Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 211726
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
1226 PM CDT SAT MAY 21 2016

.SHORT TERM...(Today and tonight)
Issued at 257 AM CDT Sat May 21 2016

Latest water vapor satellite imagery indicating upper level
closed low over the western United States and ridging over
southern Canada and Northern Plains. Latest 07z surface analysis
showing surface ridge over Wisconsin...Minnesota and Iowa and
providing mostly clear skies across the forecast area per latest
infrared satellite imagery.

Main forecast concerns today into tonight are temperatures across
the forecast area. The 21.00z GFS/NAM are in good agreement in
building upper level/surface ridge into the Upper Midwest today
into tonight. Due to the dry air aloft and 850mb temperatures in
the plus 10 to plus 13 degree Celsius range. High temperatures
will climb into the middle 70s to around 80 across the forecast
area.

.LONG TERM...(Sunday through Friday)
Issued at 257 AM CDT Sat May 21 2016

Surface ridge builds east of the forecast area Sunday. The 21.00z
GFS/NAM are in good agreement in developing southerly flow on the
backside of ridge and advect warmer air into the forecast area.
The 21.00z models suggest 925mb temperatures warming to plus 18
to plus 20 degrees Celsius by 00z Monday. Have continued warming
trend with high temperatures climbing into the upper 70s to lower
80s.

Next forecast concern is shortwave troughs embedded in the
southwesterly flow aloft to track into the Northern Plain States
and Upper Midwest Sunday night into Monday night. The 21.00z
GFS/NAM/ECMWF are in better agreement in timing of first piece of
energy into the western forecast area Monday. Both models suggest
the better moisture convergence/transport and vertical motion to
be over the far northern and southern sections of the forecast
area Monday afternoon into Monday night. This would result in the
higher chances of showers and thunderstorms to occur over northern
and southern portions of the forecast area Monday evening into
Monday night.

The 21.00z GFS/NAM are showing 0-3km shear of 20 to 30 knots and
increase instability over the forecast area late Monday afternoon
and evening. However...models continue to indicate 0-6km shear
less than 20-30 knots. With the convection potentially impacting
the far northern/southern sections and possibly scattered in
nature across forecast area...confidence in severe potential is
low and not anticipated any severe at this time.

Main forecast concerns are precipitation chances Tuesday through
Friday. The 21.00z GFS/ECMWF/GEM are in good agreement with overall
upper level pattern through the period...with southwesterly flow
aloft over the Rocky Mountains into the central United States.
Differences occur between the models with timing of each impulse
ejecting out of the upper level trough over the western United
States into the central United States through the period.
However...an active weather pattern will continue across the
forecast area through the period with a chance of showers and
thunderstorms.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1226 PM CDT Sat May 21 2016

Very quiet weather continues across the region right on into
Sunday afternoon, with high pressure slowly working through the
area. Outside of some scattered diurnally driven cumulus clouds,
skies should remain mainly clear with light winds through tonight
gradually shifting southerly and increasing up to 15 knots by
midday around KRST.

&&

.ARX Watches/Warnings/Advisories...
WI...None.
MN...None.
IA...None.
&&

$$

SHORT TERM...DTJ
LONG TERM...DTJ
AVIATION...Lawrence



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