Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 162107

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

.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 18Z TAFS through 18Z Friday afternoon)
Issued at 1120 AM CST Thu Feb 16 2017

No aviation concerns for the next 12 hours. Late tonight, there
could be ample boundary layer moisture developing (fog and low
stratus with IFR/LIFR cigs/vsbys) across portions of central/east
central Minnesota. Confidence remains low enough for the 18z Taf
for any deviation from current VFR conditions. Later shifts can
start with 4-6SM or sct002-sct005 in areas that models have
stratus forming in central/east central Minnesota. Winds will
remain from a south-southeast direction this afternoon with a more
southwest-south direction tonight/Friday.


No other aviation concerns with VFR conditions continuing.
Southeast winds this afternoon will become more south tonight and
decrease to less than 6 kts.


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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