NWS Snow Discussion

Current Discussion
fous11 kwbc 172231

Probabilistic heavy snow and icing discussion
NWS weather prediction center College Park MD
630 PM EDT sun may 17 2015

Valid 00z Mon may 18 2015 - 00z Thu may 21 2015

Days 1 to 3...

...North Dakota and northern Minnesota this evening and

Upper low over the eastern Dakotas/western MN will lift slowly NE
into southern Ontario just N of Lake Superior by 00z Tue. Strong
deep-layer ascent associated within the ccb/trowal along the
robust mid level deformation zone is getting a significant boost
from the lfq and rrq of the upper level jet streaks over the
northern MS valley and south-central Canada respectively. The
increasing caa within the boundary layer will couple with
favorable column (diabatic) cooling per the strong deep-layer
vertical ascent and precipitation rates to allow for fairly quick
transition from r or r/S over to snow this evening...with the
snowfall accumulation efficiency getting a boost closer to and
after sunset (particularly at higher elevations above 1.5 kft).
Probabilities for 4+ inches are highest across north central
ND...where upwards of 5-6" will be possible along the Canadian

The probability of significant icing is less than 10 percent days



Snow Depth