Scientific Forecaster Discussion
fxus63 kmpx 240945
Area forecast discussion
National Weather Service Twin Cities/Chanhassen Minnesota
345 am CST Wed Jan 24 2018
Short term...(today and tonight)
issued at 345 am CST Wed Jan 24 2018
Low clouds are returning slowly from the west early this morning
and have reached areas just west of the I-35 corridor at 345 am.
The effects of light winds and new, deep snow cover are on full
display this morning. Temperatures are rather cold in those
locations - lots of single digits across eastern Minnesota and western
WI where skies had also been clear overnight. However, shortly
after the clouds move in temps will tend to rise about 10 degrees
in the matter of an hour or two. Widespread 20s are being measured
across western Minnesota.
It appears the clouds will be with US for the day. Winds are light
in the cloud bearing layer, so there really isn't much to push
them out until tonight when southerly flow begins to strengthen.
Otherwise, a benign period continues.
Long term...(thursday through tuesday)
issued at 345 am CST Wed Jan 24 2018
Monday's system has been more of a blip in an otherwise quiet
winter and we are definitely back into that quiet weather pattern
we've had most of the winter, with no significant precipitation
systems expected locally really through the rest of the month.
That doesn't mean we won't have any systems move through, they'll
just be mainly dry.
The long term will be dominated by a progressive, though wavy
weather pattern. We'll start with ridging Thursday, move a trough
through Friday through the weekend, go back to ridging Monday and
Tuesday, before the next trough and a more permanent pattern
change move through mid-week next week.
For Thursday and Friday, the trough currently crashing ashore in
the pac northwest will continue east across the northern Continental U.S./Southern
Canada and dampen out. The surface low with this trough is still
pegged to run across the international border, which will place US
firmly in the warm sector. Highs Thursday and Friday and lows
Thursday night could easily be several degrees warmer than what we
have, even where a dense snow pack is in place. As we saw today,
Minneapolis warmed to 28 with the full sun. So the wild card here
is what happens with the cloud cover. Strengthening southeast
winds Thursday likely means stratus will be prevalent, but
Thursday night, we get southwest winds, which will help to start
clear out the stratus for Friday. Those southwest winds will also
likely hold temperatures up in the low 30s Friday morning, with
some locations likely remaining above freezing through the night.
The front coming through on Friday will be dry, as moisture from
the Gulf doesn't arrive ahead of the front this far north until
Friday night, when it will be moving across Michigan. Given the
threat for clouds Thursday and the fropa during the day Friday, we
stuck with a blended forecast for temps.
Friday's front will be a Pacific one, but Saturday, we'll see one
drop down from Canada and it's this one that will bring colder
air in. It looks like it will come down late enough Saturday to
give US one more day with highs above freezing, but to end the
weekend we'll have a Canadian airmass in place which will hold
highs in the teens for Sunday.
Next week, we'll see upper ridging move back in Monday, with the
next trough arriving Wednesday. Models have slowed down the
departure of sunday's Canadian airmass, with forecast highs Monday
knocked back a few degrees, with another day of highs in the
teens possible. Tuesday and Wednesday look to be repeats of
Thursday and Friday in terms of temperatures, with more highs in
the 40s likely these two days. However, the first system, which is
bringing through a Pacific front, then Canadian front, the front
coming through Wednesday will be a Canadian one. This will result
in a much tighter baroclinic with this boundary, which will at
least give US a shot at a passing rain/snow shower as it passes.
This trough the middle of next week also signals a change to a
more stable weather pattern, with ridging developing on either
coast of noam and troughing down the middle. This looks to put US
into a more prolonged period of northwest flow, with temperatures
turning quite a bit colder as we head toward the weekend of Feb
Aviation...(for the 06z tafs through 06z Wednesday night)
issued at 1108 PM CST Tue Jan 23 2018
Stratus clouds will slowly expand eastward across the area
overnight, with sites becoming MVFR and even IFR. MVFR ceilings
will persist through most of Wednesday, with western sites (kaxn
and krwf) having the highest chance of seeing late afternoon
sunshine. Winds will generally be light and variable or light
west/southwest through the period.
MVFR ceilings look even a tad slower to arrive...now looking to
set in around 12z.
/Outlook for kmsp/
Thu...chc MVFR/IFR cigs. Winds southeast 5-10 kts.
Fri...mainly VFR. Winds S-SW 5-15 kts.
Sat...VFR. Winds west 5-10 kts.