January 9th-11th Winter Storm Obs Thread

[cyclone77]

That little band hung over us for a good half hour and delivered a solid half inch or so. The snow seems extremely dry. Back to pixie dust now.

[JoMo]

Winding down here now, got probably 2" or so just looking out the window. It was enough to close down all schools around here though.

[Chicago Storm]

-SN has started here.

[snowlover2]

IND basically stayed the same.

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE INDIANAPOLIS IN

241 AM EST TUE JAN 11 2011

.UPDATE...

THE SYNOPSIS...NEAR TERM AND SHORT TERM SECTIONS HAVE BEEN UPDATED

BELOW.

&&

.SYNOPSIS...

SNOW WILL OVERSPREAD CENTRAL INDIANA THIS MORNING FROM SOUTHWEST TO

NORTHEAST AHEAD OF A STRONG UPPER SYSTEM. SEVERAL INCHES OF SNOW ARE

EXPECTED DURING THE DAY AND INTO THE EVENING. SCATTERED SNOW SHOWERS

WILL REMAIN ON WEDNESDAY BEFORE ENDING FROM SOUTHWEST TO NORTHEAST

WEDNESDAY NIGHT. ADDITIONAL MINOR ACCUMULATIONS ARE POSSIBLE.

THEN...HIGH PRESSURE WILL BUILD ACROSS THE OHIO VALLEY LATE WEEK.

HOWEVER...ADDITIONAL SNOW CHANCES WILL RETURN THIS WEEKEND AHEAD OF

A PAIR OF PLAINS LOW PRESSURE SYSTEMS. BELOW NORMAL TEMPERATURES

SHOULD CONTINUE.

&&

.NEAR TERM /TODAY THROUGH TONIGHT/...

THE SNOW HAS BEEN TAKING ITS TIME REACHING THE GROUND OVERNIGHT

DESPITE FAIRLY STRONG ISENTROPIC LIFT ON THE 290K LEVEL WITH

SATURATION IMPLIED BY CONDENSATION PRESSUTRE DEFICITS LESS THAN 10

MB. WEDGE OF DRY AIR AT 850 MB WAS SEEMINGLY TO BLAME. AT

07Z...SURFACE OBSERVATIONS WERE SHOWING THE SNOW HAS NOW REACHED THE

GROUND AS FAR EAST AS EFFINGHAM...WHERE THE VISIBILITY WAS DOWN TO A

MILE AND A HALF. RAPID REFRESH LOOKED AN HOUR OR TWO TOO FAST WITH

TIMING. WITH THE WAY THINGS ARE TRENDING PREFER A BLEND OF THE

QUICKER 00Z OPERATIONAL GFS AND SLOWER 00Z NAM WHICH WOULD BRING THE

SNOW INTO SOUTHWESTERN PARTS OF THE FORECAST AREA AROUND 09Z AND

INTO THE NORTHEAST SHORTLY AFTER 12Z THIS MORNING.

REGARDLESS...MODELS WERE ALL RIGHT ON WITH THE SYNOPTIC PATTERN AND

SNOWFALL TOTALS TODAY WITH 2 TO 3 INCHES FORECASTED THROUGH 00Z THIS

EVENING ALONG AND NORTH OF INTERSTATE 70 AND 1 TO 2 SOUTH OF I70.

MODELS BRINGING A NEGATIVELY TILTED TROUGH FROM THE NORTHERN PLAINS

TO THE LOWER OHIO VALLEY THIS MORNING DEEPENING TO AN UPPER LOW BY

18Z ACROSS EAST CENTRAL ILLINOIS AND ASSOCIATED ENERGY ROUNDING THE

BASE ACROSS EXTREME SOUTH CENTRAL INDIANA. CENTRAL INDIANA WILL

RESIDE WITHIN THE FRONT LEFT QUADRANT OF A STRONG UPPER JET

STREAK...140 KNOTS...ASSOCIATED WITH THIS ENERGY WHICH WILL PROVIDE

STRONG UPPER DIVERGENCE IN ADDITION TO THAT FROM THE NEGATIVELY

TILTED TROUGH ACROSS THE FORECAST TODAY. IN ADDITION...MODEL

SOUNDINGS WERE SHOWING 150 MB DEEP STRONG LIFT THROUGHOUT THE

DENDRITIC ZONE...AND

FINALLY...MODEL CROSS SECTIONS WERE SHOWING NEGAVITIVE EQUIVALENT

POTENTIAL TEMPERATURE VORTICITY IN THE 700 MB TO 500 MB LAYER TODAY

ACROSS THE ENTIRE FORECAST AREA WHICH IMPLIES SOME INSTABILITY.

