Area forecast discussion
National Weather Service La Crosse WI
1100 PM CDT Monday Jun 17 2013
Short term...tonight through Wednesday
302 PM CDT Monday Jun 17 2013
Main forecast focus in the short term is on rain chances tonight
into Tuesday...cool temperatures Tuesday night...and timing of the
arrival of the next disturbance on Wednesday. 19z surface
analysis shows low pressure over eastern WI with a trailing cold
front extending northwest into central Minnesota. Front is progressing
southwest and is expected to back-door through the area tonight.
Water vapor imagery shows weak short wave trough moving through WI
this afternoon and is helping fuel some convection. With cool air
aloft...instability is sufficient for good updrafts...and enough
shear as well to get some of the storms rotating. Large hail and
damaging winds already seen on a local scale.
As short wave moves through and with the loss of diurnal heating...
expect the current activity to wane through the evening hours.
Front will continue moving southwest through the area overnight...
meanwhile another short wave trough was seen over ND this afternoon
and will be moving across the local area overnight. With the front
and short wave both coming across...feel it prudent to maintain a
low chance for showers through the night. Forcing and moisture are
minimal...but not comfortable going entirely dry. Front and
disturbance exit the area on Tuesday...but as diurnal heating
takes place...could see some showers and thunderstorms develop.
Kept a low chance going over the southern zones until sunset.
High pressure builds in Tuesday night. With light winds and mainly
clear skies...good set up for radiational cooling. Deepest cold
pool over northeast WI...and will see temperatures nose-dive into the
40s. Could also be some 30s in some of the cool spots...but not
long enough or widespread enough to cause any real concern.
Upper level ridge tries to start building for the latter part of
the week...but some weak short wave troughs working through the
ridge will keep things interesting. One such wave is seen by
several of the forecast models to ride the ridge into our area
late Wednesday. Southerly winds will bring an increasing supply of
warm and moist air ahead of this...so we could see some isolated
activity. Feel the highest chance for this will be into Wednesday
night.
Long term...Thursday through Monday
302 PM CDT Monday Jun 17 2013
Active pattern seen for the end of the week into the weekend. Mean
long wave ridging over the central part of the continent through
the weekend...with a large closed circulation over the Pacific
northwest. With ridging in place...a general warming trend is
seen. However...the closed low will be sending periodic
disturbances our way...riding up and through the shallow ridge.
This scenario will make it a bit difficult to nail down timing of
specific waves and thus the rain threats. That being said...the
medium range model solutions are reasonably similar out through
the end of the week. A trough or weak cold front will set up to
the west of our region late Wednesday and Thursday. Isolated
convection is expected to form along this boundary Thursday...and
could move east into our area. Moisture transport and low level
jet look to increase and focus across the plains and upper Midwest
from time to time from Thursday night through Friday night.
The trough weakens and fills over the weekend...and ejects east
along the international border. Thus the surface low and front
will eventually cross through the area. This means rain chances
will have to be maintained through the weekend and into early next
week.
&&
Aviation...(for the 06z tafs through 06z Tuesday night)
issued at 1100 PM CDT Monday Jun 17 2013
Cold front has sagged south of krst/klse this evening...while an
upper level disturbance was spinning southeast across the northern
plains. Some -shra/isolated ts already associated with the
disturbance...and expect this to continue as it tracks into the
region by 12z. Coverage should remain scattered though...with
relatively sparse moisture transport and instability. Will
leave vcsh for both krst/klse...although these small chances are a
bit better for krst. Ceilings are VFR with the upper level features and
precipitation...mostly 5 kft or greater. Expect this VFR trend to also
continue. High pressure works in the for the afternoon and night
hours...clearing whatever clouds linger from the morning. Winds will
be easterly into tonight.
&&
Arx watches/warnings/advisories...
WI...none.
Minnesota...none.
Iowa...none.
&&
$$
Short term...mw
long term....mw
aviation.....Rieck
