Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 181913

Area Forecast Discussion
National Weather Service Gaylord MI
313 PM EDT Tue Jun 18 2019

.NEAR TERM...(Through Tonight)
Issued at 312 PM EDT Tue Jun 18 2019

...Few showers possible tonight...

High impact weather potential: Minimal. Low chances for non-severe
thunderstorms into early this evening.

Pattern synopsis/forecast: Subtle mid level wave and just as weak
surface trough making slow progress east into the western Great
Lakes early this afternoon. While overall forcing is weak and
disjointed at best, there is enough that when combined with limited
diurnal instability trends and modest deep layer moisture advection,
is drumming up a few showers and thunderstorms across the region.
Most concentrated activity so far is found across central upper
Michigan where lake breeze interaction has given a boost to surface
trough convergence. Otherwise, some filtered sunshine is being
experienced between passing mid/high level clouds and a diurnally-
driven cu field. Temperatures not too far off from what is
considered normal, with current readings in the upper 60s to middle

Expect mid level wave to dampen further with time as it heads east
tonight, with attendant surface trough axis doing the same.
Lingering limited forcing interacting on a disjointed moisture plume
looks to be just enough to keep at least an isolated shower threat

Primary forecast concerns/challenges tonight: Cloud and temperature
trends and addressing small chances for showers.

Details: "Best" shower coverage expected this afternoon and early
evening, centering on eastern upper (a bit better mid level support
and lake augmented enhanced surface convergence) and across
northeast lower (more lake induced convergence). Few hundred joules
of mixed layer cape looks to be just enough to support a few
isolated thunderstorms. Meager lapse rates and very limited
effective shear (not to mention those low cape values) precludes any
severe potential. Downward spiral of any instability this evening
will end the more organized shower activity and any thunder threat.
Still cannot completely rule out an isolated very light
shower/sprinkle for the overnight, but much of the area and most of
the time will remain dry. Plenty of clouds will keep conditions a
bit more mild than experienced the previous few nights, with lows
ranging from the upper 40s to middle 50s by morning.


.SHORT TERM...(Wednesday through Friday)
Issued at 312 PM EDT Tue Jun 18 2019

...Some showers lingering into Wed night...

High Impact Weather Potential: None.

Flattish 500mb troffing remains over the region initially, thanks to
a stationary upper low over central Quebec. Various ripples rotating
thru the region will interact with diurnal heating to produce precip
chances on Wed. By Friday though, shortwave ridging will build into
the western lakes region, in advance of another upper low over MT.
This will produce drier and warmer wx late this week.

For Wednesday/Wed night, a weak bubble of high pressure will build
into western Superior. Anticyclonic flow and somewhat drier low-
level air will be in place over nw sections vs the se. This will
result in higher pops in the se. Will need a mention of isolated
sprinkles/showers in the morning in portions of northern lower MI.
Lapse rates are not particularly steep, but there are multiple moist
layers present aloft. Overall, the pattern is similar to this
morning, when we had a few marauding sprinkles/showers still hanging
around. By afternoon though, diurnal heating will contribute to
instability and amp up the shower threat somewhat. Substantial
instability will be found downstate and points south; even the
always-moist Nam keeps SbCape values below 300j/kg. But with
differential heating boundaries and lake breezes to work off of,
that should be enough to get sct showers going, mainly se of an MBL-
TVC-Cheboygan line. Meager instability makes thunder unlikely, and
SPC keeps general thunder south of MBS. So will not mention thunder.
Some showers will linger into evening se of a CAD-Rogers line, and
even overnight toward Saginaw Bay. Plenty of cloud cover south of M-
32, just partly cloudy north.

Max temps mainly within a few degrees of 70f. Min temps mid 40s
north (with less cloud cover) to mid 50s se (more clouds).

Looks quieter for Thu and Fri, as heights build aloft (especially
Friday), and surface high pressure builds east from the western
lakes. Layered clouds will continue to be relatively abundant in
the se half of the forecast area Thu morning (and would not rule out
some stray raindrops in the far se), but that will thin in the
afternoon and evening. Some diurnal cu to deal with (especially
Thu), but we are gently capped off by 3C air at 725mb/8k ft on Thu.
Convective debris will return to nw lower MI Fri afternoon. Max
temps will gradually rebound, near 70 to the mid 70s Thu (warmest
eastern upper), mainly 70s on Friday. The beaches will be cooler
each day due to lake breezes. Min temps mid 40s to lower 50s.


.LONG TERM...(Friday night through Tuesday)
Issued at 312 PM EDT Tue Jun 18 2019

500mb ridging dead overhead Saturday corresponds with strengthening
low-level return flow. A deteriorating MCS may make a run at
northern MI by late Friday night into Saturday. That sets the table
for a period of unsettled wx. Shower chances arrives in nw lower MI
Fri evening, with the best chances for rain Sat and Sat night. Hard
to see a window for us to get strongly unstable during the period,
too much cloud cover. But thunder chances are reasonable late
Saturday thru Sunday. Model differences are pretty massive by Sunday
and early next week, with the ECMWF bringing organizing low pressure
across the region, while the GFS is quieter as a baroclinic zone
settles to our south. As a compromise, small chances for
showers/storms persist into early next week, until we gain some
clarity. Max temps mainly in the 70s.


.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 212 PM EDT Tue Jun 18 2019

VFR conditions expected through this evening, with cigs trending
lower overnight into Wednesday morning, likely producing MVFR to
IFR conditions. May see some reduced visibility with fog/mist
development later tonight into early Wednesday. A few showers are
possible, but limited coverage warrants no more than vicinity
wording at this time...and only at KAPN.


Issued at 312 PM EDT Tue Jun 18 2019

A loose pressure gradient will reside over the Great Lakes
through Wednesday with no wind/wave concerns, until winds do
increase some out of the east Wednesday night into Thursday, when
low pressure is expected to cross the Ohio river valley. Attm, no
advisory speeds expected for this as well. There will be a weak
surface trough that will slowly cross nrn Michigan into Wednesday,
that is expected to bring scattered showers (possibly isolated non-
severe thunderstorms into early this evening).




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