Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 201531
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
1131 AM EDT SAT AUG 20 2016

.UPDATE...
Issued at 1054 AM EDT Sat Aug 20 2016

Potent shortwave over Minnesota with strong synoptic forcing
enhanced by 850/300 coupled jet structure into the western Great
Lakes. 1000mb surface low southwest of Green Bay will continue to
deepen as it moves to the northeast through this evening. Pre-
frontal convective line currently pushing across Lake Michigan
will continue to propagate northeast through this afternoon.
Instability still lacking over much of northern Michigan with low
cloud/stratus issues limiting daytime heating toward
Manistee/Cadillac. But more sunshine over eastern areas where
temperatures have pushed toward 80 degrees as of late morning. The
arrival of better forcing, stronger mid level winds /40-50kts/ and
nice QG bullseye point toward continuing severe potential for the
afternoon hours. Limiting factor remains instability, with
east/southeast areas possibly a bit more primed for potential
severe weather given the sunshine this morning. Main severe threat
remains damaging winds with primarily multi-cell storms.

It is looking more and more as if there will be limited activity
with the front itself this evening, with the brunt of the action
this afternoon.

&&

.SHORT TERM...(Today and tonight)
Issued at 351 AM EDT Sat Aug 20 2016

...Potent cold front swings through the region later today...

High impact weather potential: Showers and thunderstorms today
through this evening. Slight risk for severe storms.

Overview: Stalled front stretches from the James Bay region down
through central upper Michigan and through Wisconsin, to secondary
low pressure over Missouri. A warm and soupy airmass is in place
ahead of the front through the Mississippi River valley and into
the Great Lakes region. Overnight SPC mesoanalysis reveals decent
instability across the lower lakes and midwest. More stable up
this way with very subtle mid level ridging and a bit of a warm
nose noted above 600 MB on our 00Z sounding. But there is a
northward surge of more unstable air up through Wisconsin and far
western lower Michigan along the developing warm front and "warm
advection wing" of showers and few storms bowing northward into
the Ludington/Manistee area in the last few hours.

Upstream, anticipated potent short wave is digging into the midwest
toward Iowa this morning, and expected to begin to gin up strong
surface cyclogenesis in the midwest shortly.

Today: It`s gonna rain and storm, it`s just a matter of fine
tuning the forecast timing to the extent possible. Upstream
potent short wave will advance into the midwest this morning
before swinging across the western Great Lakes later this
afternoon and tonight. Strong synoptic forcing (aided by a coupled
upper jet structure) will lead to impressive late August surface
cyclogenesis with an eventual sub 1000 MB surface low tracking
northeast across eastern upper Michigan by 06Z tonight (still a
little wobble amongst the various guidance tracks). This system
will drive a potent cold front through the region late this
afternoon through this evening and a north-south axis of
widespread showers/storms crossing the CWA.

Initially, will have to account for "warm advection wing" of
showers and a few storms arcing into northern lower Michigan.
Unclear just how far north/east this intial batch of precip will
get due to more stable conditions further north, and some high
resolution guidance has this stuff fizzling out over the next few
hours. But will carry some higher pops across the SW counties
early on and see what happens. Arrival of strong synoptic forcing
and approaching sfc low will drive axis of categorical showers/storms
into and across the region late this morning and through the
afternoon hours and have beefed up pops to flat out 100 percent.

Severe weather possibilities: Plenty of synoptic forcing and
kinematics at play with a nice QG-forcing bullseye swinging up
through northern Michigan (centered on the U.P) this afternoon and
mid level flow increasing to in excess of 50 knots ahead of the
front. Forecast instability this far north is not so impressive
however given rather anemic mid level lapse rates and a shortened
window for decent daytime heating. Nonetheless, increasing
effective bulk shear and arrival of strong synoptic support should
make up for a lack of "big" instability and lead to embedded
multi-cell storms with some rotation and damaging wind potential.
Thus SPC slight risk looks good and if we did have more instability
we would probably be in a higher risk today.

Tonight: Cold front will cross the region through the evening
hours and mark a west-east end to the precip. Behind the front,
gusty winds and strong cold advection will usher in +10C 850 MB
air, which given the very warm lake temps (> +23C) will likely
lead to some lake induced rain showers across NW lower Michigan,
along with a nice batch of deformation (wrap around) showers
slipping through upper Michigan. Welcome to our first taste of
fall.

