Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service La Crosse WI
145 PM CDT Mon Oct 14 2019
Short term...(this evening through tuesday)
issued at 143 PM CDT Mon Oct 14 2019
A weak surface ridge continues to drift southeast towards the Ohio
Valley this afternoon. Plenty of sunshine along with much lighter
winds compared with the weekend were found across the area, although
temps have remained cool for mid October in the 40s to low 50s.
Water vapor imagery this afternoon reveals an upper trough working
southeast across the northern rockies. This wave will track into the
northern plains tonight and into the upper MS valley on Tuesday.
Warm advection ahead of the surface low/cold front along with
increasing low-level moisture transport will result in increasing
clouds this evening/tonight. Showers are expected to develop by late
evening/overnight, especially from southeast Minnesota through north-
central WI on the nose of a low-level jet. A bit of MUCAPE will
likely develop in a narrow corridor ahead of the front tonight, so
an isolated storm is possible, but mainly showers are expected.
Temps tonight won't be nearly as cold as the past few nights, likely
leveling off or even rising during the overnight hours.
The front will sweep through Tuesday morning with low clouds
spreading across the area. Westerly winds will increase behind the
front with gusts likely in the 30-35 mph range. Additional showers
are possible Tuesday as the surface low passes east towards Northern
Lake Michigan with steep low-level lapse rates/cyclonic flow aloft
in the colder air behind the front. The highest precip chances may
remain across northern WI in association with the mid-level
deformation area. Highs will be in the mid 40s to mid 50s, with
relatively little diurnal change from a mild start to the day as
cold advection develops behind the front.
Long term...(tuesday night through monday)
issued at 143 PM CDT Mon Oct 14 2019
Lingering showers exit the area Wednesday morning as low pressure
moves east into the northern Great Lakes. Although surface ridging
moves in for Wednesday, there is some suggestion that clouds may be
slow to erode during the day with lingering low-level moisture. This
may make for a chilly day (highs in the 40s for most). Warmer
weather is in sight, however, as southerly return flow courtesy of
high pressure to our southeast will allow temperatures to rise back
into the 50s Thursday and even the 60s by Friday. A more active
period returns for the weekend, beginning with a chance for rain
late Friday into Saturday as a shortwave passes through our area.
Large upper level trough approaches from the west Sunday and Monday,
with models showing an area of low pressure developing and moving
into the region from the southwest. This would bring more chances
for wet weather, with plenty of moisture streaming northward out
ahead of the system in the latest model runs. Details are still
murky this far out, with quite a few differences on placement of
this system and thus precipitation amounts and temperatures for
early next week.
Aviation...(for the 18z tafs through 18z Tuesday afternoon)
issued at 1213 PM CDT Mon Oct 14 2019
VFR conditions will continue this afternoon into tonight with
winds gradually shifting southerly along with increasing mid-level
ceilings tonight. Scattered showers may develop by late this
evening. Low level wind shear will develop during the overnight as winds increase
to around 45 kts at 2 kft. MVFR to potentially IFR ceilings are
expected to develop late tonight or early Tuesday with winds
becoming gusty from the west by mid to late morning with the
passage of a cold front.