Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 201520
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
1020 AM EST Fri Jan 20 2017

.UPDATE...
Issued at 1020 AM EST Fri Jan 20 2017

Dampening upper trough axis is stretched from the upper Midwest
across the lower Great Lakes region this morning, attending
surface sits across Indiana and Ohio. Strongest QG-forcing for
ascent and main batch of precip is getting shunted eastward into
Pennsylvania and New York. Stretched out axis of precip along the
northern edge of the upper trough has been slowly advancing into
northern Michigan over the last several hours but has shown
a definite weakening/thinning trend, particularly in the last two
hours or so. Thinning band of precip will slowly work its` way up
through northern lower and eastern upper Michigan through the
course of the afternoon and evening hours.

Precip type continues to be the main concern. 12Z APX sounding
still reveals a rather deep warm nose with a max temp around 6C,
but quite the dry layer below 700 MB with lots of room for evap
cooling/max wetbulb temps around 4C. But probably enough to
partially or completely melt precip before getting to the ground.
Surface temps are still close to 32F in many locations although
they have come up a little across the SW counties with current
batch of precip rolling through, likely pulling some warmer air
down to the surface. Still believe surface temps will slowly claw
upward to above freezing in most areas before precip arrives or
rebound quick once it starts. So I`m not to concerned about freezing
rain at this point, although a little light wintry mix may be seen
in the early going.

Second issue is fog. Still a fair amount of 1/4SM fog across NE
lower and tip of the mitt...into eastern upper Michigan but is
showing signs of thinning. VSBYs improve quickly once precip
arrives. Suspect I will be able to allow dense fog advisory expire
as scheduled at noon.

&&

.NEAR TERM...(Today)
Issued at 334 AM EST Fri Jan 20 2017

High impact weather potential: Dense fog.

Pattern synopsis and forecast:

Early this morning, a closed shortwave trough aloft and it`s
associated sfc low pressure were in the central plains, with a warm
front stretching from the low, across nrn MO/srn IL and IN and
through eastern TN. An arcing band of deeper moisture and rains
ahead of this low and warm front was seen from Wisconsin, through SW
lower MI/IN and eastern TN. Forcing from DPVA/WAA and upper
divergence with a weakish 80kt upper jet were all in play. Stratus
has played out fairly well, with the GTV Bay region scouring it out
from cloud layer WAA last evening, but has since been replaced by
thicker mid and high cloud. While the mid levels on up have moistened
there, all areas of nrn Michigan were dry around 9kft and lower
(except in the stratus/near sfc layer). Temperatures in cloudy
conditions were not doing much, remaining in the low to mid 30s. The
dampness outside makes it feel pretty darn cold. Finally, fog was
widespread out there, most dense across eastern upper and NE lower,
away from the thicker mid and high cloud. A dense fog advisory has
already been issued for there.

The closed shortwave trough aloft opens up and slowly works
northward across the region through tonight, trying to budge some
stubborn mid level ridging out from the nrn/eastern Great Lakes.
Upper divergence doesn`t make it up here, as it shunts east with the
jet, but we will have some an arc of low to mid level weak WAA and
DPVA. Rains will not be as impressive for us as it is on current
radar to our south since the forcing weakens with time. However, it`s
a good bet that a band of light rain rolls through during the day
across nrn lower, and through eastern upper tonight(mixed with snow
in the higher terrain as well as eastern upper). With maybe a few
locations lingering around the 32F mark into the daylight hours this
morning, there is a long shot for early morning light freezing rain
around M-55. Nothing terribly exciting with QPF less than a tenth of
an inch most areas.

Will be dealing with continued stratus and fog issues. Stratus
filling back in across the GTV Bay region with widespread fog
lifting some during the day, before thickening back up tonight when
we may need more dense fog advisories.

Temperatures to go nowhere, with diurnal ranges of five degrees or
less most areas. Highs in the middle and some upper 30s with lows in
the lower 30s tonight.

