Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Twin Cities/Chanhassen Minnesota
507 am CST Friday Feb 27 2015
Short term...(today and tonight)
issued at 337 am CST Friday Feb 27 2015
The short term concerns are few this period as large Arctic high
drops southeast over the area.
Initially...early morning temperatures below zero once again with
some teens below where winds die off completely. Surface ridge moves
across the southwest County Warning Area into tonight so winds will likely continue
to diminish most places...below 10 miles per hour. Wind chills will bottom out
around 25 below for an hour or two early where winds remain 5 to 10
miles per hour and temperatures bottom out 10 below to 15 below. Will leave out
headline because of light winds expected into the morning.
Plenty of sunshine today once again...should yield temperatures in
the 10 to 15 degree range which remains some 15 to 20 degrees below
normal. The ridge drops south of the area overnight...with
temperatures likely bottoming out to the west around midnight as
winds increase some from southerly direction. Still should
overnight lows roughly zero to 10 below across the County Warning Area.
Long term...(saturday through thursday)
issued at 337 am CST Friday Feb 27 2015
The main focus in the long term continues to be the system for
early next week. Little sensible weather is expected prior to that
system...with the only significant concern being a shot at some
light snow across southern Minnesota and portions of western WI Saturday night.
Models have shifted much of the snow south for Saturday night due
to a slightly more zonal flow. Only the GFS maintains light quantitative precipitation forecast
over southeastern Minnesota into WI. Certainly cannot rule out a a period of very
light snow or flurries...but accumulations will be negligible.
Lowered probability of precipitation and confined any mentionable categories to the far
southeast County Warning Area.
High pressure will drift overhead Sunday night and early Monday.
Moisture will begin increasing on the backside of the high Monday
afternoon and precipitation will begin to Blossom across the
plains. Some of this may reach southwestern Minnesota late Monday afternoon...but
the brunt of it should not arrive until Monday night.
00z models have shifted the Tuesday system a bit south. This is
in response to a slightly delayed ejection of the upper low from
the southwest and a quicker arrival of the Arctic front from the
northwest. The more suppressed pattern results in a less developed
surface cyclone that tracks from Colorado to northern Illinois.
While the spread has diminished in the past 24 hours...the complex
nature of the interaction between the northern and southern
streams will probably lead to additional shifts for the next
couple days. There will likely be a stripe of heavy snow to the
north of the cyclone track...but it is not possible to pinpoint
where yet with model variability continuing. Despite the southern
trend...the deterministic models continue to show accumulating snow
across southern Minnesota and WI so maintained likely probability of precipitation.
After this system exits the East Coast...a very quiet pattern
looks to take over the Continental U.S. Through day 10. In fact...the GFS and
European model (ecmwf) show virtually no precipitation falling anywhere from
Thursday night through the following weekend.
Aviation...(for the 12z tafs through 12z Saturday morning)
issued at 507 am CST Friday Feb 27 2015
VFR throughout period. Some high clouds possible in thwe west later in the
period. Winds generally west-SW today becoming south overnight into
Saturday...less than 10 kts.
high confidence VFR through the period with winds below 10 kts.
Directional component will be from the west this morning...
200 degrees by 00z Sat...then 170 degrees by 09z Sat.
/Outlook for kmsp/
Sat..VFR. Chance MVFR late. Winds S at 15 kts.
Sun...VFR. Winds west at 10 kts.
Monday...VFR with MVFR/IFR snow likely late. Winds southeast at 10kts.