Area Forecast Discussion
Issued by NWS La Crosse, WI

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810
FXUS63 KARX 300906
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
306 AM CST Wed Nov 30 2016

.SHORT TERM...(Today and tonight)
Issued at 306 AM CST Wed Nov 30 2016

Forecast concerns continue to focus on light rain/snow today and
tonight.

Model guidance continues to support increasing chances for light
precip today into tonight as the slow-moving upper low/cold pool
aloft move overhead. Upstream early morning obs indicate a mix of
light rain/snow reports across MN. With weak forcing and the
NAM/RAP indicating surface wet bulbs in the mid 30s by afternoon,
this would support any mixed precip changing to rain during the
afternoon before temps begin to cool late in the day. However, if
any heavier convective showers occur, especially with steep low-
level lapse rates this afternoon, there would be a better chance
for some snow showers. However, expect little to no accumulation,
and this would be confined to grassy areas. The coverage of precip
will decrease overnight tonight.

.LONG TERM...(Thursday through Tuesday)
Issued at 306 AM CST Wed Nov 30 2016

The stacked low pressure system over the northern Great Lakes
Thursday morning will finally make more eastward progress away from
the region late this week. Although model soundings depict drying
above 850 mb, low-level moisture remains entrenched beneath a steep
inversion, so the low cloud cover will likely remain through at
least Friday. Any lingering light/rain snow showers should diminish
Thursday as the moist layer decreases in depth and the low pulls
away. With gradual cooling thermal profiles Thursday into Friday
along with the persistent low cloud cover, expect a modest temp
decline through late week, with limited diurnal temperature
variation and highs generally in the 30s by Friday (near seasonal
averages).

Quiet weather is expected Saturday as weak high pressures passes
east of the area. The 30.00Z GFS/ECMWF bring some light precip
across the region Saturday Night into Sunday with an upper shortwave
trough. The ECMWF shows a stronger wave and associated upper jet
streak contributing to greater forcing compared with the GFS, so
there are some differences to be ironed out.

Global models depict a transition to southwest flow aloft early next
week. With return southerly low-level flow, temps should rebound
a bit back above early December averages for Monday. However, with
substantial variability in timing/placement among model solutions
of upper waves ejecting out of the western US trough, confidence
with respect to precip chances is low early next week.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1144 PM CST Tue Nov 29 2016

IFR ceilings have been slowly advancing into the area this evening
ahead of a trough of low pressure moving slowly east across
southern Minnesota. Expecting these ceilings to be into KRST
around 06Z and then they should remain for the rest of the
forecast period. Will start KLSE with MVFR ceilings ahead of the
through and then primarily expect these through Wednesday
evening. Some flurries or sprinkles are also occurring along the
trough but with no visibility restrictions so will just have a
VCSH to handle these. A better chance for rain or a rain/snow mix
from about the middle of Wednesday morning into the early evening
as a short wave trough rotates around the upper level low. With
some steep low level lapse rates, there could be some temporary
reductions in the visibility to IFR at KRST.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&

$$

SHORT TERM...JM
LONG TERM...JM
AVIATION...04



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