Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 180418

Area Forecast Discussion
National Weather Service Gaylord MI
1118 PM EST Fri Feb 17 2017

Issued at 1028 PM EST Fri Feb 17 2017

Upper level ridge axis is sliding overhead this evening leading to
flat out clear skies across the CWA at the moment. Upstream, moisture
starved short wave trough is advancing through the upper Midwest
with associated surface low pressure stretching from south-central
Canada into the western lakes, and hard to locate cold front/wind
shift line stretching down into the central plains. Low pressure
and attending front will be sliding across the northern lakes
region late overnight through Saturday morning with little
fanfare other than a few clouds pivoting up through the region.

Meanwhile, temperatures are once again tricky with a fairly big
spread out there. Pellston and West Branch have already dipped to
25 and 28 degrees respectively as of 10 pm. Frankfort dropped to
37 early in the evening only to rebound back up to 51! Good luck
forecasting that. A decent P-gradient and persistent surface wind
should result in an overall steady or increasing temp for most
places overnight. But I have had to account for some of those cold
spots and lower the forecast lows.


.NEAR TERM...(Tonight and Saturday)
Issued at 300 PM EST Fri Feb 17 2017

...Taste of early spring continues...

High Impact Weather Potential: Nothing.

Pattern Synopsis/Forecast: Much advertised warm-up underway as warm
air advection processes continue to ramp up on backside of departing
surface high. Initial warming was partially held in check by rather
extensive area of high and mid level clouds. These are beginning to
thin rapidly from the west, and temperatures have begun to respond
accordingly, with readings now spiking well into the 30s and 40s.

Warm air advection simply increases heading through tonight as a
weak upper level wave and attendant moisture starved "cold" front
approach and eventually pass through northern Michigan. Simply no
cold air behind this frontal system, with all systems go for even
warmer temperatures on Saturday.

Primary forecast concerns: Addressing potential for some low cloud
development later tonight into Saturday. Temperature trends through
the period.

Details: Band of high/mid level clouds should rotate largely east of
the area by this evening, leaving a period of mostly clear skies.
Still some hints of stratus and patchy fog development overnight.
Not quite sold on this idea, with those stratus producing progs
already much too moist in the low levels (also very little snow melt
today to add to the near surface moisture). Last nights satellite
trends only showed a very small and narrow patch of stratus over
northeast Wisconsin. Think the best potential for stratus/fog will
be across eastern upper, but even here have gone no more than partly
cloudy. Bigger story will be those temperatures, as maintenance of a
shallow mixed layer and continued advection processes suggest
readings will rise overnight after an early evening fall-off.
Believe most areas will just flirt with freezing for a time early
this evening, with readings rising into the mid and upper 30s during
the overnight. Passage of that weak front during the early morning
will have little effect on those temperatures with simply no cold
air behind it.

Saturday`s temperatures dependent on late night cloud trends, with
more than anticipated stratus keeping reading several degrees cooler
than planned. As mentioned, not going this cloudier direction just
yet, leaving the opportunity for temperatures to shoot well above
normal. Given the mild start to the day, simply see little reason
temperatures won`t climb well into the 40s, with much of the area
across northeast lower Michigan making a run at 50 degrees.


.SHORT TERM...(Saturday night through Monday)
Issued at 300 PM EST Fri Feb 17 2017

...Mainly dry...

High Impact Weather Potential...None, but the rivers are a concern
with the snow melt.

Pattern Synopsis/Forecast...Saturday night, as the 500 mb shortwave
trough moves east of the Ohio Valley, the heights over the Upper
Great Lakes begin to rise, and with them the 850 mb temperatures.
There is a backdoor cold front that stymies the 850 mb temperatures
initially, but once the sfc high move over southern Hudson Bay/James
Bay Sunday night, the return flow begins to warm the region up as
the 500 mb ridge axis moves through on Monday. GFS hints at
precipitation getting into NW lower near MBL/FKS by 21z/Mon. ECMWF
(00z) has the precipitation in E Wisconsin.

Primary Forecast Concerns...Fog is possible on each night, but it
will depend on the saturation and strength of the inversion.
Saturday night doesn`t great with the hydrolapse not increasing much
with height, and kind of an isothermal inversion. Not to mention
that the moisture is very shallow. Initially, Sunday night looked
better on the GFS, the ECMWF looked decent, but now both models have
seemed to back off. Will see how this plays out. Will keep patchy
fog in the grids for now.

.LONG TERM...(Monday night through Friday)
Issued at 300 PM EST Fri Feb 17 2017

High impact weather potential: None.

Primary concerns through the extended period revolve around
continued well above normal temperatures and rain chances Monday
night through Tuesday. 17/12z suite of deterministic guidance, while
still consistent in the overall pattern and strength on Monday
night/Tuesday`s low pressure in southern Canada, has reintroduced
some disagreement with cold frontal and associated precipitation
timing. Will trend the forecast to represent the slower and more
consistent ECMWF/GEM rather than what`s now the outlier, GFS. All in
all, expecting rain to overspread the area from west to east during
the second half of Monday night into the day Tuesday before
diminishing Tuesday afternoon as the cold front continues to
progress eastward.

Otherwise, aside from a few scattered showers during the midweek
timeframe as several weak ripples in the flow move across far
northern areas, the main story will certainly be continued above
normal temperatures with highs ranging from the 40s to even some low
50s in spots throughout the period.


.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1118 PM EST Fri Feb 17 2017

VFR conditions anticipated tonight through Saturday as dry and
much warmer air continues to flood into the western Great Lakes.
Guidance continues to suggest some fog will develop tonight. That
may occur in spots. But with temperature/dewpoint spreads still
running 10+ degrees and a persistent surface wind through the
night, fog not likely to be much of an issue.

Weak cold front/wind shift line moves through the region early in
the day Saturday, with shallow cooler air slowly sagging down into
northern Michigan heading into Saturday night. Stratus/fog
possibilities will increase Saturday night for parts of northern
lower Michigan as that cooler air sags into the region, although
forecast certainty is not great. I do not have lower stratus in
the terminal forecast just yet, although that may be a
possibility, particularly at PLN.

Otherwise, increasing winds off the surface will lead to LLWS
conditions at all terminal sites for much of the night. Winds
weaken late and into Saturday.


Issued at 300 PM EST Fri Feb 17 2017

Southwest to west winds will pick-up tonight, although a
very stable over-water environment should prevent widespread SCA
conditions (although suppose a few isolated gusts to 25 knots are
possible on northern Lake Michigan). West winds remain a bit gusty
Saturday into Saturday evening, with light winds returning by Sunday
as high pressure builds back into the region.




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