAVORABLE FOR LAKE EFFECT SNOW WILL CONTINUE INTO SUNDAY ASWELL...WITH ENOUGH LONGEVITY TO THE FLOW THAT OUR EASTERN CWA MAYSEE SOME LIGHT LAKE EFFECT SNOW THIS WEEKEND. IT WILL BELIGHT...WITH LITTLE ADDITIONAL ACCUMULATION EXPECTED.

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Hoosier

Hoosier

Posted
Posted

snip from LOT afternoon afd:

THAT BEING SAID...STILL EXPECT ACCUMULATING SNOWFALL AROUND 2 TO 4 INCHES ACROSS THE REMAINDER OF THE FORECAST AREA...AND AM CONCERNED OF THE POTENTIAL FOR HIGHER AMOUNTS. LOOKING UPSTREAM RADAR RIGHT NOW SHOWS DECENT RETURNS OVER IOWA AND NORTHERN MISSOURI...BUT MOST DOES NOT SEEM TO BE HITTING GROUND. DRY AIR IN THE MID LEVELS TAKING A WHILE TO SATURATE...BUT COMPARING KDVN 12Z SOUNDING WITH NAM/GFS 12Z INITIALIZATION...BOTH MODELS ARE ACTUALLY DRYER IN THE MID-LEVELS THAN THE RAOB SOUNDING. ALSO CONCERNED ABOUT HIGHER SNOW TO LIQUID RATIOS AT THE ONSET OF PRECIPITATION. MODELS SHOW DEEP DENDRITIC GROWTH LAYER IN EXCESS OF 7KFT PRETTY MUCH CENTERED OVER THE FORECAST AREA. OMEGA VALUES THROUGH THIS LAYER NOT OVERLY IMPRESSIVE WITH BEST VALUES SOUTH...BUT COBB OUTPUT SHOWS HIGHER 16-18:1 RATIOS OVER THE FIRST SEVERAL HOURS OF SNOW BEFORE COMING DOWN TOWARDS 13-14:1.

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weatherguru

weatherguru

Posted
Posted

LOT pretty bullish and sounds like they're ready to ramp up if the need arises.

After such a long roller coaster ride, it's fitting this ends up another Cyclone special.

How is lot being bullish? The main event alone produced .25 to .50 QPF in North-central IL. With a onset of 16:1 ratio 2-4 inches would be good for Chicago and 3-6+ for north central and if that does end up even furthur ne and or stronger you bet Chicago will be in the 3-6+ band.

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Amos83

Amos83

Posted
Posted

Here's my forecast amount on the storm, I'm going a bit bullish but I feel my forecast should easily verify, I'm mainly focusing on the IL/MO/IN areas on this forecast so don't be alarmed people in iowa when you see my lower numbers...

g7zg.jpg

I like your map jhamps... it follows similar to what I was thinking but wasn't sure because I'm not familiar with the area. It's going to depend a lot how where/if any local banding develops but at least a large portion should see some decent snow fall over rthe next two days.

