FXUS63 KMQT 190857

Area Forecast Discussion
National Weather Service Marquette MI
457 AM EDT Thu Sep 19 2019

.SHORT TERM...(Today and tonight)
Issued at 437 AM EDT THU SEP 19 2019

Active morning with periods of very heavy, efficient rain moving
across the south central and east. Radar estimates show widespread
0.5-1.0 inch rainfall estimates across the south central with
embedded swaths of 2+ inches in spots that saw a few rounds of
stronger storms and heavy rainfall. This convection was anchored to
stout 925-850mb moisture transport, associated with a 30+ low-level
jet lifting across the area. Elsewhere, stratus began to lift
northeast as southwest flow continued to advection low-level moist
air into the region.

Today's forecast will be tricky, as the weakening, washed-out front
stalls across the south central and east half of Upper Michigan,
maintaining persistent, albeit gradually weakening, moisture
transport. This lingering deeper moisture, and a weak shortwave
progged to move in from the west later today/tonight looks to keep
chances for showers and storms throughout the day and tonight,
especially across the south central and east. However, given how
washed out the front is confidence is not high in regards to
coverage, and just how far west convection may develop later on
today. Given that the deeper moisture has stalled with the weakening
front, PWATs look to remain around 1.5 inches, so any stronger
storms will be more then capable of producing efficient, heavy
rainfall. If storms do consistently train, there could be some minor
hydro concerns - mostly in the form of ponding of water on roadways,
especially in poor drainage areas. Due to the uncertainty in
precipitation coverage over southern Schoolcraft County later today,
did opt to issue the beach hazard statement to highlight the high
swim risk for today.

Temperatures should climb into the 70s today, with mild temperatures
expected again tonight. As winds relax overnight, the above
mentioned washed-out, stalled front will allow for moisture to
linger and thus the development of fog tonight.

.LONG TERM...(Friday through Wednesday)
Issued at 456 AM EDT THU SEP 19 2019

A warm pattern continues across the Upper Lakes due to a western
CONUS trof and a ridge extending n thru the Great Lakes region. At
least thru the first half of the weekend, the warm conditions (above
to much above normal temps) and humid conditions for mid Sept will
continue under sw flow as the western trof shifts east. The trof
will cross the western Great Lakes Sun, and this will result in
cooling early next week, bringing temps back down toward normal. For
the remainder of next week, medium range models over the last 24hrs
or so have trended toward better consistency and agreement on the
pattern. Next shortwave trof reaching the western CONUS early next
week will drop out of the westerlies, cutting off over the sw CONUS.
This will allow for a progresive flow vcnty of the northern
CONUS/southern Canada with the next shortwave amplifying a bit as it
reaches the Upper Great Lakes midweek. Late week, there are
indications for at least temporary renewed western CONUS troffing
and eastern CONUS ridging. So, under the expected evolution of the
pattern next week, early week cooling toward normal temps will be
followed by brief warming Tue, then cooling again midweek (back to
around normal) due to the approach and passage of shortwave. Warming
will get underway again late week provided the western trof/eastern
ridge configuration takes shape. As for pcpn, mid-level trof
arriving Sun will provide the next meaningful chc of shra/tsra Sat
aftn/night as associated cold front moves across the area. Dry
weather will then follow until the next shortwave trof arrives

Beginning Fri, low clouds/fog will probably expand tonight, and if
so, light southeasterly low-level winds on Fri will help the low
clouds/fog potentially to persist into the afternoon for some
portions of the fcst area, especially closer to Lake MI. Even where
low clouds/fog lift, may end up with quite a bit of stratocu given
the abundant low-level moisture. Best chc of seeing more sun Fri
aftn will be over the w. Can't totally rule out isold convection,
but with weak shortwave exiting and 500mb heights rising a bit, pcpn
chance appears very limited, especially in light of capping seen on
fcst soundings and minimal low-level forcing due to light winds.
Will be another warm/humid day with high temps in the 70s F and
dwpts 60-65F. Fog/stratus may expand again Fri night, especially
east half under southerly upslope winds off Lake MI. Will be an
unseasonably warm night with min temps around 60 to the mid 60s F.

Mid-level trof moving out across the Plains on Sat with associated
cold front approaching the Upper Mississippi Valley will result in
increasing southerly winds. With mixed layer winds to around 25kt,
should become a breezy day with winds gusting to 20-30mph, strongest
west. Showers/t-storms should arrive over the w half of the fcst
area during Sat aftn and then progress eastward during the evening.
Although better shortwave dynamics will be lifting into northern
Ontario and favorable right entrance upper jet forcing will overlay
the front after it passes the fcst area, there will be the potential
for hvy rainfall with any tstms as precipitable water will be
running 1.5 to 1.75 inches, upwards of 250pct of normal.

With the cold front clearing the area Sun morning, dry weather will
return Sun, and conditions will become less humid under breezy
westerly winds. Under a favorable west wind direction, fairly tight
pres gradient and at least weak CAA, winds could gust 35-40mph on
the Keweenaw Sun. A secondary shortwave will be dropping thru the
passing trof on Sun, but given limited instability and forcing
passing by to the n, not expecting any pcpn.

Dry weather will continue Mon and probably Tue as mid-level ridge
shifts e, arriving Tue morning. Next shortwave arriving Wed will
bring the next chc of showers Tue night/Wed with dry weather
returning in its wake on Thu.

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 122 AM EDT THU SEP 19 2019

Scattered showers ended at KSAW while low level jet will bring LLWS
to KSAW through the early morning hours. VFR ceilings are expected
at KIWD and KCMX, with KSAW seeing ceilings lowering to MVFR with
moisture pooling along the surface boundary. While all three sites
will be VFR after sunrise this morning. KSAW will continue to see a
possibility of showers in the due to proximity of the surface
boundary. There is the potential for fog development late in the
forecast, especially at KSAW where better low level moisture to
exist, and also possibly at KCMX. Potential for fog increases beyond
the forecast period.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 437 AM EDT THU SEP 19 2019

A weakening front sags south of the lake and winds diminish below 20
knots throughout today. This front remains fairly washed out and
high pressure takes hold through Friday night, keeping winds below
15 knots. Saturday through Sunday, southerly winds veers westerly as
a cold front pushes east across the lake. Ahead of and behind the
front, winds of 20-30 knots are expected. It is possible there could
be a window of gales in there as well.

Occasional fog will remain possible through the end of the week,
likely until we can get drier air to move in with a stronger cold
front arriving over the weekend. The most likely locations for fog
over the west half today, especially near the Arrowhead of Minnesota
and Isle Royale. Heavy rain associated with thunderstorms that move
over the east half of the lake may also make for some foggy
conditions this morning.

Upper Michigan...
Beach Hazards Statement through this afternoon for MIZ014.

Lake Superior...
Lake Michigan...


SHORT TERM...Ritzman
LONG TERM...Rolfson
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