Scientific Forecaster Discussion
Area forecast discussion
National Weather Service La Crosse WI
1220 PM CDT Tuesday Sep 30 2014
issued at 1038 am CDT Tuesday Sep 30 2014
Adjustments made to the forecast late this morning into the
afternoon hours to account for extensive cloud cover over the
area. The cloud cover will also help to hold temperatures down.
Drier air is working in from the northeast and will help to erode
some of the cloud cover this afternoon mainly over portions of
western and central Wisconsin. 12z grb/mpx soundings show a Stout
inversion in place helping to keep the clouds around. Plan on some
breaks in the cloud cover by middle to late afternoon...when we will
see our high temperatures for the day.
Short term...(today through Wednesday night)
issued at 335 am CDT Tuesday Sep 30 2014
Forecast concerns include cloud cover today...then rain chances
tonight through Wednesday night.
Surface analysis has high pressure building in from Ontario Canada.
Northeast wind flow around this high was dragging Great Lakes
moisture/stratus cloud cover southward into the area.
Otherwise...temperatures early this morning ranging from the upper
30s across north central WI...to the middle 40s/lower 50s
elsewhere across the rest of the arx forecast area.
For today...surface/mid-level ridge of high pressure expected to
erode low stratus cloud cover from north to south by later this
morning/early afternoon. With increasing sunshine into the afternoon
hours...expect highs to top off near seasonal normals in the 60s.
Closed low located over the plains this morning will lift northward
into the Dakotas/southern Manitoba late tonight. This will push a
trough/cold front into western MN/IA. Increasing corridor of 850mb
moisture transport/isentropic lift expected to push a band of
showers and isolated thunderstorms into areas mainly west of the
Mississippi River this evening...and into western WI after midnight.
Showers and isolated thunderstorms expected across the entire area
Wednesday into Wednesday night as shortwave trough ejects north out
of the long wave trough entrenched over the plains. Plan on highs
Wednesday in the 60s with lows Wednesday night in the 50s.
Long term...(thursday through monday)
issued at 335 am CDT Tuesday Sep 30 2014
Latest GFS/European model (ecmwf) trending toward a stronger surface low moving
through the area Thursday through Friday. This is expected continue
wet period with occasional showers. Plan on some isolated thunder as
well Thursday into Thursday evening. High temperatures Thursday
expected to top off in the 60s...but then drop into the 50s on
Friday as gusty northwest winds on the backside of the low draws
colder air over the region. Lingering closed middle-level low expected
to continue shower activity into Friday night. With lows Friday
night dipping into the middle 30s across central WI...cannot rule
out a few flakes of snow. In fact...the European model (ecmwf) sounding supports this.
Plan on chilly conditions through Saturday with lingering cold
cyclonic flow aloft. Highs are expected to only climb into the 50s
despite partly sunny conditions.
Broad northwest flow from the central Canadian plains brings a
couple weak middle-level shortwaves across the region Sunday and Monday
for a chance of showers. Otherwise...below normal temperature to
continue with highs ranging from the middle 50s to the lower 60s.
Aviation...(for the 18z tafs through 18z Wednesday afternoon)
issued at 1220 PM CDT Tuesday Sep 30 2014
Stratocumulus will gradually scatter out early this afternoon with
cloud bases rising to around 3 kft. Low pressure moving northeast
across the Dakotas will spread high clouds and eventually rain
showers into the taf sites Wednesday morning into Wednesday
afternoon. IFR conditions are expected in the steadier showers
especially at krst. Plan on conditions lowering to IFR at krst
around 13z with cloud bases at 700 feet and visibilities falling to
around 2 sm in br. MVFR/IFR conditions are expected at klse but
this isn/T expected to arrive until the 15-16z timeframe on