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janetjanet998

janetjanet998

Posted
Posted

DVN

SHORT TERM...TONIGHT AND FRIDAY

FOCUS IS ON TIMING THE ONSET OF SNOW TONIGHT AND SNOW TOTALS

THROUGH CHRISTMAS EVE. BANDS OF SNOW ARE SHOWN BY MODELS TO SET

UP OVER N CENTRAL INTO EASTERN IA THIS EVENING. THIS LOOKS TO

OCCUR AS THE NORTHERN STREAM SHORTWAVE STRENGTHENS AND ADVANCES AN

AREA OF MID LEVEL FORCING SOUTHEAST ACROSS IA. AT THE SAME

TIME...INCREASING H8 WARM AIR ADVECTION AND A DEVELOPING AXIS OF

ISENTROPIC LIFT WILL LIKELY MEET UP WITH THE MOISTURE RETURN

PUNCHING NORTH INTO THE REGION TO OVERCOME THE AFOREMENTIONED DRY

LAYERS ON AREA SOUNDINGS. THIS LIFT AND EVENTUAL SATURATION SHOULD

RESULT IN SNOW DEVELOPING INTO ESPECIALLY E CENTRAL IA BY

MIDNIGHT...THEN OVERSPREAD THE ENTIRE AREA BY SUNRISE AND HAVE

RAISED POPS TO CATEGORICAL IN AN AXIS ACROSS THE CENTRAL FORECAST

AREA OVERNIGHT. BASED ON MODELS APPEARING TO BE OVERDONE WITH

QPF AMOUNTS UPSTREAM SO FAR TODAY...HAVE STAYED CONSERVATIVE WITH

A GENERAL 1 TO 3 INCH RANGE FOR OVERNIGHT TOTALS OVER E CENTRAL IA

INTO FAR W CENTRAL IL.

FRIDAY...MODELS ARE IN GENERAL AGREEMENT TRACKING THE UPPER LEVEL

SHORTWAVE SOUTHEAST INTO EASTERN IA BY EVENING...WHERE IT BEGINS

TO PHASE WITH THE SOUTHERN STREAM SYSTEM. AT THE SAME TIME...A

CIRCULATION AT H8 TRACKS FROM SW IA TO W CENTRAL IL WITH LOW LEVEL

DEFORMATION AT THE NORTHERN EDGE OF AN INVERTED SURFACE TROUGH

ALSO BRUSHING MAINLY THE SOUTHERN PART OF THE FORECAST AREA BY

EVENING. THIS...ALONG WITH JET LEVEL DIVERGENCE FIELDS AND 0MEGA

IN THE DENTRITIC GROWTH ZONE...SUPPORT MODERATE TO POSSIBLY

PERIODS OF HEAVY SNOW DURING THE MORNING HOURS...THEN DIMINISHING

TO MAINLY STEADY LIGHT SNOW DURING THE AFTERNOON HOURS...TARGETING

ESPECIALLY THE CENTRAL AND SOUTH LATE. BASED ON TRACKS OF THE MID AND

HIGH LEVEL FORCING...AND CONSIDERING POSSIBLE ENHANCED BANDS AT

THE ONSET TONIGHT...AN AXIS OF HEAVIEST STORM TOTAL SNOWFALL

AMOUNTS IN THE RANGE OF 5 TO 7 INCHES IS NOW EXPECTED ROUGHLY FROM

THE CEDAR RAPIDS/IOWA CITY AREA E-SE THROUGH THE QUAD CITIES.

EVENT TOTALS ELSEWHERE...LOOK TO BE 2 TO 4 INCHES WITH MUCH OF

EAST CENTRAL IA LIKELY IN THE 4 TO 6 INCH RANGE.

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hawkeye_wx

hawkeye_wx

Posted
Posted
SNOW WILL BE WIDESPREAD ACROSS THE FORECAST AREA FRIDAY MORNING WITH700-600 MB FRONTOGENETICAL FORCING REMAINING OVER CENTRAL IA. THISWILL KEEP FORCING IN PLACE THROUGH THE DENDRITIC GROWTH ZONE (DZ).THE DZ WILL DEEPEN DURING THE DAY WITH COLDER AIR BEGINNING TOFILTER IN FROM THE NORTH. THE PRIMARY SHORT WAVE ASSOCIATED WITHTHIS NORTHERN STREAM SYSTEM WILL MOVE OUT OF SOUTH DAKOTA AND INTOSOUTHWEST IA DURING THE DAY ON FRIDAY. SUBSIDENCE ON THE BACKSIDEWILL DRY OUT THE MID LEVELS FROM NORTHWEST TO SOUTHEAST DURING THEAFTERNOON AND EVENING AND FINALLY BRINGING THE SNOW TO AN END. SNOWRATIOS WILL BE QUITE HIGH AND SIMILAR TO YESTERDAYS THINKING AND INTHE 14-1 TO 17-1 RANGE THOUGH BRIEF PERIODS OF 20-1 ARE POSSIBLE.THIS SHOULD YIELD ADDITIONAL ACCUMULATIONS RANGING FROM 1 TO 3INCHES OVER THE FAR SOUTHWEST AND WEST CENTRAL WHERE DENDRITICGROWTH IS LOST EARLIEST TO 2 TO 4 INCHES CENTRAL AND NORTH CENTRALTO 3 TO 5 SOUTHEAST. LATEST DETERMINISTIC AND SREF RUNS STILLSUGGESTING STORM TOTAL QPF VALUES 0.50 TO 0.75 INCHES WITH GIVENSNOW RATIOS COULD PRODUCE MORE SNOW THAN FORECAST. CURRENT STORM TOTALS RANGE FROM 5 TO 8 INCHES ALONG AND NORTH OF A DENISON TO DES MOINES TO OTTUMWA LINE AND 3 TO 6 INCHES TO THE SOUTH.THEREFORE...STILL POSSIBLE A FEW LOCATIONS MAY INCH ABOVE THE 8 INCHIN 24 HOURS WINTER STORM CRITERIA FOR HEAVY SNOW. CONFIDENCE NOTHIGH ENOUGH FOR A WIDESPREAD UPGRADE AT THIS TIME.
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Cyrys

