Small Craft Advisory 79, NWS Gaylord, MI

Area Forecast Discussion
National Weather Service Gaylord MI
704 PM EDT Thu Sep 26 2019

.NEAR TERM...(Through Tonight)
Issued at 357 PM EDT Thu Sep 26 2019

High Impact Weather Potential: Minimal

Synopsis/Forecast: Overhead troughing is swinging off to our east
this afternoon. Morning showers have completely diminished and skies
have become partly cloudy. Our current Cu field is eroding from the
southwest as drier air under surface high pressure moves through the
nrn Ohio Valley. Gusty westerly winds have been very slow to decline
through the day as plenty of mechanical turbulence has counteracted
the calming nature of the surface high. The core of drier air
quickly moves off to our east early tonight as winds swings out of
the south on the backside of the high. This will bring plenty of
moisture back into the picture as PWATs climb from their low point
of less than 0.5" this afternoon to back around 1.0" tomorrow
morning. Soundings suggest we'll saturate top-down overnight
tonight, with a midlevel cloud (already encroaching into the upper
Mississippi Valley) moving into our region around midnight. There
will finally be a lull in the winds tonight before they ramp up
again (out of the south) early morning as the next surface low
moving into the Dakotas. Guidance is in good agreement with its
track and intensity as it deepens across the upper Mississippi
Valley into Ontario. Clouds will lower and start to increase in
coverage through late tonight and tomorrow with the approach of the
next low pressure system. Overnight lows will be kept from bottoming
out too much with WAA and midlevel cloud cover.

&&

.SHORT TERM...(Friday through Sunday)
Issued at 357 PM EDT Thu Sep 26 2019

High impact weather potential: Slight chance of thunderstorms Friday
afternoon and evening, mainly along and south of M-32. Locally heavy
rain also possible.

Pattern synopsis/forecast: Progressive pattern expected to end this
week, driven in large part by extended upper level jet stretching
across the entirety of the northern Conus this afternoon. Mid level
shortwave trough tucked under this upper jet core will race
northeast out of the northern Plains tonight...reaching central
Ontario by Friday evening. Attendant strong warm/moist advection
regime looks to bring our next widespread rain event Friday. Brief
return of high pressure to start the weekend gives way to northward
bowing baroclinic axis on north side of maturing southeast
subtropical ridge Sunday, bringing more rain chances along with it.

Primary forecast concerns/challenges: Addressing heavy rain concerns
and isolated thunder threat on Friday....potential for some patchy
frost Saturday night...and those additional shower chances to end
the weekend.

Details: Rapid development of deep southwest flow will usher in a
much more moist airmass into the region on Friday...all of this
occurring ahead of developing low pressure and its attendant cold
front across the far western Great Lakes. Precipitable water values
still expected to spike up to around inch and a half values across
northern Lower, with a bit lesser amounts as one goes north. Expect
shower coverage to increase during the day, becoming fairly
widespread during the afternoon and evening hours when enhanced low
level convergence is overtopped by passing mid level wave and
favorable upper jet dynamics. All surface rooted cape expected to
pass to our south and southwest, although elevated cape of several
hundred joules/kg expected to spread across much of northern lower
during period of max forcing and moisture advection. This supports
at least some elevated thunderstorm potential, although expect any
severe weather to remain well off to our southwest. Placement and
organization of upstream convection will likely have plenty to say
on eventual placement of heaviest rain axis. Pattern recognition
fits latest guidance trends of heaviest rains tied to more organized
deep convection passing by just to our south (as evident by latest
WPC excessive rain outlook placing slight risk wording to our
southwest, with northern Michigan remaining under marginal risk).
Still think some decent rain totals are possible (especially the
further south one goes), with rain totals perhaps exceeding an inch
by the time the most widespread showers end later Friday night.
Despite wet ground from recent rain, area drainage basins should be
able to handle this additional rainfall. Of course, any heavy
rain rates will be able to produce brief ponding on area roadways.

