Jan 06
Upper-Midwest winter storm on Friday
xn--vcsx75gvhj1xc.comLight snow will develop along a New Ulm, MN to Prairie Du Chien, IA line by 6AM tomorrow. Little more then a dusting will result from this initial snowfall event. Through 6 PM, more significant snow will develop along a St. Cloud, MN to Eau Claire line. One to two inches of snowfall will be possible tomorrow evening in those areas. Meanwhile, the “main event” will move in from the west. Moderate to heavy snowfall will move into the southern half of MN by 3AM Friday morning. The snowfall will finally exit the area to the north east by 6AM Saturday.
Storm totals for the event between now and Saturday morning:
St. Cloud: 5”-6”
Minneapolis/St. Paul: 4”-5”
Heaviest snowfall axis: Wahpeton, MN through Baxter, MN: 10”-12”
Discussion:
A warm front will develop along the IA/MN border overnight. This feature will be responsible for some light snow starting early in the day tomorrow and lasting through tomorrow night. Friday through Saturday: stacked low pressure (closed all of the way up to 250mb) will track from Sioux Falls, SD to Duluth during this period. The storm will move very slowly and a TROWEL and deformation zone will set up through MN during the last part of Friday, further increasing the duration of this event. The surface system will rapidly weaken Friday evening through Saturday as it lifts off to the NE. Water to snow ratios should range from 1:8 in SERN MN through 15:1 north of a Milbank, MN to Duluth line. This will serve to keep snowfall totals a bit lighter in the south.
Guidance:
Confidence is low as models have not settled on a solution. In fact, the 18Z NAM places the low track 150 mi SE of the 12Z run. This has brought it closer to the 12Z GFS, ECMWF, NGM, and UKMET solutions.
- bill
http://www.ghcc.msfc.nasa.gov/GOES/goeseastconus.html
Select "animation",
25 images to loop,
quality=100%,
zoom="high",
map="standard",
map color = "black"
Click on the Sioux Falls area. This may take a long time to load on
a slow connection. Once it loads and starts animating, increase the
speed of the animation a few notches, click "faster" a few times.
An animation like this tells a 1000 words. A few noteworthy
features today: in MN the northern extent of the stratus deck (low
clouds) is seen repidly moving to the west, while the cirrus shield
(high clouds) lifts off to the north east. Note the fresh snow in
the wake of the storm in SD. Note the "dry intrusion" now working
into western IA. Note the high cloud tops developing in north-
central IA and lifting NE towards the IA/MN border. This convection
is a result of very strong upward vertical veloticies as a
result the vort max moving in. Juxtaposed with this is a pocket of cooler
temperatures moving in at the mid and upper levels in association with the upper low. Picture in your mind a moisture "conveyer belt" moving northward through eastern IA and then lifting along the isentropic surfaces from northeastern IA into southern MN. This moisture feed rotates counter-clockwise around the upper-low while continuing to rise (the TROWEL). This is the region of the heaviest snowfall.
- bill
I hope an active spring can make up for an inactive winter.
http://www.rap.ucar.edu/weather/model/disp...r42hr18hr24hr30 (http://www.rap.ucar.edu/weather/model/displayMod.php?var=eta_850_wnd&hours=hr36hr42hr18hr24hr30)
Ok, now someone gets 2' since I said any of that.
Actually, it's better to look at isentropic fields for winter weather than a static pressure surface. But, good luck finding those on the 'net. Although I haven't checked the isentropic fields, it looks like the theta-e surfaces may ridge northward from the Gulf to just south of the "snow" region (which is the wind moves northward, is ascending along those theta-e surfaces). Not to mention the tight thermal gradient and strong frontogenesis... This looks like a classic thundersnow situation. There's actually a band that develops from southern MN through WI and into lower MI ahead of the main system for a few hours beginnning 00Z/06Z FRI...
I do think the axis of main snow will be very narrow, but also pretty intense...
http://www.rap.ucar.edu/weather/model/disp...r42hr18hr24hr30 (http://www.rap.ucar.edu/weather/model/displayMod.php?var=eta_850_wnd&hours=hr36hr42hr18hr24hr30)
Ok, now someone gets 2' since I said any of that.
At least we have blue skies with cumulus clouds, instead of stupid stratus clouds. Not to mention its almost 60F outside already. I'll take this over exciting winter weather anyday.
There's some very impressive bands of heavy snow on the north side of this system. There has to be some terrific snowfall rates in some of those bands. What's really interesting is the VERY sharp cutoff to the northern edge of the snow near MSP. It would be interesting to drive south into that. It looks like you would just drive into a wall of snow!
http://www.rap.ucar.edu/weather/model/disp...r42hr18hr24hr30 (http://www.rap.ucar.edu/weather/model/displayMod.php?var=eta_850_wnd&hours=hr36hr42hr18hr24hr30)
Ok, now someone gets 2' since I said any of that.
Mike,
LOL Thanks! Parts of southern MN will likely end up in the 20" category now! There's already nearly a foot of a new snow on the ground across southcentral MN, with heavy snow continuing to fall... The MPX morning AFD has a pretty good discussion on the event ( http://kamala.cod.edu/offs/KMPX/0503181148.fxus63.html )... The northern edge of the snowfall has been very sharp overnight, with a very small distance the difference between heavy snow and no snow.
:lol:
THE NATIONAL WEATHER SERVICE IN SIOUX FALLS SD HAS ISSUED A WINTER
STORM WARNING.
LIGHT SNOW WILL DEVELOP AROUND MIDNIGHT AND BECOME HEAVY AFTER
MIDNIGHT. SNOW MAY BE MIXED WITH OR CHANGE TO FREEZING RAIN FOR A
BRIEF PERIOD SOUTH OF HIGHWAY 34 IN SOUTH DAKOTA...AND HIGHWAY 30 IN
MINNESOTA. SNOW WILL CONTINUE THROUGH FRIDAY AFTERNOON...ENDING
EARLY FRIDAY EVENING. IN ADDITION...NORTHEAST WINDS OF 15 TO 30 MPH
WILL RESULT IN BLOWING SNOW ON FRIDAY. SNOWFALL OF 8 TO 12 INCHES IS
EXPECTED WITH THIS STORM...WITH LOCAL AMOUNTS OVER ONE FOOT POSSIBLE
ON THE EAST SIDE OF THE BUFFALO RIDGE...INCLUDING MARSHALL.
SNOWFALL WILL BECOME HEAVY...WITH 6 INCHES OR GREATER EXPECTED .
VISIBILITIES WILL BE REDUCED SUBSTANTIALLY AT TIMES DUE TO HEAVY
FALLING SNOW OR BLOWING SNOW.
#If you have any other info about this subject , Please add it free.# |