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Area forecast discussion 
National Weather Service La Crosse WI
617 PM CDT Sat Jul 12 2014

Short term...(this evening through sunday)
issued at 309 PM CDT Sat Jul 12 2014

Main forecast concerns are on severe thunderstorm potential over
northeast Iowa and far southwest Wisconsin. However...the severe
potential appears to be decreasing this afternoon as widespread
showers and isolated thunderstorms overspread these areas. The
main concern is shifting more toward a heavy rain threat for late
this afternoon into this evening.

Keeping a close eye on thunderstorm development along a cold front
and upper level disturbance this afternoon. Mesoscale models
continue to fire storms over these areas late this afternoon and
then they push this activity to the east during the evening hours.
However...the strongest 850 mb moisture transport focused south and
east of the forecast area. Effective bulk shear of 40 to 50 kts and
MUCAPE values of 1000-1500 j/kg would support supercell structures
over northeast Iowa and far southwest Wisconsin. Also...if surface
based convection develops there could even be the potential to see
an isolated tornado. However...0-1 km shear is very weak and we
would have to see the surface low and warm front make it a little
further north to have tornado potential. Precipitable water
values and warm cloud depth continues to support heavy rainfall
potential...with precipitable water values of 1.5 to 1.9 and warm cloud depth of
3.5 to 4.0 km along and south of Interstate 90. There is a
secondary boundary stretching from northwest Wisconsin southwest
through the Twin Cities area to the Interstate 90 corridor then
stretching back to the west. This boundary pushes southeast very
slowly late this afternoon into this evening and we will have to
keep an eye on convection near this boundary. If it stalls there
could enough localized vorticity to see a non supercell tornado or
two if surface based convection occurs. Also...storms near this
boundary have been fairly slow moving and would have the potential
to produce locally heavy rainfall. Showers and thunderstorms will
taper off and end this evening as a shortwave trough exits the
region.Mostly cloudy skies are expected through the evening then
we should see a decreasing cloud trend late tonight into early
Sunday morning. Plan on overnight lows in the upper 50s to lower
60s. A weak front will slide through the area tomorrow but will
mostly generate some cumulus along and south of Interstate 90.
Forecast soundings suggest we could build just enough cape for
an isolated shower or thunderstorm so have added a slight chance
for this activity during the afternoon hours. Otherwise...plan on
high temperatures ranging from the lower 70s over north central
Wisconsin to the upper 70s across northeast Iowa.

Long term...(sunday night through saturday)
issued at 309 PM CDT Sat Jul 12 2014

A deep trough dives into the region Sunday night through Monday
brining unseasonably cold temperatures and chances for showers to
the region. 850 mb temperatures fall to around 4 c Monday into
Tuesday...setting the stage for potential record cool high
temperatures. Scattered showers are expected across the area on
Monday. With the showers/cloud cover...temperatures will be rather
chilly for this time of year with highs only making it into the
upper 50s to possibly around 60 over north central Wisconsin.
Elsewhere highs will only make it into the 60s. Cannot rule out
slightly warmer temperatures over portions of northeast Iowa into
far southwest Wisconsin where highs could approach 70. Much of the
areas will be close to seeing record cool high temperatures on
Tuesday with highs only in the 60s. See climate section below for
for record lowest high temperatures for Monday and Tuesday. The
trough pulls east of the region Tuesday night into Wednesday. We
should see temperatures start to moderate Wednesday through
Thursday with highs climbing back into the 70s. High pressure will
provide dry and quiet weather Wednesday through Friday. Flow
aloft becomes zonal for next weekend and we could see chances for
showers and thunderstorms return.

&&

Aviation...(for the 00z tafs through 00z Sunday evening)
issued at 616 PM CDT Sat Jul 12 2014

The back edge of the showers is progressing steadily east and
should be past or very close to be being past klse by 00z and will
show only a vcsh there for a couple of hours this evening.
Ceilings behind the showers go back up to VFR and then based on
satellite...should scatter out by the middle of the evening.
Skies then expected to go clear overnight and with the
rain...concerned about the possibility of fog development. It does
not look like the surface winds will completely decouple and both
the 12.18z NAM and 12.21z rap soundings show winds of 15 to 20
knots just above the surface. If these winds develop as
expected...they should create enough mixing and may keep the fog
from forming. For now...will stay with the previous trends of
showing MVFR visibility at krst where the skies will clear out
first with no restrictions at klse. Secondary cold front will
come through Sunday morning swinging the winds around to the
northwest and enough mixing behind this for some gusts to around
20 knots at krst Sunday afternoon.

&&

Hydrology...
issued at 309 PM CDT Sat Jul 12 2014

A few stronger thunderstorms will be capable of producing heavy
downpours with rainfall rates of 1-2 inches per hour this
afternoon into early this evening. This will lead to ponding of
water and localized flooding is possible...especially in urban
areas.

&&

Climate...
issued at 309 PM CDT Sat Jul 12 2014

Record cool high temperatures are possible Monday and Tuesday as an
unseasonably cold airmass settles over the upper Mississippi River
valley.

For La Crosse...
Monday....forecast high 69. Record 65 in 1994
Tuesday...forecast high 68. Record 68 in 1962

For Rochester...
Monday....forecast high 64. Record 64 in 1952
Tuesday...forecast high 67. Record 67 in 1962

&&

Arx watches/warnings/advisories...
WI...none.
Minnesota...none.
Iowa...none.
&&

$$

Short term...wetenkamp
long term...wetenkamp
aviation...04
hydrology...wetenkamp
climate...wetenkamp

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