Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Twin Cities/Chanhassen Minnesota
352 am CST Wednesday Dec 11 2013
Short term...(today and tonight)
issued at 326 am CST Wednesday Dec 11 2013
Two main concerns through tonight as the Arctic air mass remains in
place...with some modification by late tonight.
Temperatures and wind spds as of 2 am have allowed for wind chill
values to fall near -30f in portions of wc/central Minnesota. Upstream
across northwest Minnesota...temperatures have fallen to near -20f which will continue
to filter across wc/central Minnesota during the pre dawn hours. Although
wind spds are not gusting as they were earlier...a 6-9 miles per hour wind
with temperatures near -20f will create dangerous wind chill values
around -35f. Therefore will continue with the wind chill warning
for central Minnesota. However...the continued wind chill warning for
portions of central Minnesota and wc WI does not seem likely due to wind
spds less than 5 miles per hour by the afternoon and temperatures rebounding to near -5
to -10f. Will let the day shift readjust west-southwest if needed.
Otherwise...will continue the same Wind Chill Advisory area with
-20 to -30f wind chill values continuing during the afternoon/evening
hours across portions of wc WI. The next concern is a fast moving
shortwave and associated brief band of light snow that will develop
across wc/central Minnesota during the evening...and quickly move east-southeast
across portions of central/ec Minnesota and wc WI by midnight. As quickly
as the snow begins...it will end prior to sunrise. Temperatures will be
tricky tonight as the coldest readings will likely occur prior to
midnight with increasing cloudiness and a SW/S wind developing.
Have developed a non-diurnal temperature trend this evening per this
Long term...(thursday through tuesday)
issued at 326 am CST Wednesday Dec 11 2013
Overall...no large-scale significant storm systems look to affect
the region but there will be small clipper-type systems that will
bring light accumulations...mainly Friday-Sat and again Monday.
Starting out...temperatures will still be tricky on Thursday due to strong warm air advection
at the start of the period. Surface high pressure will slide away to the S
and east...resulting in backside southerly flow that will allow highs to
range from the middle teens to lower 20s. The milder temperatures will last
through Friday...ahead of another chunk of Arctic air along with a
driving low pressure system from the deep south through the Ohio River
valley. Though little precipitation is expected from this system
due to it being very far displaced from the upper Mississippi
River valley...cold air will be brought down in its wake. This
will then bump high temperatures back down to the single digits above
zero on Sunday.
Going into next week...a more active northwest-southeast flow aloft will
develop. This will mean the keeping of very cold air over the
region along with the potential for minor snow accumulations sun
and Monday. The middle of the week has even more uncertainty due to
stronger influence of a zonal flow...and possibly even a slight
SW-NE tilt...which may result in a noticeable warming trend
starting on Tuesday. However...there is still much model disagreement
going into the middle of next week so will not make drastic
changes to the forecast at this time.
Aviation...(for the 06z tafs through 06z Wednesday night)
issued at 1050 PM CST Tuesday Dec 10 2013
Snow is pushing to the southeast...as are the MVFR ceilings. VFR
conditions are expected at all taf sites by 08-09z. Could see some
blsn in the Minnesota River Valley overnight with wind gusts approaching
30 knots but visible should remain at least MVFR.
Kmsp...VFR conditions through the period. Northwest winds backing
southwest late in the period.
/Outlook for kmsp/
Thursday...VFR. Winds SW 5 kts.
Friday...VFR. MVFR and -sn possible. Winds NE 10 kts.
Sat...VFR. MVFR and -sn possible. Winds NE 5 kts backing northwest 5-10 kts.
Minnesota...Wind Chill Advisory until noon CST today for mnz054>070-073>076-
Wind chill warning until noon CST today for mnz041-042-047>049.
Wind chill warning until 6 am CST Thursday for mnz043>045-
Wind Chill Advisory until noon CST today for mnz077-084-085-092-
Wind Chill Advisory until 6 am CST Thursday for mnz078.
WI...wind chill warning until 6 am CST Thursday for wiz014>016.
Wind Chill Advisory until 6 am CST Thursday for wiz023>028.