741
FXUS63 KAPX 170418
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
1218 AM EDT Sat Aug 17 2024

.KEY MESSAGES...

- Showers and a few thunderstorms continue into Saturday night.
  Locally heavy rain possible.

- Pleasant stretch of weather next week.

&&

.UPDATE...
Issued at 1058 PM EDT Fri Aug 16 2024

Synopsis: 00z surface analysis shows a 1005m occluded low over
Wisconsin...with some semblance of a warm front extending east
across central Lower Michigan.  Parent upper level low over northern
Wisconsin per water vapor imagery...one short wave trough spun
across Michigan earlier today and now extends along the St. Mary`s
River and into far northern Lake Huron...while a second wave rotates
around the southern periphery of the circulation across Wisconsin
heading into Lake Michigan.  These two waves are driving much of the
precipitation coverage over the upper Lakes this evening...with a
couple of main bands of rain extending from far eastern Upper into
southern Ontario...and a second crossing central/southern Lake
Michigan with some scattered convection in between across the
forecast area.  Moist air mass in place across the Great Lakes with
precipitable water values around 1.50 inches...widespread surface
dew points in the 60s across Michigan with some lower 70s across
Lower Michigan.  00z APX sounding had just over 400J/kg MLCAPE with
minimal CINH...thus the late day convection bubbling up.

Forecast Update: Occluded system will very slowly translate east
overnight across the upper Lakes...eventually getting into Lower
Michigan Saturday morning.  Thus rain chances will continue
overnight ahead of the approaching upper low...with an uptick in
precipitation coverage expected over northern Lower.  Weak flow and
high ambient moisture will continue the localized heavy rainfall
threat...along with areas of fog.

&&

.SHORT TERM /THROUGH SUNDAY/...
Issued at 324 PM EDT Fri Aug 16 2024

Pattern/synopsis: Stacked low, now over nw WI, will make slow
progress toward and across central/northern lower MI thru
Saturday.

Forecast: Southwest sections finally starting to break out into
some peeks of sunshine, though shallow stratocu still lingers.
Upstream MlCape values are near or in excess of 1500j/kg in WI,
but we`re still just starting to destabilize over here, and will
not see instability nearly that high. Perhaps 1000j/kg develop
into nw lower MI by early evening. Deeper shear is also
unimpressive (less than 25kt); we`re too close to the upper low
for much in the way of mid- level flow. Perhaps a stronger/
severe storm with gusty winds could push into nw lower MI thru
evening (especially to the sw of TVC). But this is an
unimpressive threat, and will continue to /not/ message it too
aggressively.

Showers/embedded storms will become more widespread again
tonight, as falling heights with the upper low approaching more
then compensating for loss of surface-based instability.
Numerous showers return to nw and n central lower MI this
evening, and expand into ne lower MI and parts of eastern upper
MI overnight. Cell movement will become slower as wind fields
weaken, and locally heavy rain will again emerge as the main
threat for overnight.

Reasonably widespread convection continues Saturday, with the
upper low slowly transiting northern MI. Probably just enough
surface heating to contribute a hint of instability by
afternoon. Winds fields and shear are negligible, and the
skinny MlCape of up to 300j/kg will not be enough for severe.
But locally heavy rain will persist with slow-moving cells,
especially in northern lower MI.

Low temps mid 60s. Max temps low-mid 70s, warmest in the eastern
UP.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Issued at 324 PM EDT Fri Aug 16 2024

Pattern Synopsis and Forecast:

The large area of upper level low pressure centered across northwest
Minnesota will drift across northern Michigan during the day
Saturday. Moisture/weak lift will linger into Sunday. This is
expected to result in mostly cloudy skies and additional showers
Saturday night and even Sunday across some areas (mainly along and
east of I-75). Drier air then advects into the region Sunday night
with increasing ridging in control through much if not all of the
work week. This setup should promote nearly ideal conditions with
mostly clear skies, low humidity and very comfortable temperatures.
No rain will be in the forecast from Monday through Friday (removed
any rogue slight chance pops). Highs through the period will slowly
warm through the 70s with lows in the mid 40s to mid 50s.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1216 AM EDT Sat Aug 17 2024

Plenty of low level moisture around should lead to IFR/LIFR fog
and tonight into Saturday morning...along with periodic showers
and some thunderstorms. Showers may be most numerous across
northern Lower on Saturday...with IFR/MVFR flight conditions
expected.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.

&&

$$

UPDATE...JPB
SHORT TERM...JZ
LONG TERM...AJS
AVIATION...JPB