Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 120449
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1049 PM CST Sat Nov 11 2017

.UPDATE...For 06Z Aviation discussion below

&&

.SHORT TERM...(This evening through Sunday)
Issued at 331 PM CST Sat Nov 11 2017

Early afternoon water vapor imagery together with RAP13 500mb
heights and winds showed a compact upper level shortwave over Lake
Superior that was outrunning its surface reflection. A broad surface
trough was draped across the region and this was the focus for
clouds and light drizzle across Wisconsin into Iowa. Meanwhile areas
to the northwest had light southwesterly winds and clear skies.

Another lower amplitude shortwave was located upstream across
Wyoming, but this is forecast to move along I-80 and shouldn`t bring
any precip to Minnesota or Wisconsin. In fact 500mb 12hr height
rises should commence overnight leading to surface high pressure
building over the Upper Mississippi River valley which will result
in light winds and dry conditions for Sunday as well. Forecast
soundings try to hold on to some afternoon cumulus so could see more
clouds than sun depending on how far south the stratus across
northern Minnesota makes is overnight. The cooler air mass together
with less sun will keep highs on Sunday only in the 30s.

.LONG TERM...(Sunday night through Saturday)
Issued at 331 PM CST Sat Nov 11 2017

Locally there look to be no significant weather systems, with a
decidedly more zonal flow resulting in temperatures bouncing around
a few degrees on either side of normal.  There still looks to be a
significant synoptic system for the end of the week into next
weekend, though that is looking to be a bigger issue for the Great
Lakes over to New England.

In terms of model spread, differences are pretty small through mid
week, but we are still dealing with a good deal of spread, mainly in
the timing department with the end of week system. In terms of
changes made with respect with the initial blended forecast, only
change was to warm highs Tuesday a bit closer to what we had.
Otherwise, spread for the second half of the week makes it tough to
push things one way or the other.

The warmest days still look to be Monday and especially Tuesday.
Though we will see warmer air coming this direction, with +10 at
925mb still progged to come up into southwest MN, as is often the
case this time of year, these warm temperatures look to come with
ample stratus. Still, with dewpoint temperatures progged to push to
near 50 on Tuesday, getting highs into the lower 50s for
southwest/south central MN will be no issue. For the Twin Cities,
it`s looking about 50/50 for hitting 50 on Tuesday. If MSP fails to
hit 50 Tuesday, it`s unlikely we`ll see it the rest of the month,
which means there`s potential for this to be just the 8th November
going back to 1872 where MSP failed to hit 50 in a month, the first
since 1997.

The warmth these two days is in response to warm air advecting north
ahead of a cold front that will be moving into western MN Tuesday
afternoon and will clear the rest of the MPX area through Tuesday
night. Deep moisture will be lacking with this system, though NAM
soundings in particular and the GFS to a lesser degree show good
potential for lots of drizzle Tuesday before deeper moisture arrives
with an h5 trough Tuesday night. QPF signal is still best for
eastern MN/western WI Tuesday night, though temperatures will be
plenty warm enough to keep precip as all rain.

Given the zonal flow, weather systems will be rather fast moving,
with cool high pressure expected for Wednesday, with Thursday
getting us back into warm advection ahead of the next front that
will come through Thursday night or Friday.  This system will have
split issues once again. The slower ECMWF/MPAS don`t phase northern
and southern stream energy until Friday, with the GFS/Canadian about
24 hours ahead on the phasing. The GFS/ECMWF are similar with
showing another round of light precip developing ahead of a cold
front that will be advancing across the area, but the GFS is a bout
18 hours faster than the ECMWF and mostly rain, while beside being
slower, the ECMWF is also colder and showing more of a rain to snow
situation on Friday. Either way though, QPF amounts are currently
predicted to be under a quarter inch, so any sort of impacts look
minimal.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1050 PM CST Sat Nov 11 2017

MVFR-level stratus clouds in the wake of a cold front will build
in overnight, particularly at northern/eastern sites
(KEAU/KRNH/KMSP/KSTC/KAXN). Ceilings around 1500 feet are
expected. Prior to the cloud cover building in (including the
advance of high clouds from the west), patchy fog will be possible
over west central WI. This could briefly affect KEAU/KRNH, but
expect the clouds to fill in fairly soon thus ending the dense fog
threat. Expect the stratus deck to scatter out by early Sunday
afternoon, although eastern sites in WI (KRNH/KEAU) could stay
socked in until Monday, or only briefly scatter out late Sunday
afternoon before filling back in. Light and variable to northwest
winds at 4-6 knots overnight, back to the west then southwest
throughout the period.

KMSP...

Expect MVFR clouds develop overnight, with bases expected to be
below 1700 ft through Sunday morning before scattering out during
the afternoon.

/OUTLOOK FOR KMSP/
Mon...VFR. Wind S 10 kts.
Tue...MVFR, with -dz late. Wind S 5-10 kts.
Wed...VFR. Wind NW 10G20 kts.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
&&

$$

SHORT TERM...JRB
LONG TERM...MPG
AVIATION...LS



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