Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 242341
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
641 PM CDT Mon Jul 24 2017

.SHORT TERM...(This evening through Tuesday)
Issued at 300 PM CDT Mon Jul 24 2017

24.20Z analysis shows broad surface high pressure across the
region. Low stratus that moved over the forecast area this morning
will gradually dissipate into this evening under the influence of
widespread subsidence. Expect mostly clear skies by late evening
into the overnight, although cloud cover is expected to increase
again late tonight into Tuesday morning as a few weakening warm
advective showers/storms move eastward from central MN. Best
chance for any storms Tuesday morning mainly across southeast MN
into west-central WI. Lows tonight will drop into the upper 40s to
near 60 degrees with light wind gradually shifting to the south.

After the small chance for showers/storms in the morning, much of
Tuesday will be dry. Southerly return flow on the backside of the
departing high will advect warm/moist air northward with afternoon
dewpoints rising back into the mid-upper 60s. With a cold front
draped across central MN, strong warming in the 900 to 800 hPa
layer will CAP the atmosphere for much of the day with MLCIN
values between 200 and 300 J/kg. Highs will rise into the upper
70s to lower 80s with southerly breezes, gusting at times up to 25
mph, especially for areas west of the MS River.

.LONG TERM...(Tuesday night through Monday)
Issued at 300 PM CDT Mon Jul 24 2017

Thunderstorm chances increase from northwest to southeast Tuesday
night into Wednesday as the MN cold front sags southward.
Depending on storm mode/evolution upstream, could see a few
linear convective segments move into the northwest forecast area
Tuesday night, but GFS is only model showing this with the ECMWF/
GEM and especially the NAM dry through 12Z Wednesday. Limited CAPE
with the best deep shear north of the local area should limit
overall severe threat.

Better severe threat, although only a slight risk per SPC Day 3
Outlook, will be Wednesday as the cold front moves across the
forecast area. Lingering morning showers/storms with considerable
cloud cover could limit destabilization later in the day. However,
even if skies clear earlier, there are still questions on the
amount and location of greatest instability. In addition, best
deep layer shear remains north and east of the forecast area, but
there are little ripples of short-wave energy in the near zonal
flow aloft that could provide the dynamic support necessary for
more organized convection. Given this, cannot rule out isolated to
scattered severe storms capable of producing large hail and
damaging winds. However, bigger concern may be locally heavy
rainfall. PWATS increase to 2 inches or more ahead of the front
and with warm cloud depths to 4-4.5 km, any storm will be an
efficient rain maker. Very difficult to provide detail on amounts/
most favored locations at this time, but something to watch over
the next 24-48 hours. Good news is that the front is fairly
progressive and this should help limit overall amounts.

Thursday into the weekend still look quite nice for late July with
broad high pressure dominating the regional weather pattern. Look
for daily highs in the upper 70s to lower 80s and lows in the mid
50s to lower 60s. The next best chance for showers and storms will
be late Sunday into Monday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 641 PM CDT Mon Jul 24 2017

VFR conditions are expected through the TAF period. High pressure
remains in control across the TAF sites tonight into early Tuesday
morning. A fast moving shortwave tracking across the area during
the day on Tuesday may bring a few showers or perhaps a
thunderstorm to KRST. This activity may also impact KLSE but will
be weakening. Confidence wasn`t high enough to add a shower or
thunderstorm into the TAF at this but will continue to monitor
closely.

&&

.HYDROLOGY...
Issued at 300 PM CDT Mon Jul 24 2017

Flood Warnings continue along the Kickapoo River from Readstown to
Steuben and along the Trempealeau River at Dodge, although water
levels continue to fall at all locations.

Conditions will be dry through Tuesday with increasing chances for
showers and thunderstorms Tuesday night through Wednesday. Some of
these storms may produce locally heavy rainfall that could result
in some additional river rises and perhaps minor flooding.

Thursday into the weekend will be dry.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&

$$

SHORT TERM...Rogers
LONG TERM...Rogers
AVIATION...Wetenkamp
HYDROLOGY...Rogers


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