Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 300426

Area Forecast Discussion
National Weather Service La Crosse WI
1126 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 06Z TAFS through 06Z Sunday night)
Issued at 1126 PM CDT Sat Apr 29 2017

VFR conditions remain in place late this evening but a quick look
to our south reveals lower MVFR conditions creeping northward as
deeper moisture increases. Will need to watch a developing batch
of showers first thing early this morning that could potentially
clip RST with some very light rain, but confidence remains low.
Higher confidence that we will see MVFR conditions overspread the
area during the morning hours, with increasing coverage of showers
into the afternoon and especially evening hours as low pressure
approaches. It is that late evening period when IFR ceilings will
also likely start to make an appearance, with winds the next 24
hours steady-state from the northeast and becoming gusty to around
25 knots through much of Sunday.




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