Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 250756

Area Forecast Discussion
National Weather Service La Crosse WI
256 AM CDT Sun Jun 25 2017

.SHORT TERM...(Today and tonight)
Issued at 256 AM CDT Sun Jun 25 2017

At 2 AM, the latest water vapor imagery showed that vigorous
short wave which brought the showers and storms to the area on
Saturday afternoon and evening was centered over Traverse City
Michigan. Another vigorous system was over Manitoba. This one will
one will move southeast across the Minnesota Arrowhead today and
northern Wisconsin tonight. With unusually cold air aloft (500 mb
temperatures 4 to 5 standard deviations below normal), expect
another round of showers and thunderstorms to move or develop in
the area between 25.16z and 26.02z. The highest rain chance will
be found along and north of Interstate 94. Like Saturday, the
soundings show and inverted V below the cloud layer, skinny CAPE,
and very weak 0-3 km and 0-6 km shear. As a result, there will be
the potential of wind gusts up to 40 mph and small hail with the
stronger cells.

For tonight, a short wave trough over southern Saskatchewan will
move southeast across southern Minnesota and eastern Iowa. Much of
the forcing and moisture with this one looks to be just southeast
of our area. As a result, kept southeast Minnesota and northeast
Iowa dry.

.LONG TERM...(Monday through Saturday)
Issued at 256 AM CDT Sun Jun 25 2017

On Monday, another short wave trough will move southeast through
the Upper Mississippi River Valley. This system will bring another
round of afternoon and evening showers and storms. While the
0-1 km mean layer CAPES (less than 500 J/kg) and the shear is
weak, soundings continue to show an inverted V sounding and skinny
CAPE. As a result, any stronger storms will have the capability of
producing gusty winds and small hail.

From Monday night into Tuesday, a ridge of high pressure will
provide dry weather across the region. With 850 mb temperatures
climbing into the 9 to 12C range and plenty of sunshine on Tuesday,
high temperatures will climb into the mid and upper 70s.

From Tuesday night into Wednesday night, a short wave trough will
be moving through the region. Moderate to strong moisture
transport moves into the region late Tuesday night and lingers
across the area on Wednesday. This will like keep showers and
storms going across the area. As a result, not overly surprised
that the models keep the best instability west of the region. With
this said, the 0-3 km shear is strong. This could result in some
bowing segments.


.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 940 PM CDT Sat Jun 24 2017

Cigs: Modeled RH fields and current satellite imagery show an area
of mvfr/vfr cigs sinking southeast across nd/northern MN - with the
models bringing it across the TAF sites by 12z Sun (or so). Should
get a little diurnal bump as Sunday wears on, and likely scattering
out Sunday evening.

WX/vsby: Another round of shra/ts similar to today for Sunday, as a
shortwave/favorable low level lapse rates/instability work on the
available moisture. Perhaps a bit better chances east of the
Mississippi river. Main threat time would be from 19-00z.

See some threat for valley fog at KLSE for the first part of the
overnight tonight - especially if winds remain decoupled. Clouds
coming in from the north and 10 kts or greater winds just off the
deck will be limiting factor. Shallow? Will leave P6SM for the
moment, but trends will monitored.

Wind: west northwest through Sunday. Will stay up mostly tonight,
although could stay decoupled at KLSE until sunrise, then increase
some on Sunday. Expect some gustiness by late morning, with again
enhanced gusts around any stronger shower/storm.




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