Area Forecast Discussion

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.
Upper Michigan...
Lake Superior...
Lake Michigan...