Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Milwaukee/Sullivan WI
143 PM CST Tue Nov 19 2019
Tonight and Wednesday...forecast confidence is medium to high:
High pressure will build into the area tonight and hang around on
Wednesday. After sprinkles/flurries end by early evening today,
dry weather is expected through Wednesday under the high.
The main issue for tonight and tomorrow will be cloud cover and
potential fog. Given moist low levels and light winds along with
current reduced visibilities in a few spots, do think there will
be some fog tonight. Clouds are likely to hang around as well,
which may inhibit the development of widespread dense fog. Any fog
that does form should improve by mid-morning Wednesday.
Models are split on cloud cover tomorrow. Some show clearing and
milder temps, particularly in the southwest. Others hang on to the
stratus for another day. Did warm temps up a bit for
tomorrow, but stayed away from the mildest solutions give the
potential for the clouds to stick around.
Wednesday night through Thursday...forecast confidence is high.
High pressure shifting from the Gulf Coast to the mid-south today
through Wednesday will allow for an increasing southerly fetch off
the Gulf of Mexico. This is occurring as a system ejects out of
the desert SW on Wednesday, which will increase the strength of
the moisture return. Low to mid 50 degree dewpoints are expected
to make it into the area Thursday afternoon. The main upper low
and surface low will track across north-central WI Wednesday night
through Thursday. This keeps US in the warm sector and with those
dewpoints streaming into the area it's not out of the question to
hear a rumble or two as the cold front swings through Thursday
afternoon/evening. At this point though, instability looks to be
too limited to include thunder in the forecast.
Models are in close agreement in the bulk of the heavy rain moving
in early Thursday morning. Pw's are over 1 inch, which is about
the climo Max and that should allow for quantitative precipitation forecast totals to approach 1
inch in the northwest and closer to a half an inch in the southeast.
Highs warm into the mid 50s for much of southern WI and with the
strong low level jet it will end up being a fairly breezy day.
Thursday night through Monday...forecast confidence is high.
Drier and colder air quickly filters in Thursday night behind the
front with lows falling into the 20s. Quick on the heels of the
Thursday system a sheared trough will drop east/southeast across the area
by Friday morning. This feature should help to scour out any
lingering moisture making for a mostly sunny day but noticeably
cooler with highs only in the low to mid 30s.
High pressure shifts over the area through the weekend keeping US
under a cooler west/northwest flow. Highs warm a degree or two each day
from Friday into Sunday. Dry weather is expected through the
weekend with any precip remaining across IL/in. Heading into early
next week high pressure builds north/NE into the Ohio Valley, which will
turn winds more to the south. Temps keep the warming trend going
for Monday with values close to normal for this time of year.
Tuesday and beyond...forecast confidence is low.
There remains considerable uncertainty in how guidance wants to
handle a strong system moving through the central US next week.
Run to run consistency in much of the guidance has been poor. What
does look to occur is deep return flow off the Gulf is expected
which will lead to a good amount of moisture flowing north towards
the area. The exact track of the low will determine what the
precip type will be. The GFS has been sticking to the warmer
solution keeping US all rain. The European model (ecmwf) is wavering back and forth
between rain and snow. For what it's Worth the GFS did have a
slightly better handle on this Thursday system in the extended
period than the European model (ecmwf) did. So, that could be slight hint towards
the possibly warmer solution. Still a lot remains to be determined
so stay tuned.
Though there could be a couple breaks in the cloud cover this
afternoon and again Wednesday, it seems that stratus will largely
remain in place through tomorrow. Ceilings may bounce between
IFR/MVFR into this evening, with lower ceilings then settling in
for the night. Given light winds and moist low levels from recent
rain and snow melt, still think there will be some fog tonight.
Not confident in dense fog given the widespread cloud cover, but
some reduction in visibility is likely.
May see a few flurries or sprinkles through this afternoon, with
dry weather then likely tonight and Wednesday as high pressure
Light west to southwest winds will continue into Wednesday
morning as high pressure builds into the Ohio River valley.
A stronger low will move through later this week, with gusty
southerly winds ahead of the system Wednesday night into Thursday.
Winds will then become northwest Thursday evening into the night.
Gusts could reach gale force at times late Wednesday night
through Thursday, particularly over the open waters.