Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 220840
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
340 AM EST Wed Feb 22 2017

.NEAR TERM...(Today and tonight)
Issued at 339 AM EST Wed Feb 22 2017

...Some fog, then warm, then rain...

High impact weather potential...some dense fog this morning, in
particular near Saginaw Bay.

S to sw low-level flow is once again in place, just ahead of a
strung-out cold front that stretches from the northern plains toward
western Superior. Shroud of mid/high clouds covered most of the
region, though back edge is working into nw lower MI. Radiational
cooling was favored in eastern sections, before the clouds arrived.
Some fog seen in eastern upper MI and near Saginaw Bay, where some
cooling occurred before higher clouds arrived. Morning fog is the
initial concern, then how warm does it get? Rain chances will then
increase late today into tonight, and fog may get a chance to
return. So a lot to look at.

Today...fog/stratus was only very slowly expanding, as shroud of
higher clouds prevents rapid growth. However, with that starting to
thin in nw lower, a window exists for faster development there,
especially for MBL/CAD. As is, we already have persistent dense fog
at OSC, with recent expansion into West Branch (Y31) and HTL. Will
issue a dense fog advis for this morning for some se counties, and
may need to add additional counties with time. Eastern upper has
persistent fog, sometimes dense, at the twin Saults, intermittent in
other parts of Chip Co. Will refrain from a fog headline there for
now.

Mid/high clouds, generated by strengthening warm advection aloft, is
associated with a fair amount of virga across upper MI and northern
Lake MI. Some precip is definitely reaching the ground in central/
eastern upper MI, per MQT radar. Will need to mention sct sprinkles
and/or showers to start the morning in some spots, especially
eastern upper MI.

Mid/high clouds will depart this morning, and stratus/fog is not
especially widespread. Anticipate late Feb sunshine will be
sufficient to erode low clouds, and provide a period of decent
sunshine in most locales. Temps will zoom upward in response (like
yesterday). Sub-850mb warm advection will be considerable, with
925mb temps edging up toward 12c by midday. We won`t mix that high
(it`s only February, folks), but a little sunshine will produce a
considerable response in temps. Max temps look to be in the 40s in
eastern upper MI, and mid 50s to lower 60s in northern lower.
Records:
 Sault Ste Marie 44 (1984)
 Gaylord         55 (1984)
 Alpena          60 (1930)
 Traverse City   57 (1930)
 Houghton Lake   64 (1930)
GLR/TVC seem likely to fall; the rest are in danger (HTL the least
so).

Finally, low pressure along the wavy front to our west will advance
into WI this afternoon. F-gen and deformation forcing north of this
low is expected to develop some showers today. Some of these will
reach eastern upper MI late in the day, and perhaps portions of the
nw lower MI coast. Clouds will again be on the increase late in
these locales, with another mention of rain showers.

Tonight...surface low will cross northern lower MI tonight, and be
just ne of Georgian Bay by morning. Trailing cold front will cross
northern MI tonight, ending our spell of near-record warmth. Some
showers will accompany the low, especially along and north of its
track. A low-amplitude shortwave will steepen mid-level lapse rates,
helping support at least a small chance of precip everywhere. There
had been a touch of thunder associated with the low earlier in the
night in eastern SD and sw MN. Nam does bring an instability plume
(mucapes 200-500j/kg) into northern lower MI tonight; most likely
place for thunder would be along its northern periphery, per SPC day
1 outlook. Nam is likely a bit aggressive with its low level
moisture fields and thus cape. Will refrain from adding thunder at
this time. Pops will range from likely in Straits and eastern upper,
to chance/slight chance further south. This will be almost all rain,
but toward daybreak enough cooler air in sneaking into western
Chip/Mack to warrant mixed rain/snow there.

A window for fog development exists tonight, during the light wind
regime as the low passes overhead. Some patchy fog will be mentioned
in eastern upper and parts of northern lower MI. Min temps in the
30s to lower 40s.

&&

.SHORT TERM...(Thursday through Friday)
Issued at 339 AM EST Wed Feb 22 2017

...A messy end to the work week...

High Impact Weather Potential...A wintry mix including accumulating
snowfall and possibly some icing will impact parts of northern
Michigan Thursday night into the weekend. Some thunder also possible.

