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January 11-12 Snow/Mixed Precip


Hoosier

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12z RGEM is fairly juicy across parts of IL, IN, and OH.

 

 

P-type maps have LAF riding the snow/s**** line for quite a bit of the event. No real surprise there. Knowing how WAA is usually underdone on the models, you know where this is going for here...

 

Exhibit A

 

 

 

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12z RGEM is fairly juicy across parts of IL, IN, and OH.

 

attachicon.gif1:10 12z rgem qpf.png

 

P-type maps have LAF riding the snow/s**** line for quite a bit of the event. No real surprise there. Knowing how WAA is usually underdone on the models, you know where this is going for here...

Certainly a concern for icing it appears, at least over this way.  Depending on timing, could be a mess with the football game and parties etc.

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12z RGEM is fairly juicy across parts of IL, IN, and OH.

 

attachicon.gif1:10 12z rgem qpf.png

 

P-type maps have LAF riding the snow/s**** line for quite a bit of the event. No real surprise there. Knowing how WAA is usually underdone on the models, you know where this is going for here...

 

Exhibit A

 

attachicon.gifI_nw_r1_EST_2015011012_036.png

 

 

I noticed the 00z Euro ticked warmer for us.  Feeling a little more confident than yesterday that the max snow ends up north of us but we don't need much of a south/colder shift.

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Most offices seem to be going conservative with this one so far.  Ratios don't look too high at this point...maybe like 12:1 or 13:1 in areas farther entrenched in the cold air (perhaps locally higher?)

 

DTX says moisture and instability looks good for decent snowfall rates.

 

Really, the only problem they're seeing is how brief the period of best forcing looks to be (at least at this point)...

 

 

 

THE SOUTHWEST FLOW WILL BRING A GOOD DEAL OF MOISTURE INTO THE AREA

BY SUNDAY NIGHT. SPECIFIC HUMIDITIES OF 3-4 G/KG ARE FORECAST TO LIFT

INTO SE MI ALONG THE 290K SFC. MODEL SOUNDINGS SHOW A POTENTIAL FOR

GOOD SNOWFALL RATES...WITH A DEEP LAYER BETWEEN 0 AND -10C CAPPED BY

A LAYER OF LOW STATIC STABILITY AND LIFT WITHIN THE -10 TO -18C

LAYER. THE CURRENT MODEL SOLUTIONS HOWEVER SUGGEST ANY PERIOD OF

DECENT FORCING WILL BE FAIRLY BRIEF. THERE IS ALSO A CONCERN THAT

THE LOWER PORTIONS OF THE FRONTAL SLOPE /ACROSS THE OHIO VALLEY/ MAY

BE THE MORE ACTIVE PORTION OF THIS SYSTEM. THEREFORE FORECAST SNOW

ACCUMS ACROSS THE SRN HALF OF THE AREA SUN NIGHT/MON MORNING WILL BE

KEPT AROUND AN INCH AT THIS TIME.

 
But like IWX says, all it's going to take is...
 
1. For the northern stream wave to slow down slightly and dig slightly further SW
 
2. For models to be underdoing the strength of the SW shortwave slightly (which does happens with these southern stream waves)
 
...for higher snowfall amounts to occur...
 

 

