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March 9-11 Snow/Rain Storm


turtlehurricane

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The models have definitely shifted today. Before they showed all rain in Madison, now the 18z GFS has 0.8" liquid equivalent snow during the backside. Temps crash so the ratios would actually be decent. 18z NAM as 0.5" liquid equivalent snow.

 

Will be fun to watch the 00z come in, wouldn't be that surprised if it changes back to all rain though.

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The models have definitely shifted today. Before they showed all rain in Madison, now the 18z GFS has 0.8" liquid equivalent snow during the backside. Temps crash so the ratios would actually be decent. 18z NAM as 0.5" liquid equivalent snow.

 

Will be fun to watch the 00z come in, wouldn't be that surprised if it changes back to all rain though.

 

I definitely was about to start a thread on this if the 0z models continued to cave and show a good storm.  Definitely seems like the potential of a narrow stripe of 4-6" (perhaps 4-8" snows) likely somewhere in the state.

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I've been watching the model runs today closely too. Models seem to be onto something. Will see if it's mostly and rain and a little snow, or a bigger percentage snow after the rain.

 

This was the GFS at 18z.

 

post-2499-0-23566800-1362780368_thumb.pn

 

Then here is what the EURO was showing. White polygon is the approximate snow area on each map.

 

post-2499-0-51842900-1362774952_thumb.pn

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I've been watching the model runs today closely too. Models seem to be onto something. Will see if it's mostly and rain and a little snow, or a bigger percentage snow after the rain.

 

This was the GFS at 18z.

 

post-2499-0-23566800-1362780368_thumb.pn

 

Then here is what the EURO was showing. White polygon is the approximate snow area on each map.

 

post-2499-0-51842900-1362774952_thumb.pn

 

What are the QPF amounts of the different shades of purple?

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Almost looks like some lake enhancement at the end of the storm on the Euro the way the QPF boundaries line up along the western shore of Lake Michigan.  Geos, you would well again based on the Euro, though it is one of the southern solutions at this point.

 

It actually snows in SE WI, N MI, NE IL for 3 more frames past the last one above. I can guesstimate about 0.50" from just those maps.

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Albeit a bit warm, looks like the NAM will be interesting on the backside.  1003mb low cutting through Gary, IN.

The thicknesses collapsing just west of here as the deformation zone moves in.

 

Edit: weenie NAM run incoming.

 

Haha. I have to wait for soundings, but Milwaukee Waukesha looks like a sweet spot in addition to Madison and RFD over to Cyclone.

 

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Haha. I have to wait for soundings, but Milwaukee looks like a sweet spot in addition to Madison and RFD over to Cyclone.

 

Yep, just west of Milwaukee down through Rockford.  I had a feeling the NAM would give us one sweet run, even though that is clearly the top end of feasibility.

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Huge area of precip approaching from the plains, looks like this one has alot of moisture to work with. Might eek out some flakes on the front side, but SPC mesoanalysis says low levels are above freezing so more likely not. A brief period of freezing rain is possible though, especially if winds are calm.

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Huge area of precip approaching from the plains, looks like this one has alot of moisture to work with. Might eek out some flakes on the front side, but SPC mesoanalysis says low levels are above freezing so more likely not. A brief period of freezing rain is possible though, especially if winds are calm.

 

I think you're golden for the secondary low.  Most of the models I'm seeing now, including local news stations', have Milwaukee on the rain/snow line for most of it (I'm presuming low going between Milwaukee and Chicago) and Madison in snow for awhile.

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I think you're golden for the secondary low.  Most of the models I'm seeing now, including local news stations', have Milwaukee on the rain/snow line for most of it (I'm presuming low going between Milwaukee and Chicago) and Madison in snow for awhile.

I wouldn't say golden but at least we're in the game now. Like Geos' graphic shows there's gonna be quite a cut off, that could easily end up north or south of where the models are showing it now. This is definitely going to be a nowcasting sort of storm.

 

Classic early spring system, seems like we get these rain to snow transitions every year around this time. Central and northern WI and MN are usually the winners with this setup.

