Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 222006
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
406 PM EDT Thu Jun 22 2017

.SHORT TERM...(This evening through Friday)
Issued at 406 PM EDT THU JUN 22 2017

Water vapor imagery and RAP analysis show a deep mid-level low over
southern Manitoba (500mb height anomalies around 230m). Low is
embedded in overall broad, low-amplitude troffing centered over
central N America. In the weakly cyclonic flow across the n central
CONUS, shra/tstms have been tracking from the eastern Dakotas/IA
toward Lower MI today, aided by right entrance of 120kt upper jet
extending from northern MN across northern Ontario and low to mid
level frontogenesis. Northern edge of this pcpn extends about as far
n and w as a Watersmeet to Marquette line.

As upper jet axis and frontogenesis drift se tonight, ongoing shra
and isolated embedded thunder will also shift se. Much, if not all,
of the shra should be se of the fcst area by 06z. Otherwise, over
the next 24hrs, the deep mid-level low over southern Manitoba will
open up as it moves ese, with remnant vort max passing across
northern Lake Superior Fri aftn. Ahead of it, another shortwave trof
currently over MT/ND will also shift e, moving across Upper MI late
tonight/Fri morning. Not really anything going on ahead of the
latter wave. Farther w and nw under colder mid-levels, isold shra
are developing in nw ND. Given arrival of wave late tonight/Fri
morning, these shra will likely have dissipated before reaching the
area.

On Fri, remnant of the Manitoba mid-level low will arrive at a more
favorably aligned time with respect to daytime heating. Lingering
low-level moisture over the eastern fcst area combined with Lake
Superior lake breeze aided windshift may support sct -shra over the
eastern fcst area inland from Lake Superior in the aftn. No mention
of thunder was included in fcst. However, with model consensus for
mlcape of a couple hundred j/kg, not out of the question that there
could be a rumble or two of thunder. To the w, cooling mid-levels
under somewhat sharper troffing might support a few sprinkles or an
isolated -shra inland. At this point, lack of instability suggests a
mention of pcpn in fcst is not warranted. Otherwise, looks like a
breezy day under deep mixing. Expect gusts to 20-30mph over the w
and central, strongest over the Keweenaw. Deep mixing should also
support dwpts falling to or blo lowest guidance, but no fire wx
issues given the surplus of rainfall over the last couple of weeks.

.LONG TERM...(Friday through Wednesday)
Issued at 355 AM EDT THU JUN 22 2017

Upper level troughing and resulting cool weather pattern still on
track to begin to settle across Upper Great Lakes on Fri. Main sfc
low near 1000mb starts day over northern Ontario with lead cold
front already east of the forecast area by daybreak on Fri. Weaker
front may slide across through the day but deep drying should result
in mainly dry conditions. Suppose with pooling of 50-55F dwpnts off
northern Lk Michigan and Green Bay and temps into the 70s could see
up to 250j/kg of sbcape and potential for isolated showers over the
southeast especially if there is any type of additional forcing from
shortwave trough working through. With upper level jet axis still
overhead into the aftn ahead of upper troughing, could also be
pockets of upper level divergence to help convection along. Limited
moisture will keep chances very low.

Upper trough expands over the Great Lakes this weekend into early
next week. Daytime highs will stay below normal. Coolest days will
be Sat and Sun as stronger shortwave trough and enhanced rain
chances affect area (Sat) and with lowest temps aloft rotating
across (Sun). Readings both of these days will be in the upper 50s
near Lk Superior and into the upper 60s far south central. Steep mid
level lapse rates up to 6.5-7c/km at times with several shortwaves
and pockets of enhanced moisture and sfc troughs wrapping through
the region within the large scale trough will lead to daily chances
for showers and some thunderstorms Sat through at least Mon, with
maximum coverage occurring during peak heating late morning through
aftn into early evening and/or when stronger shortwaves come across.
On days the thunderstorms are stronger, at least small hail would
occur. Could also see some more cold air funnel episodes (similar to
what occurred Mon of this week). As water temps warm up on Great
Lakes, getting to the point where this type of upper trouging/cold
air advection regime could even lead to waterspouts, though waters
may be just cool enough to not support that at this time.

Troughing begins to break down by middle of next week. Temperatures
should warm back toward normal levels and the periodic chances of
rain should end at least for a day or two. By late next week should
see rain chances increase yet again as strong low crossing central
Canada and cold front extending south across the plains allows warm
and humid air to stream north into the Upper Great Lakes.
&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 135 PM EDT THU JUN 22 2017

VFR conditions will likely prevail at KIWD/KCMX/KSAW thru this fcst
period. Per radar imagery, some -shra will affect KSAW this aftn,
but do not expect conditions to drop out of VFR as heavier pcpn will
pass by to the s of the terminal. Gusty winds will develop Fri
morning, especially at KCMX which is more exposed to westerly winds.
Gusts up to 30kt are expected late morning thru the aftn.
&&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 406 PM EDT THU JUN 22 2017

Vis satellite imagery has given hints of patchy fog on Lake Superior
today. This patchy fog may linger tonight and then perhaps thru Fri
over far eastern Lake Superior. Winds will remain generally below
20kts into early next week. Stongest winds should occur later
tonight thru Fri evening when gusts may reach 20-25kt at times.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&

$$

SHORT TERM...Rolfson
LONG TERM...JLA
AVIATION...Rolfson
MARINE...Rolfson



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