Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 181743
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
1243 PM EST Sat Feb 18 2017

.UPDATE...
Issued at 936 AM EST Sat Feb 18 2017

Cold front passing through with barely a whimper this
morning, with crystal clear skies and well above normal
temperatures. Readings continue to vary considerably across the
area, although those earlier chilly locations have begun there
upward diurnal response. Skies will remain mostly sunny today,
with just perhaps a few passing high clouds across the north this
morning. Off-the-deck warm nose (local 12z sounding had an
unbelievable +11C reading centered at 810 mbs!) will slowly cool
through today. Despite this, given exceedingly warm start to
surface temperatures and abundant sunshine, still expect
temperatures to make a run into the lower/middle 50s south of the
big bridge, with readings just a touch cooler to its north.

&&

.NEAR TERM...(Today and tonight)
Issued at 349 AM EST Sat Feb 18 2017

High impact weather potential: None.

Pattern synopsis and forecast:

Upper level ridging covered much of the conus east of the Rockies,
with one weak cut off low working toward the lower Mississippi
valley, undercutting this large scale ridging. Another shortwave
trough was pushing through the ridge across Ontario and the far nrn
Great Lakes with an associated sfc low in Manitoba/western Ontario.
The air mass was very dry with even high level cirrus hard to come
by. The warm advection is pretty much maxed out over nrn Michigan
with H8 temps around +12C back through srn Wisconsin. All of this
warm air was out ahead of a weak cold front from central Lake
superior through NW Wisconsin. As stated in previous discussions,
there isn`t much true cold air behind this front, but lower BL
temperatures were seen across western Ontario and Manitoba where
there has been some patchy/areas of stratus development. From a
temperature standpoint, readings were all over the map. Some of the
most protected low lying areas were coldest in the middle 20s, with
areas in more wind/mixing still as warm as 50F (Frankfort).

The shortwave and sfc low pressure will quickly cross through
Ontario today, and off the New England coast by Sunday morning. The
weak cold front drives through this morning and will likely aid
pressure gradient winds in adding a bit more mixing into the strong
inversion. Any additional mixing will result in significant warming
since the inversion is so strong. Temperatures should have no
problem hitting the lower to middle 50s across much of lower
Michigan, (warmest NE lower due to downsloping and where snow cover
is low). Eastern upper likely hitting the middle 40s. Skies expected
to be rather sunny today with no morning stratus or clouds around
the region. The slightly cooler BL air from Manitoba/Western Ontario
will gradually drop into nrn Michigan later today and through
tonight. The development of patchy/areas of stratus increase through
the night, especially across eastern upper and far nrn lower, aided
by nocturnal cooling. Fog not likely to be too bad in these areas
due to a tighter pressure gradient, but better snowmelt and weaker
winds across areas further south will lead to a more fog than
stratus scenario. Low temps generally in the lower 30s.

&&

.SHORT TERM...(Sunday through Monday)
Issued at 349 AM EST Sat Feb 18 2017

...Some low stratus possible on Sunday...

High Impact Weather Potential...None.

Pattern Synopsis/Forecast...Anomalous upper ridge will build into
the Great Lakes region Sunday into Monday, with 700mb and 500mb
heights climbing 2 to 3 standard deviations above the mean across
northern Michigan. Temperatures on Sunday will be tempered somewhat
due to NW flow aloft parallel to the 850mb temperature gradient and
a backdoor cold front over southeast Ontario preventing the warmth
to our southwest from advecting downstream. That all changes on
Monday as ridging becomes more amplified and WAA develops in earnest
over Michigan. High pressure at the surface will keep the area dry
through Monday afternoon with precip chances increasing Monday
evening as low level moisture quickly rises.

Primary Forecast Concerns...With a rather benign weather pattern in
place, the only forecast concerns will revolve around cloud cover
and fog potential. The NAM (and, to a lesser extent, the GFS)
continues to show shallow low level moisture lingering below 900mb
across eastern Upper and far northern Lower through the day on
Sunday that could indicate some low stratus potential. The NAM
develops a stronger subsidence inversion to trap the low level
moisture, whereas the GFS shows a weaker inversion with less low
level moisture. With plenty of snow melt occurring on Saturday and
cooler air streaming into our north with the backdoor cold front
over southern Ontario, feel the NAM is more on the right track with
the stratus potential across our north during the day. Partly cloudy
skies Sunday night and light winds under the surface high will allow
for a chance of patchy fog. Temperatures Sunday and Monday will be a
bit cooler (but still mild) with highs ranging from upper 30s north
to upper 40s south.

.LONG TERM...(Monday night through Friday)
Issued at 349 AM EST Sat Feb 18 2017

High Impact Weather Potential...Minimal.

The next system will push through the region Monday night into
Tuesday as strong WAA takes hold ahead of an approaching cold front
and strong shortwave trough. Models are showing a significant influx
of moisture across the Upper Great Lakes with PWATs around an inch
Monday night. This would be 3 to 5 SD above the mean for late
February according to the GEFS and NAEFS. For perspective of this
potential rarity, there has only been one instance of KAPX recording
a PWAT of 1 inch or higher in February, according to SPC and WFO
UNR`s sounding climatologies. Despite the impressive moisture
influx, instability will be limited by nighttime temperatures
dropping into the 30s. Wouldn`t completely rule out a rumble of
thunder or two across our south, however. Looks like mainly just
rain across northern Michigan, but across eastern Upper where
temperatures are expected to drop to around freezing Monday night,
there may be a bit of snow or freezing rain mixed in. The rain will
push out of the area Tuesday afternoon/evening.

A fast moving clipper-type system will brush northern Michigan on
Wednesday bringing another chance of rain. Temperatures will drop a
bit behind a cold front associated with this system, but still look
to remain on the mild side through the end of the work week. A much
stronger system looks to be on the horizon for the end of the week
(Thursday night through Saturday) with a return to some snow as
colder air wraps in with it.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1240 PM EST Sat Feb 18 2017

VFR conditions through this evening under mostly clear skies and
light winds. Still some potential for light br and stratus
development overnight, although trends support much of this
activity remaining across eastern upper Michigan. Have tentatively
put in some minor vis restrictions at all sites, dropping KPLN to
near IFR conditions during the early morning. However, this is a
very low confidence forecast. Any fog/stratus should lift Sunday
morning.

&&

.MARINE...
Issued at 349 AM EST Sat Feb 18 2017

Very stable overlake conditions are keeping winds in check despite
stronger flow aloft. The passage of a weak cold front today will put
at least a little dent in this stability while the gradient remains
somewhat decent enough for some low end gusts tipping advisory
levels later today and tonight. The better chance for these winds
will be across the nrn nearshore waters. Lighter winds by Sunday
with high pressure. Winds turn more SE/south Monday and increase
Monday night. Despite increasing stability in warm advection, could
see advisory level winds.


&&

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

$$

UPDATE...MSB
NEAR TERM...SMD
SHORT TERM...MEK
LONG TERM...MEK
AVIATION...MSB
MARINE...SMD



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