Cyrys

Posted
Posted

If my 3-5 forecast pans out, then I should be right around 50" for the season. Any snow from this point forward is above our winter average. The MSP airport needs around 4 to break their December monthly snowfall record(sitting at 3rd all time right now) and just over an inch to crack the 40 mark for the season. If it's gonna keep snowing like this, I'm hoping this winter beats out the winter of 2000-2001. It was the snowiest winter while I have lived here totaling 75.8" I believe the winter of 96-97 also had a similar total to this..

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JoMo

JoMo

Posted
Posted

If my 3-5 forecast pans out, then I should be right around 50" for the season. Any snow from this point forward is above our winter average. The MSP airport needs around 4 to break their December monthly snowfall record(sitting at 3rd all time right now) and just over an inch to crack the 40 mark for the season. If it's gonna keep snowing like this, I'm hoping this winter beats out the winter of 2000-2001. It was the snowiest winter while I have lived here totaling 75.8" I believe the winter of 96-97 also had a similar total to this..

I hope you are dry the rest of the winter. thumbsupsmileyanim.gif

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cyclone77

cyclone77

Posted
Posted

If someone want snow, invite Cyclone to your holiday party.

Haha. Yeah it's been a pretty good month from here down towards LAF. Big D and the Minnesota members are the true winners so far. Still a long way to go.

Looks like the heaviest will actually fall from Hawkeye down through the QC, and down to around Peoria. Probably a nice 5-6"+ in that band. I'm going with 4" here. Good to see Hawkeye and points southwest finally getting in on some good snow. The bullseye of up to 9" will probably fall near Ames/Marshalltown.

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LizardMafia

LizardMafia

Posted
Posted

I thought I read on his blog that's he out of town for Christmas. We'll have to rely on the COOPs...

Anyways, I'm going 2-4" for LAF and 3-5" for IKK.

A little bold for you don't you think? ;)

I'm thinking the same 2-4" sounds good.. Maybe we get a little over performance like earlier this week?

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Chicago WX

Chicago WX

Posted
Posted

A little bold for you don't you think? ;)

I'm thinking the same 2-4" sounds good.. Maybe we get a little over performance like earlier this week?

At the moment I see no reason we won't get to at least the 2" mark. 4" is probably going to be a lot to ask for, but you're right, we've done pretty well (even overachieved) with most of the snow events so far this season. Hopefully it continues.

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IWXwx

IWXwx

Posted
Posted

#1248 Chagrin Falls Posted 21 December 2010 - 04:14 PM

promet.png



"Every 6 hrly update of the NAM, GFS and DGEX is a "FOX NEWS ALERT" with the American flag waving in the background.

God Bless America!"

I was just wondering how that Euro hugging thing is working out for you on this storm.

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GordoFabulous

GordoFabulous

Posted
Posted

While things are quiet, I thought I would throw out a question to help me understand what I'm looking at in the models. I've lived in central Indiana just about my entire life, and I'm well aware of what big snowstorms in Indiana look like on the surface: a low forms in east Texas and rides up the Mississippi and Ohio rivers. What does that look like on the 500mb Vort map?

It seems like those classic snowstorms have a setup not all that different from what we have now, the pieces just shifted a little, so if a met could make a comparison between those and what the models show now, I would really appreciate it. Thanks.

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