Pattern Synopsis/Forecast...A cold front will be dropping southeast
across northern Lower Thursday morning, stalling further downstate
later in the day. Drier and cooler air will build in behind the
front, allowing for a fairly quiet day across northern Michigan.
Focus then quickly shifts to a rapidly developing system out over
the Central Plains that will begin to impact northern Michigan late
Thursday evening or early Friday morning. A broad area of strong WAA
out ahead of this system and resultant precipitation will overspread
northern Michigan Thursday night from southwest to northeast. Precip
onset time seems to be trending later with recent model runs, likely
not beginning until after 03Z or perhaps even 06Z Friday. Increasing
moisture transport (thanks to a modest LLJ stretching all the way
from the Gulf states to northern Lower) will lead to substantial
rises in PWAT by Friday morning...climbing 2 to 4 standard
deviations above the mean and likely approaching 1 inch. A warm
front with strong attendant low/mid level frontogenesis then lifts
through northern Lower during the day Friday (likely as far north as
M-32 or M-68), placing much of the forecast area within the warm
sector and providing some impressive omega. Despite a strong warm
nose just above the surface, enough elevated instability (up to a
few hundred J/kg of MUCAPE) will develop during the day that will
support the chance of some thunder mainly south of M-72.

Primary Forecast Concerns...With the intense low progged to track
through northern Michigan, ptypes will be the main forecast
concern/challenge. As the precip overspreads the area Thursday
night, the dividing line between rain and snow looks to initially
lie roughly along M-55. A wintry mix will be possible within this
transition zone, which is expected to slowly creep north through the
night as stronger WAA pushes in from the south. The 22.00Z NAM
brings a pronounced 10C warm nose as far north as the Straits during
the day on Friday, whereas other deterministic models remain quite a
bit cooler. In general, we`re looking at a transition to all rain
across northern Lower during the day Friday, while eastern Upper
will see snow transitioning to a wintry mix and perhaps some rain
across southern Mack/Chip counties.

It`s still rather early to put a whole lot of confidence in precip
types/amounts, but the way the current forecast is panning out, it
looks like light icing amounts (a few hundredths of an inch) will be
possible Friday morning near the Straits and across the Tip of the
Mitt. Could see more substantial icing amounts develop across
Chippewa County later in the day into Friday night...something that
will have to be monitored as we get closer to this event. Snowfall
amounts Thursday night still look minor (an inch or less). On
Friday, eastern Upper could see another few inches with lesser
amounts south of the bridge.

&&

.LONG TERM...(Friday night through Tuesday)
Issued at 339 AM EST Wed Feb 22 2017

High Impact Weather Potential...Wintry mix and accumulating snow
will be possible Friday night into Saturday. Accumulating lake
effect snow possible Saturday night through Sunday night.

A cold front and strong CAA will sweep across northern Lower Friday
evening as the surface low tracks across the Tip of the Mitt. Behind
the front, PWATs will drop like a rock within the dry slot, which
will likely lead to a lull in precip (or perhaps some areas of
drizzle or freezing drizzle) for much of northern Lower overnight
into Saturday morning. As colder temperatures filter in Saturday,
areas of rain will transition back to snow, with some lake
enhancement possible later in the day as winds turn NW and 850mb
temps drop. Winds will become gusty midday and through the evening
as the system departs.

We then head into a colder lake effect snow pattern Saturday night
through early Monday as 850mb temps drop to around -16C. Winds will
vary direction a little bit through this period and low level
moisture will be a limiting factor. W to NW snowbelts will likely
see some accumulating snow through this period.

Fairly quiet then for later Monday through much of Monday night, but
the next approaching system will bring a chance of snow changing to
rain on Tuesday. Considerable variance between the
GFS/ECMWF/Canadian out that far, however.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1145 PM EST Tue Feb 21 2017

Areas of fog will develop overnight across most of Northern Lower
Michigan...dropping vsbys to MVFR/IFR in many locations. The fog
will mix out shortly after sunrise on Wednesday...returning VFR
conditions to all TAF sites for the remainder of the day.
Light/variable winds overnight will become SW AOB 10 kts on
Wednesday.


&&

.MARINE...
Issued at 339 AM EST Wed Feb 22 2017

S to sw winds today, ahead of low pressure and associated cold
front that moves thru tonight. Winds/waves will stay below
advisory criteria. Stronger nw to n winds late tonight and early
Thursday, perhaps approaching advisory levels. Better chance for
headlines will be Thu night/Friday, with e winds that may
approach gale force at times.

&&

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

$$

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


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