Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 200752
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
352 AM EDT WED JUL 20 2016

.SHORT TERM...(This evening through Wednesday)
Issued at 314 PM EDT TUE JUL 19 2016

Upper ridge centered from southern Plains to south central Canada
shifts slightly east into Wed. At the sfc, high pressure over the
Great Lakes bringing quiet weather to the cwa late this aftn into
this evening will slide east while trough over the northern plains
slowly eases east. Warm front tied into trough over the plains will
stay southwest of Upper Michigan, keeping the extreme heat/humidity
over the northern Plains to the Mississippi River valley. Attn in
short term is on stronger shortwave currently in at least a couple
pieces moving into southern Manitoba and over central ND. May also be
an additional wave forming wnw of these two, though that really has
not taken shape yet.

Expect as this area of shortwave energy tops the ridge it will slide
across northern MN to northern WI and western Upper Michigan late
tonight toward daybreak on Wed. MUCAPE over 3000j/kg stays anchored
over northern plains beneath sharp ridge but gradient of MUCAPE will
be located from MN into Upper Michigan. h85-h3 thickness indicate
that if organzied shra/tsra top the ridge or redevelop later this
aftn/evening they would track over at least parts of Upper Michigan
into Wed morning. 0-1km shear over 20 kts indicates that complex
could maintain strength as it moves through. Overall there is a
least a small chance of severe storms - damaging winds would
probably be the primary hazard with a forward propagating MCS-moving
over parts of Upper Michigan late tonight into Wednesday morning.
Given there is already a well developed shortwave that will be
tracking across and persistent tsra, along with h85 convergence/warm
air advection that should be maintained thanks to that wave aloft,
does appear that chances of showers/storms moving through is
favorable. Not sure on the extent of severe weather though.

Additional shra/tsra on Wed a bit more uncertain. Does appear that
there is stronger subsidence/drying in the wake of the cluster of
shortwave energy currently topping the ridge aloft. This shows up as
large area of darkening on WV loop fm southern Saskatchewan sw
across MT so it is conceivable that after activity moves through in
the morning, the rest of the day may be more quiet. Could also see
outflow boundaries from the morning shra/tsra help to focus more
shra/tsra during peak heating in the aftn/evening hours. MLCAPEs
rise up over 1000j/kg in the aftn so if the focus for lift is there,
certainly could see stronger storms. At least now though it appears
larger scale lift from additional storms looks on the smallish side
and it may become overall more capped h8-h7 as the day progresses.
For pops/wx will ride with higher chances in the morning dropping
off to slight chances in the aftn. SPC has all the area in Margainal
risk on Wed. That seems reasonable with uncertainty on strength of
storms in the morning and questions about redevelopent in the aftn.

With the idea that shra/tsra will be less in the aftn, looks like it
could get hot mid-late aftn into early Wed evening. H85 temps top
out at least if 20c if not 21-22c. Soundings suggest mixing height
may be 50-75mb lower, but still should see max temps push toward the
90 degree mark or even low 90s over much of western cwa. Mid-upr 80s
elsewhere. Dwpnts rising well into the 60s seems reasonable based on
upsream readings today. Could see max apparent temps into the mid
90s over west cwa, as long as skies stay mostly sunny in the aftn.

.LONG TERM...(Thursday through Tuesday)
Issued at 352 AM EDT WED JUL 20 2016

Nam shows a 500 mb ridge across the central U.S. with a trough on
both coasts and the upper Great Lakes in the ring of fire with the
westerlies just to the north of the area. Any little shortwave that
tops the ridge could kick off some convection and this will be hard
to forecast and time these for this forecast period. For this
reason, confidence is low with this forecast for Thu. Forecast
hinges on MCS development tonight and how much clouds and
instability occur for Thu along with heating. Will go middle of the
road for now and go chance pops. Do not want to go with likely pops
for Thu at this point. WIll go with less convection right now which
will lead to more heating and ended up raising temperatures in a few
places. Heat indices get up close to 100 in a few spots and will
highlight this in the hwo product. The slight risk for Thu for our
area also seems warranted with large hail and damaging winds being
the main threat. Cold front moves through on Thu night and then
dries out Thu night into Fri and continued dry for Fri into Fri
night. Did not make too many other adjustments to the forecast for
temperatures beyond Thu.

In the extended, GFS and ECMWF show a broad 500 mb ridge over the
southern U.S. 12z Sat with a broad trough in the pacific nw and
northern Rockies. The shortwave in the northern Rockies heads east
into the upper Great Lakes and brings a cold front through the area
12z Sun with some cooler temperatures coming back for early next
week. This shortwave moves over the top of the ridge and digs into
the Great Lakes region on Mon into Tue with the ridge starting to
build up again in the Rockies on Tue, so a return of warmer air will
be in the near future. Temperatures will remain above normal for
this forecast period. Have some pops in for Sat into Sun with likely
pops in for Sat night. Starts to dry out Mon with cooler and drier
air moving in and have Mon night and Tue dry for now.
&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 126 AM EDT WED JUL 20 2016

Although high pres is departing, vfr conditions will prevail at
KIWD/KCMX/KSAW thru this fcst period. As heat and moisture push back
into the area on s to sw winds behind the high, some shra/tsra could
develop this morning. Since confidence remains low, retained only a
vcsh mention.
&&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 314 PM EDT TUE JUL 19 2016

Winds will stay below 20 knots through the forecast period under
relatively a weak pressure gradient and high overwater stability.
Warm and humid air will flow across Lake Superior Wednesday through
Friday, which will allow fog to form, locally dense at times.
&&

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

$$

SHORT TERM...JLA
LONG TERM...07
AVIATION...Rolfson
MARINE...JLA


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