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March 11-12th Winter Storm Part 2


Chicago Storm

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I hope no one expected those craziest nam runs to verify at face value. A classic blast from the past (2007-08). A 5-10" storm still a good bet, perhaps a bit less than it as looking like tho morning but way more than at any time the previous week before yesterday.

 

Goofy TV mets around here were showing those maps.

 

You would think that one would lose credibility, but what do I know

 

:weenie:

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I hope no one expected those craziest nam runs to verify at face value. A classic blast from the past (2007-08). A 5-10" storm still a good bet, perhaps a bit less than it as looking like tho morning but way more than at any time the previous week before yesterday.

What ... you didn't believe the 20-30" runs ... those runs had to be a lock ... come on just look at our climo ... these 4-8" storms are just a waste of time ... dime a dozen in these parts ... ;)

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I'd be very careful accepting the 12z runs at face value.  Given the banding/potential thunder involved, I wouldn't be surprised to see some areas overperform.

 

Given the cobb output off the NAM for PIA (over 4 inches in 2 hours), thunder is the only way I'm seeing that.

140312/0700Z  19  01020KT  32.4F  RASN    0:1| 0.0|| 0.00|| 0.00|| 0.177    0:1|  0.0|| 0.00|| 0.00|| 0.68   87|  0| 13140312/0800Z  20  01019KT  32.3F  SNOW    8:1| 1.3|| 0.00|| 0.00|| 0.152    8:1|  1.3|| 0.00|| 0.00|| 0.83   92|  0|  8140312/0900Z  21  01019KT  32.1F  SNOW   14:1| 1.7|| 0.00|| 0.00|| 0.119   11:1|  3.0|| 0.00|| 0.00|| 0.95  100|  0|  0140312/1000Z  22  02019KT  30.8F  SNOW   18:1| 2.6|| 0.00|| 0.00|| 0.142   13:1|  5.5|| 0.00|| 0.00|| 1.09  100|  0|  0140312/1100Z  23  01018KT  29.0F  SNOW   13:1| 1.1|| 0.00|| 0.00|| 0.083   13:1|  6.6|| 0.00|| 0.00|| 1.17  100|  0|  0140312/1200Z  24  01019KT  27.6F  SNOW    5:1| 0.0|| 0.00|| 0.00|| 0.004   13:1|  6.7|| 0.00|| 0.00|| 1.17  100|  0|  0----------------------------------------------+----++-----+-------------++--------------++-------------++-----------+---+
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Gonna add an inch to my original call and go 3-5" for LAF.  Changeover time and how much precip is left obviously will dictate amounts and a changeover on the faster side could mean slightly higher totals.  Will be interesting to see what if any effects the recent warm temps will have on accumulation, especially on paved surfaces.  Falling temps, decent rates and the bulk of the snow coming overnight/morning would argue against that being much of an issue but we'll see.  I think the rural areas around here have a good chance at experiencing blizzard conditions but it will be tougher to do in LAF proper.

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I did a preliminary search of LAF records to see how many days there have been with a high temp of 60+ and at least 3" of snow the following day.  So far I have gone back to 2000 and found exactly zero such days.  May check earlier years later today but want to wait and see if we actually make it to 60 so I'm not doing all this for nothing. 

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Atta boy Ricky

 

AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL  
1234 PM CDT TUE MAR 11 2014  
   
DISCUSSION
 
 
1234 PM CDT  
 
WINTER STORM UPDATE...  
 
CONTINUING TO ASSESS 12Z MODEL DATA FOR IMPENDING WINTER STORM.  
SURFACE OBSERVATION ANALYSIS SHOWS 996 MB LOW IN CENTRAL KS  
ROUGHLY BETWEEN SLN AND HUT...NORTH OF LATEST RUN OF RAP MODEL.  

TRENDS SO FAR SUPPORT THE AXIS OF HEAVIEST SNOW IN GOING FORECAST  
AND HAVENT MADE ANY CHANGES TO THIS YET...WITH ONLY TWEAKS TO LATE  
AFTERNOON POPS AS BAROCLINIC ZONE STARTS TO SHIFT SOUTH AND RAIN  
COMMENCES IN FAR NORTHERN CWA. RAIN SHOULD QUICKLY FLIP OVER TO  
SNOW THIS EVENING IN NORTHERN ILLINOIS AS COLDER AIR FILTERS IN  
FROM THE NORTH.  
 
OF BIGGEST CONCERN WITH THE SNOW LATE TONIGHT IS THE BAND OF VERY  
STRONG 850-700 MB FGEN OVERLAID BY NEGATIVE EPV...AS WELL AS THE  
PRESENCE OF 50-100 J/KG OF MUCAPE. THIS HIGHLIGHTS POTENTIAL FOR  
CONVECTIVE SNOW BANDS AND RATES OF 2 INCHES PLUS PER HOUR  
WHEREVER THIS SETS UP. KEEPING TOTALS IN CHECK WILL BE  
PROGRESSIVE NATURE OF SYSTEM WITH MIDLEVEL TROUGH REMAINING  
OPEN...SO WOULD ONLY EXPECT A FEW HOUR PERIOD WITH THE REALLY  
HEAVY RATES IN ANY GIVEN AREA. NONETHELESS...COULD SEE SOME  
ISOLATED TOTALS TO OR EVEN A BIT ABOVE 8 INCHES IN WARNING  
AREA...WITH THIS MOST LIKELY TO OCCUR ROUGHLY ALONG AND A BIT EAST  
OF I-55 CORRIDOR.  
 
