Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 240810

Area Forecast Discussion
National Weather Service La Crosse WI
310 AM CDT Wed May 24 2017

.SHORT TERM...(Today through Thursday)
Issued at 310 AM CDT Wed May 24 2017

The upper low will move south towards the Mid-Mississippi Valley
today. As this occurs, upper level ridging will begin to approach
from the west later today and tonight. NAM soundings show steep
low-level lapse rates and with upper level cold pool still
lingering across the area, a few showers will remain possible
today, but coverage will be more spotty with decreasing influence
from the upper low. Any showers will dissipate by late afternoon
with the surface high building overhead tonight into Thursday.
Clearing should begin to work into the region tonight with some
diurnal cumulus development possible on Thursday along with an
increase in high clouds. With moist ground and light winds, some
fog development could occur late tonight depending on how much
clearing occurs. With more sunshine, after a few days in the upper
50s to low 60s, highs on Thursday should reach near 70 in most
areas with light winds.

.LONG TERM...(Thursday night through Tuesday)
Issued at 310 AM CDT Wed May 24 2017

Late this week through the Memorial Day weekend, an upper low
initially centered over the southern Canadian prairies Thursday
night will gradually sink south and eastward into the Great Lakes
region through the weekend. Model guidance has indicated that a
few shortwaves embedded in west/southwest flow ahead of the upper
trough will traverse portions of the Upper Midwest Thursday night
into Saturday. At least a few showers/storms are possible by
Thursday night into Friday as low-level warm advection develops
with increasing deep layer moisture in association with the
approaching shortwave energy. On Saturday, the 24.00Z ECMWF would
keep the majority of the area dry while the GFS brings a
shortwave up into the area with at least some rain threat. Temps
on Friday/Saturday will be near seasonal norms in the low to mid

As the upper trough rotates southeastward into the Midwest Sunday
into early next week, there will be periodic showers/storms,
likely at least partially diurnally driven due to proximity to the
upper low. Although there are chances for precip for many periods
through the holiday weekend, plenty of dry hours are likely, and
the periods of higher rain chances will continue to be refined. A
relatively cool northwest flow pattern will persist into the early
to middle part of next week with highs mainly in the 60s.


.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1151 PM CDT Tue May 23 2017

Ceilings have been very slow to come down this evening with most
locations remaining VFR. Forecast soundings from the 24.03Z RAP
still suggest that MVFR to possibly IFR ceilings should develop
overnight. Plenty of low level moisture available from all the
recent rains for at least a short period of lower ceilings. Will
not take either site below 1000 feet but down into the 1000-1500
foot range. Even less confident now about any fog forming and for
now have taken this out of the forecast. Satellite is showing some
breaks trying to form in the clouds and if one of these were to
work over either airport, fog would likely develop quickly with
the light surface winds and cooling that would occur. Still
expecting moisture trapped in the cyclonic flow to keep MVFR
ceilings in place into Wednesday afternoon before these lift to
VFR late in the day or early in the evening.


Issued at 310 AM CDT Wed May 24 2017

Minor flooding will continue along portions of the Mississippi River
this week and also the Trempealeau River at Dodge as a result of the
recent heavy rains. Monitor river levels closely if you have
interests along these rivers




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