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FXUS63 KMQT 221024

Area Forecast Discussion
National Weather Service Marquette MI
624 AM EDT Tue Oct 22 2019

.SHORT TERM...(Today and tonight)
Issued at 303 AM EDT TUE OCT 22 2019

Upper air pattern consists of a 500 mb closed low over west central 
Wisconsin which will head northeast to central Ontario by 12z Wed. 
The wraparound part of this storm will be moving through the area 
for this forecast period. The dry slot that is over the area now 
will move out and pops will start to increase again as the 
wraparound part of the storm moves in. This is covered well in the 
going forecast. Could be a little snow mixed in with the rain 
showers over the west tonight in the higher terrain, but will not 
amount to much. Overall, did not make too many changes to the going 

.LONG TERM...(Wednesday through Monday)
Issued at 418 AM EDT TUE OCT 22 2019

Although the significant winds and rain are mostly done with, the 
medium range weather will continue to be dominated by the slowly 
departing low pressure system, forecast to be west of James Bay by 
Wednesday morning. Moist and seasonably cool cyclonic flow in the 
mid-levels will keep clouds and precip chances around Wednesday and 
even into Thursday. Timing out the individual vort lobes rotating 
around the main upper low probably isn't a worthwhile endeavor at 
this point, but the main focus for precip will be lake enhancement 
becoming pure lake-effect for a brief period. 850 mb temps around -4 
to -5 C Wednesday moring would support lake sfc delta T's of about 
11 C, enough for lake-enhanced upslope precip over the Keweenaw, 
Gogebic Range, and Michigamme Highlands/Hurons Mountains. Models are 
also pretty insistent on resolving a W wind/shoreline convergence 
band from just about Munising on east. With less orographic forcing 
there and lake-based instability still marginal at best, not as 
confident about that materializing but nonetheless included it in 
this forecast anyway rather than bucking all of the models. Snow-
lovers will have to keep waiting, however, as this is still 
primarily lake-effect rain outside of a few hours of wet flakes over 
the higher terrain of the western U.P. where wet bulb zero heights 
briefly drop to as low as about 800 feet. Should note that our tools 
want to development freezing drizzle in some spots because the 
precip is too shallow, but given warm ground temps, don't think that 
will be much of an issue. It looks breezy area-wide Wednesday as 
well with 20-25 mph gusts, and maybe some 35-40 mph gusts over the 
Keweenaw Wednesday morning with a favorable west wind direction.

By Wednesday night, further CAA aloft allows for enough lake-based 
instability for more of a pure lake-effect rain/snow shower mix, 
still over the WNW lake-effect belts, with delta T's now approaching 
13-14 C and inversion heights around 6000-7000 feet. However mid-
level heights rise Thursday morning and drier air finally advects 
in, bringing an end to lake-effect precip over the west half almost 
as quickly as it began. Have just chance POPs by sunrise and even 
those disappear by afternoon. L-E rain should linger over eastern 
Lake Superior and clip the shoreline near Grand Marais into the day 
thursday until that too wraps up around sunset Thursday. Snowfall 
totals through the end of the day Thursday are less than an inch, so 
any snow that does fall will be negligible.

With colder air aloft now thoroughly in place (850 mb temps still 
progged to drop to about -8 C) and the gradient wind finally 
relaxing, Friday moring still looks chilly. Once again relied on the 
coldest guidance for moring lows, which end up in the low 20s over 
the notoriously cold spots to around 30 lakeshores. Saturday moring 
could be similarly cold, but it's not as clear cut. WAA begins 
overnight ahead of the next system, which could lead to some cloud 
development or could help develop a stronger surface-based 
inversion. That warming trend becomes apparent by Saturday afternoon 
with highs in the 50s under plentiful sunshine. As for Sunday, 
there's some uncertainty on precip chances. A northern stream wave 
in the GFS shears out the southern stream and prevents a stronger 
low pressure area from developing like in the EC and CMC. NBM was 
almost completely dry so had to introduce at least chance POPs. Too 
early to write-off Sunday completely, though. Regardless of a rain-
maker, cold air dumps back in over the Upper Great Lakes for the 
beginning of next week. At the moment the air mass behind the 
frontal system looks too dry to support any noteworthy lake-effect 
precip, despite the air aloft being plenty cold.

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 624 AM EDT TUE OCT 22 2019

Low-level moisture will wrap back into the area thru the morning, 
resulting in conditions at all terminals falling back to low MVFR 
with some IFR possible at times. Shra coverage will also increase. 
Increasing westerly winds are expected at KIWD and especially KCMX 
late aftn/evening.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 303 AM EDT TUE OCT 22 2019

Quick hitting storm force winds are done now and the wraparound part 
of the storm will move in for early in this forecast period. The 
wind gets up close to gales through Wed and there could be a few 
gale force gusts at times across Lake Superior, but will not go with 
any gale warnings for now as the low is weakening and pulling away 
for this early forecast. After Wed, next strong wind event would be 
Fri night and Sat where the wind would get up to 30 knots out of the 
south and southwest. There could be a few gale force gusts in 
western Lake Superior, but confidence is low right now.

Upper Michigan...
  Lakeshore Flood Advisory until 8 PM EDT this evening for MIZ013.

  Lakeshore Flood Warning until midnight EDT tonight for MIZ014.

Lake Superior...
Lake Michigan...
  Gale Warning until 8 PM EDT this evening for LMZ221-248-250.



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