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fxus63 kmpx 161113 

Area forecast discussion
National Weather Service Twin Cities/Chanhassen Minnesota
613 am CDT Mon Sep 16 2019

issued at 605 am CDT Mon Sep 16 2019

Updated to include 12z aviation discussion below.


Short term...(today through tuesday)
issued at 235 am CDT Mon Sep 16 2019

Surface analysis early this morning shows a sagging surface front
from the western Dakotas through the mid-Mississippi River valley
through the Great Lakes, with weak high pressure sitting over
MN/WI. Aloft, a much more amplified look is taking shape with a
ridge axis setting up along the Mississippi River while a sharp
longwave trough moves onshore the western Continental U.S..

For early this morning, the moisture concentration underneath the
nightly inversion in conjunction with light winds in western WI
into eastern Minnesota will again make for plenty of fog formation. Best
chances for dense fog look to be north of I-94. Satellite imagery
does show another surge of low level moisture in the form of
ground fog coming into southeastern Minnesota but this looks to run into
an area of drier dewpoints and is not expected to cause areal
dense fog issues. As such, will maintain the dense fog advisory
for western WI into east-central Minnesota.

Once the fog Burns off, plenty of sun can be expected along with
warm temperatures. Continued increasing 500 mb heights along with
strong insolation should aid temperatures surging into the 80s
area-wide, and potentially close to 90 in far west-central Minnesota.
Clouds will increase late in the day into tonight as the surface
front to the south becomes disjointed, allowing a warm frontal
feature to lift north over western Minnesota and the Dakotas while the
eastern portion of the front sags southeast and away from the
area. In conjunction with the increase in isentropic lift in this
scenario, an approaching modest low level jet with appreciable upper level
diffluence may work to produce isolated showers/thunderstorms
moving northeast from eastern Nebraska and South Dakota through
western Minnesota early morning Tuesday. Not looking for much at
all in the way of coverage (isolated at best) through the day on
Tuesday. As for temperatures on Tuesday, very little difference
from today is expected, with the entire coverage area expected to
reach the 80s.

Long term...(tuesday night through sunday)
issued at 235 am CDT Mon Sep 16 2019

Minimal changes to the long term forecast were made. It will be a
warmer than normal and active for this time of year.

By Tuesday evening, a potent shortwave will be lifting northeast
across Wyoming into the Dakotas, with the pv axis extending
southeast through Minnesota overnight. At the surface, a deepening
surface low will move into Manitoba with a frontal boundary
extending south through the Dakotas. The low level jet will
intensify Tuesday night and with the front not expected to reach
western Minnesota until Wednesday morning, strong southerly flow and low
level convergence locally will lead to convection across the local
area. Pwats will increase to around 1.8", threatening daily
records for mid September, along with modest cape. Deep layer
shear will be unidirectional and while individual cells will move
fairly quickly, training cells appear likely overnight given the
850-300mb mean wind will become parallel to the low level jet especially
from 06-12z. Given this, could foresee localized 1-2" rainfall
amounts overnight into Wednesday morning. In terms of severe
weather, enough cape and speed shear exists for the potential for
some large hail, mainly in western Minnesota, which has been included in
a marginal risk. The front will move through on Wednesday, and end
up stalling southeast of our area as the main upper wave
continues moving northeast into Canada. We retain chance pops
Wednesday night across far southern Minnesota and parts of western WI
given the proximity of the front.

An amplified trough across the west will keep our southerly low
level flow going through later in the week, and while it won't be
quite as warm as the first half of the week, daytime highs will
still be running about 10 degrees above normal. This trough will
end up taking a similar path to the previous one, but will be
larger and stronger. Hence, it looks to be active, most likely
Friday night into Saturday, with a frontal passage sometime
Saturday leading to drying and cooling conditions with temps
falling to near normal by Sunday.


Aviation...(for the 12z tafs through 12z Tuesday morning)
issued at 605 am CDT Mon Sep 16 2019

Areas of fog around Keau may still make for MVFR-IFR conditions
for the first couple hours of this taf. Otherwise, solid VFR
conditions expected throughout this set. High clouds will
gradually increase today. Breezy S winds expected, with speeds
around 15g25kt. additional concerns.

/Outlook for kmsp/
Tue...VFR. Chc IFR with thunderstorms and rain likely late. Wind S at 10-15 kts.
Wed...VFR. Chc MVFR/tsra. Wind west-southwest 10-15 kts.
Thu...VFR. Chc thunderstorms and rain late. Wind southeast 5-10 kts.


Mpx watches/warnings/advisories...
WI...dense fog advisory until 10 am CDT this morning for wiz014>016-

Minnesota...dense fog advisory until 10 am CDT this morning for mnz043>045-



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