Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 231108

Area Forecast Discussion
National Weather Service La Crosse WI
608 AM CDT Fri Sep 23 2016

Issued at 359 AM CDT Fri Sep 23 2016

Have canceled the flash flood watch for Michell, Howard,
Winneshiek, Allamakee, Crawford, and Richland Counties. The threat
for additional heavy rain has shifted further south. The flood
watch continues from Floyd eastward through Grant county where 1
to locally 2 inches of rain could fall this morning. Considerable
river flooding continues across the area.


.SHORT TERM...(Today and tonight)
Issued at 256 AM CDT Fri Sep 23 2016

Forecast concerns today are on ongoing thunderstorms across portions
of northeast Iowa, but this activity should be diminishing
considerably this morning. Focus then turns to lingering shower and
thunderstorm chances across much of the area through the day.
Widespread flooding continues today.

Currently watching a stalled out front across northeast Iowa which
is the focus for thunderstorms/heavy rainfall this morning. The
moisture transport that is helping to drive the heavy rain along the
warm front finally subsides by mid morning today. Also, a weak
shortwave helping to drive this activity, pushes east later this
morning. Meanwhile a deep trough was digging into the western conus.
The trough starts to lift north pulling a surface low, currently
over the high plains, north. The warm front then edges northward and
becomes oriented parallel with the surface/near surface flow. The
unseasonably moist and warm airmass remains over the region
however. Will hold onto low chances for showers and a few
thunderstorms, but he it appears the threat for additional heavy
rain from late this morning into the overnight hours is low.

.LONG TERM...(Saturday through Thursday)
Issued at 256 AM CDT Fri Sep 23 2016

Main forecast concerns in the long term are on thunderstorm chances
late Saturday afternoon into Sunday with the potential for a some
strong to severe storms with the threat for heavy rain. The
environment will remain conducive for heavy rain during this
timeframe with precipitable water values of 1.6 to 1.9 and warm
cloud depth approaching 4 km. The good news is that these storms
should be more progressive than what we have seen recently but given
the saturated ground across the area, it won`t take much rain to
initiate flash flooding. A few strong winds gusts are also possible.
Thinking severe weather threats outside of heavy rain, should be
fairly limited. It appears that the strongest shear lags well
behind the front. Also, given that much of the activity moves in
late in the day on Saturday into Saturday night, CAPE should also
be limited. A few showers may linger across the area Monday into
Tuesday as the upper low/trough meander across the region. We then
finally look to enter a drier period from Wednesday through the
end of the work week as upper ridging builds across the region.


.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
Issued at 608 AM CDT Fri Sep 23 2016

Very moist boundary layer will lead to widespread IFR stratus
early this morning...gradually improving to MVFR by later this
morning. Conditions expected to deteriorate again late tonight
into IFR/LIFR.


.HYDROLOGY...Through next week.
Issued at 256 AM CDT Fri Sep 23 2016

Widespread river flooding continues across much of the area. Some of
the worst flooding is occurring across northeast Iowa and
southwest into west central Wisconsin. Most of the rivers will
crest over the next few days.

The Mississippi River will also experience flooding
later this weekend into next week mainly downstream of Winona.
Mainly minor flooding is forecast. Continue to monitor river
levels and forecasts closely.




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