Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 161731 AAB

Area Forecast Discussion...UPDATED
National Weather Service Twin Cities/Chanhassen MN
1231 PM CDT Sun Jul 16 2017

.SHORT TERM...(Today and tonight)
Issued at 300 AM CDT Sun Jul 16 2017

Early morning surface analysis shows high pressure sitting atop
the Upper Mississippi River Valley with a cold front sagging
south of the region, from the Great Lakes through central Iowa
then northwestward through Montana. A secondary cold front, more
important to the midweek weather, has come onshore the Pacific
Northwest. Aloft, A large dome of high pressure is aligned from
the Dakotas to Texas with longwave trough axes on the east and
west CONUS coasts. While the center of the ridge in the deep south
is expected to remain in place through Monday morning, the axis
of high pressure will pivot to take on a more SW-NE orientation as
it shifts across the area through tomorrow. At the surface, the
high pressure area will shift east into the Great Lakes and
southeastern Canada during the day today. At the same time, the
cold front out west will cross the Northern Rockies through this
afternoon then shift into the central Dakotas by daybreak Monday
morning. Despite the approach of the cold front, the deep high
pressure will keep the area dry and also slightly cooler on the
backside of the first departing cold front. Highs will run 5-10
degrees cooler than yesterday with dewpoints around 10 degrees
less, making for a much more pleasant day. Plenty of sunshine is
expected today with a few passing clouds, then skies are expected
to clear out tonight with high pressure maintaining its influence.

One noteworthy item: the Space Weather Prediction Center has
maintained its G2 forecast (moderate geomagnetic storm watch) due
to a coronal mass ejection (solar flare) expected to arrive
tonight. The lack of cloud cover tonight in conjunction with the
CME arrival may likely make for good viewing conditions for the
expected aurora borealis.

.LONG TERM...(Monday through Saturday)
Issued at 310 AM CDT Sun Jul 16 2017

The western conus ridge breaks briefly into MN Monday and then
flattens leaving the area close to baroclinic zone/quasi-
stationary front across southern MN into at least midweek. This
leave the area vulnerable to periods of heavy rain and severe

Monday looks to be hot with a frontal system off to the northwest
of the cwa through the day. Heights at 500mb rise to around 590
decameters into southern MN and this should provide some capping
ahead of the front. With 925 mb temepratures around 30c...some
100 degree readings not out of the question to the far west out
ahead of the incoming front. We dont expect too much in the way of
convection developing with just a small chance over the northwest
cwa mainly after 21z Mon. Severe weather will be a possibility as
at least scattered convection develops along the front into Monday
night, affecting mainly the west and northern cwa. The main
threats being hail and damaging winds.

The front sags into southern MN Tuesday night and the area will
continue to be under the threat of severe weather and locally
heavy rain with PW`s increasing to over 1.5 inches. Both the ECMWF
and the GFS bring a short wave across the region during the day
Tuesday and which should help maintain the threat of storms during
the period. This will likely limit temperatures some as well.

Wednesday and Wednesday night look like another busy weather day
with severe weather remaining a threat and a continuing heavy rain
signal from both the GFS and ECMWF. Both models trend another
short wave into the area with the GFS driving it east across the
area about 6 hours faster. The ECMWF brings the better shot of
thunder and rain mainly Wednesday night across southern MN with
the GFS moving it slowly through during the day Wednesday and
continuing over the south into Wednesday night. PWs rise to 2.5
inches on the GFS with the NAEFS showing a 2 to 3 Standardized
anomaly over the southern third of the state into Wednesday. This
looks to be he greatest threat for more organized heavy rain with
some 3 plus totals not out of the question.

The models then drive the front south of the area into Thursday
which should provide a mainly dry period into Thursday night. The
flow remains more westerly into the weekend with the longer term
models driving another frontal system through the area Saturday
or Sunday.


.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1231 PM CDT Sun Jul 16 2017

VFR conditions expected throughout. The low stratus along I-94
should continue break up and lift this afternoon. Light easterly
winds will gradually take on a southerly component overnight, with
gusts near 15 kts expected on Monday. Forecast soundings show
potential for some MVFR stratus Monday morning, but at this time
confidence too low to put BKN/OVC in the TAF, but tried to hint at
the possibility with SCT/FEW.

KMSP...No weather impacts are expected and no significant changes
from the general discussion.

Tue...Mainly VFR with MVFR/-TSRA possible in the
afternoon. Winds SW 10-20 kt becoming W around 10 kt.
Wed...Mainly VFR with MVFR/-TSRA possible. Wind SE 5-10 kt.
Thu...VFR with MVFR/-TSRA possible. Wind SE at 5-10 kt.




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