.LONG TERM...(Sunday through Friday)
Issued at 351 AM EDT Sat Aug 20 2016

(8/21)Sunday...The 500 mb trough moves through the forecast area in
the morning so that the axis is east of the region around 18z, with
some residual moisture associated with the sfc low and the 500 mb
low. 850 mb temperatures fall quickly through the day from +7c to
around +6c and with the water temperatures around 22C in N Lakes
MIchigan and Superior, will expect that the LE rain will be the
result. However, as is usually the case with these types of early
season events, there won`t be much in the way of banding, and the
rain will be more like drizzle. Dry air begins to move into the
region after 00z, and the chances of rain begins to fall apart.

(8/22)Monday...For the most part, the only moisture in the region is
the 700-500 mb moisture associated with the warm advection wing
north of Upper Michigan during the afternoon. The lower levels (850
mb and below) show the RH<50% as the 850 mb temperatures warm up
again into the middle teens C. So the day itself looks dry. The
forecast becomes problematic overnight as the GFS and ECMWF both
begin to produce some rain under the 500 mb jet streak (40knots) and
along a weak baroclinic zone, mainly in Upper Michigan. Based on the
moisture profiles of the soundings, not impressed and have the
chances at slight for the most part.

Extended (Tuesday through Friday)...Tuesday, any rain in the
region lifts north as the 500 mb ridge begins to builds over the
region. Models break down the ridge and push the 500 mb trough
into the Northern Plains, this looks similar to the system that
is/will push through the the Upper Great Lakes now/and later
today. However, it looks like it pushes out of the region by
Thursday morning so that the Thursday and Friday turn out dry.

&&

.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 715 AM EDT Sat Aug 20 2016

Patchy low clouds and fog out there for the early going today
along with a small batch of showers/isolated thunder moving
through the TVC and MBL areas. But a period of VFR conditions
should materialize at all terminal sites this morning.

Then, potent August low pressure system will ramp up in the
western Great Lakes as we go through the day and track up through
eastern upper Michigan this evening, driving a strong cold front
through the region. Expect an fairly narrow axis of showers and
thunderstorms to roll W-E through northern lower Michigan during
the afternoon and early evening hours. Some strong-severe storms
are possible.

After FROPA, solid MVFR cigs anticipated through the rest of the
night and gusty SW-W winds arrive with gusts pushing the mid to
high 20 knot range. Showers end W-E this evening although renewed
rain showers will spread back into NW lower Michigan toward
morning.


&&

.MARINE...
Issued at 351 AM EDT Sat Aug 20 2016

Active weather for the next 36 hours with showers and storms
anticipated today through this evening, and showers persisting
through Sunday. Cannot totally rule out waterspouts tonight into
Sunday morning.

Gustier SW winds will develop today as a potent storm system
swings into the region. Strong cold front crosses the region
tonight and will usher in gale force wind gusts for some nearshore
areas. Will hoist gale warnings or small craft advisories for all
nearshore zones for later today through Sunday evening.


&&

.APX Watches/Warnings/Advisories...
MI...BEACH HAZARDS STATEMENT from 2 PM EDT this afternoon through
     Sunday afternoon for MIZ020-025-031.

     BEACH HAZARDS STATEMENT from this evening through Sunday
     afternoon for MIZ016-019.

LH...GALE WARNING from 5 AM to 11 PM EDT Sunday for LHZ346>349.

     SMALL CRAFT ADVISORY until 11 PM EDT Sunday for LHZ345.

LM...GALE WARNING from 11 PM this evening to noon EDT Sunday for
     LMZ323-342-344>346.

     SMALL CRAFT ADVISORY until 6 PM EDT Sunday for LMZ341.

LS...SMALL CRAFT ADVISORY until 8 PM EDT Sunday for LSZ322.

     GALE WARNING from 5 AM to 8 PM EDT Sunday for LSZ321.

&&

$$

UPDATE...Keysor
SHORT TERM...Adam
LONG TERM...JSL
AVIATION...Adam
MARINE...Adam



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