Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 221050
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
550 AM CDT Thu Aug 22 2019

.SHORT TERM...(Today through Saturday Night)
Issued at 238 AM CDT Thu Aug 22 2019

Cooler stretch of nice and dry weather set to continue right on
through at least Saturday, with little in the way of significant
weather concerns. Early morning analysis places broad low level
ridging centered across Hudson Bay but branching southward through
the entirety of the Upper Midwest/Northern Plains, complete with an
expansive area of quite low dew points intact over those same areas.
Meanwhile, a fairly robust shortwave is noted across southern
Ontario and dropping south, expected to cross our area through the
afternoon hours today. Not much in the way of moisture with that
system, though persistent upglide in the 300-305K layer has produced
some mid level cloud cover north of I-90 overnight, with additional
mid level clouds tied to the actual wave itself.

Those initial mid clouds may try to dissipate and/or work east by
by mid morning as the warm advection wanes, though with additional
clouds (advective and diurnal) likely beneath the shortwave and
associated cold pool, particularly east of the Mississippi River.
That same area could also see a few rain drops as well with
steeper low level lapse rates in place, though pronounced capping
around 700mb coupled with a very narrow instability plume suggests
nothing worse than a few sprinkles skirting central Wisconsin
after 18Z. Better scattered shower chances should be found
downwind of Lakes Superior and Michigan where sufficient cold air
and over- lake instability will be in place (a teaser of things to
come over the coming months).

Otherwise, Thursday night through Saturday night continue to look
quiet, with some diurnal cumulus at times and increasing likelihood
for river valley fog as we further deepen the light wind layer with
the center of low level ridging edging closer. Temperatures look the
coolest today, with parts of central WI stuck only in the 60s
given added clouds but readings generally holding near to below
normal right on through Saturday, complete with some very
comfortable nights well into the upper 40s to middle 50s.

.LONG TERM...(Sunday through Wednesday)
Issued at 238 AM CDT Thu Aug 22 2019

Good agreement among medium range guidance for our weather pattern
to break down as high pressure slowly gives up ground to increasing
southerly flow by later Sunday and especially Monday. All the while,
good agreement as well for stronger Pacific energy to manifest
itself as broad upper troughing over western Canada and through the
northern Rockies, with that setup driving a couple of stronger
shortwaves through our area the first half of the work week. Still
just a touch of timing disagreement out there, but the overall idea
for increasing rain chances by later Sunday night into Monday looks
on track, with additional chances into Tuesday as upper troughing
hangs across the area. For the moment, Wednesday looking mainly dry
but cooler again, with a strong trend in guidance toward another
stretch of below normal temperatures for mid to late week as broad
upper troughing holds firm over the region. With that said, can`t
totally rule out a few showers for Wednesday pending the placement
of the upper trough axis, so will maintain consensus very small
rain chances for the moment.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 550 AM CDT Thu Aug 22 2019

Some river valley fog to contend with this morning. Plan on this
lifting between 13-14z. Meanwhile, a couple mid-level troughs
will rotate through the region today through tonight, producing
scattered to broken VFR cumulus/altocumulus with bases at or above
5kft. Will have to watch for more river valley fog early Friday
morning which may impact KLSE.

&&

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

$$

SHORT TERM...Lawrence
LONG TERM...Lawrence
AVIATION...DAS


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