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fxus63 kmpx 210555 aab 

Area forecast discussion...updated
National Weather Service Twin Cities/Chanhassen Minnesota
1155 PM CST Wed Nov 20 2019

Short term...(this evening through Thursday night)
issued at 250 PM CST Wed Nov 20 2019

Forecast remains on track regarding the widespread rainfall
developing this evening into tonight, with rainfall eventually
expected to change over to light snow tomorrow morning. Forcing
aloft will continue to increase this evening as a shortwave
approaches out of ND, aided by plenty of strong warm air advection
and isentropic ascent in the low levels. As the atmosphere saturates
tonight, a widespread shield of rainfall will develop out ahead of a
surface low tracking from western Iowa through central WI, with a
shield of light continuing to our north along a cold front dropping
south through northern Minnesota. Rainfall is expected to be
heaviest during the overnight hours, especially just from southern
Minnesota through west-central WI, where models depict a
frontogenesis band developing to the northwest of the track of the
surface low. Precipitable water values will range from 0.75-1" across the area which
are near record values for late November, so this looks to be an
efficient rainfall producer for this late in the year. Rainfall
amounts look to range from a quarter of an inch to half an inch
across central Minnesota, to 0.75-1 inch across southeastern Minnesota and
west-central WI.

While the rain is ongoing, the cold front to our north will pass
through the area and cause temperatures to quickly drop below
freezing. Expect to see a changeover from rain to light snow
during the morning tomorrow, but this changeover looks to occur
after the bulk of precipitation has already fallen. Snow
accumulations of half an inch to an inch are possible across
central Minnesota and along/north of the US-8 corridor in WI where
an early transition will allow for snow to fall for a few hours.
Elsewhere, expect only a dusting to a rain/snow mix as snow only
falls for an hour or two on the back end of the precipitation.
This transition is expected to occur for most of the area during
the morning commute so there could be a few slick spots on the
roads, especially on elevated surfaces as temperatures continue to
fall during the morning. The precipitation is expected to be
mostly east of the County Warning Area by noon, with strong northwest winds
developing as the precipitation ends. Temperatures will only reach
the mid 20s to mid 30s Thursday afternoon, and fall into the
teens across most of the County Warning Area by Friday morning. Some additional
slick spots on roads Thursday evening into Friday morning as any
moisture remaining on the roads from Thursday morning quickly

Long term...(friday through wednesday)
issued at 250 PM CST Wed Nov 20 2019

The extended period will remain progressive as the mean flow aloft
continues from the west/northwest, with a slow transition to
west/southwest by the end of the period. With the progressive
nature, timing, and amplitude of the short waves embedded in this
flow, confidence in the forecast will remain below average in the
extended period. Even the ensembles have too much spread to
determine which system next week will actually affect the upper

The ec/GFS deterministic model run for this morning are fairly
similar in the long wave pattern through early next. Although the
overall mean remains similar, differences arise in the amplitude of
a short wave moving across the region late in the weekend, and
especially next week.

First, the ec has a stronger signal on a developing short wave vs.
The GFS on Sunday/Sunday night. Surface feature are similar with a
trough of low pressure moving through, but the ec has developed an
area of quantitative precipitation forecast along this trough. The GFS remains dry, and holds the
frontal boundary just to the south of Minnesota on Monday. The ec
moves this frontal boundary well to the south across the Central
Plains. A blend of models support a slight chance, but due to the
lack of deep moisture, and no strong upper level features, am
leaning toward a drier forecast, at least until Monday evening. The
differences are even larger by mid week as the GFS supports a very
strong storm system ejecting out of The Rockies, and into the
plains, upper Midwest. The ec, and the Gem support a more southerly
track for early/midweek, but still develop a large storm system by
the end of the week. This is due to differences short wave energy
and associated surface features, along with timing. Therefore, very
low confidence on any one solution, especially considering
temperatures and the potential of significant snowfall during the
Holiday week.

Even though next week is highly uncertain in terms of where/when and
how much precipitation develops, the long wave pattern is conducive
on an active period. Each individual run of the models will get more
refined as we get closer to the weekend, and into early next week on
the potential of a large storm system. It is just too early to
follow individual model runs. But, the large scale trough does
support an active period.


Aviation...(for the 06z tafs through 06z Thursday night)
issued at 1155 PM CST Wed Nov 20 2019

Conditions will deteriorate to IFR at all taf sites overnight.
Rain is advancing north and will engulf the region as well. The
rain will turn to snow from west to east late tonight and Thursday
morning before ending a few hours after the transition occurs.

Kmsp...becoming MVFR between 06-07z with IFR expected after 09z.
Rain should turn to light snow around 14z and then end by 16z.

/Outlook for kmsp/
Fri-sun...VFR. Wind west 5-10 kts.


Mpx watches/warnings/advisories...


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