QUESTIONS STILL EXIST WITH WHERE STRONGEST FORCING AND MOISTURE WILL
DEVELOP BUT CENTRAL TO SOUTHERN HALF OF THE FORECAST AREA REMAINS
FAVORED GIVEN LATEST MODEL SUITE. WATER VAPOR THIS MORNING SHOWS
SOUTHERN SHORT WAVE OVER THE SOUTHWEST CONUS WHICH WILL LIFT
NORTHEAST THROUGH MONDAY. NORTHERN STREAM SHORT WAVE EXPECTED TO
DROP INTO THE AREA AT SAME TIME AND BEGIN TO PHASE BUT IT APPEARS
JUST EAST OF THE AREA. THIS MEANS A MORE PROGRESSIVE SYSTEM WITH A
QUICK BURST OF WARM AIR ADVECTION TYPE SNOW AHEAD OF THESE SHORT
WAVES. BAROCLINIC ZONE WILL TIGHTEN AS THEY APPROACH WITH SOUTHERN
STREAM WAVE PULLING GOMEX MOISTURE NORTH. ARCTIC WEDGE WILL BE SLOW
TO RETREAT AND MODIFY. MODEL SOUNDINGS AT THE MOMENT FAVOR SNOW
ACROSS THE ENTIRE AREA BUT A WARM NOSE OF 0 TO 1C BEING SHOWN BY GFS
AND NAM12 IN TOP DOWN METHOD ACROSS EXTREME SOUTHERN CWA. IF WARM
AIR ADVECTION ENDS UP BEING A BIT STRONGER OR SPREADING FURTHER
NORTH MAY HAVE TO INTRODUCE A PERIOD OF SLEET OR FREEZING RAIN OVER
FAR SOUTHERN AREAS. TOP DOWN PROCEDURE OFF OF 00Z MODELS CONFINED
THIS MIX TO SOUTHERN HALF OF OUR MOST SOUTHERN COUNTIES SO FOR NOW
PREFER TO LET THE RAIN SNOW LINE CONTINUE ALONG SOUTHERN BORDER
AREAS AND REFINE OVER THE NEXT 24 HOURS AS SYSTEM APPROACHES.
SNOWFALL AMOUNTS STILL LOOK TO BE IN THE 1-3 OR 2-4 INCH RANGE
DEPENDING ON THIS WARM NOSE AND STRENGTH OF FGEN FORCING.
 
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I noticed the 00z Euro ticked warmer for us.  Feeling a little more confident than yesterday that the max snow ends up north of us but we don't need much of a south/colder shift.

 

Yep. Not much QPF with this one, but I'm hoping we can pull out 1.3" of snow to get to dd's for January. Though I guess that other p-type counts too...

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It's not on the CIPS analog list but this setup reminds me of 1/4/14. That was the day prior to the 'PV Blizzard' that nailed Indiana, when much of northern IL had solid fgen driven snows as the sfc Arctic front and 850 mb front only slowly progressed southward. Progged surface, 850 and 500 mb fields for Sunday night are quite similar to 1/4/14, including the path of the h5 vort max. If you click around the SPC Meso archive and compare to the model fields for Sunday night, the similarities are definitely apparent, though surface high is stronger and farther east in this case. Timing is key though, so things could still shift back south. If 12z guidance is similar or better, we're likely in line for some decent snow given banding potential in this setup.

 

 

Found LOT's writeup about that.  3-6" with locally higher amounts

 

http://www.crh.noaa.gov/news/display_cmsstory.php?wfo=lot&storyid=99400&source=2

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At this point I'm leaning toward something like 2-3" of a snow/sleet combination for LAF.  Can't entirely write off the possibility of a little freezing rain but the warm intrusion doesn't look strong enough at this point, so I'm thinking it will be all or almost entirely all snow/sleet.  If the worst case scenario were to pan out with sleet, I could envision over a half inch of that with Tim and I getting visions of Groundhog Day 2011 dancing in our heads, but hopefully we can keep the sleet down. 

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At this point I'm leaning toward something like 2-3" of a snow/sleet combination for LAF.  Can't entirely write off the possibility of a little freezing rain but the warm intrusion doesn't look strong enough at this point, so I'm thinking it will be all or almost entirely all snow/sleet.  If the worst case scenario were to pan out with sleet, I could envision over a half inch of that with Tim and I getting visions of Groundhog Day 2011 dancing in our heads, but hopefully we can keep the sleet down. 

 

Good call. I've been thinking some kind of combo of 1-2" snow, 0.10-0.20" other stuff. Should be thrilling. :D

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Good call. I've been thinking some kind of combo of 1-2" snow, 0.10-0.20" other stuff. Should be thrilling. :D

 

 

Basically on the same page.  If that amount of other stuff falls as sleet and applying a 3:1 ratio for the sleet comes out to a half inch or just above on the higher end.

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