Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 281602

Area Forecast Discussion
National Weather Service Gaylord MI
1102 AM EST Mon Nov 28 2016

Issued at 1036 AM EST Mon Nov 28 2016

Deep low pressure was over the Dakotas/MN border with a tight
pressure gradient over nrn Michigan resulting in gusts roughly
between 20-25 mph. The initial round of LLJ/WAA/DPVA forced rain
showers has pretty much dissolved/shifted north, with extensive
and thick stratus and patchy drizzle moving in from SW to NE. This
scenario was already painted in the current forecast and not too
many changes were made.

Drizzle will be the main precipitation until late this afternoon
and mainly tonight, when much stronger LLJ/WAA/DPVA and upper
divergence in 140kt jet all start lifting into nrn Michigan.
Working with deep moisture advection (PWATS around 250% of
normal), moderate to heavy rain showers will overspread the
region. More than an inch of rain is definitely in the mix under
this setup. As previous discussion mentioned, latest river
forecasts suggest that rivers will be able to handle the total
possible rainfall, even the maximum forecast rainfall up to
1.25". Finally, such strong forcing coupled with a leading edge
of steeper mid level lapse rates (6-6.5c/km), could lead to a few
rumbles of thunder late tonight.


.NEAR TERM...(Today and tonight)
Issued at 309 AM EST Mon Nov 28 2016

...Becoming windy and wet...

High Impact Weather Potential: Soaking rains and increasingly gusty
southeast winds. Gales on some of the big waters.

Pattern Synopsis/Forecast:  Well advertised November gale wrapping
up nicely across the northern Plains as strong mid level short wave
pivots across South Dakota and equally impressive 160+ knot upper
jet core punches across Oklahoma and Kansas. Attendant surface low
already pushing sub 980mb levels at it pivots north into far
southeast South Dakota. System will deepen a touch more until
occlusion process occurs this morning. Increasingly defined warm
front stretches southeast from this low center, with increasing
amounts of western Gulf of Mexico moisture propelling north within
the warm sector. Impressive surge of deep layer theta-e advection
tied to this northward bowing moisture surge, and when coupled with
falling mid level heights and strong mass convergence on nose of 60+
knot low level jet, is kicking off an elongated band of showers to
our southwest. However, this initial low level jet core is already
showing signs of weakening (as are the showers), and will continue
to do so through this morning. This low level jet reintensifies
later today well to our south, with focus for best rains tied to it
and primary mid level circulation to our west for much of the day.

After intial rapidly decaying band of showers pivots overhead today,
wet weather threat looks to ramp up significantly this evening as
additional energy rotates northeast out of base of central Plains
trough. Low level jet core responds accordingly, pivoting north and
setting its sights on our area through the overnight hours. Forcing
on those nose of this jet axis, working over one unseasonably moist
airmass (precipitable water values aoa 0.75 inches...well above the
90th percent tile for today`s date), will no doubt drive an area of
rain through our area tonight.

Primary Forecast Concerns: Rain timing and amounts. Addressing
increasingly windy conditions, particularly on the big waters.

Details: As mentioned, decaying band of showers will rotate overhead
this morning. Guidance derived soundings/cross section analysis
shows more of a drizzle look thereafter as mid level moisture strips
out, all-the-while low level moisture/low clouds remain. Steady
rain, possibly heavy at times, returns from south to north late
today, centering across our area this evening through the early
morning hours of Tuesday. Dry slot arrives toward Tuesday morning,
ending the better rain threat, particularly south of the big bridge.
Not completely out of the question for a rumble of thunder or two
along the leading edge of this dry slot. As for rain totals, looks
like much of the area will receive greater than a half an inch, with
amounts nearing or even exceeding an inch possible, especially
across eastern upper Michigan. Unless something unexpected happens,
it appears rivers should easily handle this amount of liquid.

As for winds...look for those to become gusty southeast today,
increasing in speed tonight as the pressure gradient further
tightens. Don`t foresee any overland issues, although some gusts
pushing 40 mph appears possible right along the Lake Huron Coast
tonight. Far bigger issue will be over the big waters. See those
details in the marine section down below.


.SHORT TERM...(Tuesday through Wednesday night)
Issued at 309 AM EST Mon Nov 28 2016

...Windy Tuesday with rain ending. Then rain creeps back into
northern Michigan Wednesday...

