785
FXUS63 KMQT 091816
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
216 PM EDT Thu May 9 2024

.KEY MESSAGES...

- Clipper system brings chances for thunderstorms to the far
  western areas of Upper Michigan Friday afternoon and Friday
  evening.

- Chances for thunderstorms return on Sunday for the west and
  central portions of the Upper Peninsula.

- Multiple passing low pressure systems will keep rain and
  thunder chances in the forecast next week, but uncertainty on
  timing and track remains.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 216 PM EDT Thu May 9 2024

Deeper moisture associated with a midlevel trough pivoting
through the Lower Great Lakes continues to settle south of the
forecast area. Meanwhile, a shortwave ridge axis extends
northeastward from eastern MT to near Hudson Bay. Strong
subsidence between these features continues to spread into the
UP, and surface ridging will continue to build in overnight.
Very dry airmass evident on low- level water vapor imagery
supports model forecast PWATs falling to around 0.25 inches, or
-1 to -2 standard deviations tonight. Diurnal cu/sc exist in
various areas across the UP this afternoon, including along a
convergence boundary where better low-level moisture still
exists on the inland side of the Lake Michigan lake breeze
circulation. These should quickly dissipate with the loss of
diurnal heating tonight, leaving mostly clear skies aside from
possibly a bit of midlevel cloudiness over the eastern UP. It
looks like an ideal setup for radiational cooling, especially
over the western half where the high will be centered, so took
low temps down a couple of notches by blending in METMOS
guidance. This should yield upper 20s over the west half and
low/mid 30s elsewhere.

&&

.LONG TERM /TONIGHT THROUGH WEDNESDAY/...
Issued at 447 AM EDT Thu May 9 2024

Dry weather ends Friday afternoon as shortwave over the
Manitoba/Ontario province line dives southeast into Upper MI and WI.
Mixing ahead of the shortwave is expected to result in lower RHs
into the upper 20s to 30s. That being said, there are no major fire
weather concerns as highs for the day are expected in the mid 50s to
mid 60s (cooler near the lakeshores), winds are expected to remain
light below 15 mph, and precip is on the way. Some lake breezes are
also likely late morning/early afternoon off both lakes which should
help RHs recover some and result in some variable winds. PVA kicks
off showers mainly after 2 PM EDT over the far west. As the cold
front moves east over the UP then, showers move east with it. With
mid level lapse rates ~7C/km and the 5/9 0z HREF mean MUCAPE around
100j/kg (individual models plotting up to 200-400j/kg) there is a
slight chance for thunderstorms over the far western UP. That said,
bulk shear is lacking (mainly below 25 kts) and the forcing
mechanisms do not appear as strong later in the day. Severe weather
is not expected. Chances for showers continue east across the UP
Friday night as temps fall into the mid 30s to mid 40s.

As the trough moves southeast toward New England on Saturday,
additional shortwave energy advects over the UP suppling enough
forcing for some slight chances of showers, mainly over the east on
Saturday. Chances for showers and thunderstorms return again on
Sunday as a sfc low over northern Ontario moves east, tracking a
cold front across the UP. As we move into next week, there are
discrepancies on precip timing and track and thus confidence
diminishes. The GFS has a weak shortwave for later in the day Monday
forcing some showers and potentially thunderstorms while the ECMWF
stays dry with sfc ridging extending over the UP through Tuesday.
The next best chances for showers and thunderstorms arrive mid to
late next week when a shortwave riding east along the U.S./Canada
border earlier in the week arrives at the Great Lakes. With current
spread in the guidance, opted to leave NBM chance PoPs as is.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 153 PM EDT Thu May 9 2024

VFR conditions are expected to prevail throughout the TAF period. A
patch of SCT/BKN stratocu around 3.5kft will likely linger through
the evening, but clear skies will return overnight. Northerly to
northeasterly winds will continue to gust around 20 kt for the
remainder of the daylight hours before becoming light and variable
overnight.

&&

.MARINE...
Issued at 447 AM EDT Thu May 9 2024

Northeast winds of 15-25 kts will diminish this morning, falling
back below 20 kts across the lake as high pressure builds over the
lake and stability increases. With this weak high pressure
maintaining over the lake through tonight, winds likely will remain
below 15 kts into the weekend as the stability remains. The
exception to this is Friday night behind the cold front when the
combination of cold air advection and downsloping off the
northwestern shores of the lake may result in some gusts nearing 20
kts along the lakeshore areas. Some thunderstorms over the far
western portions of the lake are also possible with the passing cold
front. Winds increase to around 15-20 kts on Sunday as another cold
front passes over the lake; some thunderstorms over the west half of
the lake are possible with this cold front as well. Winds
otherwise hold around 10-20 kts into the early parts of next week.

&&

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

&&

$$

SHORT TERM...Thompson
LONG TERM...Jablonski
AVIATION...Thompson
MARINE...Jablonski