&&

.SHORT TERM...(Tonight through Sunday)
Issued at 334 AM EST Fri Jan 20 2017

...Fog again for Saturday night into Sunday...

High Impact Weather Potential...Fog Saturday night into Sunday could
be dense at times. Also, mixed precipitation is possible late Sunday
night into Monday

Pattern Synopsis/Forecast...The 500 mb low that is out in the Plains
today will continue to spin out in the Plains on Saturday as well
which will continue the light sfc low, keeping the moisture trapped
below the inversion, and thus will continue the fog issues for
another night. Not to mention that another round of showers will
move into the region, as the lows (sfc and 500 mb) move toward the
Upper Great Lakes. The gradient around the sfc low looks pretty
slack so that wind flow should be light, allowing for the dewpoint
to be warmer than the snow pack (around 32F) and thus fog, into
Sunday. It may even last into Monday as the dewpoint depression
again remain low, and the dewpoints above the snow pack
temperatures.

However, the thing to watch for the lows Sunday night into Monday
dropping to below freezing in E Upper and possibly portions of NE
Lower. So if the "rain"(probably more like drizzle) falls there may
be some slick spots with the below freezing temperatures on the bare
roads.

Primary Forecast Concerns...Models are hardly convincing on the
Freezing drizzle/rain scenario for Sunday night. GFS show FZRA, with
saturation up through -10c. NAM is decidedly drier from -5c up, so
probably drizzle, but definitely freezing. ECMWF is a little warmer
at the sfc, but the moisture never makes it above 0c. So it looks
like more like just drizzle. That`s probably what will happen
drizzle with fog as the there is little cold advection to get the
temperatures below freezing.

.LONG TERM...(Sunday night through Thursday)
Issued at 334 AM EST Fri Jan 20 2017

High Impact Weather Potential...While the temperatures Monday
through Thursday bounce above and below freezing, which will cause
wintry mixes of precipitation, the Wednesday storm may be a bit of a
concern.

Extended (Monday through Thursday)...Monday the rain with the 500 mb
shortwave trough moves through the Upper Great Lakes, with the weak
sfc waves. Ridging Tuesday looks to keep things dried out.
Wednesday, with the storm moving into the Upper Great Lakes,
moderate amount of snow is possible in E upper and portions of N
Lower IF the track holds. However, Wednesday is day 6, so will
mention it here that it is a concern, but leave it out of other
products for now. Thursday looks like light snow, may be some lake
effect, depending on which models 850 mb temperatures verify. The
ECMWF is colder than the GFS, so it would suggest some LES, while
the GFS is a little warmer, and doesn`t have the instability.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
Issued at 614 AM EST Fri Jan 20 2017

Low pressure and a warm front to our south will bring a round of
light rain to the airports later today and this evening. A soupy
near sfc air mass holds under a strong inversion across PLN/APN
and this LIFR/IFR stratus is not expected to go away. Thickening
mid level cloud will lower to low end VFR at TVC/MBL through today
as the light rain arrives, and back into IFR/LIFR tonight.
Expecting all areas in this very low stratus heading through
tonight with fog really never going away. Quarter mile or less
VSBYS at PLN/APN well into this morning, with improvement into the
day and with the rain, then a good chance at dense fog again
tonight.


&&

.MARINE...
Issued at 334 AM EST Fri Jan 20 2017

The pressure gradient remains pretty weak through Saturday night with
fairly light east to SE winds. Not much precipitation with just a
band of light rain crossing today and some additional light rains
through the start of next work week.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...DENSE FOG ADVISORY until 11 AM EST this morning for MIZ008-
     015>018-022>024-028>030-034>036.
LH...NONE.
LM...NONE.
LS...NONE.
&&

$$

UPDATE...TBA
NEAR TERM...SMD
SHORT TERM...JSL
LONG TERM...JSL
AVIATION...SMD
MARINE...SMD



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