Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 202037
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
337 PM EST Mon Feb 20 2017

.NEAR TERM...(Tonight and Tuesday)
Issued at 326 PM EST Mon Feb 20 2017

...Rain and Fog tonight Rain ending Tuesday...

High Impact Weather Potential...Minor river flooding following the
rain and snow melt. Dense fog possible, but not likely with the
rain.

Pattern Synopsis/Forecast...Return flow is increasing as the sfc
trough/cold front off to the west is pushing toward the Upper Great
Lakes. Rain on MRMS is just into W Upper and W Wisconsin. It will
continue to fight a lot of dry air ahead of it as the sfc RH is
around 35% in the western counties of the forecast area. Dewpoints
are creeping up with the stations in the west like CAD, MBL and FKS
are 32 or 33F. As the moisture increases from the strong warm
advection, will begin to see fog develop. At this point, it looks as
if the fog will remain at 3 miles of better as the moisture
increases, but with the rain, we may not see much restriction below
that.

The rain will continue through the night as the cold front
progresses through the forecast area. It looks there could be some
thunder with the frontal passage, as the lapse rates, and the strong
low-level jet feeds into the system. However, it looks like the
thunder threat is low, so have it as slight chance. The front looks
to be through the forecast area, around 12z/Tue allowing for some
trailing showers through about mid day. Models
(GFS/NAM/ECMWF/NMM/ARW/SREF) all in agreement that the rain is out
of the northern Michigan and most if not all of the Lake Huron by
21z, and the region by 00z.

Primary Forecast Concerns...Fog if it gets soupy, which is possible
with these systems, but with the winds and the rain, feel that minor
fog, with patches of denser fog are possible. However, tuesday will
be a day to watch to see how the snow melt, and rain fall do
anything to the rivers. The plus side is that there are large chunks
of N Lower where the snow has melted. The rest of the region has
about 2 to 3 inches of water equivalent, but not all of it will melt
in 12 hours. Today, the only river that is expected to approach
Action stage is the Manistee River near Sherman, and it has a 20%
chance or lower of exceeding minor flooding (15Ft). So will keep an
eye on that one and the Rifle River near Sterling for the next day
or two.

&&

.SHORT TERM...(Tuesday night through Thursday)
Issued at 326 PM EST Mon Feb 20 2017

...Record setting warmth possible on Wednesday...

High Impact Weather Potential: Nothing from a sensible weather
standpoint. Still monitoring river rises over the coming days.

Pattern Synopsis/Forecast: Unrelenting warmth set to continue for at
least a few more days as much modified Pacific air dominates much of
the northern Conus. Not an overly active stretch of weather through
the short term, although a fast moving and amplifying wave looks to
bring a bout of showers to northern areas Wednesday night. This
system will also send a more bonafide cold front through the region
Thursday, starting the step-down process to more typical late
February weather for these parts.

Primary forecast concerns: Just how warm to go Wednesday and
addressing the rain chances late Wednesday and Wednesday night.

Details: A mild and dry Tuesday night sets the stage for possible
record warmth on Wednesday. Morning sunshine and deepening southwest
flow ahead of fast moving shortwave should only help the cause, as
will a nearly complete loss of the snow pack for much of northern
lower Michigan. Weak warm front looks to take shape during the day
across far northern lower Michigan/the Straits, placing much of the
area south of the big bridge squarely in the warm sector. Guidance
progs show this well, with much of northern lower well into the 50s,
and the southeast half of the area making a run at 60 degrees. This
will suffice for now, although as cool as guidance numbers have been
compared to reality during this warm stretch, would not be at all
surprised if some areas were several degrees warmer. Taking a quick
look at record temperatures for the date suggests nearly all records
are in jeopardy of falling, with Houghton Lake (64 degrees back in
1930) having the best chance to survive. That warmth continues right
into the first half of Wednesday night as southwest flow further
intensifies with approach and passage of that amplifying shortwave
trough. Per trends, best forcing and focus for moisture convergence
looks to remain across Lake Superior and points further north.
Proximity of system does support at least some low end shower
chances across the north later Wednesday into Wednesday night.
Moisture and forcing starved cold front crosses the area overnight
into Thursday morning. While post-frontal northwest to north winds
do usher in a progressively cooler and drier airmass Thursday, real
cold air will still be locked up well to our north. So, while it
will definitely be cooler on Thursday, with highs largely in the
40s, these are still 10 or more degrees above normal for the date.

As for those river rises, much of the snowpack will be largely gone
by Tuesday night and Wednesday, with the exception being across the
snow belts of eastern upper Michigan and the interior highlands of
northern lower. Combination of warm temperatures and increasing
dewpoints will do a number on this existing snow, and would not be
at all surprised if nearly all of northern lower is essentially snow-
free by Thursday morning. Rivers will of course respond to this
runoff, but lack of any significant rain during this period should
keep rivers within their banks. Of course, this will continue to be
monitored in the coming days.

&&

.LONG TERM...(Thursday night through Monday)
Issued at 326 PM EST Mon Feb 20 2017

High Impact Weather Potential: A system moving through Fri/Sat will
bring a wintry mix for much of northern Lower. Areas that remain all
snow, which right now look to be mostly north of the Straits, could
pick up a few inches of accumulating snow.

Low pressure moving out of the Plains will move into the region over
the weekend. Strong H5 cutoff low will continue to strengthen the
low as it enters the Great Lakes. Good return flow with an open Gulf
will give the system plenty of moisture to work with, but it looks
like a good portion of the precip will fall as rain or perhaps a
rain/snow mix especially across northern Lower. Lake effect will
linger through Saturday as a brief shot of cold air pushes south.
This push of cold air will return temperatures to more seasonable
readings through the weekend, though the will still be a touch above
normal.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1216 PM EST Mon Feb 20 2017

At the moment, mainly high thin clouds are over the region with
nothing below 12k feet until well back into Wisconsin. This will
continue into the afternoon, although the high clouds will thicken
later this afternoon.

This evening and through the night, there will be several things
that are of concern...

Low level Wind Shear will begin to make an appearance around 00z
as the inversion strengthens from the elevated warm advection and
the nocturnal processes. This will lead to winds of 35-45 kts at
roughly 2000 feet until the cold front passes through the region.
The rain will start up in the region around 00z in E Upper, and
probably closer to 03z in NW Lower as the front approaches(06z for
NE Lower). As the front moves through the region, there is a small
chance with the steepening lapse rates (700-500 mb ~6C/km), and
with a few lightning strikes out in Minnesota this afternoon,
have put the slight chance in the grids, but left them out of the
tafs for now. Fog will increase as the dewpoints rise to over
freezing, especially with the rain, will expect that there will be
areas of fog to contend with.

&&

.MARINE...
Issued at 326 PM EST Mon Feb 20 2017

Tonight through Tuesday...Small craft advisories were issued this
morning, as the winds were expected to increase through the day.
Offshore winds along the Lakes are beginning to hit small craft
criteria, and are expected to continue into tonight. However, once
the cold front moves through the region Tuesday morning, the
gradient relaxes and the winds will diminish through the day. Winds
on Tuesday night increase a bit, but are expected to be below small
craft criteria, and Wednesday looks like light winds through the
day.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...SMALL CRAFT ADVISORY until 7 AM EST Tuesday for LHZ345>349.
LM...SMALL CRAFT ADVISORY until 7 AM EST Tuesday for LMZ323-341-342-
     344>346.
LS...NONE.
&&

$$

NEAR TERM...JSL
SHORT TERM...MSB
LONG TERM...ALM
AVIATION...JSL
MARINE...JSL



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