Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 281943
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
343 PM EDT Tue Mar 28 2017

.NEAR TERM...(Tonight through Wednesday)
Issued at 340 PM EDT Tue Mar 28 2017

...Quiet tonight with more sun Wednesday...

High Impact Weather Potential...None.

Pattern Synopsis/Forecast...Surface high pressure over central
Canada will continue to build into the Upper Great Lakes tonight
into Wednesday. As it does so, it will continue to advect cooler,
drier air in from the north. Further upstream, a weak vort max
moving across the Keweenaw Peninsula can be subtly observed on water
vapor imagery this afternoon but is struggling to generate much
cloud cover due to a very dry airmass in place there. This feature
will cut across eastern Upper and Tip of the Mitt this evening, but
under increasing subsidence and drier air expect most of northern
Michigan to remain mostly clear this evening and overnight...aside
from some passing cirrus and localized cloud cover near Lake
Michigan. Temperatures are expected to fall into the mid 20s to low
30s overnight.

On Wednesday, the Canadian high will continue to slowly drift across
southern Ontario, sending a surge of colder 850mb temperatures
southward into the eastern Great Lakes. This will lead to continued
cold air advection across northern Michigan, but temperatures will
still be at or just above seasonal normals for late March. Under
plenty of sun early (cirrus increasing from the southwest in the
afternoon), highs should climb into the upper 30s in far northern
Chippewa County to upper 40s across our south.

Primary Forecast Concerns...With mostly clear skies and light winds
overnight, there is some potential (albeit rather low) for patchy
fog development overnight. Areas near Lake Michigan were slower to
clear out of the clouds earlier today and thus haven`t been as well-
mixed as the rest of northern Michigan this afternoon. As a result,
dewpoints are currently a tad higher nearer to Lake Michigan this
afternoon, so if any fog were to develop tonight feel it would
be more likely there. That being said, think the advection of drier
air from the north may be enough to inhibit any fog development.

&&

.SHORT TERM...(Wednesday night through Friday)
Issued at 340 PM EDT Tue Mar 28 2017

...Mixed precip expected Thursday and Thu night...

High impact weather potential...wintry mix Thursday and
especially Thursday night, including some potential freezing rain.

High pressure over Hudson Bay and far ne Ontario will move slowly
but steadily eastward, allowing low pressure to eject from the
southern plains. Cloud cover will increase Wed night, and precip
will develop ne-ward into at least portions of northern MI on
Thursday (at the latest). Precip trends are the main concern.

Model spread remains considerable with this system. Interaction with
a northern stream wave transiting the US-Canada border is important.
The Nam has no interaction at all, leaving the southern stream
system to slow greatly in the mid-MS Valley region. This leads to a
much longer-duration event, and way higher QPF. This would be
ugly...if it pans out. ECMWF/GFS are both inclined to keep the
system much more progressive. However, there has been a sharp
northward trend with the 12Z guidance, which reverses the trend seen
in the previous 24 hours. The Nam is discarded given its lack of
support and its generally poor performance, but confidence remains
somewhat low.

Wed night...mid/upper level moisture will be pushing into the 500mb
shortwave ridge over the Lakes region. Sub-700mb dry air will, for
the most part, hold off precip development. However, f-gen forcing
aloft will be increasing overnight in southern sections, and will
attempt to at least locally overcome the dry air downstairs. Will
boost pops slightly in far southern areas. This would fall as snow,
though not enough for accums.

Min temps upper 20s to lower 30s.

Thu-Thu night...increasing isentropic ascent will steadily overcome
leftover dry air. Highest pops in order Thu afternoon and especially
evening, with categorical in much of northern lower and chancy pops
reaching eastern upper MI. Precip coverage will be diminishing from
w to e overnight. There are a number of p-type concerns. On Thu,
anticipate any early snow to go over to mostly rain as the BL warms.
QPF will be light in the early going, so any snow accums early Thu
will be minimal. However, increased precip rates/weak cool advection
on an easterly breeze/diminishing diurnal heating will allow a
window for precip to turn back to snow by early evening in parts of
n central and ne lower MI. Meanwhile, a 900-800mb warm nose will
expand into southern sections during the night, making snow unlikely
south of M-72 but bringing sleet/freezing rain into the picture,
especially over the higher terrain. Meanwhile, a downsloping east
breeze will try to keep things all liquid west of TVC-CAD.

Overall, this is starting to look a little messier. Snow accums will
be still be limited, as areas where snow will be the prevalent p-
type (far northern and ne lower MI) will see less in the way of QPF.
And any snow will be on the wet/sloppy side. Will have some 1-2 inch
totals in parts of n central and ne lower MI. Will introduce some
small ice accums (less than a tenth of an inch) for the CAD-HTL
area. The above now warrants a mention in the haz wx outlook.

Max temps in the upper 30s to around 40f. Min temps in the upper 20s
to lower 30s.

Friday...weakening surface low will slowly move east across the
upper OH Valley, and the primary forcing shortwaves in both streams
will also move east. Precip will have diminished substantially by
daybreak, and will only hang on to a chance for mixed rain/snow in n
central and ne lower MI. Anticipate partly sunny skies arriving in
eastern upper and nw lower MI. Max temps 40-45f.

&&

.LONG TERM...(Friday night through Tuesday)
Issued at 340 PM EDT Tue Mar 28 2017

High pressure will dominate northern Michigan`s weather almost to
the end of the extended period, bringing "warm" weather in the upper
40s and lower 50s during the daytime with mostly sunny to partly
cloudy skies and for the most part, precipitation free, besides a
slight chance of rain/snow showers with a shortwave traversing the
area Saturday night for eastern upper. Next chance for more
widespread precipitation is hinted by long range models beginning
around early next week as a storm system approaches from the central
Great Plains.

Lows will be in the upper 20s Saturday morning and moderate to the
mid 30s by Tuesday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 148 PM EDT Tue Mar 28 2017

Low stratocu has rapidly scoured out across northern Michigan. VFR
conditions for the rest of today with just some passing cirrus as
high pressure builds into the region. With mostly clear skies
and light winds overnight, would start to think about possibility
of some br. However, we`ll also be dealing with encroaching drier
low level air that is expected to limit fog/mist potential.
Wouldn`t entirely rule out some br, but if it does develop,
KMBL/KTVC/KPLN would have the best chance for perhaps MVFR
visibilities. Winds will remain light through the period, becoming
more northeasterly on Wednesday along with increasing cirrus.

&&

.MARINE...
Issued at 340 PM EDT Tue Mar 28 2017

High pressure nosing into the Upper Great Lakes will keep things
quiet tonight through Wednesday night. Winds will stay light out of
the north tonight, becoming more northeasterly on Wednesday. Clouds
will increase Wednesday afternoon and evening ahead of an
approaching system that will bring the next chance for precipitation
(rain/snow on Thursday with potential for a wintry mix Thursday
night). Some advisory-level wind gusts may be possible Thursday into
Friday.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&

$$

NEAR TERM...MEK
SHORT TERM...JZ
LONG TERM...TJL
AVIATION...MEK
MARINE...MEK


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