Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 271826

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
126 PM CDT Thu Oct 27 2016

.updated for 18z aviation discussion below...

Issued at 951 AM CDT Thu Oct 27 2016

Updated to add morning pops for light rain extending from STC
through the metro area. Also lowered temps 2-4 degrees in WI due
to cloud cover and colder temps this morning. There will be much
solar heating this afternoon. rest of forecast unchanged.


.SHORT TERM...(Today and tonight)
Issued at 306 AM CDT Thu Oct 27 2016

The main forecast concern is whether breaks in the overcast occur
later today which will lead to higher temperatures then
forecast. However, with abundant boundary layer moisture holding
through the afternoon and little mixing until late in the day, do
not believe much sunshine is expected. Only areas of sunshine may
occur along the lee of the Buffalo Ridge, but the wind direction
is not conducive for a downslope component. Therefore, even in
this area more cloud cover will limit daytime heating. Afternoon
temperatures reflect the anticipated persistent clouds with
readings in the 40s in west central Wisconsin, to the low to mid
50s across central and southern Minnesota, with near 60 along the
Buffalo Ridge.

Late today, and into tonight, a storm system will begin to
intensify along the Canadian border with strong low level winds
developing from the south-southwest. These winds will mix the
boundary layer and cause any remaining cloud cover to move out of
the area. However, breezy conditions will lead to nearly steady
temperatures overnight, with rising temperatures possible along
the lee of the Buffalo Ridge.

.LONG TERM...(Friday through Wednesday)
Issued at 306 AM CDT Thu Oct 27 2016

Friday through Sunday...Friday will commence with broad upper
level ridging over the central CONUS while a compact low pressure
wave moves onshore central California. A weak surface low
pressure system will drift eastward along the Canadian
international border Friday through Saturday but will be of little
consequence due to the ridging and very little moisture associated
with this system. By Saturday morning, the west coast low will be
located in eastern MT/WY, but in a much weakened state along with
meager upper level support. Nevertheless, it will drag some
Pacific moisture with it over the Rockies and it will progress
eastward into the Upper Mississippi River Valley by Saturday
afternoon. Some very weak upper level ripples in the mean zonal
flow will accompany the surface feature, just enough to produce
scattered rain showers for Saturday afternoon and evening. The
compact nature of this system plus the fairly unimpressive
moisture depth will spell only up to about a quarter of an inch of
rain at best. The fairly benign system will then shift into the
Ohio Valley region by Sunday morning while upper level ridging and
surface high pressure regain control over the region for Sunday.
The most impressive aspect of this part of the forecast will be
the warm temperatures expected for Friday. Being in the warm
sector ahead of the Saturday system plus the deep ridging helping
to increase H5 heights will produce max temperatures from the
lower 60s to lower 70s, some 15-20 degrees above normal for late
October. Highs will then come closer to (but still above) normal
through the rest of the weekend, running in the low-mid 50s.

Monday through Wednesday...While ridging again dominates the
eastern CONUS early next week, a better organized longwave trough
feature will move onshore the northern California/southern Oregon
coast late Sunday. This feature will cross the Rockies early
Monday, picking up and helping develop a low pressure center that
will be carried through the Dakotas and Minnesota late Monday into
early Tuesday. This will be followed by a more clipper-like system
for Tuesday night into Wednesday morning. Each feature may bring a
few rain showers through the region but nothing more. Temperatures
will remain slightly above normal during the period, meaning that
no winter weather is expected through the middle of next week.


.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 120 PM CDT Thu Oct 27 2016

Lower end confidence on overall low cloud trends into tonight.
Couple of scenarios that could play out. IFR/MVFR cigs did erode
briefly this morning to the southwest. However moist southerly low
level flow continues and trends on hires models ceiling forecast
is not looking too good for widespread improvement. The northern
and eastern areas may remain in the lower cigs into tonight...before
the lower level flow turns more southwest. This should erode the
lower ceilings to the northeast into the night...with just high
clouds remaining. Started out with lower clouds...with possible
improvement to the southeast into the evening. Tried to erode
clouds to the east later tonight. Followed the .5km condensation
pressure deficit humidity prog from the latest RAP which was
slowest on drying out the lower layer. Southeast to south winds 5
to 10 mph into tonight becoming more sw and becoming gusty ahead
of the cold front which moves into western MN Friday morning.

Lower confidence on overall low cloud trends into tonight. We
could see lower end mvfr cigs remaining into the night...perhaps
finally lifting to the northeast after 06z...with trend of lower
level humidity progs from the RAP. This should become more evident
during the afternoon and could update to leave in the mvfr into
tonight. Expect southeast to south winds into the period...becoming
more southwest and gusty into Friday afternoon ahead of the cold

Fri nite...VFR. northwest 5 to 10 kts.
Sat...VFR with MVFR/SHRA possible. Wind N at 5-10 kts.
Sun...VFR. Wind SSE 5 kts.




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