Scientific Forecaster Discussion
fxus63 kmkx 231108
Area forecast discussion
National Weather Service Milwaukee/Sullivan WI
608 am CDT Sat Jun 23 2018
VFR should prevail through the next 24 hours.
Light north to northeast winds today and near calm tonight. Mid
and high level cloud cover southeast will scattered out, but high
level clouds should increase late this afternoon and evening.
Previous discussion... (issued 300 am CDT Sat Jun 23 2018)
Today and tonight...forecast confidence is medium...
Mid and upper level low over the upper Ohio Valley is weakening
and moving off to the eastern Great Lakes. A weak mid/upper ridge
over southern Wisconsin today quickly breaks down as a weak upper
low moves into the upper Mississippi Valley this evening, then
across southern Wisconsin as it continues to weaken tonight.
Little in the way of 700 mb relative humidity. There is a limited amount of 850
mb rh, a weak cap and modest zero to 1 km cape of around 100
joules/kg late afternoon. As a result shower potential is low,
with fairly high 600 to 300 mb relative humidity for high level clouds.
Sunday - confidence...medium
500 millibar progs show gradually building heights with elongated
shear zone across northwest through east central WI. Some weak
waa out west but appears enough dry air in place with low level
anticyclonic flow to keep the area dry.
Monday - confidence...medium
mid level ridge axis shifts to our east. We start to get into a
southwest flow with a lead shortwave coming through. Main energy
hangs back in the plains. Surface/850 anticyclone will be off to
our east with a strengthening se low level flow. The GFS shows
better waa and more northeastward advancement of qpf. The NAM and
European model (ecmwf) keep much of the area dry.
Monday night and Tuesday - confidence...medium
this looks to be an unsettled period. Low level jet will pivot through with
moist/thermal advection Monday night. Degree of storm reload
potential and subsequent coverage/intensity on Tuesday will
likely hinge on degree of clearing/instability that sets up in the
wake of the overnight/early morning activity. Given enough
heating/cape buildup, some storms could end up being on the hefty
side with mid level energy encroaching the area. Cwasp numbers
look worthy of retaining the highlight of a severe potential
for Tuesday afternoon/evening within the severe weather potential statement.
Wednesday and Thursday - confidence...medium
will keep things largely dry this period as high pressure drifts
through. Some low level troughing may result in some shower
potential Wednesday but this looks largely north or northeast of
Thursday night and Friday - confidence...medium
another chance of showers/storms returns with developing warm
front. 850/925 temps will be rising with building 500 millibar
heights to near or above 590dm. Blended temps may need some
boosting in the wake of this warm/moist push that arrives.
Aviation(09z tafs)...VFR should prevail through the next 24 hours.
Light and variable winds overnight will give way to light northerly
to northeast winds on Saturday. Mid and high level cloud cover
has scattered out, but high level clouds should increase late this
Marine...winds and waves below small craft conditions.
Winds look to be north to northeast today and and Sunday, before
becoming easterly Sunday night into Monday. Waves are expected to
remain under 2 feet through the weekend.