Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 141645
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
1145 AM CDT Thu Mar 14 2024

.KEY MESSAGES...

- Highest confidence for >.25" across NE Iowa/srn WI with some
  low 30- 40% probabilities for 1" or more. Isolated thunder
  chances far south.

- A series of cold fronts to bring colder weather for
  Sunday/Monday with below normal temperatures.

- Precipitation chances after today remain low for 0.05" (0-20%)
  through early next week.

&&

.DISCUSSION...
Issued at 355 AM CDT Thu Mar 14 2024

Overview:

For the third day in a row, RST set a new daily record
high with 68 at degrees.  The previous record was 66 degrees in
2012. LSE topped out at 70 degrees, 1 degree shy of the 2015 record
of 71 degrees. The MPX 14.00 sounding showed deep mixing to
above 650mb with a large spread in low level dewpoints allowing
for much above normal/record temperatures with an 850mb
temperature around 7 deg. C. Precipitable water was 0.35 inches.
The KDVN 14.00Z sounding had steep lapse rates with 0.69"
precipitable water.

Latest water vapor satellite imagery, heights, and lightning showed
the closed low over the Four Corners region with leading trough
energy over parts of IA/NE/MO/KS.  This was also where clusters of
storms in a west to east fashion were ongoing. A 100kt upper level
jet extended from the Southwest U.S. into the Plains with broad
upper level divergence in the left front exit region of the jet.
700mb warm air advection was noted in this region with steep mid-
level lapse rates.  850mb warm advection was also focused in this
area with deep moisture/10 deg C dewpoints from eastern Kansas into
Missouri.  A broad 45-55kt low level jet stretched from eastern
Kansas across Missouri into southern Iowa.  The latest subjective
surface map had a 1000mb surface low over northeast Kansas with the
warm front across northern Missouri int central Illinois. The
SPC mesoanalysis page showed the 500-1000mb MLCAPE was also over
eastern Kansas into Missouri and parts of Illinois. Deep layer
shear was also 50 to 60kts. Areas near and just north of the
front; parts of KS/SE Neb/srn IA/northern MO/wrn IL are in the
slight and enhanced risk for severe storms overnight. The storms
were more elevated into southern Iowa. Farther north, a second
area of mid level frontogenesis/warm air advection was noted
within an area of steep mid level lapse rates. Virga and accas
were noted earlier in the day locally with some rain reaching
the ground at LSE by 03Z and and area of showers toward RST and
AUM. By 06Z, an easterly low level flow was dominant with
surface dewpoints in the 40s at RST, but still dry air in the
20s across most of western WI.

Highest confidence for >.25" across NE Iowa/srn WI with some low 30-
40% probabilities for 1" or more:

A couple of areas of surface low pressure are forecast to ride along
the surface front today as mid-tropospheric shortwave trough energy
tracks from the Missouri River Valley toward the Mid-Mississippi
Valley.  The local forecast area remains on the cool side of the
front with the best moisture transport across Missouri into Illinois
and toward Indiana/Ohio through 00Z.  The main precipitation axis
pushes across Illinois into Indiana and Michigan this morning,
however wrap-around precipitation develops on the cool side of
the 850mb front and in an area of strong mid level warm air
advection combined with the upper level vorticity advection. The
hi-res cams take this first area of convection southeast of the
local area by 15Z with bands of precipitation rotating westward
and translating east during the day. The bulk of the cams keep
the higher rainfall amounts of 0.25" or more across NE Iowa/srn
WI with 60-80% probabilities. Farther north, the probabilities
for 0.1" drop of to 20% or less north of I90. It is interesting
to note that the 1" probabilities are greatest toward PDC with
30-40%, however there are some low 20-30% probabilities of 1"
from Houston toward Vernon county with a second band. This may
be due to a farther northwest location of the FV3 as the rest of
the hi-res cams are southeast of this area. The lowest
confidence is where narrow banding may set up on the northwest
side of the system, thus left some low 0.05 to .15" amounts
north of I90, but mostly dry for Taylor into Clark Co. These
amounts have trended lower over the last 24hrs. The CAMs
generally weaken the forcing this evening, so any lingering
precipitation should weaken and diminish with northeast and
north flow increasing.

Not as mild today with the clouds and precipitation for some, but
still above normal with highs in the 40s and 50s. Forecast soundings
show convective temperatures in the upper 40s, however moisture is
shallow, so quite a bit of sunshine Friday, but some clouds possible
with the heating.  Highs Friday top out in the upper 40s and lower
50s with westerly flow ahead of cooler air for Saturday.  Clouds
will be on the increase Saturday with high in the 40s to lower 50s.

Much cooler for Sunday/Monday with below normal temperatures:

Reinforcing cold air overspreads the area Saturday night with much
cooler temperatures Sunday.  Highs will mostly top out in the 30s
with a few lower 40s.  The cold air remains in place for Monday with
highs again in the 30s.  A clipper-type system moves through Tuesday
with a warm-up into the 40s.  Although we currently have highs in
the 50s similar to the EC, the GFS is trending not as warm for
Wednesday.

No significant precipitation chances through the extended, however
we`ll have to continue to monitor low light snow or rain/snow
chances.

&&

.AVIATION /18Z TAFS THROUGH 18 FRIDAY/...
Issued at 1144 AM CDT Thu Mar 14 2024

CIGS: track of low pressure system to the south and drier air
already in place across the local area is working against
progression north of lower cigs (and pcpn). Latest meso models hold
the MVFR cigs south and will move the forecast for KRST/KLSE this
way. Mid/upper level clouds look to scatter out later this evening.

WX/cigs: dry air sub the mid clouds is working against pcpn making
it to the sfc - aside from perhaps a few sprinkles. Will trend the
forecast dry with no vsby impacts.

WINDS: northeast winds swing more northerly tonight with an
accompanying diurnal tick-down in speeds.

&&

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

&&

$$

DISCUSSION...Zapotocny
AVIATION...Rieck


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