Scientific Forecaster Discussion
fxus63 kmpx 150354
Area forecast discussion
National Weather Service Twin Cities/Chanhassen Minnesota
1054 PM CDT Sat Sep 14 2019
Short term...(this evening through Sunday night)
issued at 308 PM CDT Sat Sep 14 2019
Thunderstorms developed on a line of increasing Theta-E advection
where an elevated cumulus field continued to grow during the morning
across southern Minnesota. Regional satellite imagery also noted
an increasing area of low level moisture that was evident over the
southwest part of Minnesota. This is where the actual warm
frontal boundary had lifted from the previous location in northern
Iowa. Upstream, a broad area of mid level cloudiness across
northern Minnesota will be the main player of scattered
showers/storms later this evening as a stronger short wave moves
southeast across the northern plains, and interacts with the
increasing moisture across southern Minnesota. Initially, the main
area of showers and storms will affect far east central
Minnesota, and into west central Wisconsin before sunset. An
increasing cap behind the initial bands of storms should hinder
any additional development farther to the west until this evening.
The forecast of storms redeveloping remains questionable for this
evening as a frontal boundary moves southeast across Minnesota, and
the stronger short wave moves north of the region. Although low
level moisture remains in place, the cap could hold off any
redevelopment of storms until the short wave arrives. So, chances
for storms this evening are based on this forecast. After midnight,
the frontal boundary will have moved through the region. Residual
moisture could lead to areas of fog developing. The best area of fog
will form in central Minnesota, and into west central Wisconsin
where low level mixing will be minimal. Sunday and Sunday night will
be dry with increasing humidity levels as winds shift back to the
south. This will be the beginning of a very warm period next week.
Long term...(monday through saturday)
issued at 308 PM CDT Sat Sep 14 2019
Next week continues to look like it will feature above normal
temperatures and dew points, as an upper ridge edges eastward to
the central part of the country. A trough moving into the west
will continue to approach the region, with broad southwest upper
flow taking hold. This pattern will allow the occasional short
wave to arrive over the northern plains and upper Midwest, but
there are some timing differences. At this stage it does look like
the first such wave will bring a chance of precip Tuesday-
Wednesday, and then as the western trough gets closer, Friday-
Saturday looks like another opportunity for thunderstorms. But it
is difficult to pin down the specific time frames at this point
late next week as spread increases substantially in various
ensemble members, and a consensus approach is the best bet. All in
all, it looks like next week will be quite warm and somewhat
humid with some potential for a tropical connection.
Aviation...(for the 06z tafs through 06z Sunday night)
issued at 1154 PM CDT Sat Sep 14 2019
Few changes to the going tafs, with stratus expected to hang on in
WI, with dense fog forming across central Minnesota. Confidence is high
that stc sees very poor conditions tonight, with dense fog
possible at axn/rwf/mkt as well. We'll be putting the sun in
Sunday tomorrow afternoon with light west winds.
Kmsp...should see fog develop outside of the Metro, especially to
the west, but should be nothing worse than some br/bcfg at msp.
Otherwise, Sunday will be a beautiful weather day.
/Outlook for kmsp/
Mon...VFR. Wind S 15g25 kts.
Tue...VFR. Chc MVFR/thunderstorms and rain late. Wind S at 10-15 kts.
Wed...VFR. Chc MVFR/tsra. Wind SW 10-20 kts.