007
FXUS63 KMQT 090859
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
459 AM EDT Tue Jul 9 2024

.KEY MESSAGES...

- Scattered showers and thunderstorms this afternoon along the
  Lake Superior lake breeze.

- Overall, a drier pattern is upcoming compared to the last few
  weeks. Though some areas of 15-35% chance of precipitation
  continue into the weekend, most locations will see several
  days of dry weather.

- Very warm over the weekend with high temperatures well into
  the 80s F. A 10-20% chance of high temperatures at or above
  90F.

&&

.SHORT TERM /THROUGH THIS AFTERNOON/...
Issued at 155 AM EDT Tue Jul 9 2024

GOES-16 nighttime microphysics imagery shows mostly clear skies
across the U.P. early this morning. However, some localized fog has
been seen near K.I. Sawyer, with patchy fog looking to develop
across much more of the interior areas of Upper Michigan the rest of
the pre-dawn hours as the mostly clear skies will allow temperatures
to bottom out to the dewpoint. Once we get past sunrise, expect the
patchy fog across the area to burn-off.

Expect sunny skies over Upper Michigan today as another very weak
shortwave moves through the area and a surface high pressure sets up
over Lake Superior. This surface high will allow the Lake Superior
lake breeze to dominate the wind profile by the afternoon hours. In
addition, the forcing from the lake breeze and the CAPE produced by
the sunlight will allow some lake breeze rain showers and
thunderstorms to form by the afternoon hours. While we may see the
convection start up in the north central initially early this
afternoon, expect the rain showers and thunderstorms to move with
the Lake Superior lake breeze boundary further south with time;
expect the rain shower and thunderstorm activity to be relegated to
around the northern half of Menominee County by the late afternoon.

Overall, outside of the rain showers and thunderstorms, today should
be another fairly pleasant day. The highs could get to around 80 in
the interior areas, whereas near Lake Superior the highs will be
closer to the low 70s.

&&

.LONG TERM /TONIGHT THROUGH MONDAY/...
Issued at 459 AM EDT Tue Jul 9 2024

While medium range models show some differences in the amplitude of
the flow across Canada and the U.S. over the next 7 to 10 days, the
upcoming pattern progression is generally well agreed upon. Western
N America mid-level ridging is currently forcing troffing over
central N America. Over the next few days, a shortwave moving off of
the ne Pacific into Canada will flatten the ridge and force height
rises/positive height anomalies to spread downstream across southern
Canada. A second wave will quickly follow off of the ne Pacific late
week. As ridging then rebuilds over western N America, that wave
will be forced se, leading to modest trof amplification over eastern
Canada and the ne U.S. during the mid week period next week. For
Upper MI, this evolution of the pattern will support an overall
drier pattern as compared to the last several weeks. While there may
yet be additional isold aftn shra/tsra driven by modest aftn
instability inland from Lake Superior on Thu/Fri (15-20pct chc), dry
weather will prevail for the vast majority of the fcst area. There
are indications for a shortwave to pass early weekend, and that
should expand the area for potential isold/sct shra/tsra. The next
potential of a greater coverage pcpn event as well as possible svr
storms will be late weekend/early next week in association with the
onset of eastern troffing. As for temps, the spreading of positive
height anomalies downstream across southern Canada will herald a
warming trend beginning Thu, leading to a very warm/humid weekend
with highs well into the 80s to 90F. Cooler weather will follow once
eastern troffing develops early next week. Looks like there will be
a couple of pleasant U.P. summer days in the midweek period next
week as Canadian high pres settles over the Great Lakes region.

Beginning tonight, any lingering shra from this aftn over s central
Upper MI will end around sunset. Quiet conditions overnight should
lead to patchy fog development over the w where lower level wind
fields are lightest. To the e, light nne winds off of Lake Superior
into the n central and eastern fcst area may end up leading to
widespread stratus/fog development as moist marine air advects
inland/upslopes off of the lake and over land where air temps will
be falling to around the dwpt temp of the marine layer air advecting
off of the lake. This will be all the more likely if fog/stratus is
over the lake today. Current GOES night-fog imagery does in fact
show fog over portions of northern and eastern Lake Superior, and it
seems unlikely that this fog would disperse today. So, expanding
stratus/fog seems like a good bet into the n central and e tonight.

