Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 191701
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1201 PM CDT Sun Mar 19 2017

.updated for 18z aviation discussion below...

.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 18Z TAFS through 18Z Monday afternoon)
Issued at 1205 PM CDT Sun Mar 19 2017

Southerly flow ahead of next cold front progged to move east to
west this afternoon/tonight. Gusty se-s south winds ahead will
relax from west to east this afternoon as the front approaches.
Some cumulus/statocu developed in deeper moisture over east
central MN late this morning and this will shift east into
Wisconsin for the afternoon. Models still develop some instability
ahead of the front...in deeper moisture flux...so will mention
vcsh at KEAU later this afternoon. This axis shifts east and south
through 00z. High pressure will nose in behind the front shifting
winds more nw-n. Some mid level moisture travels from the Dakotas
into southern MN overnight and Monday as upper jet axis shifts
off to the east.

KMSP...VFR conditions to prevail throughout the period. Mix of 5k
to 10k foot clouds this afternoon...and more mid/high level clouds
tonight into Monday. Gusty southerly winds ahead of front this
afternoon...should relax by evening...and fropa around 06z-07z
with winds becoming nw-n into Monday.

/OUTLOOK FOR KMSP/
Tue...VFR. Wind N 5-10 kt.
Wed...Mainly VFR. Chance of MVFR in -RA/-SN late. Wind SE 5-10
kt.
Thu...Mainly VFR. Chance of MVFR in -SN early and -RA late. Wind
SSE 10 kt.

&&

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

$$

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


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