Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 170436

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1036 PM CST Thu Feb 16 2017

Issued at 1033 PM CST Thu Feb 16 2017

Updated to include 06z aviation discussion below.


.SHORT TERM...(This evening through Friday)
Issued at 300 PM CST Thu Feb 16 2017

An east-southeast wind was persistent through the early afternoon
across most of western Wisconsin, and portions of east central and
south central Minnesota. Winds turn to a southwest direction
across west central and into southwest Minnesota where the air
mass behind the wind change was unseasonably mild. The different
wind component and a more persistent high level cloud deck, kept
temperatures from rising into the mid to upper 40s across east
central/south central Minnesota. However, just on the other side
of this wind shift, temperatures rose into the 50s, to lower 60s.

There are some differences in forecast temperatures tomorrow as
deterministic and mos guidance numbers have been consistently
lower on highs compared to a blend/bias corrected. Some of these
differences are 5 to 10 degrees cooler than the blend/bias
corrected which does seem odd. Today`s cooler highs were more
related to a different air mass source region, and more cloud
cover. However, tomorrow winds will become more south-southwest
where the air mass is much milder. Plus, skies should be clearer
by Friday. Only concern is boundary layer moisture increases
significantly just north and east of I-94. This increasing
moisture produces a solid area of low clouds/fog forming in MPX
northeastern forecast area, or just north-northeast of I-94. I
believe this is more related to an offset of model grid points of
where the snow cover exist across central Minnesota. This could be
related to the cooler guidance numbers vs. the blend/bias
corrected. Anyway, kept temperatures similar to the previous
forecast with highs approaching the mid 60s along the
Iowa/Minnesota border, to low to mid 50s in central Minnesota and
west central Wisconsin where snow cover remains.

.LONG TERM...(Friday night through Thursday)
Issued at 300 PM CST Thu Feb 16 2017

The warm streak remains on track across the area through the
forecast period. Record high temepratures are possible through
about Monday with record high minimums possible at a few locations
especially Sunday night.

Readings remain some 20 to 25 degrees above normal across most of
the cwa into early next week. The only are limited will be along
out far northern periphery were some snow cover remains. The
latest NOHRSC snow depth analysis has anywhere from 2 to 6 inches
in that region. Much of this will be gone by the end of the
weekend. Overnight lows will likely remain at or above freezing
tonight into next Thursday night...which would at least tie the
streak of overnight lows remaining above freezing in February.
That record of 6 days occurred Feb 15-20, 1998.

The next precipitation chance arrives later Sunday night to the
southwest and across the area Monday into Monday as a upper
trough/surface cold front moves through. The GFS continues to show
some instability associated with the return flow/waa pattern late
Sunday night to the southwest and that spreads northeast into
Monday. We will continue to mention isolated thunder threat during
this period. That may linger to the east into Monday evening as
the main cold front moves through.

The long term deterministic models continue to diverge some as to
the development of the next potential storm to affect the area
later next week. The GFS continues its more southern track with
upper level flow remaining split. If this occurs...the greatest
snow threat will remain farther south over southern MN into
northern IA. The 12z ECMWF is also very consistent over the last
three model runs with storm development/movement. It takes the
southwestern upper trough northeast with the deep surface
occluding over southern MN. This would favor the more northerly
track of any significant snow...from the Dakotas into northern MN.
The 12z GEFS 21 member ensemble did shift the higher
probabilities of greater that 4 inches of snow in 24 hours across
central and southern MN. Still plenty of time for models to
shift...but it remains likely the system will be a rain changing
to snow scenario.


.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1033 PM CST Thu Feb 16 2017

Solid VFR conditions expected throughout this TAF set. Mainly
high clouds will pass across the region. Small chance of some MVFR
conditions in central-western MN during the early morning hours
should winds drop off close to calm but this is dependent on snow
cover which is rather meager at this point. Thus, have maintained
VFR conditions. Winds will gradually veer from SE to SW through
the next 24 hours with speeds mainly in the 5-10 knot range.

KMSP...No significant weather impacts expected.

SAT...VFR. Wind WNW at 5-10 kts.
SUN...VFR. Wind SSE at 5-10 kts.
MON...VFR. SHRA Likely. Isold TSRA. Wind S 10 kts.




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