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Area forecast discussion 
National Weather Service Twin Cities/Chanhassen Minnesota
554 PM CST Tuesday Dec 1 2015

Update...for 00z aviation discussion below


Short term...(today and tonight)
issued at 554 PM CST Tuesday Dec 1 2015

Surface low this afternoon over southwest Minnesota is in the process of
filling...with the surface energy transferring to a low developing around
Western Lake Superior. There is a surface trough snaking up through
western/central Minnesota between these two features. This system is certainly
well wound up and occluded...with the warm sector /characterized by
temperatures in the middle 30s/ wrapping around northern through western
Minnesota...while the cold air is coming down through the Dakotas into
Nebraska...Iowa and up into southeast Minnesota. Beside the middle level dry slot...a
water vapor loop shows the other issue we are having with getting
significant precipitation anymore with this system and it is the loss of
deep moisture. The plume of tropical moisture from the Pacific that
was feeding this system yesterday has since been sheared off to the
east and is now working up from Texas toward New England...leaving
the closed 500 mb how over southern Minnesota with less and less moisture to work

For the rest of tonight...weak fgen and warm advection of all
things in the wake of the surface trough mentioned above will lead to a
band of light snow working across Minnesota. There is fairly good agreement
among the cams with this band and of light precipitation remaining more or
less stationary across central/western Minnesota through midnight...but will
start to slowly March east thereafter. This will likely bring some
light snow back to the I-35 corridor late tonight into early
Wednesday morning and bring some light snow/flurries into western WI
Wednesday morning. this band moves east...the filling in
of the 700 mb low also leads to a decrease in the temperature gradient
across the area...which in turn will lead to a diminishing in the
forcing via not much snow is expected to be left by the
time it gets to WI. For snowfall amounts...have an additional inch
this evening along/west of a Madison to Long Prairie line...with
minimal amounts elsewhere.

For the headline...saw no reason to let it go through
canceled it this afternoon. As mentioned above...additional snowfall
amounts are expected to be minimal...with a tour of mndot traffic
cams across western/central Minnesota showing roads are only wet at best. So
with no additional impacts expected...decided to get rid of the advisory

For lows tonight...favored the higher end of guidance /NAM and
sref/...especially for eastern Minnesota/western WI. Current satellite trends and
925-850 relative humidity forecasts do not suggest any clearing will occur finding it hard to buy into the lows in the middle/upper
teens models such as the GFS/European model (ecmwf) are showing for tonight for eastern
Minnesota into western WI.

No weather concerns are expected on Wednesday...with main forecast
challenge being timing clearing skies from west to east. Right
now...the farther west of a New Ulm to Mora line you are...the
better chance you have at seeing some sun in the afternoon. The
farther east you get...the better the chance is that you get to
spend yet another day under overcast skies.

Long term...(wednesday through monday)
issued at 554 PM CST Tuesday Dec 1 2015

A relatively unusual forecast for early December with high
confidence on near zero probability for precipitation...along with
seasonably warm temperatures. Theres not much else to say other than
the dry and above normal through the weekend.

The upper level pattern will bring active weather across North
America. This is contradictory to the opening the
justification is that the active weather will be in the Gulf of
Alaska and across Canada...well north of central Minnesota and western WI.
A storm track such as this brings repeated Lee side warming over
Alberta and Montana...which will be reoccurring Reservoir of mild
air that will keep temperatures near to above the seasonal average
for early December. Forecast soundings show limiting mechanical
mixing in the boundary layer with a relatively weak wind profile. In
addition...the higher albedo from the snowpack will also limit the
daytime not anticipating runaway temperatures...but
rather 5 to 10 degrees above normal.


Aviation...(for the 00z tafs through 00z Wednesday evening)
issued at 554 PM CST Tuesday Dec 1 2015

Intermittent light snow showers are possible tonight into
Wednesday morning...along with patchy freezing drizzle. Kaxn will
be the most affected...where visibilities in the 1-2sm range will persist
this evening. The forcing will weaken with progression
east/southeast...but MVFR visibilities will still be possible as the band
swings across. Low-end MVFR to IFR ceilings will also become
prevalent overnight. Precipitation should come to an end by 15z
Wednesday...but clearing and VFR conditions will likely not arrive
until middle to late afternoon at Minnesota sites and until Wednesday evening at
WI sites. Light and variable winds become northwesterly for
Wednesday at speeds below 10 kts.

expect ceilings to continue degrading below 1700 feet this evening...then
stay there through Wednesday morning. Scattered flurries will
occur this evening as well...but attendant visibility restrictions are not
anticipated until slightly stronger forcing moves in between 10z
and 15z. Low cloud deck is expected to scatter out late Wednesday

/Outlook for kmsp/
Thursday...VFR. Winds SW 5-10 kts.
Friday...VFR. Winds S 5-10 kts.
Sat...VFR. Winds SW 10 kts.


Mpx watches/warnings/advisories...


Short term...mpg
long term...jrb

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