SO...ALL THESE FACTORS IN CONCERT SHOULD ALLOW FOR HIGHER SNOW

AMOUNTS THEN THE MODELS OR HPC...PRETTY CLOSE TO WHAT WE ALREADY HAD

GOING WITH 2 INCHES OR SO SOUTHWEST INCREASING TO 3 TO 5 INCHES

ELSEWHERE AND ISOLATED 6 INCH AMOUNTS POSSIBLE NORTH OF I70....BUT

AT THIS TIME WINTER WEATHER ADVISORY STILL LOOKS TO BE THE BEST WAY

TO GO...BUT WILL HAVE TO KEEP AN EYE ON NORTHERN PARTS OF THE

FORECAST AREA. NEEDLESS TO TODAY...POPS ARE 100 PERCENT TODAY. THE

ACTIVITY WILL BE WINDING DOWN THIS EVENING FROM SOUTHWEST TO

NORTHWEST AS THE BEST LIFT...SEEN IN 850-500 MB Q-VECTOR

CONVERGENCE...DEPARTS. STILL...WRAPAROUND SNOW EXPECTED AS THE

SYSTEM DEPARTS TONIGHT WITH PERHAPS SOME LAKE ENHANCED SNOWS

NORTHEAST. SO...KEPT LIKELY POPS IN THERE TAPERING TO SMALL CHANCE

SOUTHWEST.

MOS TEMPERATURES ARE NOT THAT FAR OFF AND WITH FOCUS MORE ON SNOW

POTENTIAL...WILL GO WITH MOS BLEND WHICH LOOKS REASONABLE.

[Chicago Storm]

MKE going with a WWA for lakeside counties for 3-5"...maybe higher if things go perfectly.

OBVIOUS FORECAST CONCERN IS SNOW AND AMOUNTS FOR TODAY INTO TONIGHT.

FIRST SHORT WAVE ROTATING AROUND UPPER LOW WL BRING BETWEEN 1 AND 2

INCHES TO WRN CWA OVERNIGHT. INCREASING FORCING BEGINNING TO OVERWHELM

LINGERING DRY LAYER OVER PORTIONS OF ERN CWA AND EXPECT WIDESPREAD

-SN OVER THE ENTIRE REGION BY EARLY MORNING. SRN WI REMAINS ON

NORTHERN FRINGE OF STRENGTHENING SHORT WAVE CURRENTLY OVER CENTRAL

MS VLY REGION AS IT TRACKS INTO THE OH VALLEY TODAY AND THIS EVE.

ENHANCED FORCING FROM UPPER LEVEL JET STREAK AND FULL WIND

FRONTOGENESIS REMAIN SOUTH OF THE AREA. HOWEVER WEAK WARM AIR

ADVECTION AND PERSISTENT ISENTROPIC UPGLIDE CONTINUE THROUGH THE

MORNING...SLOWLY DIMINISHING FROM WEST TO EAST FROM MID-AFTERNOON

INTO THE EARLY EVENING. PERIOD OF STRONGEST FORCING DURING THE MRNG

AND EARLY AFTN. WIDESPREAD 0.15 TO 0.25 QPF WITH SNOW LIQUID RATIOS

AVERAGING 15 TO 1 YIELDS WIDESPREAD 2.5 TO 4 INCH AMOUNTS.

HOWEVER...NEED TO CONSIDER LAKE ENHANCEMENT IN AREAS BORDERING LAKE

MICHIGAN. AVERAGE SEA SURFACE TEMP OF 2.5 DEGREES C YIELDS DELTA-T

OF 16 DEGREES FOR DURATION OF THIS EVENT. USING NAM BUFKIT...LAKE

INDUCED CAPE INCREASES TO AROUND 250 J THIS AFTN WITH INVERSION

HEIGHT AROUND 4.5KT. INCRNG ELY WNDS AND LAKE ENHANCED SNOW HAVE

ALREADY PRODUCED ABOUT AN INCH IN NRN SHEBOYGAN COUNTY OVERNIGHT.

LOW LEVEL WINDS BEGIN TO BACK LATER THIS MRNG THROUGH THE AFTN

INCREASING FETCH LENGTH AND LOW LEVEL CONVERGENCE ALONG THE

LAKESHORE COUNTIES.