Cold front expected to exit stage right overight Friday, ending the
shower threat in the process. Start of the weekend still looks dry
and seasonably cool as Canadian high pressure builds into the
northern Great Lakes. Mostly clear skies, especially Saturday
evening, and a cool overhead airmass does support some chilly
overnight lows Saturday night. With that said, not sure full
decoupling will be realized with center of high pressure passing by
to our north. Combine that with what should be some increasing late
night high clouds and one has to wonder just how cold temperatures
become. Noticed latest statistical guidance has trended a bit
"warmer", dipping our coldest locations into the mid and upper 30s.
Cold enough to produce some patchy frost in sheltered areas, but as
far as a widespread frost (headlines?)...just not seeing that given
latest trends.

Plenty of uncertainty on Sunday with regards to additional rain
chances as dry east low level flow undercuts strengthening elevated
moisture return. Increasing mid level heights on northern flank of
maturing subtropical ridge also may act to hinder rain chances some.
And no doubt best moisture convergence and dynamics remain well west
of our area through the day. Current just chancy pop idea will
suffice for now, with still plenty of time to work out the finer
details in the coming days.

.LONG TERM...(Sunday night through Thursday)
Issued at 357 PM EDT Thu Sep 26 2019

High impact weather potential: Perhaps more significant rain early
next week?

Western trough/eastern subtropical ridge configuration looks to
reach maturity heading into the beginning portions of next week.
Still plenty of uncertainty on just how far north active low level
baroclinic axis will be displaced, although expected proximity of
this zone supports additional shower and thunderstorm chances right
through this period. Will definitely need to monitor, as pattern
recognition supports some significant rain totals as passing waves
ejecting from western trough interact with what should be an
excellent supply of subtropical moisture. Of course, plenty of
changes are possible, if not expected, as yet to be determined
mesoscale convective processes will have plenty to say on the exact
placement of the baroclinic zone.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 700 PM EDT Thu Sep 26 2019

High pressure will slide south of Michigan tonight as a cold front
enters the Western Great Lakes region by Friday morning. Chances
of showers will increase Friday morning as this feature approaches
Michigan...with widespread showers and possibly a few
thunderstorms expected for all of Northern Lower Michigan Friday
afternoon and evening as the front swings thru our region.
Conditions will gradually deteriorate to MVFR as widespread precip
develops during this time. Southerly winds ahead of the front will
strengthen to 15 to 25 kts by midday Friday...with a few higher
gusts possible. Also...LLWS will develop very late tonight into
Friday morning.

&&

.MARINE...
Issued at 357 PM EDT Thu Sep 26 2019

Gusty westerly winds slowly subside through this evening. There will
be a brief lull in wind intensity tonight as they switch around to
out of the south-southwest, but the nearshore waters will still
remain in near craft advisory criteria through the night. Winds ramp
up quickly tomorrow morning as a new low pressure system moves into
Ontario, and drags a cold front across our region. Shower chances
start to move into Lake Michigan shortly before sunrise, and last
through the day Friday.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...BEACH HAZARDS STATEMENT until 8 PM EDT this evening for MIZ016-
     020-025-031-099.
LH...SMALL CRAFT ADVISORY until 7 AM EDT Saturday for LHZ345>349.
LM...BEACH HAZARDS STATEMENT until 8 PM EDT this evening for LMZ346.
     SMALL CRAFT ADVISORY until 5 PM EDT Friday for LMZ323.
     SMALL CRAFT ADVISORY until 8 AM EDT Friday for LMZ341-342-
     344>346.
     GALE WARNING from 8 AM to 5 PM EDT Friday for LMZ341-342-344>346.
LS...SMALL CRAFT ADVISORY until 7 AM EDT Saturday for LSZ321-322.
&&

NEAR TERM...STJ
SHORT TERM...MB
LONG TERM...MB
AVIATION...MR
MARINE...STJ