Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 222104

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
404 PM CDT Tue Aug 22 2017

.SHORT TERM...(This evening through Wednesday)
Issued at 359 PM CDT Tue Aug 22 2017

Early afternoon water vapor together with GFS 500 mb heights and
winds showed confluent northwest flow across the region which
meant subsidence and surface high pressure. Seasonably cool air
aloft led to a few clouds and rain showers across northeast MN
and northern WI, but most of the area was mostly sunny this
afternoon with northwest winds around 10 to 20 mph.

Expect clear skies again tonight and much of Wednesday, but a
quick-moving upper level shortwave trough will move approach the
region late Wednesday and be the focus for a few rain showers.
HiRes models show the best chance for rain north of I-94, so tried
to mirror that in the precip chances. May be a little too quick
with pops, so would not be surprised to see the timing slowed a
bit if that trend continues.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 359 PM CDT Tue Aug 22 2017

In the longer term, we`ll briefly see northern stream upper ridging
build over the center of the Continent from Thursday into the start
of the weekend, although the main upper ridge and warm temperatures
associated with it stay well to our south/west. After that we will
once again see redevelopment of a more full latitude western ridge
during the first half of next week, setting us up for more somewhat
cool and mainly dry northwest flow. The main period of interest in
terms of weather across our area will be during the first part of
the weekend as we see a period of some warm advection and moisture
return over the region.

We will see a few showers and perhaps isolated thunder drop through
the area tomorrow night as a compact shortwave trough drops
southeast through the area. Thursday should be dry with high
pressure and subsidence re-asserting itself over the region.
However, chances for showers/thunderstorms will start to increase
from west to east Friday into Saturday as low pressure develops over
the northern Plains and return flow works into our area. This system
will make slow eastward progress, eventually moving through our area
Saturday night and Sunday. The period looking to have the best
combination of forcing and deep moisture looks to be Saturday
afternoon/evening, when we could see fairly widespread precipitation
of a half inch or more, with locally higher amounts associated with
more persistent convection. The surface low weakens and essentially
washes out over the area Sunday and Monday, with some spotty chances
for precipitation lingering as we don`t see a strong push of drier
air until perhaps Tuesday.


.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 101 PM CDT Tue Aug 22 2017

VFR conditions throughout. Northwest winds will gust around 20 kts
this afternoon, but decrease around sunset. Expect light winds
overnight and into Wednesday. A quick moving system will bring a
few showers down from the northwest across the region Wednesday
afternoon, but this is past the time frame of the 24 hr TAF.


VFR conditions throughout. Could see some scattered showers
moving close to MSP by 22-24Z, but confidence at this time is too
low to include mention in the TAF.

Thu...VFR with MVFR possible. Wind SE at 10 kts.
Fri...VFR with MVFR/-SHRA possible. Wind SE at 10 kts.
Sat...VFR with MVFR/-SHRA possible. Wind S at 10G20 kts.




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