LAKE EFFECT SNOW FLOW CHART YIELDS LAKE ENHANCEMENT ADDING MODERATE

ACCUMULATIONS OF 3 TO 5 INCHES IF ADDING WEAK TO MODERATE QG FORCING

SUPPORT...AND MINOR ACCUMULATIONS OF AROUND AN INCH IF FORCING

NEUTRAL. ALSO THINKING LIMITING FACTOR WL BE BACKING WINDS FROM 080

DEGREES LATE THIS MRNG TO 010 DEGREES BY LATE AFTN. THIS WL RESULT

IN LAKE ENHANCEMENT NOT LINGERING IN ONE AREA FOR MORE THAN AN HOUR

OR TWO /HOPEFULLY/.

NEVER THE LESS...LAKE ENHANCEMENT WL BUMP UP AMOUNTS OVER LAKESHORE

COUNTIES BY AT LEAST AN INCH PUSHING AMOUNTS TO 3 TO 5 INCHES IN

THESE AREAS. PER COLLABORATION WITH GRB AND LOT...WL ISSUE WINTER

WX ADVY INTO THE EARLY EVENING FOR THESE AREAS. SNOW WL ALSO BE

AFFECTING MRNG AND AFTN COMMUTES AS WELL.

WL HANG ONTO HIGHER POPS IN THE EARLY EVE IN THE EAST DUE TO

LINGERING LOWER CONDENSATION PRESSURE DEFICITS AND WEAK ISENTROPIC

UPGLIDE.

[Chicago Storm]

THE NATIONAL WEATHER SERVICE IN CHICAGO HAS ISSUED A WINTER

WEATHER ADVISORY FOR SNOW...WHICH IS IN EFFECT

FROM 6 AM THIS MORNING TO 8 PM CST THIS EVENING.

* TIMING...SNOW WILL INCREASE IN COVERAGE AND INTENSITY EARLY THIS

MORNING. THE STEADIEST SNOWFALL...BECOMING MODERATE AT

TIMES...IS EXPECTED TO OCCUR BETWEEN ABOUT 9 AM AND 3 PM TODAY.

* ACCUMULATIONS...3 TO 5 INCHES ACROSS THE ADVISORY AREA...WITH

UP TO 6 INCHES POSSIBLE IN LOCALIZED COVERAGE NEAR LAKE MICHIGAN.

* HAZARDS...LIGHT TO OCCASIONALLY MODERATE SNOW. LOW VISIBILITY.

* IMPACTS...ROADS WILL BECOME SNOW COVERED. VISIBILITY REDUCED

TO A MILE OR LESS AT TIMES.

[michsnowfreak]

Well all the models are looking good! The Euro, which was dry all week, has come around to 0.30", an exact match to the NAM and the 6z GFS looks better too!. DTX has issued an advisory for total storm accumulations of 4", which to me is kinda weird to not say a range (though in the forecast they do say 2-3" today and up to 2" tonight, which is technically 4-5").

SHORT TERM... TODAY AND TONIGHT

A WINTER WEATHER ADVISORY WILL BE IN EFFECT FOR THE SOUTHEAST CORNER

OF OUR AREA FROM NOON TODAY TO MIDNIGHT TONIGHT. THIS WILL INCLUDE

THE REGION ROUGHLY FROM PORT HURON TO PONTIAC TO ANN ARBOR AND SOUTH

TO THE OHIO BORDER. THE ADVISORY WILL BE IN PLACE MAINLY TO

HIGHLIGHT THE STRONGEST PART OF THE SYSTEM MOVING THROUGH SE

MICHIGAN DURING THE PEAK EVENING DRIVING PERIOD AND FOR SNOWFALL OF

2 TO 3 INCHES EXPECTED DURING THE 6 HOUR PERIOD FROM ABOUT 3 PM TO 9

PM. LIGHTER SNOW IN ADVANCE OF AND TRAILING THE PEAK PERIOD WILL

RESULT IN SYSTEM TOTALS AROUND 4 INCHES IN THE ADVISORY AREA BY

SUNRISE WEDNESDAY MORNING. ELSEWHERE AROUND SE MICHIGAN, THE

FORECAST TREND WITH THIS PACKAGE WILL HAVE SLIGHTLY HIGHER SNOW

ACCUMULATION TO ACCOUNT FOR MODEST ENHANCEMENT FROM LAKE HURON INTO

THE SAGINAW VALLEY AND THUMB, MAINLY TONIGHT.

