Area Forecast Discussion
Issued by NWS La Crosse, WI

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168
FXUS63 KARX 281840
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
140 PM CDT Fri Apr 28 2017

.SHORT TERM...(Tonight through Saturday Night)
Issued at 140 PM CDT Fri Apr 28 2017

GOES Water Vapor imagery this afternoon showing a mid-level wave
pinwheeling eastward through western IA. Regional radar showing
leading edge of showers associated with the wave brushing northeast
IA/far southwest WI. Drier airmass in place across our area appears
to be impeding northward progress of the precipitation. Still looks
like some of this scattered light shower activity will eek into
areas south of I-90 late this afternoon. Otherwise, plenty of high
and mid-level cloud from this system invading our area with
temperatures at 1 PM ranging from 40 to 50 degrees.

For tonight, look for that wave to pass south of the area while
surface high pressure builds southeast out of the Northern Plains.
This will push showers out of the area by midnight skies remaining
mostly cloudy through the overnight hours. Clouds and north winds of
5 to 10 mph should mitigate widespread frost potential. Coldest
temperatures will likley occur across the sand country of central WI
with readings in the upper 20/lower 30s expected. However,
frost/freeze headlines not being issued for that area yet.
Temperatures expected to bottom out in the middle/upper 30s.

Another passing mid-level trough Saturday along with nose increasing
850mb moisture transport will produce a likelihood of showers across
far northeast IA/southwest WI. Rain chances dwindle rapidly
northward as the forecast area remains in drying northeast surface
flow regime. Look for the clouds and scattered showers will hold
temperatures down across the south in the 45-50 degree range with
slightly warmer temperatures in the lower 50s expected north of I-90.

Increasing rain chances will be seen Saturday night with a second
surge of 850mb moisture transport ahead of low pressure lifting out
of the Southern Plains. Some of this rain could be mixed with some
snow northeast of I-94 in the colder air. Plan on overnight lows in
the 35-40 degree range.

.LONG TERM...(Sunday through Friday)
Issued at 140 PM CDT Fri Apr 28 2017

Models in good agreement, lifting low pressure up out of the
Southern Plains into area Saturday night through Sunday Night for a
rainy/cool period. GFS/NAM continue to indicate 1-1.5 inches of
precipitable water wrapping up ahead of the low as it becomes
vertically stacked Sun night. In addition, the NAM is indicating
some elevated MUCAPE in the 2-7km layer of 250-500J/kg to support
some embedded thunder. Appears heaviest rainfall will be later
Sunday afternoon into Sunday evening when this TROWAL signature
rotates northward across the area. Look for the heavier shower
activity to trail off from south to north after midnight Sunday
night as the dry slot works in. Overall through the periods looks
like 1-2 inches of rain can be expected. With fairly saturated
soils, a lot of this rain will go into runoff into area streams and
rivers. While river levels are expected to rise, no flooding is
anticipated at this time. Look for very cool conditions Sunday
otherwise with highs only in the 40s.

Showers continue to be likely Monday as stacked low is dead overhead
with resulting cool/cyclonic flow. Otherwise looking cool with highs
in the middle 40s to the lower 50s.

Scattered showers look to continue Tuesday as cool cyclonic flow
lingers overhead. Plan on highs again in the middle 40s to the
lower/middle 50s.

Good news then for the rest of next week as it appears dry with a
warming trend. Look for highs Wednesday in the middle and upper 50s,
warming into the lower/middle 60s by Friday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1159 AM CDT Fri Apr 28 2017

An area of showers across Iowa has been making slow northward
progress this morning. These will continue to advance to the
north/northeast but with lots of dry air in place over the area,
they should stay to the south of both airports. Once these showers
move well off to the east overnight, a brief period of clearing
may occur before the next round of clouds moves in from the south
ahead of the next system. Opted to not detail this clear period as
either way VFR conditions will prevail as cloud heights will be
above ten thousand feet through the period.

&&

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

&&

$$

SHORT TERM...DAS
LONG TERM....DAS
AVIATION.....04



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