Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 201026
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
626 AM EDT Thu Apr 20 2017

.NEAR TERM...(Today through Tonight)
Issued at 254 AM EDT Thu Apr 20 2017

...Soaking rains, especially this morning...

High Impact Weather Potential: While widespread heavy rain is not
expected, rain that does fall will be enough to further exacerbate
already high river levels.

Pattern Synopsis/Forecast: Troughing rotating into northwest
Minnesota continues to intensify with subtle shortwave trough merger
and under region of modest coupled upper jet structure. Strong
moisture advection on nose of robust 60+ knot H8 centered low level
jet running out ahead of the primary wave, kicking off a large area
of showers with embedded thunderstorms across the western Lakes.
Leading edge of this activity just now pushing onshore off Lake
Michigan, and looks to quickly overspread the rest of the area
through the early morning hours. Nothing terribly impressive with
regards to upstream rain amounts so far, with most areas receiving
well under an inch overnight. No doubt, however, that some of the
embedded deeper convective cores have produced locally heavy rain
amounts.

Trough will continue to deepen, eventually closing off on its
journey across the northern Lakes later today through the overnight.
Attendant rather weak surface reflection slides across northern
lower Michigan in the process. Intense forcing on nose of low level
jet departs quickly this morning, with deformation dynamics and
modest mid level lapse rates helping lighter precipitation linger
this afternoon and tonight.

Primary forecast concerns: Rain amounts and thunder potential,
especially this morning. Temporal and spatial resolution of lighter
showers this afternoon and tonight. And finally, precipitation type
will need addressing tonight.

Details: Band of rain, with perhaps some embedded non-severe
thunderstorms, will sweep steadily east across the area first thing
this morning. Definitely looks like a good soaking rain, but
transient nature of forcing should definitely keep rain totals from
getting too out of hand. With that said, see little reason most
areas won`t pick up a good half inch or more, with some locales
possibly tipping the scales at over an inch by the time the
steadiest rains push off to the east later this morning. Definitely
not enough for any widespread flooding concerns, but brief pockets
of heavy rain will likely cause some ponding on area roadways for
the morning commute. Additional runoff will increase river levels,
with the latest River Forecast Center progs now indicating the Rifle
River near Sterling to exceed flood stage by early Saturday morning.
Other rivers are expected to remain in their banks, but definitely
something to monitor heading through the remainder of this week.
Focus for better shower coverage shifts north this afternoon into
eastern upper Michigan as mid level dry slot punches across areas
south of the big bridge.

Core of troughing pushes into the region tonight, with system
backside moisture and just enough forcing to continue the light
shower threat, once again with the greatest chances the further
north one goes. Cold air advection ramps up overnight as the surface
low pushes into Ontario. Guidance derived soundings continue to
advertise a shallow enough surface rooted melting layer to result in
a rain/snow mixture, or even brief periods of all snow, across
eastern upper Michigan. Melting layer also becomes very shallow
across the higher terrain of norther lower by morning, although lack
of moisture in the ice nucleation layer may produce drizzle instead
of any type of rain/snow mixture.

&&

.SHORT AND LONG TERM...(Friday through Wednesday)
Issued at 254 AM EDT Thu Apr 20 2017

...Changeable conditions over the next several days...

As you might expect across northern Michigan during this time of the
year, don`t get too used to the weather of today because it`s likely
to change tomorrow or the next day. This should be the case over the
next week or so at a minimum. Chilly temperatures are expected again
Friday followed by a quick warm up Saturday. However, this should be
short lived as a moisture starved cold front moves through Sunday
returning cooler conditions which appear to last into early next
week. Warming is then expected again Tuesday with another cool down
likely Wednesday. Overall, a fairly dry stretch of weather is
expected over the next few days with just some lingering wrap around
showers possible Friday morning as low pressure moves off to our
east. Can not totally rule out the rain mixing in with a little wet
snow across eastern upper and the higher terrain of northern lower.
The next chance for rain then holds off until what looks like
Tuesday with better chances on Wednesday as low pressure moves into
the region.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 618 AM EDT Thu Apr 20 2017

MVFR/IFR producing low cigs and reduced visibility to continue
right through most of this taf period. Band of showers with
embedded thunderstorms quickly moving off to the east, likely to
clear Alpena by later this morning. That will leave behind
scattered lighter showers. More of same tonight as low level
moisture pivots around departing low pressure.

&&

.MARINE...
Issued at 254 AM EDT Thu Apr 20 2017

Low pressure and its attendant warm front approaching the region
will tighten the pressure gradient across the big waters this
morning. Gusty east winds will be the result, with some low end
gale gusts still expected for a handful of nearshore zones...especially
on northern lakes Michigan and Huron and through the Straits.
Winds will diminish some heading through tonight. But gusty winds
will persist through the rest of the work week with small craft
advisory conditions likely persisting.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...SMALL CRAFT ADVISORY until 6 AM EDT Friday for LHZ349.
     GALE WARNING until 5 PM EDT this afternoon for LHZ345>348.
LM...SMALL CRAFT ADVISORY until 6 AM EDT Friday for LMZ323-344>346.
     GALE WARNING until 5 PM EDT this afternoon for LMZ341-342.
LS...SMALL CRAFT ADVISORY until 6 AM EDT Friday for LSZ321-322.
&&

$$

NEAR TERM...MSB
SHORT TERM...AJS
LONG TERM..AJS
AVIATION...MSB
MARINE...MSB



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