Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Milwaukee/Sullivan WI
344 PM CDT Mon Oct 14 2019
Tonight and Tuesday...forecast confidence is high.
A sfc ridge will shift newd across srn WI this evening. Areas of
frost should develop by late evening into the overnight, but
temps will then begin to warm via sly winds and warm advection. A
frost advisory is not expected. Low pressure will track from the
nrn High Plains to near msp by 12z Tue in response to a strong
upstream shortwave trough. The shortwave trough will initiate
cyclogenesis from msp to Lake Huron for Tue-Tue nt. Low to mid
level warm, moist advection late tnt and Tue am will bring sct
showers and isold tstorms to srn WI with an advancing dry slot for
the afternoon. Sly winds Tue am will gradually shift wly with the
cold frontal passage in the afternoon. Temps will warm into the
middle 50s to lower 60s before fropa on Tue.
Tuesday night through Friday...forecast confidence is high.
The departing low will have some wrap around low level moisture
and bring the chance for drizzle across the area Tuesday night.
Dry conditions look to return around dawn Wednesday. As the low
shifts northeast into eastern Ontario, gusty northwest winds will
move in behind it with gusts up to 35 mph. The strongest winds
will be during Wednesday morning. Winds will decrease through the
rest of the day Wednesday as upper level ridging builds in
bringing pleasant conditions for Thursday and Friday. Temperatures
will gradually rise through the week, but there could be some
frost Thursday morning as temperatures will be in the low to mid
Friday night through Monday...forecast confidence is medium.
An advancing upper level trough and 850mb warm air advection will
bring rain chances back to the area late Friday night into
Saturday morning. We will be on the backside of the 500mb
vorticity wave and the 850mb front by Saturday evening. The rest
of the night into Sunday morning looks to remain dry, but we'll
have to watch some slight chances for showers. A deepening upper
level low will move into the area Sunday evening. Areas of
positive vorticity advection will rotate around the low and bring
periods of rain Sunday evening through Monday. This will be the
best chance for rain this week.
Aviation(21z tafs)...VFR conditions this afternoon and tnt. Low level wind shear
will be possible for early Wed am over south central WI via a
swly 35-40 kt low level jet. Stratus of 1-3 kft will then overspread srn WI
from west to east during the daylight morning hours and last much
of the day. Sct showers and isold tstorms are forecast.
Marine...a ridge of high pressure of 30.0 inches from se Minnesota to
Illinois will move across Lake Michigan late this afternoon and evening.
Modest westerly winds will shift southerly for late tonight.
Developing low pressure around 29.7 inches will then move from
Minnesota to nrn Lake Michigan on Tuesday and continue to deepen to 29.4
inches as it moves to Lake Huron Tuesday night. The passage of the
deepening low and cold front will shift the winds to westerly,
then northwesterly for Tuesday night and Wednesday with gales
possible. A gale watch is in effect for all of Lake Michigan from 09z
Wed until 00z Thu. A Small Craft Advisory will precede the gale
watch from Sheboygan to Winthrop Harbor for 12z Tue to 09z Wed.
Lm...gale watch from late Tuesday night through Wednesday evening for
Small Craft Advisory from 7 am Tuesday to 4 am CDT Wednesday for