Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 141840

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
140 PM CDT Fri Jul 14 2017

.Updated for 18z aviation discussion...
Issued at 125 PM CDT Fri Jul 14 2017


.SHORT TERM...(Today and tonight)
Issued at 412 AM CDT Fri Jul 14 2017

The short term concern is clearing trend today and resultant high
temperatures. Then any convective risk over far northern cwa late

The latest fog satellite product indicates some bkn-ovc stratocu
over much of the cwa. Some clearing beginning to the far north.
Once it does clear temepratures drop off into the lower 50s
quickly with the threat of some fog. The clearing should continue
slowly to the south and east this morning as the high pressure
ridge moves east. Sunshine is expected for much of the afternoon.
This should help temepratures warm through the 70s to the east,
with some lower 80s to the far west.

Later tonight, some high clouds will move into the northwest cwa
ahead of the incoming cold front. Convection is expected to be
limited with this feature as mid level capping develops. Most
HIRES models are not showing any real development along this
boundary overnight. The deterministic models do try and develop
some light QPF associated with there mainly isolated convection.
We will hold onto the slight chance PoP over the far northern cwa
late tonight for now.

.LONG TERM...(Saturday through Thursday)
Issued at 412 AM CDT Fri Jul 14 2017

Much of the extended portion will be dominated by surface high
pressure, meaning infrequent periods for precipitation. However,
there will be two main frontal systems pushing through the region:
one on Friday night through Saturday and another late Monday
through Tuesday.

The first system will follow high pressure departing the area and
will bring a noticeable increase in both warm air and moisture.
Ridging from 850mb-700mb will allow temperatures to climb to
around 90 degrees on Saturday while dewpoints rise through the 60s
into the lower 70s. This will allow for heightened instability but
the disjointed nature of the system features will make for meager
storm initiation. The main area for storms look to be in far
eastern MN into western WI Saturday afternoon and evening, and
will be mainly driven by how much influence a nearby upper level
trough can contribute to the surface features and deep moisture.
There is even the potential for severe thunderstorms given the
strong instability and ramped up bulk shear but there is also
plenty of uncertainty in timing/placement at this time.

The second system will come after high pressure regains control
over the area for Sunday and Monday. Another surge of warm air
and moisture from the deep south will develop in advance of a
Pacific-origin system that will interact with another shortwave
trough disturbance dropping in from central Canada. This system
will be a little more organized than the weekend system and a
little more prolonged, hence several periods of PoPs in the
forecast. High pressure will then become the prevailing feature
for the latter half of the week.


.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 125 PM CDT Fri Jul 14 2017

VFR conditions expected this afternoon through tomorrow. The
nagging stratus will slowly lift and dissipate this afternoon with
clear skies expected by the evening. Light and variable winds
should eventually become southerly. Overnight a few showers will
move across northern Minnesota and Wisconsin, but these are
expected to stay north of the TAF sites and should produce nothing
more than mid/high clouds.

VFR conditions throughout. Clouds should break up this afternoon,
and clear out this evening. Light winds will become southerly
overnight and southwesterly on Saturday. A few thunderstorms are
possible late Saturday afternoon, but it looks like they will be
east of MSP so did not include mention in the TAF.

Sunday...VFR. Northeast wind 5 to 10 kt becoming east.
Monday...MVFR possible early, otherwise VFR. Southeast wind 5 to
15 kt becoming south 10 to 20 kt.
Tuesday...MVFR with TSRA possible early. Wind S at 10kt




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