Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Twin Cities/Chanhassen Minnesota
527 PM CST Sat Mar 8 2014
Short term...(this evening through sunday)
issued at 247 PM CST Sat Mar 8 2014
Middle level moisture across western Minnesota has been slowly eroding
across southern/eastern Minnesota as of 2 PM. Expect some middle level
cloudiness this evening...but overall skies will become mostly
clear. Initially wind speeds will remain light from the SW/west this
evening allowing for temperatures to fall steadily. After midnight...SW/SSW
winds will increase allowing for temperatures to rise...especially across
wc/SW Minnesota. Was concern about fog/low clouds developing late
tonight/Sunday in the wake of increasing SW/south-southwest winds and dew points
rising into the 20s/30s. But...even if some low clouds develop...
moisture above the boundary layer is expected to dry significantly
by late morning/early afternoon. So...any clouds in the morning will
quickly mix out and dissipate. This will set the stage for the
highest temperatures this year as the Mercury rises into the low 50s
along the Lee side of the Buffalo Ridge where snow cover is
minor...to the lower to middle 40s elsewhere.
Long term...(sunday night through saturday)
issued at 247 PM CST Sat Mar 8 2014
Rather quiet and mild conditions expected for the bulk of the
upcoming week...resulting in great degree of snowpack loss. Very
progressive pattern ultimately portrays the exit of the perpetual
trough over eastern noam...giving much higher 500 mb heights across the
central Continental U.S.. the net gain will be noticeable warming throughout
the week...at points even resulting in above normal temperatures.
There will be one 12-18 hour period...Monday night into Tuesday...where
precipitation looks likely...especially for far southern Minnesota...but otherwise the
upcoming week looks dry.
With the warm front east of the region by Sun night...the mild temperatures will
remain in place ahead of the weak system due to push through Monday
night into Tuesday morning. Clouds increases during the day on Monday...then
precipitation moves into southwestern Minnesota late Monday night and spreads eastward on Tuesday.
The main complication is how far north the precipitation comes...with a
secondary issue of how much snow falls over far southern Minnesota...an issue
already seen with this past Tuesday. Quantitative precipitation forecast rises to the 0.20-0.30 area
and there will be a mix of both -ra and -sn with this system...
with mainly rain at the start and the finish...and mainly snow
around daybreak Tuesday morning. In addition...snow ratios may well be as
high as 14:1 or as low as 8:1...and that would make for a
significant different in snowfall. At this time...am looking for around 2
inches near the Iowa border but localized forcing could easily
push that much higher. Can definitively say the bulk of the precipitation
from this system will fall over Iowa...but it will not take much of
a shift northward to bring advisory-type snowfall over southern Minnesota so this will
need to be monitored closely. Once this system exits to the southeast
later Tuesday...high pressure with incoming ridging aloft will prevail Tuesday
night through Thursday. Another frontal system looks to pass through the
region Friday but this system appears devoid of enough moisture to
include precipitation at this time so have left the rest of the forecast period dry.
As for temperatures...a discernible break from the cold winter
temperatures will be upon the region as highs every day will be at least
in the middle 30s...and when discounting the modest Post-frontal cold air advection
for Tuesday into Wednesday...highs will commonly be in the 40s and possibly
around 50 in southwestern Minnesota. This will result in plenty of snow loss across
the region. Local tools still advertise 5-8 inches being lost over
the cost of the upcoming week. Thankfully the area will not be
receiving much in the way of precipitation to completely exacerbate
flooding concerns but the potential for ice jams will be growing
with the higher temperatures expected.
Aviation...(for the 00z tafs through 00z Sunday evening)
issued at 523 PM CST Sat Mar 8 2014
VFR conditions expected for the next 24 hours. Middle/high level
clouds will increase late tonight and Sunday...but will remain at or above
fl100 through the period. Winds will back southerly tonight and
veer back southwest with some gusts to 20+ knots Sunday afternoon.
Kmsp...no additional concerns from general discussion.
/Outlook for kmsp/
Monday...VFR. West wind 5-15 kts becoming northwest.
Tuesday...MVFR ceilings possible. Northwest wind 5-15 kts.
Wednesday...VFR. Northwest wind 5-10 kts.