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Hydrologic Statement made through LOT

 

HYDROLOGIC OUTLOOKILC007-031-037-043-053-063-075-089-091-093-097-099-103-105-111-141-197-201-INC007-073-089-111-127-092200-HYDROLOGIC OUTLOOKNATIONAL WEATHER SERVICE CHICAGO IL200 PM CST FRI MAR 8 2013 /300 PM EST FRI MAR 8 2013/...MINOR FLOODING POSSIBLE LATE SUNDAY INTO NEXT WEEK DUE TO ACOMBINATION OF SNOWMELT AND RAINFALL...A LOW PRESSURE SYSTEM WILL BE AFFECTING NORTHERN ILLINOIS ANDNORTHWEST INDIANA BEGINNING LATE SATURDAY. THIS SYSTEM HAS THEPOTENTIAL OF PRODUCING RAINFALL OF BETWEEN 0.75 AND 1 INCH. THISRAINFALL...COMBINED WITH SNOWMELT RUNOFF...COULD LEAD TO SIGNIFICANTRISES ON AREA STREAMS ALONG WITH PONDING OF WATER IN LOW LYING AREAS.RECENT WINTER STORMS HAVE DEPOSITED SIGNIFICANT AMOUNTS OF SNOWACROSS NORTHERN ILLINOIS AND NORTHWEST INDIANA. SNOW DEPTHSCURRENTLY RANGE FROM 3 TO 6 INCHES IN AREAS ALONG AND SOUTH OF I-80.NORTH OF I-80...SNOW DEPTHS ARE BETWEEN 6 AND 12 INCHES...WITH THEDEEPEST SNOWPACK IN AREAS BORDERING THE WISCONSIN STATE LINE. MOREIMPORTANTLY...WATER EQUIVALENTS OF THE EXISTING SNOWPACK RANGEBETWEEN 1 AND 2.5 INCHES.ANOTHER CONCERN IS THE FROZEN GROUND BENEATH THE SNOWPACK. FROSTDEPTHS ARE CURRENTLY BETWEEN 6 AND 10 INCHES. THE KEY FACTOR THATWILL DETERMINE THE AMOUNT OF RUNOFF THAT OCCURS WILL BE THE RATE OFFROZEN GROUND THAW THAT OCCURS BEFORE AND DURING THE PERIOD WHENSNOWMELT AND RAINFALL IS IN PROGRESS. AT THE PRESENT TIME...THETHINKING IS THAT A SIGNIFICANT AMOUNT OF FROST WILL STILL REMAIN INTHE GROUND DURING THE HIGHEST SNOWMELT RATES. THIS WOULD RESULT INRUNOFF OF THE RAIN AND SNOWMELT INSTEAD OF THAT WATER INFILTRATINGINTO SOIL. HOWEVER...THERE STILL IS UNCERTAINTY REGARDING THE AMOUNTOF FROST THAW THAT WILL OCCUR. IN ADDITION...HEAVY RAINFALL DURINGTHE MELT PERIOD WOULD RESULT IN HIGHER RUNOFF RATES REGARDLESS OFTHE FROST DEPTH.PERSONS LIVING IN LOW LYING FLOOD PRONE AREAS SHOULD CONTINUE TOMONITOR LATER FORECASTS AND STATEMENTS ON THE INCREASING FLOODPOTENTIAL LATER THIS WEEKEND AND INTO NEXT WEEK.$$MORRIS
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DVN all in on heavy snow for Hawkeye, and of course Dubuque.  Dubuque can't be denied. 

 

 

THE DEFORMATION ZONE FOR THIS SYSTEM APPEARS WILL BE QUITEIMPRESSIVE WITH AT LEAST ADVISORY SNOWS AND ALSO THUNDER-SNOW...AGREEWITH TRENDS PAST 6-12 HOURS OF SOLUTIONS OF LOCALLY 6+ INCHES. ONLYMODERATE CONFIDENCE OF TRACK OF HEAVIEST SNOWFALL WITH BEST ESTIMATEROUGHLY ALONG AT DBQ TO IOW TO IRK LINE DUE TO HOW OCCLUSION OCCURS.AGAIN...THIS GOING TO BE CHANGING PROBABLY DYNAMIC SYSTEM AS RATE OFOCCLUSION AND IT/S DEPTH ARE STILL VERY QUESTIONABLE.  BEST ESTIMATEIS KINEMATICS AND MOISTURE FLUX PROFILES SUPPORTIVE OF EVEN STRONGERAND MORE RAPID DEFORMATION ZONE WITH HEAVIER SNOWS THAN 6 INCHES ANDWINDS OF 25 TO 35+ MPH INCREASINGLY PROBABLE.
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