FXUS63 KMPX 191813

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
113 PM CDT Mon Aug 19 2019

Issued at 113 PM CDT Mon Aug 19 2019

Updated to include 06z aviation discussion below.


.SHORT TERM...(Today through Tuesday)
Issued at 354 AM CDT Mon Aug 19 2019

No significant changes to the previous forecast, other than
increasing pops slightly for Monday night across the southwest.
Today will be sunny and a bit warmer as the surface high pressure
shifts eastward and allows southerly return flow on the back side to
advect warmer air and higher dewpoints across the region. This can
be seen but Precipitable Water values of 1.5 inches across western
Minnesota Monday evening, while western Wisconsin remains at less
than an inch.

The low level moisture together with steeper mid-level lapse rates
will lead to MUCAPE values in excess of 2000 J/kg Monday night along
the Minnesota/Dakota border. Meanwhile a weak shortwave trough,
which as of Sunday night was located over northern California, will
move eastward and provide the lifting mechanism for scattered
thunderstorms Monday night. Although this is subtle feature, there
is a fairly impressive response in H850 theta_e advection, so did
increase pops a bit higher than guidance in southwest Minnesota.

On Tuesday a cold front will move through the region and provide
additional chances for showers and thunderstorms, but at this point
it looks like most locations will have just increased cloudiness,
and perhaps some light rainfall.

.LONG TERM...(Tuesday night through Sunday)
Issued at 354 AM CDT Mon Aug 19 2019

The middle of the week will start out dry with a taste of fall in
the air as a cold front moves through the region and brings highs in
the 70s, with lows in the 50s for Wednesday and Thursday. The next
shortwave trough approaches Thursday night into Friday, and this
will bring in warmer air and be the focus for another chance for
thunderstorms. Looking ahead, warmer temperatures and increased
humidity should last through next weekend.

Cold air advection will continue Tuesday night as surface high
pressure builds across the region. Wednesday will a great day to be
outside, with light northerly winds, low humidity, and highs in the
mid to upper 70s. The same holds true for the start of Thursday as

Throughout the day on Thursday, surface high pressure will again
track eastward and southerly winds will develop on the back side
which will bring a warmer and more humid air mass across western
Minnesota. This warm and humid air mass will overspread the rest of
Minnesota and Wisconsin over the weekend. Meanwhile, both the GFS
and ECMWF are in good agreement with a more zonal upper level jet
developing across the northern CONUS. This will increase the deep
layer shear profile. If convection does manage to develop this
weekend, it could be somewhat organized. Lack of instability is a
limiting factor. It is still way to early to latch on to any one
forecast, but the big picture perspective does merit this as
something worth watching.


.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 113 PM CDT Mon Aug 19 2019

VFR with mostly clear skies through this evening, with
thunderstorm chances developing after midnight at AXN/RWF/RNH and
mid to late morning at STC/MSP. Ceilings will begin to lower
overnight with MVFR conditions expected by tomorrow morning at
Minnesota terminals, and by late morning at RNH/EAU. IFR ceilings
appear possible across western Minnesota where ceilings will be
lower. A thunderstorm complex is expected to develop over
southwest Minnesota and dive south across iowa overnight, but
confidence is low on how widespread thunderstorm coverage becomes
north of this complex through tomorrow morning. Best chances for
-tsra will be at AXN/RWF/MKT, but have included a prob30 mentions
 at all MN terminals.

KMSP...Ceilings are expected to lower overnight, with MVFR
ceilings expected by mid-morning. Two periods of -shra/-tsra
appear possible, late morning/early afternoon and then again
tomorrow evening, but confidence remains low in how widespread
coverage will be at the terminal.

Wed...VFR. Wind NW 5-10 kts.
Thu...VFR. Wind NE 5 kts.
Fri...VFR. Wind SE 5-10 kts.





NWS MPX Office Area Forecast Discussion