Scientific Forecaster Discussion
fxus63 kmpx 272009
Area forecast discussion
National Weather Service Twin Cities/Chanhassen Minnesota
309 PM CDT Sat may 27 2017
Short term...(this evening through sunday)
issued at 109 PM CDT Sat may 27 2017
A band of fgen to the northwest of an mesoscale convective vortex going across Iowa has a
band of light rain working up into the southern Twin Cities Metro
this afternoon. This will likely spread into the Eau Claire area
through the afternoon, but dry air below 8k feet may result in
more virga/sprinkles as opposed to measurable rain, so kept pops
confined to no high than the 30s.
For tonight, guidance last night showed another fgen band
developing over north central Iowa and building toward western WI
for tonight, but guidance this morning as really backed off on
this band of precip, pushing it southeast as strong convection
getting going down in the Ozarks that will spread toward the
Tennessee Valley will help keep the southern forcing to the south.
We are also watching northern stream energy moving south across
Saskatchewan on the southwest side of an h5 low centered over
northern Manitoba. Guidance has slowed how fast this northern
stream energy gets here tomorrow, with popup afternoon showers
Sunday looking to stay confined to mainly central Minnesota and northwest WI, so
did reduce pops tomorrow south of I-94. In fact, Sunday really is
not looking all that bad. NAM shows US mixing a bit above 800mb,
which will ensure frequent gusts up around 25 mph by the
afternoon, but other than that, we should see a fair amount of sun
and mixing up to h8 will allow US to warm comfortably into the
upper 60s to lower 70s, so we should put together one more nice
day Sunday before we finally turn cooler, cloudier, and showerier
for Memorial Day.
Long term...(sunday night through saturday)
issued at 300 PM CDT Sat may 27 2017
Not much change in the extended period with a cool period from
Sunday night through Wednesday, with a moderating trend by late in
the week, and into next weekend.
First, instability showers will form across Minnesota, and into
western Wisconsin Monday afternoon. The core of the coldest air
will move overhead Monday night, and into Tuesday before slowly
retreating to the east by midweek. Typically, the best time period
for showers/thunderstorms will occur during the mid/late afternoon
hours which will likely be the case Monday/Tuesday. Most of the
models depict the deepest moisture associated with the upper low
across northern/eastern Minnesota, and into Wisconsin. This is
also where the best chance of showers/thunderstorms will occur.
Further to the southwest in west central/southwest/south central
Minnesota, moisture depth is shallower keeping any threat on the
development of showers/thunderstorms to a minimum. Temperatures
will reflect the cooler air mass and relatively low chance of
sunshine. Upper 50s/lower 60s seem reasonable both Monday and
Tuesday afternoon, with the best chance of holding in the 50s in
central Minnesota on both days.
The mean upper air pattern will slowly become more supportive of a
warming trend by the end of the week as the persistent upper
trough moves further to the east across eastern Canada. Although
it doesn't look like above normal temperatures past next week,
humidity levels should begin to rise as a more southerly flow
Aviation...(for the 18z tafs through 18z Sunday afternoon)
issued at 109 PM CDT Sat may 27 2017
Band of rain south of msp has been holding together better than
expected, but see it remaining just south of msp. May hold
together enough to make it into eau around 20z, but not overly
confident the forcing will hang together to allow it to reach
there. After this, the next potential shot of showers comes
between 6z and 12z up between axn and stc as shortwave currently
over SW Saskatchewan rotates into central Minnesota. This is a low
confidence/low coverage scenario, so have kept those tafs dry.
Otherwise, only area where models look to be a bit underdone is
with wind potential tomorrow, with mixing up over h8, some gusts
up around 30 kts look possible by the afternoon in Minnesota.
Kmsp...rain just south of the field may through a sprinkle or two
to the ground through 20z, but would be of little impact, so kept
going trend in the taf. Expect coverage of diurnal shower
activity Sunday to be in central/northern Minnesota, so have kept the taf
/Outlook for kmsp/
Mon...VFR. Chc -shra. Wind northwest 10-20 kts.
Tue...VFR. Wind northwest 10-20 kts.
Wed...VFR. Wind northwest 5-10 kts.