With onshore winds on Wed, low clouds/fog may end up dominating the
day from around the Marquette area to Munising, along Pictured
Rocks, to Grand Marais. Otherwise, on Wed, the remnants of Beryl
will be passing by to the s and se of the fcst area. In the aftn,
general model consensus is for ~200-500j/kg of MLCAPE to build. Best
potential of isold/sct convection owing to the instability will be
where low-level flow has some convergence due to the influence of
the Lakes. Models point toward eastern Upper MI, closer to Lake MI,
as a focusing area and also interior western Upper MI though signal
is a little weaker in that area. Due to the deep layer flow around
Beryl, any shra/tsra will move from ne to sw over the e and from n
to s over the w. High temps will range from the lwr 60s lakeside
from around Marquette eastward to around 80F interior w.

Any lingering shra will end around sunset Wed evening. Some
fog/stratus may continue to persist into the eastern fcst area Wed
night. Otherwise, a quiet night with little/no wind may support some
radiation fog development again.

On Thu, models indicate a bit more instability will build compared
to Wed aftn, but drying column aloft may prevent instability from
yielding any shra/tsra across the fcst area. For now, fcst will
reflect a 15-20pct chc of shra/tsra across interior central in the
vcnty of the Lake MI and Lake Superior lake breezes. Any shra would
likely be short-lived due to 15kt or less of deep layer shear. Fri
may be a similar setup to Thu, but light southerly gradient flow on
backside of high pres would bring any potential isold convection
closer to Lake Superior compared to Thu.

Over the weekend, warming under sw flow will send high temps well
into the 80s F. Ensemble guidance indicates a 10-20pct chc of
widespread high temps aoa 90F. This probability increases near Lake
Superior in areas that see downsloping under s to sw winds. Passing
shortwave supports the potential of some shra/tsra later Sat/Sat
night.

Late weekend/early next week, timing of main shortwave that brings
cooling to the area is uncertain. Ahead of that wave, other subtle
waves are indicated to progress thru w to wnw flow into the Upper
Great Lakes. Given the substantial instability that will be avbl
with the very warm/humid conditions over the Upper Mississippi
Valley/Upper Great Lakes, there will be a risk of svr storms.
However, as would be expected at this time range, timing of
shortwaves and resulting convection, including movement of
convection that does develop and whether Upper MI is actually
affected, is highly uncertain. Will be something to monitor over the
weekend/early next week.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 116 AM EDT Tue Jul 9 2024

VFR will be the predominant condition at IWD/CMX/SAW through the
period. There is still potential for fog at SAW/CMX for the
remainder of the nighttime hours. Confidence in periods of fog is
higher at SAW, which saw the most rain this evening; indeed, some
localized fog is being seen on the latest observations and the GOES-
16 nighttime fog product. Any fog that forms will quickly burn off
shortly after sunrise. Light winds and VFR conditions prevail
through the rest of the period. Diurnally driven afternoon
thunderstorms are possible (25-30%) in the interior UP tomorrow, but
are not likely to directly impact any of the terminals.

&&

.MARINE...
Issued at 459 AM EDT Tue Jul 9 2024

A weak pres gradient will dominate over and in the vcnty of Lake
Superior for the next several days. Result will be winds across Lake
Superior under 20kt and often under 15kt. Some increase in winds
will occur over the weekend with high pres to the e and low pres
troffing to the w.

Fog currently plaguing portions of northern and eastern Lake
Superior will expand to the s today/tonight as winds become
northerly. This fog is likely to be locally dense and will need to
assess potential for marine fog advy based on obs, vis satellite
imagery and web cams during the day today. The fog may linger on Wed
across southern portions of the lake, roughly in the area btwn
Granite Island and Whitefish Pt.

&&

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

&&

$$

SHORT TERM...TAP
LONG TERM...Rolfson
AVIATION...TAP/Thompson
MARINE...Rolfson