High Impact Weather Potential...heavier rains should be ending, but
the winds along Lake Michigan will probably increase to Gales for

Pattern Synopsis/Forecast...500 mb low over the Dakotas continues to
spin waves of energy out over the Upper Great Lakes, with the sfc
low underneath it, but still deepening somewhat. This deepening,
which moves north of ANJ, sets up a tight pressure gradient that
produces gales on Lake Michigan in the coastal convergence zone
along the lakeshore of NW Lower. However, this is short lived, as the
sfc low begins to rotate into the Upper Great Lakes slackening the
gradient, and bringing the light rain back into the region.

850 mb temperatures fall off to below zero C on Wednesday, but only
to about -3c at the most. This will bring us to a mix of rain and
snow overnight. Probably all snow for a bit in the interior.

Primary Forecast Concerns...Winds increase over the region on
Tuesday, but the main concern looks to be Lake Michigan with the
tighter gradient and the coastal convergence getting wind gusts to
35 knots possible. Think that there is an outside shot at getting to
40 knots, but that would the max as the gradient begins to slacken
during the afternoon.

Rain amounts on Tuesday look light as the warm front continues
north, and the rain goes north with it. Tuesday night will be dry.
Wednesday, the rain moves back in from the south as the 500 mb low
rotates over us and brings precipitation back into the region. The
concern on Wednesday/Wednesday night is the rain changing to snow a
little earlier as colder air moves into the region. The ECMWF shows
slightly cooler temperatures at 850 mb and the GFS shows that cooler
air is just upstream. The concern is that if the low moves out
faster, the cooler air would change the rain over sooner and over a
broader area. The track and speed of the low needs to be watched to
see how this evolves.

.LONG TERM...(Thursday through Sunday)
Issued at 309 AM EST Mon Nov 28 2016

High temperatures look to trend cooler through the weekend as
Thursday ends up a little above normal, and by Sunday temperatures
are around normal (normal highs range from 35 to 39F). Friday
looks like there could be some lake effect snow as the 850 mb
temperatures fall off to around -8C through Saturday. However, the
models then split on the solutions with the GFS having a shallow
trough over the Great Lakes Sunday. The ECMWF has piece of energy
that digs the trough in the Plains, and rapidly develops a sfc low
out of the Lower Mississippi Valley and into the Upper Great Lakes
by Monday morning. The GFs would put us in light lake effect. The
ECMWF keeps us dry until the night, and then brings us possible
snow storm by Monday morning. Will lean toward the GFS as the
ECMWF scenario is based on the Desert SW low ejecting out into the
Plains, causing the develop, which it has trouble with.


.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 633 AM EST Mon Nov 28 2016

Band of showers will give way to MVFR overcast today as low level
moisture overspreads the region. Current low level wind shear
will end, only to redevelop again tonight. Cigs will continue to
lower overnight as a band of moderate to heavy rain spreads north
across all the taf locations. IFR cigs/vis likely as this occurs.
Gusty southeast winds through the forecast.


Issued at 309 AM EST Mon Nov 28 2016

Southeast winds will continue to ramp up today and tonight
as the pressure gradient tightens. Widespread advisory level winds
can be expected along with gales, which will generally be felt
across Lake Huron and Whitefish Bay. Winds become southwest and
decrease in speed some Tuesday as a warm front swings north of the
area. Advisory level wind and wave action will remain through
Tuesday, with even the potential for some gale force wind gusts, this
time on northern Lake Michigan.

Periods of light rain/drizzle can also be anticipated today, before
heavier rains move in tonight.


LH...SMALL CRAFT ADVISORY until 7 PM EST this evening for LHZ346>349.
     GALE WARNING from 7 PM this evening to 7 AM EST Tuesday for
     SMALL CRAFT ADVISORY until 4 PM EST Tuesday for LHZ345.
LM...SMALL CRAFT ADVISORY until 4 PM EST Tuesday for LMZ323-341.
     SMALL CRAFT ADVISORY until 7 AM EST Tuesday for LMZ342-344>346.
     GALE WARNING from 7 AM to 4 PM EST Tuesday for LMZ342-344>346.
LS...SMALL CRAFT ADVISORY until 7 PM EST this evening for LSZ322.
     GALE WARNING from 7 PM this evening to 7 AM EST Tuesday for
     GALE WARNING until 7 AM EST Tuesday for LSZ321.


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