Saturday Forecast Discussion: Upslope enahncement, blowing snow among impacts

Winter Storm Watches have been expanded to include Rapid City and other areas of the Black Hills Region, with details starting to come together.

FRIDAY AFTERNOON UPDATE: Winter Storm Warnings and Advisories have been posted for the Black Hills and surrounding areas.

Picture 1

  • Chief Meteorologist Bob Riggio will have your full forecast at 5:30 on Newscenter1, make sure to tune in for details!

FRIDAY MORNING FORECAST DISCUSSION

Picture 1

  • A quick recap of Friday shows very nice, very warm temperatures for this afternoon with light winds turning Northeast in the afternoon.
  • Most of our expected rain/snow activity will wait until Saturday.

Picture 2

  • Winter Storm Watches have been expanded to include Rapid City, the I-90 Corridor and areas South of the Black Hills.
  • These will update throughout the day with warnings and advisories likely to expand this afternoon and evening with more specifics, so be sure to stay tuned.
  • The timelines start Saturday morning for the Black Hills, and start Saturday afternoon and evening for areas out towards the plains.

Picture 3

  • Rain/snow activity could start as early as 3 AM Saturday, but there will be pockets of dry air at the surface that could prevent precipitation deep into Saturday morning, so if you don’t see something right away, that might be why.

Picutre 4

  • By late Saturday morning we should start seeing better coverage of precipitation, with dry pockets still holding out in some areas.
  • Temperatures will be dropping from the 30s to the 20s through the morning and afternoon, eventually to the teens by the evening hours.
  • Winds will be picking up from the Northeast, then clocking North and Northwest by the afternoon and evening.

Picture 17

  • Sustained winds will be around the 15-20 MPH range, but we can see gusts up to 40 MPH, switching from Northeasterly to North and northwesterly by Saturday evening.
  • Blowing snow, and patchy low visibility will be possible – particularly East of the Black Hills along the hogbacks, and areas of Box elder, Bear Butter, Highway 212, Highway 44 and SD-79 stretching South towards Hot Springs.

Picture 5

  • By Saturday evening, we’re in full swing. The biggest hint I have that upslope enhancement will be a big player here is the dry pocket over Newcastle. This is the computer models picking up on down-slope winds… which means upslope winds are likely for the Northern and Eastern Foothills.

Picture 7

  • Here’s a gut-check of possible accumulations along the I-90 corridor and Northern Hills. I am taking the heavy hand here, most maps won’t show accumulations this high.
  • Keep in mind that these numbers will be ALL over the place, depending on individual neighborhoods… but folks living along this corridor should at least be prepared for the possibility of these numbers being very real. Upslope enhancement can really get things going in a hurry, with high snowfall rates and stubborn snow bands. Anyone who’s lived along this corridor know exactly what i’m talking about. This is one of those cases.
  • If you see numbers less than this, consider it a win.

Picture 6

  • Here is a look at possible accumulations for the rest of the region through Sunday afternoon, notice that areas North of I-90 does not expect large accumulations as of now.
  • Once you start heading south of I-90, accumulation expectations starting moving into the 3″-6″ range, with maybe even 4″-7″ near the Nebraska border.
  • The Black Hills themselves will have upslope enhancement in the Northern and Eastern foothills, with downslope dry pockets in places like Newcastle, and possibly Edgemont which could lead to smaller accumulations.

Picture 8

FORECAST DISCUSSION

For most of us, we’ll be sitting and home watching the snow from our living rooms, snuggled up with some good video games (me) or a good book…. so eventual snow accumulations will matter little in the end and is more of a curiosity!

For those have to work outdoors in this, I wanted to take a heavy hand to the forecast here… because calving season is in full swing and I want ranchers and land owners to be prepared for these conditions. The combination of possible heavy snow bands, gusty winds and blowing snow could make conditions very difficult to work in… and I wanted to do my best to drive that point home. I don’t want anyone caught out in this unprepared – especially given our particularly cold temperatures and gusty winds. The hope here, is that none of these numbers come to fruition and … worst case scenario, I get a few bad emails about a de-bunked forecast.

This is a dynamic, fluid forecast and we’ll be changing numbers right up to the finish line… that’s a promise. I would much rather communicate my uncertainty on this than pretend i’ve got this forecast nailed – that’s why I’m showing some of the higher tier scenarios in this case.

I apprecaite all of you who trust us with your forecast, and i’ll be sure to be watching this system vigilantly over the next 48 hours… updating this forecast discussion as new information becomes available. Happy good Friday, be safe out there, and thanks to all of you who are social distancing and putting your friends and family before yourself. You’re rock stars. -Brant

Picture 10

 

 

Categories: Local News, Weather Daily