Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 190846
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
346 AM CDT Sun Mar 19 2017

.SHORT TERM...(Today and tonight)
Issued at 305 AM CDT Sun Mar 19 2017

Surface analysis early this morning shows the center of high
pressure over the western Ohio Valley region while a warm front
is draped over the Dakotas. Aloft, a large ridge axis is positions
over the northern-central Plains while a potent upper level low
meanders over the Mid-Atlantic region. As the day progresses, the
ridge axis and warm front will move over the Upper Mississippi
River valley region in concert with one another, which despite the
passage of high clouds will spell a strong warming trend for the
WFO MPX coverage area. More pronounced southerly flow plus the
increase in H7-H5 heights will allow temperatures to warm to the
mid 50s in western WI to the mid 60s in western MN. By late
afternoon, the ridge axis will be positioned well to the east of
the region with the upper level flow becoming more zonal. In
addition, closely following the passage of the warm front will be
an approaching cold front (associated with a low pressure center
in central Canada). Along with the warmer temperatures today will
be an increase in low level moisture, evidenced by dewpoints
climbing to the upper 30s and lower 40s. This will actually create
some modest instability, particularly in western WI, where models
continue to show LI`s dropping below zero and MUCAPEs rising to
several hundred J/kg. Middle and upper level moisture will be
lacking as will a strong enough trigger in the upper levels so all
that can be expected are some isolated showers in southeastern MN
into western WI later this afternoon into the early evening
hours. The cold front will pass through the region by late
evening, allowing cooler and drier high pressure to enter from the
northwest tonight into Monday morning.

.LONG TERM...(Monday through Saturday)
Issued at 305 AM CDT Sun Mar 19 2017

The extended period will become more progressive by late this
week, and into the weekend. The progressive pattern is due to a
powerful jet that is forecast to dig across the Rockies, and into
the mid section of the nation by late this week.

The EC/GFS/GEM and the mean GFS 50H ensemble are consistent with
this pattern shift by late in the week. Differences occur in the
amplification of the mean trough as it moves across the CONUS with
the EC further south compared to the GEM/GFS. However, moisture
return, and the depth of the moisture associated with a storm
system moving out of the Rockies, should allow for a widespread
area of precipitation to develop across the Plains, and into the
Upper Midwest. Timing, placement of the heaviest precipitation
remains uncertain, especially considering the progressive nature
of long wave pattern developing. Placement of the moisture
transport of the 85/70H vectors/magnitude needs to be watched
considering the anomalous high precipitable water content expected
by Thursday night/Friday. A high probability of PWAT values above
3 standard deviations is also indicated by Friday. This would
lead to an increasing chance of heavy rainfall based on these
conditions. Once this system moves through Friday, a day or so of
a break before another strong storm moves across the Rockies and
into the mid section of the nation. Again, this looks to be a
progressive pattern meaning that the drier pattern will become
wetter.

As for thermal profiles, and the increasing transport of
mild/moisture air, it looks to be all rain, and not much in the
way of snow. In addition to the progressive/wetter pattern, the
air mass is still not abnormally warm for the Upper Midwest.
Therefore, it will be mild, but not record warmth.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 923 PM CDT Sat Mar 18 2017

Made no substantive changes to earlier forecast. Reasoning remains
similar, with high pressure drifting east overnight we`ll see
light winds. But, the winds will pick up from the southeast and
eventually south on Sunday as a frontal boundary approaches from
the west. Chances for showers still look best from near I-35 east
during mid to late afternoon. A thunderstorm is possible, but best
chance for that looks to be south of the forecast sites. Still
don`t have enough confidence in coverage of activity to try and
time in anything specific, so kept a mention of VCSH for now. Any
ceilings still look to be VFR.

KMSP...Primary uncertainty is with chances for showers Sunday
afternoon, but not yet sold on there being enough coverage to go
with more than VC at this point.

/OUTLOOK FOR KMSP/
Monday...VFR. North wind 5 to 10 kt.
Monday night...VFR. Variable wind 5 kt or less.
Tuesday...VFR. North wind 5 to 15 kt.
Tuesday night...VFR. Northeast wind around 5 kt.
Wednesday...VFR. Southeast wind 5 to 10 kt.

&&

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

$$

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



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