Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 272332
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
632 PM CDT Sun May 27 2018

.SHORT TERM...(This Evening through Monday)
Issued at 309 PM CDT Sun May 27 2018

The heat is on! Another hot day underway out there as I type this,
courtesy of anomalous upper ridging in place over much of the
central CONUS (586 dm heights - not bad for late May) ahead of yet
another western trough meandering over Utah. Local airmass comprised
of 925mb temps pushing 30C toward the I-35 corridor and slightly
cooler values to the east has worked with notable drying per 12Z
MPX/GRB RAOBs to deliver deep mixing of dew points and subsequent
rapid heating today, with early afternoon temps already well into
the 90s (LSE has already broken their record high at 97 degrees).
Have been watching an earlier MCS to our west on the nose of
broad moisture transport overnight, though that feature has been
weakening with time with just some cirrus spilling east into
anticyclonic flow over the crest of the ridge.

However, a remnant vort with that MCS will be watched closely
tonight as it interacts with increasing moisture transport once
again over east-central Minnesota into central and northern
Wisconsin after 06Z. That should help fuel renewed convection just
to our north in an axis of 30+ knots of 0-3km shear (maybe a little
better storm organization), the southern fringe of which could sneak
toward the I-94 corridor later tonight - worthy of at least a chance
mention for storms up that way. Otherwise, looking like another day
of heat for Memorial Day with a very similar thermal regime to
today, though even a touch warmer as 925mb temps push an impressive
31-32C toward the I-35 corridor. Returning southerly flow should
also help keep dew points "up" more than today, with some potential
that we may need a Heat Advisory for parts of the area as heat index
values push 100 degrees. By late afternoon, will have to watch areas
generally north of I-90 with hints of pooling moisture and CAPE
along a weak boundary/convergence axis. Mesoscale convective models
continue to ramp up the idea that we may broach the cap after 20Z
tomorrow, with scattered storms firing along that feature in an axis
of 2500+ J/kg MLCAPE. Given the pattern setup on the northern
fringe of the upper ridge, can`t rule out that idea and have
expanded small precip chances, though very weak shear means any
storms will be outflow-dominant and probably short-lived but could
produce some gustier winds given inverted-V look to soundings by
afternoon.

.LONG TERM...(Monday Night through Sunday)
Issued at 309 PM CDT Sun May 27 2018

Summertime type of pattern looks to continue through the work week,
but with the added "fun" of tracking the remnants of Alberta at is
likely gets pulled well to the north on the backside of our
departing upper ridge by midweek. First things first, it does look a
little cooler for Tuesday with 925mb temps cooling to 22-26C but
can`t rule out some scattered afternoon convection given weak to nil
capping in place, though with a lack of a well-defined trigger
mechanism.

Wednesday looks a bit more interesting as we track Alberto`s
remnants likely to slide north somewhere from eastern Wisconsin into
western Michigan. Recent trends suggest a more westerly track as the
mid/upper level ridge building over the eastern Great Lakes is
slower to arrive, and it is possible that system could even track a
little farther west. Interaction between the tropical remnants and
an upper wave approaching from the Dakotas suggests increasing
chances for showers and storms on Wednesday, and pending the exact
track, can`t rule out a heavier rain risk as PWAT values surge to
around 2 inches near the track of Alberto. Any severe weather
threat, however, looks very low with very weak shear in place on the
western fringe of the circulation.

Thereafter, dare I say things look quiet and seasonable, albeit a
little warmer than normal for the end of the work week and into next
weekend as low level ridging branches southward into the area while
the remnants of Alberto very slowly meander through the eastern
Great Lakes. There remains some small potential for a slower
evolution of that system as it combines with shortwave energy
advancing into the northern Great Lakes, though those details will
emerge as we get a little closer. Per current guidance trends, heat
may well build back north later in the weekend ahead of the next
emerging western CONUS trough, along with increased chances for
showers and storms. All in all, looking very summer-like heading
into the first few days of June.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 632 PM CDT Sun May 27 2018

Partly cloudy/sunny skies will be the rule at KRST/KLSE through
the period with cloud cover being limited to cirrus blow off from
potential thunderstorms to the north and west. Winds will be light
and if not variable, favor a south-southwesterly directional
component.

&&

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

$$

SHORT TERM...Lawrence
LONG TERM...Lawrence
AVIATION...Rogers


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