Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 200451

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1051 PM CST Sun Feb 19 2017

Issued at 1021 PM CST Sun Feb 19 2017

Updated to include 06z aviation discussion below.


.SHORT TERM...(This evening through Monday)
Issued at 310 PM CST Sun Feb 19 2017

Extensive high cloudiness has shrouded the Upper Midwest this
afternoon as moisture begins increasing from the southwest.
Despite this, we have broken record highs at MSP, STC, and EAU
with upper 50s to mid 60s across the region. The low clouds have
broken up quite a bit across the Plains today, but expecting these
to redevelop later tonight as deeper low level moisture begins
reaching the area. The low level moisture increase will bring us
monthly record lows tonight if we remain warm enough until
midnight Monday night.

Most of the showers will remain south of Minnesota through
tonight, but will lift north quickly across primarily eastern
and central Minnesota early to mid morning. Hi-res models continue
to show the potential for embedded thunder with this round and
the GFS/NAM are particularly bullish with the intensity, dropping
1/2-1 inch through early afternoon. This rain will continue
expanding while shifting east across WI during the late morning
and afternoon.

Some clearing may occur across MN by mid afternoon before the
front and we do have the potential to jump with temperatures. A
few hi-res models even show some additional showers or storms
developing on the front, but at this point we should be worked
over enough to prevent much of a severe threat.

.LONG TERM...(Monday night through Sunday)
Issued at 310 PM CST Sun Feb 19 2017

Confidence remains high for the abnormally warm temperatures to
continue through Wednesday as the upper air pattern holds with
fairly flat flow across the northern CONUS. Eventually this does
begin to break down as a strong western CONUS trough moves ashore
to toward the second half of the week.

The Monday weather system exits into Monday evening with a
lingering threat of a thundershower over western Wisconsin early
in the evening. Little in the way of significant cooling occurs
behind this trough. We retained the record/near record high
temepratures for this period. The more significant cold front
drops into the area later Wednesday/Wednesday night with cooler
temperatures leading into the next forecast storm system.

The deterministic models continue to develop a potent winter
storm which will affect portions of the Northern Plains and Upper
Midwest Thursday night into at least Friday night. Both the 12z
ECWMF and Canadian models drive the western CONUS energy northeast
with a deep surface low lifting to into Iowa by Friday morning and
into southern Wisconsin by Friday night. The GFS is less amplified
and drives the system a tad farther to the south. THe 12z GEFS
probability plots continue to focus in on about the southern half
of the cwa during the period. It does paint high probabilities for
greater than 10 inches of snow in 12 hours over the southern
third of MN into Wisconsin. We will retain the highest pops for
the event in this area and trail them off to the northwest. The
12z CIPS analog for the event highlights the 3/13/2006 storm which
dropped a swath of snow 8-18 inches across southern MN into
Northwest Wisconsin. The mean probability for greater than 6
inches of snow for the top 15 analog storms paints a similar trend
as well. Still plenty of time for the storm track to shift with
the trough associated with the forecast storm still well off the
west coast. Still...confidence is increasing for a significant
storm to affect at least part of cwa later this week. Stay tuned.


.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1021 PM CST Sun Feb 19 2017

VFR conditions to start with upper level ceilings but conditions
will steadily deteriorate during the early morning hours with
ceilings heading to MVFR levels. Showers and a few thunderstorms
are expected at all sites after daybreak tomorrow through late
afternoon at all MN TAF sites and into the evening hours at the WI
TAF sites. Consistency in the model timing of IFR conditions for
central-eastern MN into western WI, generally from midday into the
evening hours from west to east, has allowed for the inclusion of
TEMPO groups showing IFR visibilities with MVFR ceilings during
the expected time of heavier rain. Low ceilings will then linger
beyond the duration of rain, likely to around 21/00z, with VFR
conditions thereafter. The other concern is the continued showing
of strong winds around 2 kft, in the 40-50 knot range, ongoing by
20/06z initialization time and lasting through 09z-12z. Have
maintained LLWS mention at all sites.

KMSP...VFR to start then MVFR conditions expected to develop
between 12z-15z tomorrow morning. Mainly due to ceilings but
visibility may also drop to MVFR should heavy enough showers
develop. IFR conditions also cannot be ruled out and is more
likely with visibility in heavier rain rather than ceiling so have
included a TEMPO group as such. LLWS looks likely to continue into
the morning push with surface SE winds close to 10 kt in
conjunction with SW winds around 45 knots. MVFR ceilings likely to
linger into late Monday afternoon then VFR conditions likely
Monday evening.

Tue...VFR. Wind SW at 5-10 kts.
Wed...VFR. Wind SW at 10G15 kts becoming NW late.
Thu...VFR. CHC MVFR/-RA/-SN in the afternoon, then LIFR/+SN
possible Thu night. Wind NE 5-10 kts.




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