Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 291910

Area Forecast Discussion
National Weather Service La Crosse WI
210 PM CDT Sat Apr 29 2017

.SHORT TERM...(Tonight through Sunday Night)
Issued at 210 PM CDT Sat Apr 29 2017

Water Vapor imagery this morning has convectively induced mid-level
shortwave trough ejecting northeast through MO. Plenty of high cloud
ahead of this wave and batch of showers/thunderstorms pushing
northward toward the area. Drier northeast surface flow across our
area, thanks to high pressure over Ontario Canada, was keeping
showers at bay just south of the area for now. Otherwise,
temperatures as of 1 pm were in the 45-50 degree range. Breezy
northeast winds of 10 to 20 mph putting a raw touch to the already
chilly temperatures.

Look for that wave over MO to continues pushing northeast across
IA/IL this evening. Forcing from this feature looks to push
scattered showers into areas mainly south of I-90 later this
afternoon into this evening. We should see a lull in the showers
after midnight as the wave passes east along with better moisture
transport and as that drier northeast flow continues. Plan on
overnight lows in the middle 30s to near 40.

Stacked/closed low lift north from the Southern Plains Sunday with a
respectable slug of moisture transport wrapping toward the area in
the afternoon. Drier northeast surface flow will likely fight
intrusion of showers heading in but showers will then quickly fill
in by afternoon with stronger forcing. Corridor of precipitable
water values in the 1-1.5 inch range quickly lifts into the area in
the afternoon along with elevated/2-7km MUCAPE values in the 250-
500J/kg range for a rapid uptick in showers/isolated-scattered
thunderstorms. Look for the bulk of the heaviest shower activity to
lift north of the area after midnight as the dry slot from this
system works in. Temperatures will suffer on Sunday due to the
northeast flow/precipitation with highs only expected to be in the
40s, which is close to our normal lows for this time of year.

Right now, appears widespread 3/4 to 1.5 inch of rainfall is likely
from Sunday into Sunday night for likely rises on streams and rivers
given moist soils and runoff potential. However, given progressive
nature of this band of precipitation, no flooding is expected.

.LONG TERM...(Monday through Saturday)
Issued at 210 PM CDT Sat Apr 29 2017

Chilly/showery conditions continues Monday, tapering off into
Tuesday as the stacked low slowly moves across the area. Plan on
highs Monday in the  45-50 degree range and upper 40s to middle 50s

Warmer temperatures moving in for Wednesday amd Thursday but will
have to watch tricky northwest flow aloft which pushes a trough
through the region. Looks dry overall but could squeeze out a few
showers. Otherwise, looks like temperatures rebound into the 55-60
degree range Wednesday and upper 50s to middle 60s for Thursday.

Friday and Saturday looking nice at this point as a ridge of high
pressure builds in from the Northern Plains. Plan on highs well
into the 60s.


.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1206 PM CDT Sat Apr 29 2017

The first round of showers approaching from the south is having a
hard time overcoming the low level dry air in place. The area of
high pressure to the north will maintain this dry northeast feed
and expecting the showers to stay to the southeast of both
airports this afternoon and evening. Not a whole lot of change is
expected in the overall pattern through Sunday morning. The area
of high pressure will hold strong over the northern Great Lakes
while the area of low pressure over Oklahoma starts to advance
northeast. The best forcing for rain will remain well to the south
of the area closer to the surface and upper level lows but look
for showers to be advancing northward across southern Iowa. This
should start to push some lower ceilings toward the area and will
take these down to MVFR for late tonight through Sunday morning.
Not expecting IFR conditions until the dry air can be overcome by
the showers later Sunday.




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