LIKELY BECAUSE OF BANDING POTENTIAL...HIGHER RES GUIDANCE SHOWING  
A VERY SHARP CUTOFF TO PRECIP IN NORTHERN CWA...AND THINK THIS IS  
OVERDONE...BUT THERE WILL BE A GRADIENT IN SNOW AMOUNTS ROUGHLY IN  
LINE WITH GOING FORECAST.
FARTHER SOUTH IN WATCH  
AREA...UNCERTAINTY REMAINS OVER HOW FAST CHANGEOVER WILL OCCUR AND  
HOW MUCH PRECIP WILL FALL AFTER CHANGEOVER...SO WILL MAKE A  
DECISION ON HEADLINE FOR SOUTHEAST CWA WITH AFTERNOON ISSUANCE.  
FINALLY...WINDS REMAIN A SIGNIFICANT CONCERN AS WELL LATE TONIGHT  
INTO WEDNESDAY MORNING...WITH SOUNDINGS SUPPORTING NORTHERLY WIND  
GUSTS TO 40+ MPH. THIS WILL EXACERBATE IMPACTS TO WEDS AM COMMUTE  
EVEN AS SNOW WINDS DOWN.  
 
RC/JEE  
 

 

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I did a preliminary search of LAF records to see how many days there have been with a high temp of 60+ and at least 3" of snow the following day.  So far I have gone back to 2000 and found exactly zero such days.  May check earlier years later today but want to wait and see if we actually make it to 60 so I'm not doing all this for nothing. 

 

Heck, I,ll bet there hasn't been many, if any, times it's happened with 55° the day before.

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Atta boy Ricky

AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 1234 PM CDT TUE MAR 11 2014

DISCUSSION

1234 PM CDT

WINTER STORM UPDATE...

CONTINUING TO ASSESS 12Z MODEL DATA FOR IMPENDING WINTER STORM.

SURFACE OBSERVATION ANALYSIS SHOWS 996 MB LOW IN CENTRAL KS

ROUGHLY BETWEEN SLN AND HUT...NORTH OF LATEST RUN OF RAP MODEL.

TRENDS SO FAR SUPPORT THE AXIS OF HEAVIEST SNOW IN GOING FORECAST

AND HAVENT MADE ANY CHANGES TO THIS YET...WITH ONLY TWEAKS TO LATE

AFTERNOON POPS AS BAROCLINIC ZONE STARTS TO SHIFT SOUTH AND RAIN

COMMENCES IN FAR NORTHERN CWA. RAIN SHOULD QUICKLY FLIP OVER TO

SNOW THIS EVENING IN NORTHERN ILLINOIS AS COLDER AIR FILTERS IN

FROM THE NORTH.

OF BIGGEST CONCERN WITH THE SNOW LATE TONIGHT IS THE BAND OF VERY

STRONG 850-700 MB FGEN OVERLAID BY NEGATIVE EPV...AS WELL AS THE

PRESENCE OF 50-100 J/KG OF MUCAPE. THIS HIGHLIGHTS POTENTIAL FOR

CONVECTIVE SNOW BANDS AND RATES OF 2 INCHES PLUS PER HOUR

WHEREVER THIS SETS UP. KEEPING TOTALS IN CHECK WILL BE

PROGRESSIVE NATURE OF SYSTEM WITH MIDLEVEL TROUGH REMAINING

OPEN...SO WOULD ONLY EXPECT A FEW HOUR PERIOD WITH THE REALLY

HEAVY RATES IN ANY GIVEN AREA. NONETHELESS...COULD SEE SOME

ISOLATED TOTALS TO OR EVEN A BIT ABOVE 8 INCHES IN WARNING

AREA...WITH THIS MOST LIKELY TO OCCUR ROUGHLY ALONG AND A BIT EAST

OF I-55 CORRIDOR.

LIKELY BECAUSE OF BANDING POTENTIAL...HIGHER RES GUIDANCE SHOWING

A VERY SHARP CUTOFF TO PRECIP IN NORTHERN CWA...AND THINK THIS IS

OVERDONE...

To me, these guys have done a helluva job this winter. Given model variability and inconsistencies many of their calls and discussions have taken into account a number of other complex factors. Kudos! It's more then looking at three models and choosing the compromise.

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To me, these guys have done a helluva job this winter. Given model variability and inconsistencies many of their calls and discussions have taken into account a number of other complex factors. Kudos! It's more then looking at three models and choosing the compromise.

 

 

They've had a solid winter for sure

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Heck, I,ll bet there hasn't been many, if any, times it's happened with 55° the day before.

 

 

Going to have to correct my original post.  I found a case from March 2008 where we had a high of 60 on the 3rd and about 5" of snow on the 4th.  LAF airport doesn't have snow measurements for these years so I'm having to use other sources to verify.

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