Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 150441
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
1141 PM CDT Mon May 14 2018

.SHORT TERM...(Tonight and Tuesday)
Issued at 215 PM CDT Mon May 14 2018

A west-east running sfc front hangs well south of the area (near
ia/mo border) while another cold front associated with an upper
level shortwave is sinking southeast across northern MN. Showers
have fired in response to the forcing, with a few thunderstorms to
the south where some instability was coming into play.

Mesomodels keep the showers going across northern parts of the area
into the overnight as the front/trough combo make their way east. In
the south, a couple ripples in the upper level flow provide some
focus for further shower/storm development tonight. HRRR/RAP/MesoWRF
keep this activity south, with the NAM12 nudging into northeast
IA/southwest WI. Think the NAM is a bit too far north, but will hold
onto small pops to cover the possibility.

.LONG TERM...(Wednesday through Monday)
Issued at 215 PM CDT Mon May 14 2018

Models still trending with spinning a shortwave trough out of the
southern branch of the 500 mb flow northeast to across the region
Fri night. In the northern stream, a shortwave trough will trail the
southern bit of energy into the region, with both the GFS and EC now
suggesting these may/will merge after they swing east. Better
agreement between the two on timing/strength/positioning of these
various features. End result is a good shot for showers Fri night-
Sat. Timing (night time) will keep instability in check, but
certainly enough into the evening for some thunderstorms. Wind shear
relatively weak at this time...so severe threat looks low. Moisture
transport holds mostly south, and warm cloud depths shallow compared
to recent days. PWs suggest near 1 1/2 inches though. On the whole,
don`t see heavy rain as a significant concern at this time - and
certainly northern parts of the region would welcome some rain.

After a relatively warm end to the work week, cooler - but still
seasonable - air moves in for the weekend.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1141 PM CDT Mon May 14 2018

The showers to the north of both airports are slowly dissipating
and no longer pose a threat for a VCSH for the rest of the night.
The showers did load the boundary layer with moisture and with the
light winds fog has formed reducing the visibility down to MVFR
and IFR. Of course, KRST has the lowest visibility with less than
a mile and LIFR conditions. Will maintain the fog through the
night before dissipating it early Tuesday morning. This should be
about the time the clouds are scattering out allowing VFR
conditions to develop at both airports for the rest of the day.

&&

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

$$

SHORT TERM...Rieck
LONG TERM....Rieck
AVIATION...04



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