857 
FXUS63 KMPX 032115
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
315 PM CST Sun Feb 3 2019

.SHORT TERM...(This evening through Monday night)
Issued at 300 PM CST Sun Feb 3 2019

Tonight's forecast is highly dependent on surface and road
temperatures as the predominate weather type tonight will be
freezing drizzle or freezing rain. 

A weak surface low moved across southern Minnesota earlier today,
with a subtle feature that led to colder air draining southeast 
across the Minnesota River Valley. This led to surface 
temperatures dropping below freezing as far east as south central
Minnesota during the early afternoon. However, further to the 
north across the Twin Cities metro area and in west central 
Wisconsin, temperatures remained nearly steady as the slightly 
higher terrain kept the colder air from moving back to the north. 
In addition, winds were more from the north vs. the west where the
colder air drained along the Minnesota River Valley. Further to 
the south across Iowa, temperatures rose into the 40s and 50s.

This boundary to the south will be critical if a weak surface low
moves from southeast South Dakota, northeast along the 
Minnesota/Iowa border. This will lead to the warmer air advecting 
back northward into southern Minnesota, mainly south of the 
Minnesota River Valley. Depending upon if the colder air holds in 
far southern Minnesota, west of I-35, will depend on whether 
drizzle, or freezing drizzle will start this evening. Confidence 
is higher near the Minnesota River Valley vs. along the border of 
Iowa on freezing precipitation developing. Further to the 
northeast across east central Minnesota, and west central 
Wisconsin, not until winds become more west/northwest later 
tonight will temperatures fall below freezing, and lead to 
freezing drizzle/freezing rain. Too many uncertainties in this 
forecast to deviate on the current Winter Weather Advisory. 

The atmospheric moisture will begin to moisten up this evening,
and especially after midnight. This means the confidence is much
higher on precipitation developing after midnight vs. this
evening. The higher precipitation amounts will remain in south 
central Minnesota, and west central Wisconsin where locally one 
quarter of an inch is likely. Further to the west, amounts are 
highly dependent on when the atmosphere moistens up to allow for 
more rain vs. drizzle. 

After 12z, much drier/colder air will move across the region with
temperatures falling through the morning. Wind chill values drop
to near -25F in west central Minnesota during the day, but not
enough to warrant a current Wind Chill Advisory. Otherwise, dry
conditions will continue through Monday night.

.LONG TERM...(Tuesday through Sunday)
Issued at 245 PM CST Sun Feb 3 2019

An active weather pattern is expected this week along with below 
normal temperatures. A deep trough will remain over the Western 
CONUS through mid week before it begins shifting Eastward toward the 
Central CONUS Thursday into Friday. A shortwave and associated jet 
energy will bring chances for snow Tuesday afternoon into Wednesday. 
Warm air advection ahead of the wave will allow for the possibility 
of light snow starting Tuesday morning. There is also a slight 
chance for freezing drizzle as the system departs Wednesday morning 
with drying air aloft. The ECMWF continues to show less 
precipitation than the GFS, so kept QPF near the average, near 0.10-
0.15 inches with the possibility of 1-3 inches of snowfall 
accumulation in Southern MN. If the higher QPF does pan out, than 
there would be potential for areas of 4+ inches of snowfall.

A Colorado Low is expected to develop on Wednesday and eject into 
the Central Plains and lift into Illinois while remaining vertically 
tilted. This will bring another round of snowfall for MN/WI, but it 
is still too early to say exact amounts, especially with continued 
model discrepancies. The ECMWF brings the surface low to Central 
IL at 00Z Friday, whereas the GFS has the surface low near Chicago
by 12Z Thursday. Consensus indicates potential for near 0.25" of 
QPF and 4+ inches of snowfall by 00Z Friday.

Cold air advection and upper level troughing will follow the 
Colorado Low with wind chills below -25 forecast for Thursday night 
and Friday in Western MN. Upper level ridging is progged to 
encompass the Central CONUS by Saturday, allowing for temperatures 
to moderate to near normal by Sunday. Both the ECMWF and GFS 
indicate potential for another Colorado Low-like system developing 
with potential for precipitation across the Midwest on Sunday. 

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1130 AM CST Sun Feb 3 2019

Recent airport observations have indicated that they are near or 
slightly below airport minimums as of 1130 AM, especially in west
central Wisconsin where the dense fog continues. Elsewhere, 
cigs/vsbys will remain in the IFR or LIFR range through 00z, with 
little chance of precipitation. The best chance of precipitation 
occurs after 3z, with the most likely time frame between 6z and 
15z Monday. KAXN has the best chance of all -SN, with KMKT-KMSP- 
KRNH having the best chance of -FZRA/-FZDZ during the overnight 
hours. KEAU should stay above freezing until the change over to 
-SN. Confidence is still fairly high that freezing precipitation 
will develop this evening in portions of southern/eastern 
Minnesota, and into west central Wisconsin. Lower confidence on 
the amount of freezing precipitation. After 12z, any freezing 
precipitation will change over to -SN or end. Cigs/Vsbys should 
begin to rise Monday morning with gusty northwest winds 
developing. 

KMSP...

Main change to this TAF period is to hold onto the lower
cigs/vsbys through the early afternoon, with an introduction of
PROB30 after 3z. Confidence still remains high enough to hold onto
the FZRA after 6z. 

/OUTLOOK FOR KMSP/

Mon Aftn...MVFR with -SHSN. Wind NW 15G25 kts. 
Tue...VFR/MVFR with IFR/-SN likely late. Wind N bcmg E 5 kts. 
Wed...MVFR chc IFR. Chc -SN in mrng. Wind NW 10G20 kts.


&&

.MPX WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory from 9 PM this evening to 9 AM CST 
     Monday for WIZ014>016-023>025.

MN...Winter Weather Advisory from 9 PM this evening to 9 AM CST 
     Monday for MNZ042>045-049>053-057>063-065>070-073>078-
     082>085-091>093.

     Dense Fog Advisory until midnight CST tonight for MNZ074>077-
     082>085-091>093.

&&

$$

SHORT TERM...JLT
LONG TERM...AMK
AVIATION...JLT