Scientific Forecaster Discussion
fxus63 kmpx 232053
Area forecast discussion
National Weather Service Twin Cities/Chanhassen Minnesota
353 PM CDT Mon Oct 23 2017
Short term...(this evening through tuesday)
issued at 353 PM CDT Mon Oct 23 2017
A very powerful storm system will develop over the next 36 hours
across the Great Lakes region as a broad upper level trough with a
textbook pv signature merges with a cutoff low over the Tennessee
River valley. Once this merger takes place, expect to see
bombogenesis take place with the surface low deepening from around
1008 mb this morning over western Indiana to 979 mb by Tuesday
morning over the eastern u.P. Of Michigan. As this surface low
deepens, cold air advection will intensity across the upper
Midwest and maintain an unstable boundary layer tonight. Forecast
soundings continue to indicate 45 kt winds toward the top of the
boundary layer, so while it isn't likely to persist continuously,
occasional gusts of 45-50 mph are likely later tonight across
much of Minnesota, spreading eastward to Wisconsin for Tuesday.
Issued a Wind Advisory for Minnesota tonight/Tuesday and for Wisconsin
As the system develops this evening, some wrap around rain showers
may develop east of I-35. It doesn't appear enough cold air will
be in place at the surface for much snow, but cannot rule out a
few flakes late tonight before drier air moves in Tuesday.
Long term...(tuesday night through monday)
issued at 353 PM CDT Mon Oct 23 2017
Winds will quickly subside early Tuesday evening as surface
ridging briefly moves in. Another low pressure system developing
ahead of the next surge of cold air will pass east across the
northern plains Wednesday night and northern Minnesota Thursday.
Western and southern Minnesota should reach the warm sector
Wednesday afternoon when temperatures may reach the low to mid
60s. Cold front will pass through Thursday with temperatures
tumbling by afternoon.
With the positively tilted trough axis deepening Thursday night,
the surface low should also deepen and slow somewhat over
Wisconsin. The GFS and European model (ecmwf) continue to advertise a good band of
wrap around precip accompanying this system, although the timing
between the two continues to be an issue with the European model (ecmwf) slowing
down several hours with the 12z run. The NAM and Canadian keep
much of it to the north. Thus, consistency issues spatially and
temporally continue to degrade overall confidence. However, the
pattern is favorable for the first snowfall of the season for much
of the area and probabilities with the gefs are fairly high. Some
areas could see an inch or two in a worst case scenario, with the
more likely bet being an inch or less if the period of snow does
The northwest flow will persist into early next week, keeping
temperatures below normal. An even colder shot of air may spill
down by the middle of next week following a cold front Monday or
Aviation...(for the 18z tafs through 18z Tuesday afternoon)
issued at 135 PM CDT Mon Oct 23 2017
MVFR cigs across western Minnesota will likely continue eastward this
afternoon, but should lift somewhat before reaching mkt and msp. A
few rain showers are likely this evening across WI and far
eastern Minnesota, otherwise dry conditions expected. Gusty northwest
winds expected through the period.
Kmsp...could see a brief period of MVFR cigs mid to late
afternoon. Most of the rain will be east tonight, but can't rule
out one or two nearby.
/Outlook for kmsp/
Wed...VFR. Wind west-northwest 10 kts.
Thu...VFR with -ra/MVFR cigs late afternoon, becoming -sn Thu eve.
Wind west 10-15 kts becoming northwest 20g35kts.
Fri...VFR. Wind northwest at 10-15 kts.
WI...Wind Advisory from 7 am to 6 PM CDT Tuesday for wiz014>016-
Minnesota...Wind Advisory from 7 PM this evening to 6 PM CDT Tuesday for
Wind Advisory from 7 am to 6 PM CDT Tuesday for mnz044-045-052-
Wind Advisory until 6 PM CDT Tuesday for mnz047-054>056-064-065-