Scientific Forecaster Discussion
fxus63 kmqt 201115
Area forecast discussion
National Weather Service Marquette Michigan
715 am EDT Sat Jul 20 2019
Short term...(today and tonight)
issued at 406 am EDT Sat Jul 20 2019
Wake low winds on the back side of showers and thunderstorms
impacted parts of south central Upper Michigan and Lake Michigan
earlier this morning; however, things have quieted down since then.
We're still dealing with the mild and humid conditions this morning,
as a weak stationary front continued to slowly pushing east-
southeast across central and eastern Upper Michigan this morning.
Low pressure currently analyzed across eastern parts of Lake
Superior, along with the stationary front draped southwestward into
east-central Wisconsin will continue to gradually push south this
morning. With this boundary being the main bifurcation point between
the excessive heat/humidity and resulting extreme instability,
convection expected to re-develop along this boundary is expected to
remain well south of the area today. While the robust thunderstorms
will remain to our south today, a secondary cold front currently
stretched west to east across southern Canada will gradually push
south across Upper Michigan later today and tonight. There will be
rather limited instability to work with, so convection that does
develop may put down some light rain at best. Confidence is highest
across the south half of the area. Otherwise, today will be a far
more pleasant day with temperatures about 10 to 15 degrees cooler.
With primarily north to northwest winds developing today, the warmer
spots will be across the south central and other locations that see
some downslope warming. Humidity levels will be a bit elevated early
on in the day, but much drier air will work in behind the above
mentioned cold front.
Compared to recently, tonight is shaping up to be a beautiful night
with temperatures finally dropping back down to near-normal for this
time of year. With drier air working into the region tonight, along
with light winds and clearing skies, temperatures could fall into
the upper 40s across the interior west. Elsewhere, overnight lows in
the 50s are expected.
Long term...(sunday through friday)
issued at 448 am EDT Sat Jul 20 2019
Models suggest that the quasi-zonal pattern will amplify into next week
as a ridge develops from the SW Continental U.S. Into Alberta/Saskatchewan
with a downstream trough from Quebec into the eastern Continental U.S.. the
resulting NW flow through the northern Great Lakes will bring
seasonably cooler and drier air into Upper Michigan. Later in the
week, a vigorous shrtwv is expected to move from
Alberta/Saskatchewan to northwest Ontario bringing a trough/front
toward the region.
Sun-Mon, dry weather will prevail as sfc high pressure builds
eastward from the northern plains. Comfortable July weather is
expected with highs in the mid 70s and lows in the upper 40s to
lower 50s. Dewpoints will also drop into the upper 40s.
Tue-Wed, expect increasing temps as the high settles toward the Ohio
Valley with westerly low level flow also bringing warmer air and
slightly more moisture. Weak shortwaves in the NW mid/upper level
flow could trigger some isold shra. However, only slight chance pops
for Wed were mentioned. With little moisture inflow and marginal
instability, any pcpn amounts will be light.
Thu-Fri, the models/ensembles were in reasonable agreement with the
timing of the shrtwv and front edging toward the northern Great
Lakes. Warm air advection and moisture advection increase enough to support at
least chance pops for shra/tsra by later Friday into Friday night.
Temperatures will climb back above normal into the lower to mid 80s
Aviation...(for the 12z tafs through 12z Sunday morning)
issued at 715 am EDT Sat Jul 20 2019
Pesky shallow ground fog brought intermittent LIFR conditions to
kiwd this morning, but visibilities and ceilings improved rapidly
right after sunrise. VFR conditions with thickening mid-level clouds
are expected today, along with breezy winds at kcmx/ksaw. There is a
chance kiwd could see some shower activity later today, so did
include mentions of vcsh for now. Tonight, light winds and clearing
skies are expected.
Marine...(for the 4 am Lake Superior forecast issuance)
issued at 406 am EDT Sat Jul 20 2019
Patchy fog remains possible across Lake Superior today, especially
across the north central and northeast, until a cold front drops
south later today/tonight and Ushers in much drier air. Otherwise,
southwest to west winds 15 to 20 knots are expected later today
ahead of the approaching front. Winds turn northerly tonight and
look to remain so through the end of the weekend at speeds below 20
knots. Early next week, cooler air dropping south over Canada will
allow for north-northwesterly winds between 15 and 20 knots.