JUDGING FROM THE SUITE OF OBSERVATIONS AT PRESS TIME, THE LATEST

MODEL SOLUTIONS ARE ABOUT ON TRACK WITH THE COVERAGE AND INTENSITY

OF SNOW REACHING THE GROUND TO OUR WEST. MODEL SOUNDINGS ALSO DEPICT

THE LAYER OF DRY AIR OVER SE MICHIGAN QUITE NICELY COMPARED TO THE

00Z DTX SOUNDING. ALL OF THIS ADDS CONFIDENCE TO THE ONSET TIMING BY

NOON NEAR THE OHIO BORDER TO EARLY AFTERNOON IN THE NORTHERN THUMB

AS ISENTROPIC LIFT RAMPS UP IN ADVANCE OF THE WAVE. MODEL DEPICTIONS

OF SYSTEM RELATIVE ISENTROPIC LIFT SHOW GOOD PRESSURE ADVECTION ON

THE 285K SURFACE CARRYING 1 TO 2 G/KG SPECIFIC HUMIDITY OVER LOWER

MICHIGAN. THIS SUGGESTS A SOLID 2 TO 4 INCH ACCUMULATION DURING THE

PERIOD FROM ABOUT NOON TODAY TO MIDNIGHT TONIGHT, BUT WITH MOST OF

THAT COMING WITH THE PASSAGE OF THE UPPER LOW AND MID LEVEL TROWAL

DURING THE MID AFTERNOON THROUGH EARLY EVENING PERIOD. IT IS

EXPECTED THAT THE CENTER OF THE COMPACT UPPER LOW WILL MOVE BY TO

OUR SOUTH BUT WILL BRING ENOUGH COOLING ALOFT TO STEEPEN MID LEVEL

LAPSE RATES. THIS WILL LIKELY ENHANCE LIFT IN THE TROWAL AXIS AS IT

MOVES ABOUT DIRECTLY OVER THE ADVISORY AREA. MODEL SOUNDINGS ALSO

SHOW GOOD THERMODYNAMIC PROPERTIES FOR SNOW GROWTH. WHILE NOT

ISOTHERMAL, THE SOUNDINGS SHOW GOOD SATURATION AND RESPECTABLE

RESIDENCE TIME IN THE DGZ DURING THE PEAK OF THE EVENT. ALL

TOGETHER, THIS IS EXPECTED TO RESULT IN A BURST OF HEAVIER SNOW JUST

IN TIME TO HAMPER THE EVENING COMMUTE IN THE DETROIT AREA.

THE OTHER CONCERN IN OUR AREA IS THE POTENTIAL FOR ENHANCEMENT FROM

LAKE HURON INTO THE THUMB AND SAGINAW VALLEY. THE NAM12 INDICATES A

FAIRLY STRONG COMPONENT OF VERTICAL MOTION CENTERED AROUND 850 MB TO

GO ALONG WITH THE LARGER SCALE FORCING ON THE NORTH AND WEST FLANK

OF THE SYSTEM. MODEL SOUNDINGS IN THAT AREA INDICATE INCREASING

CONVECTIVE DEPTH, ESPECIALLY AFTER MIDNIGHT BUT WITH MODEST

INSTABILITY FROM THE LAKE SURFACE USING A WATER TEMP OF 3C. FOR NOW,

DECIDED TO JUST INCREASE THE TOTAL ACCUMULATION THERE INTO THE 2 TO

4 INCH RANGE AND HOLD OFF ON A HEADLINE CONSIDERING MOST OF THAT

WILL FALL FROM MID EVENING THROUGH THE OVERNIGHT HOURS.

[snowstormcanuck]

Classic dry air radar signature. The donut hole.

[michsnowfreak]

Classic dry air radar signature. The donut hole.

Yeah, but as I said yesterday, virga is not wasted qpf. Snow start time here is progged between noon per gfs and 2pm per nam.

[snowstormcanuck]

Yeah, but as I said yesterday, virga is not wasted qpf. Snow start time here is progged between noon per gfs and 2pm per nam.

I was just pointing it out as an interesting radar interpretation fact (although for 90% of the board, probably pretty obvious ). Not concerned about dry air affecting the precip beyond what's expected. Per DTX AFD, everything's on schedule.

[mnchaser]

Right around 6.5 inches for us, closing in on the big fat 60..65 is the all time record for Mankato..kinda low you would think.

[Chicago WX]

Looking at radar, it sure doesn't seem like things are looking too good for LAF. The heaviest returns right now are focused over SE IL and C/S IN at the moment. Should probably bode well for those in IND, BMG, DAY, CVG, CMH, etc.

-SN and about 1" already here in IKK.

[Baum]

pixie dust storm in full tilt west of Chicago....better get the lake involved if were going to reach 3-5....

