Area Forecast Discussion
Issued by NWS Gaylord, MI

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922
FXUS63 KAPX 141610
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
1110 AM EST Tue Nov 14 2017

.UPDATE...
Issued at 1106 AM EST Tue Nov 14 2017

Stratus once again covering most all of nrn Michigan and had to
increase sky cover. Only far NE lower not in the stratus, but
it`s making an effort to get there. It`s battling some downsloping
right now, and think that may hold the stratus at bay. We also
have some higher level cloud working toward us, out ahead of
tonight`s shortwave that spreads warmth, thickening clouds and
eventual rain. Rain to spread in more so overnight with a rather
wet and gloomy day on Wednesday. Cold advection Wednesday
afternoon to possibly ignite lake effect rain, which gradually
turns to snow through Wednesday night.

Prior to all this, there is solid evidence in fcst sounding data,
that low level moisture thickens in growing moisture flux off
Lake Michigan (strengthening SW winds and overlake instability).
Top of the moisture does not reach -10C and looks ideal for
drizzle.

&&

.NEAR TERM...(Today through Tonight)
Issued at 239 AM EST Tue Nov 14 2017

...Not as cold with widespread rain developing late tonight...

High Impact Weather Potential...Minimal.

Pattern Synopsis/Forecast...Strong high pressure has shifted just SE
of Michigan early this morning...while our next low pressure system
is organizing to the lee of the Rockies. Southerly flow is
strengthening over the Plains...Mississippi Valley and the far
Western Great Lakes region between these two systems. Arrival of
drier low level air across Michigan has scoured out some low
cloudiness and has lifted cigs in areas where low clouds remain.
Temps are holding in the low to mid 30s under residual cloud
cover...while temps have fallen into the mid to upper 20s where
skies have partially cleared.

Some mid clouds are already moving thru portions of Northern
Michigan and Northern Wisconsin along and north of the eastern edge
of the initial warm front associated with the developing upstream
system. These mid clouds will gradually increase and lower as we
head thru the day in response to strengthening WAA and mid level
moisture advection ahead of the system. Precip chances will begin to
increase later this afternoon across our far NW CWA...and will
spread SE thru the rest of our CWA during the evening. Precip will
become widespread overnight as deep moisture and strong low level
convergence/upper level divergence arrive along and ahead of the
approaching cold front. Low level temp profile shows all precip
should remain of the liquid variety thru tonight.

High temps will warm into the upper 30s and lower 40s this
afternoon. Diurnal temp swing will be small thanks to ongoing low
level WAA and thick cloud cover. Overnight lows will only fall a few
degrees into the mid to upper 30s.

&&

.SHORT TERM...(Wednesday through Thursday)
Issued at 239 AM EST Tue Nov 14 2017

...Wet midweek weather...

High Impact Weather Potential: Minimal.

Pattern Forecast: Warm air advection/isentropic ascent is expected
to be squarely atop northern Michigan come Wednesday morning
associated with a deepening area of low pressure trekking over lake
Superior into southern Ontario throughout the day. As low pressure
continues to move eastward, a cold front is expected to press west
to east across the forecast area later in the day with a surge of
colder air aloft sweeping in Wednesday night into Thursday, leading
to the potential for lake effect processes to ramp up for a period
of time behind the departing system.

Primary Forecast Concerns/Challenges: Widespread precipitation
Wednesday morning followed by increasing lake effect induced precip
chances Wednesday night.

Deep layer moisture continues to increase across northern Michigan
Tuesday night into Wednesday morning with PWs progged to rise
between 0.75-0.90" by 12z/Wed. Formidable forcing aloft coincides
with the uptick in moisture as mid level shortwave energy aloft
arrives into the western Great Lakes. All this leading to
widespread, steady rain across the bulk of northern Michigan through
the morning hours. Latest trends continue to suggest the system`s
cold front tracking west to east across the forecast area late in
the morning through mid afternoon, taking the bulk of the widespread
rain with it. Additional QPF through the day Wednesday on the order
of a two to four tenths of an inch, bringing event totals to 0.35-
0.75"...highest across eastern Upper and the near the Lake Huron
shoreline.

