Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Twin Cities/Chanhassen Minnesota
550 am CST sun Feb 1 2015
Update...for 12z aviation discussion below
Short term...(today and tonight)
issued at 300 am CST sun Feb 1 2015
Early morning water vapor imagery shows the trough responsible for
significant snowfall accumulations in Iowa digging toward the
southern MS valley region. This feature will pivot across the
nations midsection today...and bring prolonged accumulating snow
regionally. Per hires models...as the trough nears...and associated
forcing lifts a tad farther north toward central Minnesota...accumulating
snow will also expand slightly north. As mentioned in previous
discussions...the infusion of dry northeasterly low level air will hinder
northward expansion of the accumulating snow to some extent. Expect
the delineation between snow and no-snow to generally be a Willmar
to Twin Cities to Cadott Wisconsin line. Accumulations should range
from around one half inch along the northern end to between 3 and 6
inches in the advisory area of south central Minnesota which includes
Interstate 90. Winds will be brisk as well...so areas that receive
new snow can expect some blowing and drifting to occur today.
Temperatures will remain fairly steady today...with highs ranging
from the single digits above zero in west central Minnesota...to between 10
and 15 across the remainder of central/southern Minnesota and west central
Clearing skies tonight and lightening winds will lead to sub-zero
lows...especially across south central Minnesota with the fresh snow.
Long term...(monday through saturday)
issued at 300 am CST sun Feb 1 2015
High confidence on a mainly dry forecast in the extended period
based on west-northwest/northwest flow and precipitable water values blw normal for
this time of year. Plus most of the upper level features/forcing
will remain south of the region this coming week.
The cold period for next week remains on track...but not
abnormally cold for this time of year. Lows once again will fall
below zero...with highs in the teens and 20s. Next weekend
precipitation chance/S remain questionable based on longer term
models increasing moisture associated with a more westerly flow
and Pacific moisture advecting across The Rockies and into the
plains. Surface analysis is also not favorable for any substantial
precipitation...with the surface low/frontal boundary across northern
Minnesota. One weather item that seems more likely is warmer temperatures...especially
considering a more Pacific air mass...vs Canadian or modified
Aviation...(for the 12z tafs through 12z Monday morning)
issued at 550 am CST sun Feb 1 2015
Snow will affect kst-krwf-krnh-Keau this morning...with IFR visibilities
and MVFR ceilings. Kstc and kaxn will remain out of the snowfall area.
Snow should taper off by 17z...with VFR ceilings/visibilities arriving. Gusty
north/northeast winds will gradually diminish...and graddualy
become southwesterly at speeds at or below 5kts overnight.
should see snow come to an end within 2-3 hours of the taf
issuance...with VFR conditions developing by 18z. There will be
about a one hour period centered on daybreak that 1700ft ceilings are
a possibility. Low clouds are replaced with few-scattered cirrus this
afternoon. Gusty northeast winds diminish this afternoon...and
become northwest under 5 kts by Monday morning.
/Outlook for kmsp/
Monday...VFR. Wind SW 5-10kt.
Tuesday...chance MVFR/-sn. Wind west 5 knots.
Wednesday...VFR. Wind northwest 10-15 knots.
Minnesota...Winter Weather Advisory until noon CST today for mnz082>085-