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Area Forecast Discussion (AFD)

Issued by Marquette, MI (MQT)

FXUS63 KMQT 252334

Area Forecast Discussion
National Weather Service Marquette MI
734 PM EDT Sun Aug 25 2019

.SHORT TERM...(This evening through Monday)
Issued at 230 PM EDT SUN AUG 25 2019

Upper air pattern consists of a 500 mb ridge across the upper Great 
Lakes with a shortwave over the plains this morning. This shortwave 
heads east and affects the upper Great Lakes on Mon. Nam shows some 
850-500 mb q-vector convergence and deeper moisture on Mon. Dry for 
tonight, then pops move into the area on Mon. Overall, did not make 
too many changes to the going forecast except slowed down the 
progression of pops eastward tonight into Mon.

.LONG TERM...(Monday night through Sunday)
Issued at 353 PM EDT SUN AUG 25 2019

A deepening low pressure system will be underway to begin this 
period, continuing a widespread rain event across Upper Michigan. 
This low pressure system will dictate our weather through the end of 
the work week as multiple embedded troughs pass across the cwa. 
There should be a few dry slots as the low spins off towards Hudson 
Bay, but overall expect chances of rain through Friday. Models agree 
on returning high pressure for Saturday, but disagreements begin 
leading into Sunday and Monday.

On Monday night into Tuesday, GFS was a little out front compared to 
other models and have trimmed likelys to the west with chances 
remaining elsewhere. Rain becomes likely from to west to east 
through the overnight hours, as a slight chance of isolated thunder 
was left in this forecast. As mentioned before, the low is forecast 
to deepen as it moves north towards Hudson Bay, stretching an 
elongated trough axis south across Upper Michigan. This should bring 
multiple chances of precipitation through the work week as well as 
gusty conditions through Friday. There is a decent chance at a 
period or two with gales over the lake, which may lead to minor 
lakeshore flooding/erosion given the continued elevated lake levels. 
As the low moves north, west to northwesterly winds will aloft will 
drag 850 temps down to near 5C. It is possible that this adds the 
chance at a few lake-effect/enhanced showers across portions of 
north and western Upper Michigan, though it is unknown how much the 
lake will cool off with winds/waves prior to Wednesday. Otherwise 
highs on Wed should reach 60 in the west, albeit with a struggle, 
and mid 60s elsewhere. Highs will rebound slightly on Thursday to 
low to mid 70s as WSW winds return. Another trough and associated 
cold front Friday morning should bring temperatures down again, 
struggling to reach 70 Friday/Saturday.

Model forecasts have been inconsistent and carry different solutions 
starting on Saturday into Monday. 00Z GFS held on to a high pressure 
system through Monday, leaving Labor Day weekend dry. 06Z/12Z GFS 
have begun to develop another low pressure system and chance for 
rain Sunday into Monday. The 00Z GEM mirrored the GFS slightly, 
however, the 12Z GEM now has a low developing a day or two later 
than the GFS though, coming through Tuesday into Wednesday. ECMWF 
have a round of quick showers pass to the north on Sunday, but 
remain dry until a low pressure system moves into the Great Lakes 
region Tuesday afternoon. Favoring the dry solution still for now 
given previous forecast and model trends for Labor Day Weekend. GFS 
hasn't been consistent the last few runs, as the EC and GEM have 
fairly decent agreement on high pressure through Labor Day with rain 
returning sometime early to mid next week.

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 722 PM EDT SUN AUG 25 2019

VFR conditions are expected through the forecast period for all 
sites. Winds will be gusty out the south-southeast especially late
in the day on Monday with gusts exceeding 20 knots possible mainly
at KIWD and KSAW. Rain will be moving into KIWD and KSAW towards 
the end of the forecast period with the approach of a warm front. 

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 230 PM EDT SUN AUG 25 2019

The wind will remain at or below 20 knots into Mon afternoon and 
then increase to 20 to 30 knots Monday night. There could be some 
southeast gale gusts to 35 knots Mon night across central and 
eastern Lake Superior. 20 to 30 knot winds will then persist across 
all of Lake Superior Tue through Wed with a cold front moving 
through the area. Winds then diminish to 15 to 25 knots Thu into Fri.

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