Cooler and significantly drier air is ushered in behind Wednesday`s
frontal passage with H8 temps steadily falling through Wednesday
night to roughly -8 to -10 C. Resultant increase in over-lake
instability and brisk northwesterly winds will yield a decent chance
for lake effect shower development. Forecast soundings continue to
peg a rather slow cooling of the lowest 1-1.5kft, holding off a
transition to snow showers until late evening-overnight. That said,
wouldn`t be shocked to see snowflakes mix in across eastern Upper
and the higher terrain of northern Lower during the early evening
hours. Surface high pressure gradually building into the area will
make its presence felt as early as Thursday morning with drier
air/subsidence bringing an end to any lingering lake effect. With
only a limited opportunity for snow showers, not a whole lot in the
way of accumulation anticipated over the typical lake belts of
interior northern Lower and eastern Upper - perhaps a few places
pick up a minor accumulation.

.LONG TERM...(Thursday night through Monday)
Issued at 239 AM EST Tue Nov 14 2017

High impact weather potential: A potentially strong system arrives
this weekend with a myriad of possible issues including rain, gusty
winds and eventually snow.

Focus through the extended forecast period revolves around the
Friday through the Sunday/Monday timeframe as a Pacific originated
mid level wave is expected to carve out troughing across the center
of the CONUS with attendant cyclogenesis underway lee of the
Rockies. Said low pressure is expected to deepen as it approaches
and eventually crosses the Great Lakes Friday night-Saturday.
Noticeably gusty winds and increasing rain chances will commence as
early as Friday afternoon (perhaps a bit of mixed precip to start?)
...continuing into Saturday before the system`s cold front sweeps
east across the forecast area allowing winds to veer northwesterly
and for much cooler Canadian air to spill into northern
Michigan...possibly providing an extended period of lake effect snow
through the remainder of the weekend. A lack of recent guidance run-
to-run consistency precludes much in the way of confidence in many
of the details including timing, intensity, track and snow
chances/amounts, but the Friday through Monday timeframe certainly
warrants keeping an eye on moving forward.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 613 AM EST Tue Nov 14 2017

Areas of MVFR cigs across portions of NW Lower Michigan will lift
to VFR during the afternoon/early evening...but will gradually
lower again later tonight as widespread rain showers develop from
west to east ahead of an approaching cold front. Southerly winds
will gradually increase today and tonight to 10 to 20 kts with
higher gusts expected.


&&

.MARINE...
Issued at 1106 AM EST Tue Nov 14 2017

Went ahead and issued Gale Warnings for the NW lower coastal
nearshore waters. SW low level winds strengthen tonight ahead of
developing low pressure, that works through Lake Superior
Wednesday. A cold front passes Wednesday afternoon and the
gradient remains tight for gales to persist through at least
Wednesday night. These gales will also be possible toward the end
of the forecast period for all other nearshores, and will likely
wait before issuing any gale watch. This low pressure will also
bring in a swath of rain late tonight into Wednesday, with lake
effect rain and snow showers for Wednesday night into Thursday.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...SMALL CRAFT ADVISORY from 7 PM this evening to 7 AM EST Thursday
     for LHZ345>349.
LM...GALE WARNING from 7 PM this evening to 7 AM EST Thursday for
     LMZ323-342-344>346.
     SMALL CRAFT ADVISORY until 7 AM EST Thursday for LMZ341.
LS...SMALL CRAFT ADVISORY from 7 PM this evening to 7 AM EST Thursday
     for LSZ322.
     SMALL CRAFT ADVISORY until 7 AM EST Thursday for LSZ321.
&&

$$

UPDATE...SMD
NEAR TERM...MR
SHORT TERM...MG
LONG TERM...MG
AVIATION...MR
MARINE...SMD



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