Area Forecast Discussion
Issued by NWS Twin Cities, MN

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953
FXUS63 KMPX 260454
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1054 PM CST Sat Feb 25 2017

.SHORT TERM...(This evening through Sunday)
Issued at 301 PM CST Sat Feb 25 2017

Surface analysis this afternoon shows an approaching cold front
from ND with a surface low over far NW MN. High pressure dominates
much of the central CONUS. Aloft, one sharp longwave trough is
exiting into New England while another is developing over Manitoba
into southern Idaho. This trough will produce enough lift in
conjunction with the approaching front to produce isolated to
scattered snow showers in mainly northern and eastern portions of
the WFO MPX coverage area through midday tomorrow. Little to no
accumulations are expected. Cloudy skies will linger through much
of the day tomorrow as the front will settle over central MN into
northern WI while the upper trough shifts into the Great Lakes.
Little in the way of airmass change will take place. Therefore,
high temperatures tomorrow will be rather similar to high
temperatures today, running in the upper 20s to mid 30s. Lows
tonight will be a bit warmer due to the blanket of clouds across
the area. Min temps will drop to the upper teens to mid 20s.

.LONG TERM...(Sunday night through Saturday)
Issued at 301 PM CST Sat Feb 25 2017

The main forecast concern in the extended period is precipitation
chances late Monday night/Tuesday, along with precipitation type as
a warm layer aloft moves overhead.

Weak west-northwest flow aloft will become more southwest early
next week as two storm systems moving east/southeast off the
west coast, combine, and move inland. This will set the stage for
a series of weak shortwaves riding northeast along this southwest
flow aloft until Wednesday as the mean trough moves through the
mid section of the nation.

Ahead of the expect system late Monday night & Tuesday, warmer air
aloft will surge northward ahead of a developing storm system in
the Rockies. An old frontal boundary from today`s system will
linger in the region which will likely be the focal point of
moisture convergence as the storm system begins to move out of the
Rockies, and into the plains. All three models, EC/GFS/GEM
increase boundary layer moisture ahead of this system Monday
night. This may allow for stratus, low clouds and fog to form
before any upper level energy moves into the area. Therefore,
drizzle or freezing drizzle is likely, especially in areas where
the heavy snow fell a couple of days ago. Depending upon the
strength of the low level jet expected to develop Monday night,
will lead to an area of moisture convergence and likely an
expanding area of light precipitation, especially on the nose of
this jet. Although most of the lift is associated with the low
level jet Monday night/Tuesday, as energy from the storm moving
out into the plains Tuesday, precipitation will likely increase in
coverage and intensity. The stronger of the upper level energy
moving out of the Rockies Tuesday is associated with the southern
jet, so as a surface low begins to form in the plains Tuesday,
most of this energy should be south of Minnesota. This scenario is
highly dependent on frontal boundary position and the energy
moving out across the plains. Therefore, chances of precipitation
could either decrease or increase based on these factors.

Past Tuesday, a cool period is expected for a few days before the
mean flow becomes more west/southwest next weekend. This type of
flow will again provide for milder temperatures with 40s not out
of the question this time next week.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1054 CST Sat Feb 25 2017

MVFR or lower ceilings and visibilities will persist overnight and
early Sunday morning across central MN along a slow moving cold
front. The snow should reach KAXN by TAF issuance and continue off
and on through the night. The -SN will brush KSTC in the early
morning along with MVFR ceilings. Not confident the -SN and MVFR
ceilings will reach farther south to the other TAF sites. SW winds
8-14 knots overnight becoming WNW 8-14 knots with FROPA on Sunday
along with some gusts to around 20 knots.

KMSP...Have deviated a little from the previous VFR forecast
and inserted a tempo group for MVFR ceilings in the morning,
roughly 12-16z with the cold front slipping in from the north.
Also included VCSH for the possibility of some -SN.

/OUTLOOK FOR KMSP/
Mon...VFR becoming MVFR. Chance -RASN Mon night. Wind S 5-10 kts.
Tue...MVFR likely. Chance -RASN. Winds E 5 kts shifting to N.
Wed...MVFR ceilings possible. Otherwise VFR. Winds N 5-10 kts.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
&&

$$

SHORT TERM...JPC
LONG TERM...JLT
AVIATION...RAH



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