[buckeye]

Looking at radar, it sure doesn't seem like things are looking too good for LAF. The heaviest returns right now are focused over SE IL and C/S IN at the moment. Should probably bode well for those in IND, BMG, DAY, CVG, CMH, etc.

-SN and about 1" already here in IKK.

at the current moment it looks like the models were too far north with the best forcing....southern, IN, northern KY, sw OH getting hammered.

[Chicago WX]

at the current moment it looks like the models were too far north with the best forcing....southern, IN, northern KY, sw OH getting hammered.

Yep, congrats. This should be a good one for you guys.

I should have stuck with my panic-induced, downgraded, 1-3" for LAF from yesterday. Would have been spot on it seems. Stupid models.

[hawkeye_wx]

Pretty much a yawner around here. I only got 1.9 inches overnight and it has stopped snowing.

[buckeye]

Yep, congrats. This should be a good one for you guys.

I should have stuck with my panic-induced, downgraded, 1-3" for LAF from yesterday. Would have been spot on it seems. Stupid models.

too early for that. flake one hasn't even fallen here yet....and who knows what this does, where it weakens and where it may intensify.

[A-L-E-K]

Pretty much a yawner around here. I only got 1.9 inches overnight and it has stopped snowing.

you can probably extrapolate amounts like this east into Chicago. Season trends FTL. On the plus side i'm hearing rumblings that the obnoxious blocking might be nearing an end, so if we can get 2" or so down, it would be a nice base heading into a snowier pattern.

High end light snow here, pathetic flake size but coming down pretty good, visibilit probably .7 or so.

[A-L-E-K]

too early for that. flake one hasn't even fallen here yet....and who knows what this does, where it weakens and where it may intensify.

You look pretty golden based on radar returns, duration won't be great but you should see a solid period of moderate snow and reach advisory accums.

[buckeye]

Pretty much a yawner around here. I only got 1.9 inches overnight and it has stopped snowing.

it also looks to me that as this takes on a pivoting character to it, some of the returns to the north are becoming heavier and intensifying, moving back west towards you. (check out area south of ft.wayne). This is far from written.

[A-L-E-K]

it also looks to me that as this takes on a pivoting character to it, some of the returns to the north are becoming heavier and intensifying, moving back west towards you. (check out area south of ft.wayne). This is far from written.

I was just typing something like this. Cedar Rapids is a bit far west, but for other posters caught in between, as the Ohio valley low get going you will see a band organize further north of the 700 low and we should see our best rates pick up, especially lakeside as we get a better weak flow off the lake.

[Chicago WX]

too early for that. flake one hasn't even fallen here yet....and who knows what this does, where it weakens and where it may intensify.

Eh, radar seems to be telling the story. Looks like the low level jet is producing all of the intense snow with this one...which is pointed at the southern 1/2 of IND and then into southern/central OH. I think you'll do quite well.

Snowing pretty well here in Kankakee right now.

[Powerball]

Updated HPC Forecast FTW...

[A-L-E-K]

getting close to low end moderate as a ok band tries to hug the coast in northern cook county. would really like to see returns fill in down in Northern Indiana and pivot over the lake into this area.

EDIT: It's pretty foggy and quite warm, but based on visibility i think we have gone over to moderate snow now. Flake size still small but it's coming down at a nice clip.

[buckeye]

pixie dust just started here.

[A-L-E-K]

pixie dust just started here.

congrats on the rapid saturation per radar returns, you look pretty golden.

[Paweatherguy1]

at the current moment it looks like the models were too far north with the best forcing....southern, IN, northern KY, sw OH getting hammered.

Oo

Very much agreed. I feel that even the current nam is about 50 miles too far north.

[Chicago WX]

LAF going to go bust with this one. This thing is developing too late/too far east for anything appreciable. Good for southern/central IN and OH though. Also the dry punch that is just southwest in IL, should effectively shut this thing down soon for LAF. No biggie though, we were long overdue for a stinker.

[michsnowfreak]

Updated HPC Forecast FTW...

[snowstormcanuck]

Looking at radar, it sure doesn't seem like things are looking too good for LAF. The heaviest returns right now are focused over SE IL and C/S IN at the moment. Should probably bode well for those in IND, BMG, DAY, CVG, CMH, etc.

-SN and about 1" already here in IKK.

Yeah, I was expecting to see the best returns a good hundred miles further north on the national composite. Implications aren't good here either. 12z NAM came in a fair bit further south with the northern extent of its QPF field, and even it looks like it's still too far north.