Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 251706
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
1206 PM CDT THU AUG 25 2016

.SHORT TERM...(Today and Tonight)
Issued at 300 AM CDT Thu Aug 25 2016

Short term concerns are minimal today except for on-going river
flooding. Quiet weather next few days should help with flood clean
up and recovery.

Still tracking upper wave or low that is moving across southern
Manitoba. Current trajectory is southeast but as wave opens up it
should progress east as short term guidance suggests. Either way
lower surface dew points have worked into area behind slow moving
front.

Outside of some mid and high level clouds from convection to the
south, it should remain quiet today with mix of clouds and sun.
Cooler temperatures on tap.

As surface high moves in for tonight, mostly clear skies and light
winds may aid in valley fog formation, even with drier air regime.
Not expecting widespread issues but more typical valley or bog
formation to some degree. Also lowered minimum temperatures in usual
bog areas of Wisconsin.

.LONG TERM...(Friday through Wednesday)
Issued at 300 AM CDT Thu Aug 25 2016

By Friday upper troughing starts to take place to the west as next
wave drops into slowly amplifying flow. While Friday itself should
remain quiet will have to watch for modest moisture return aided by
low level response and lift ahead of approaching wave across
northern tier states. This could spread rain into the area Friday
evening. Some suggestion in 25.00z guidance of quicker return and
have adjusted the forecast database to reflect this.

In assessing any severe weather threat for Friday night or
Saturday main question is amount of instability in quick returning
flow. Again guidance is fairly consistent with better CAPE values
remaining just south and east of the area. Even with some hints in
models that Precipitable Water approaches 1.5 inches, lack of
deeper instability may limit convection that would lead to heavier
rainfall. All in all this bears watching.

Good news the rain threat should push out of the area after
Saturday. Zonal flow restablishes itself with less predictability in
details. Upper ridge may even build in west of region towards mid
part of next week for gradual warmup.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1206 PM CDT Thu Aug 25 2016

Looks like a period of VFR conditions expected. High level
ceilings this afternoon from the complex of showers and storms
passing by to the south. The skies should become mostly clear
overnight as high pressure builds in from the west. This raises
the concern for valley fog overnight. However, the 25.12Z NAM
forecast soundings show that while the surface winds will decouple
and become light, the winds just above the surface should remain
at or above 10 knots for much of the night. In addition, the winds
will be from the northwest which will help to bring in some drier
air, so not anticipating much in the way of valley fog to form.

&&

.HYDROLOGY...
Issued at 300 AM CDT Thu Aug 25 2016

Still have moderate to major flooding on many northeast Iowa rivers.
Main problem areas are in the Upper Iowa and Turkey River basins
where warnings continue. Some high water also in Kickapoo River
basin in southwest Wisconsin but that is improving.

Should see most locations crest or fall today with couple of dry
days on tap. Will need to watch rainfall going into weekend. Current
precipitation forecasts would imply about 0.5 to 1.0 inches across
forecast area.

&&

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

$$

SHORT TERM...Shea
LONG TERM...Shea
AVIATION...04
HYDROLOGY...Shea


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