FXUS63 KMQT 200529
Area Forecast Discussion
National Weather Service Marquette MI
129 AM EDT Fri Jul 20 2018
.SHORT TERM...(This evening through Friday)
Issued at 414 PM EDT THU JUL 19 2018
WV imagery and RAP analysis indicated a mid/upper and sfc low over
sw MN. The leading edge of pcpn with WAA/isentropic ascent ahead of
the low was slowly lifting to the ne through wrn WI. Any
thunderstorms remained farther south over ern IA, where MUCAPE
values were near 1k J/Kg. Otherwise, srly low level flow
prevailed through Upper Michigan with sct cu and a few high clouds.
Tonight, model trends with fcst moisture advection, isentropic lift,
and QPF suggest that the best rain chances/coverage will move into
wrn Upper Michigan overnight. However, instability to support tsra
will remain south of the area. Pcpn amounts should also remain
light, generally at or below 0.10 inch.
Friday, as the low slowly moves through srn WI, the heaviest pcpn
will continue to remain to the south of Upper Michigan and the
highest POPs will remain over the wrn CWA, closest to the stronger
700-300mb qvector conv. Expect enough diurnal heating to boost
MLCAPE values into the 500-1000 J/Kg range with potential of isold
thunderstorms over the south and east. Highs should climb into the
lower 70s near the WI border to around 80 east.
.LONG TERM...(Friday night through Thursday)
Issued at 347 PM EDT THU JUL 19 2018
Main concerns in the long-term forecast will be the precipitation
potential Friday night through the weekend along with the associated
cooler than normal temperatures.
Friday night through Sunday, Models are showing very similar
evolutions of a closed low moving through the Upper Great Lakes
through this time period. The models have converged on the upper-
level and surface low sliding across WI. This will lead to
increasing shower and thunderstorm chances for Friday; however,
dwindling instability will keep mainly rain showers and cloud cover
in place from Friday night through at least Sunday morning. The
increased cloud cover and intermittent precipitation through the
weekend, will keep temperatures below normal for this time period,
generally in the upper 60s to mid 70s, coolest downwind of the Great
Lakes. Doesn't look like a lot of rain, but the southeast half of
the U.P. could see rainfall totals around a quarter to a half inch.
That's good news as those locations have been especially dry over
the past couple months.
Monday through Thursday, models are depicting a surface low and
and upper level trough sliding across Canada. The main impact this
would have is perhaps an increase in cloud cover Monday into
Tuesday as a weak, moisture starved front slides through the area.
Another small chance of rain showers is possible Tuesday night
into Wednesday as the aforementioned lows sink a bit farther south
across Ontario. This will allow a stronger cold front to slide
through the area along with some additional moisture. At this
point, with timing and placement similar among the models, will
stick with the consensus blend, bringing a few scattered showers
for Tuesday night into Wednesday. Temperatures will likely be in
the 70s for most locations with a few 80 degree readings possible
for inland locations.
.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 129 AM EDT FRI JUL 20 2018
Light showers continue along the Wisconsin border this morning with
heavier precipitation holding off to the south. While there is some
uncertainty on how far north the heavier precipitation moves, latest
model trends and observations support keeping IFR ceilings out of
the forecast for KSAW and KCMX. At KIWD, low-end MVFR ceilings are
possible for a time Friday morning and early afternoon, but with
limited upstream observations from the air mass moving into the
area, confidence was not high enough to include lower ceilings at
this time.Pprecipitation diminishes in the evening with ceilings
improving to VFR through the evening.
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 414 PM EDT THU JUL 19 2018
Expect winds generally 15-20 kts with a few times of gusts over 20
kts through Saturday as a low pressure system slowly crosses the
western Great Lakes. High pressure building in Sunday through early
next week will result in winds staying mostly 15 kts or less.