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fxus63 kmpx 151140 

Area forecast discussion
National Weather Service Twin Cities/Chanhassen Minnesota
640 am CDT sun Sep 15 2019

issued at 631 am CDT sun Sep 15 2019

Updated to include 12z aviation discussion below.


Short term...(today through monday)
issued at 449 am CDT sun Sep 15 2019

Surface analysis early this morning shows a north-south oriented
weak surface front bisecting Minnesota and extending southwest
into the Central Plains. Modified Pacific high pressure sites over
the northern-central rockies. Aloft, a broad ridge of high
pressure encompasses the western Continental U.S. While broad troughing is
setting up over the eastern Continental U.S..

Much of central Minnesota into western WI via surface obs and webcams
showing visibilities under 1/2sm, with many 1/4sm, due to calm
winds and plenty of low level moisture caught under the nightly
inversion. Not expecting this fog to dissipate until a couple
hours past sunrise so have issued a fairly expansive dense fog
advisory across much of the area thru 9am. Will monitor to see if
any more expansions in area are needed before expiration.

Otherwise, once beyond the morning fog, an exceptional day is on
tap with clearing skies and temperatures climbing to the upper 70s
to mid 80s under the building dome of high pressure. The ridge
axis will slide east from The Rockies this morning to the
northern-Central Plains by this evening then become aligned over
the Mississippi River by daybreak Monday morning. Mainly clear
skies are expected to continue tonight through tomorrow with even
warmer temperatures expected for Monday. Highs tomorrow will range
through the 80s, with highs near 90 possible in western Minnesota.

Fog does again look likely early Monday morning and continuing
through daybreak so this will be monitored for the potential of
another dense fog advisory, especially with the resumption of
morning school bus runs and additional commuters on the roadways.

Long term...(monday night through saturday)
issued at 449 am CDT sun Sep 15 2019

By Monday evening, the upper ridge axis will be nearly directly
overhead, with the upstream trough expected to become negatively
tilted Monday night as it pivots across the Pacific northwest. It
will feel like a mid-Summer night Monday night with dew points
around 70 degrees and hence overnight lows likely remaining in the
lower 70s.

Tuesday will be another warm day with highs in the 80s once again,
but do include some slight chance pops for mainly the afternoon and
evening. With a surface low deepening across the western Dakotas by
late afternoon, expect breezy southerly winds of 15-20 miles per hour with
gusts up to 30 miles per hour (mainly western mn) not out of the question
Tuesday. Shortwave energy ahead of the aforementioned upper trough
could lead to showers and thunderstorms especially during the
evening. Given the airmass, cape will be fairly decent as will shear
parameters, which will present a marginal risk of large hail and
damaging winds as the Storm Prediction Center day 3 outlook indicates. There are still
timing issues for how fast the main shortwave and the surface front
move out of the region, so chance pops linger through Wednesday in
eastern Minnesota and western WI where destabilization is possible Wednesday
afternoon depending on the location of the front associated with
this system.

Beyond Wednesday, yet another impressive amplified longwave trough
will dig across the western Continental U.S. Which will reinforce the ridge
that had just been broken down by the Tuesday-Wednesday system. It
won't be as warm as the first couple days of the week, but with
average highs only around 70 degrees by this weekend, above normal
temperatures are expected to continue.


Aviation...(for the 12z tafs through 12z Monday morning)
issued at 631 am CDT sun Sep 15 2019

IFR-or-lower conditions across western and central Minnesota due to
ground fog this morning. Trying to spread into western WI but
insolation is likely to burn it off before such degraded
conditions reach krnh-Keau. Kmsp itself looks to remain free from
fog but the satellite airports are dealing with it at
initialization time. Fog is expected to burn off 14z-15z then
solid VFR conditions will prevail. Ground fog is possible once
again tonight but will hold off at this moment before adding in
another round of IFR-or-worse conditions.

Kmsp...while chances are not favorable for kmsp to see IFR fog,
some MVFR conditions for a few observations cannot be ruled out
prior to 15z. Otherwise, solid VFR conditions are expected. Fog
cannot be ruled out for the Monday morning push but chances are
too low to include at this point.

/Outlook for kmsp/
Mon...VFR. Wind S 15g25 kts.
Tue...VFR. Chc MVFR/thunderstorms and rain late. Wind S at 10-15 kts.
Wed...VFR. Chc MVFR/tsra. Wind SW 10-20 kts.


Mpx watches/warnings/advisories...
WI...dense fog advisory until 9 am CDT this morning for wiz014-023.

Minnesota...dense fog advisory until 9 am CDT this morning for mnz041>045-



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