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November 15-17th Snow Prospects


Geos

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Here is the GGEM with actual ratios taking in:

 

http://www.tropicaltidbits.com/analysis/models/gem/2014111400/gem_asnow_us_15.png

D**n, that is alot of snow for NE/SD/IA!  If the 00z Euro shows anything similar, I think the trends will continue.  Tomorrow runs may even be better now since the models will be gathering even better data.  BIG differences from yesterday for sure.

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I'am with you James. But what a poorly detailed discussion by DMX-- no mention of it in the body. DMX is noted for poor discussion over the years...http://www.hpc.ncep.noaa.gov/wwd/day2_psnow_gt_04.gif

The two loudest sounds known to man: a gun that goes bang when it is supposed to go click and a gun that goes click when it is supposed to go bang.

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Dry air and limited dynamics further east and north. If you really want to geek out (I know you do!!) read this mornings AFD out of La Crosse. http://forecast.weather.gov/product.php?site=ARX&issuedby=ARX&product=AFD&format=CI&version=1&glossary=1

 

 

STRONGER TREND AMONG THE MODEL CONSENSUS SENDS RATHER STRONG 500-

300MB PV ADVECTION ACROSS THE AREA SAT AFTERNOON/EVENING. THIS
WITH MDT/STRONG 285-310K ISENTROPIC LIFT...WHICH IS MAINLY BETWEEN
700-350MB...AND 300MB AGEOSTROPHIC FLOW/DIVERGENCE BETWEEN JET
MAXES NORTHEAST AND SOUTHWEST OF THE AREA. DEEP SATURATION OF THE
COLUMN INDICATED BY SOUNDINGS/X-SECTIONS FOR MUCH OF THE AREA MUCH
OF SAT AFTERNOON/NIGHT. HOWEVER...DUE TO THE COLD COLUMN/AIRMASS
PW VALUES ONLY AROUND 1/3 INCH CENTERED ON 00Z SUN. DEEP DENDRITIC
GROWTH ZONE /DGZ/ INDICATED SAT AFTERNOON/EVENING...TO THE TUNE OF
300MB IN A ROUGHLY ISOTHERMAL LAYER BETWEEN 900-600MB. BULK OF THE
FORCING/LIFT SIGNAL IS ABOVE 700MB...ONLY OVERLAPPING THE TOP OF
THE DGZ LAYER. STEEP LAPSE RATES IN THE 600-350MB LAYER FOR GOOD
VERTICAL MOTION RESPONSE TO THE FORCING/LIFT ALOFT...BUT THE
NEARLY ISOTHERMAL DGZ LAYER WILL BE MORE RESISTANT TO LIFTING.
FORCING/LIFT IN THE 925-700MB PORTION OF THE COLUMN IS QUITE WEAK
AND LOOKS INEFFECTIVE AT PRODUCING MUCH FOR UPWARD MOTION IN THE
COLUMN BELOW 700MB. GIVEN THE LIFT IS HIGHER UP AND LIMITED UPWARD
MOTION IN THE DGZ PORTION OF THE COLUMN...HAVE CONCERNS ABOUT
SNOW-WATER RATIOS. TREND AMONG MODELS IS FOR THE STRONGER SHORTWAVE/
FORCING/LIFT ALOFT TO SQUEEZE MORE QPF OUT OF THE COLUMN ACROSS
THE AREA. HIGHER QPF BUT LOWER SNOW-WATER RATIOS...SNOW AMOUNTS IN
THE FCST GRIDS FOR SAT/SAT NIGHT REMAINED ABOUT THE SAME...IN THE
1 TO 3 INCH RANGE. HIGHEST WEST/SOUTH WITH BIT STRONGER LIFT AND
HIGHER PW VALUE AIR. DID RAISE SNOW CHANCES FOR SAT AFTERNOON/
EVENING TO 80-100 PERCENT FOR MAINLY THE SOUTH 3/4 OF THE FCST
AREA. NO HEADLINES AT THIS TIME BUT MAY YET NEED A SNOW ADVISORY
FOR PORTION OF THE FCST AREA IF THE STRONGER TREND CONTINUES AND
SNOW-WATER RATIOS END UP ON THE HIGHER SIDE...MORE IN THE 15 TO
20 TO 1 RANGE.
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Far as WGN tv Met's go, they have been saying 1-3", heavier north and northwest suburbs.

 

12z GFS parallel

 

 

 

Rooting for the 2" line to make it to the lake at least.

 

12z 4km NAM brings the 3" line further towards the lake.

 

 

Mercer Island, 350 ft

2021-2022: 11.6", 02/21

2020-2021: 15.6"

2019-2020: ~10"

2018-2019 winter snowfall total: 29.5"

2017-2018: 9.0", 2016-2017: 14.0"

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GEOS any idea what ratios those maps are using?

 

Definitely not 10:1. Looks like closer to 15-18:1.

 

You can compare it to the total accumulated precipitation map and try to figure out what the ratio might be.

 

http://www.tropicaltidbits.com/analysis/models/nam4km/

 

---

 

CMC snowfall at 10:1. Northern wave shifted south.

 

 

 

MKX snowfall map.

 

10402761_888879831130266_171019247378695

Mercer Island, 350 ft

2021-2022: 11.6", 02/21

2020-2021: 15.6"

2019-2020: ~10"

2018-2019 winter snowfall total: 29.5"

2017-2018: 9.0", 2016-2017: 14.0"

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