Wednesday, November 12, 2014

Time to Find Your Parka

Public weather briefing

The weather over the weekend just may rationalize the playing of Christmas music in the middle of November. An unseasonably cold air mass from the north will give conditions more like mid to late December for the forecast period. This feature closely resembles the one which led to the extremely cold weather in the U.S. last winter. Intermittent snow on Saturday and Sunday morning (totals near 1 inch) will give way to light flurrying conditions through Monday. Winds will continue to be moderate out of the north and west. But the highlight (more like a lowlight) will be the cold temperatures, which aren't expected to rise above 30 over the forecast period.


Tonight. Chance of flurries with winds 5-10mph out of the northwest. Low of 20.


Thursday. Slight chance of flurries in the morning with moderate winds around 10mph. High of 30.


Thursday night. Potential light flurries early in the evening then becoming cloudy. Light winds from the northwest and low of 18.


Friday. Mix of sun and clouds with high temperatures flirting around 30 degrees.


Saturday. Bundle up for Badger football! Slight chance of snow and highs again near 30 degrees.


Outlook for Sunday through Tuesday. Chances for snow through Saturday night and Sunday morning totalling roughly an inch. Cold temps persist, rarely reaching the 30s. [CONFIDENCE: MEDIUM]



Forecast Discussion

A maturing surface cyclone centered east of the Great Lakes will continue to advect cold air into our area through the rest of the week, at which point flows become more zonal. An upper trough seen in the GFS at 700mb will make its way through southern Wisconsin over Wednesday night, which may give rise to light flurries which will continue into Thursday. This can be attributed to a very slight amount of positive vorticity advection from the plains.


Late Thursday into Friday, the 700mb vertical velocity switches to negative over our area. This subsiding air will keep conditions dry into Friday, at which point an arctic air mass to our west will drop night time temperatures below 20.


Come Saturday, slight warm air advection from the Great Plains can be noted as well as increased increased vertical motion at 18Z Saturday. The models are in moderate agreement, hence our medium forecast confidence. GFS and NAM both suggest snow falls nearing 2 inches, while the Canadian model only 1. By Sunday, the 500mb trough axis will move on east from our area. Slight vertical motion at 700mb over the area at 6Z and 9Z Sunday suggest more flurries which taper off later through the night.


The beginning of the week unfortunately will be marred with more wind out of the northwest and thus cold temps. The 850mb at 18Z Monday shows Wisconsin situated between a in geopotential minimum northeast of the Great Lakes and a ridge to our southwest. No indication of instability, vertical motion, or precipitation early next week.


All in all, Arctic air continues to slam the forecast are over the weekend with weak favorable dynamic conditions for measurable snow Saturday into Sunday.

Daniel Knuth

Rebecca Schultz

No comments:

Post a Comment

All comments will be reviewed before being posted to the blog. Any inappropriate comments will not be tolerated.