Area Forecast Discussion
Issued by NWS Gaylord, MI

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000
FXUS63 KAPX 171744
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
1244 PM EST Tue Jan 17 2017

.UPDATE...
Issued at 1018 AM EST Tue Jan 17 2017

Worst of the icy conditions is now over as widespread
precipitation departs and temperatures have warmed a few degrees
above freezing across northern lower Michigan. This trend should
continue for the remainder of the day, with just some spotty light
rain and drizzle south of the bridge, and a very light wintry mix
to the north. No significant ice or snow accumulations are
expected however. Now, despite the departure of freezing rain,
secondary and untreated road surfaces will likely remain ice
covered today, and that will continue tonight as readings once
again drop a few degrees below zero. Have cancelled the inherited
winter weather advisory, although will continue to highlight those
ice road concerns in our updated hazardous weather products.

&&

.NEAR TERM...(Today and tonight)
Issued at 315 AM EST Tue Jan 17 2017

High impact weather potential: Freezing rain and accumulations.

Pattern synopsis and forecast:

Sfc low pressure and it`s associated slightly negatively tilted
upper trough are crossing nrn Il early this morning. Initial round
of WAA precip underneath double jet structure upper divergence,
and ahead of analyzed vorticity advection has weakened over the last
few hours as it moves into extremely dry air out ahead of it, as
seen on 00Z APX sounding. Strongest of forcing has worked in over
the GTV Bay region where the best reflectivities have been, while
sfc temperatures were at freezing or just below, with warming and
above freezing readings aloft and atmospheric saturation for
limited/no further wetbulb effects. Hence, precipitation has mainly
been freezing rain with just some intermittent snow/sleet mainly on
the front end of the precipitation. Forcing is stronger out ahead of
the main upper trough with the addition of DPVA, and was working
into srn Lake Michigan where additional precipitation was developing.

Heading into and through this morning, the initial round of WAA and
DPVA with the vort max weakens as it continues to move into very dry
air to the north. Meanwhile, additional DPVA joins upper divergence
and WAA as the sfc low works into srn lower, and results in the
strongest forcing through daybreak. Worst conditions over this time,
with continued cool/dry easterly low level flow keeping sfc temps at
33F or below (slightly warmer in downsloping flow across coastal
areas of NW lower). The atmosphere slowly saturates north through
nrn lower while this is going on, with warming temperatures aloft. A
great setup for primarily freezing rain. Now, as far as QPF, all
signals point toward the greatest QPF working in across the SE CWA.
This makes sense with the main upper trough and shortwave crossing
SRN lower. The deep moisture and forcing only scrapes eastern upper,
with minimal QPF expected there. Most of the precipitation arrives
when temps climb to 32F/33F, but even a degree or two above
freezing, cold road surfaces will continue to result in icy
conditions, while secondary roads will be quite slippery/hazardous.
For the most part, the advisories follow the expected transition to
a cold rain (maybe into early afternoon for the highest of terrain
around Gaylord), and will not tweak ending times. Day crew can
follow temperature trends to make those tweaks. Main idea, is that
this is primarily a freezing rain event for nrn lower, with the
impacts of such to continue even after the true freezing rain ends,
especially secondary roads.

The deepest moisture gradually exits through morning with maybe
things ending as a bit of freezing drizzle/drizzle. The sfc low
pushes through the eastern Great Lakes by evening while sfc
troughing lingers back across lower Michigan resulting in some
possible patchy light rain/mixed precip. Nice inversion aloft will
trap lower level moisture for cloudy conditions through much of the
night, but dry air sneaks into the western CWA late for possible
clearing skies.

Highs 32F-36F with lows tonight lower half of the 20s in eastern
upper to upper 20s/near 30F south.

&&

.SHORT TERM...(Wednesday through Friday)
Issued at 315 AM EST Tue Jan 17 2017

...Fairly quiet stretch of weather...

A blocky and stopped up pattern looks to set up across the region.
This is in the form of a rex block with ridging to the north and
troughing to the south which will make it tough for weather systems
to make it too far north into northern Michigan through the upcoming
weekend. However, there is some extended model disagreement on this
with the 17/00z ECMWF now depicting low pressure moving up into the
area Friday while a majority of other models dampen out the wave
before it makes it this far north. Confidence on this pattern which
is rather anomalous is on the fair at best but will side with the
drier guidance for now. Extended models do agree that the block
moves off to the east leading to a better chance of precipitation
early next week (mainly in the form of rain). Temperatures will be
on the mild side for sure as there is little to no cold air to be
found anywhere close to us.

Wednesday into Thursday night...Models are in good agreement that
very little is going on during this time. It`s too warm aloft for
any over lake instability. The one issue is cloud cover with model
soundings trying to hold onto a bit of low level moisture. Overall
partly cloudy skies and mild temperatures are expected with highs in
the upper 30s to middle 40s and lows in the middle 20s to lower 30s.

.LONG TERM...(Friday night through Monday)
Issued at 315 AM EST Tue Jan 17 2017

Mainly dry and mild weather is expected through the weekend as
long as the ridge to the north hold it`s ground and allows for the
dry easterly flow to shield the area from systems to the south. By
early next week this pattern breaks down allowing low pressure to
make it up into our neck of the woods leading to the chance for
mainly rain Monday. Rather mild conditions expected to continue
through the period with cooler conditions perhaps returning by the
middle of the week.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1242 PM EST Tue Jan 17 2017

While freezing precipitation has ended, IFR producing low
clouds/mist/fog will continue right through tonight. Most
widespread fog should be found across interior areas, but expect
some reduction in visibility at all taf locations at times this
afternoon through the overnight hours. Slow improvement expected
from northwest to southeast Wednesday, with much better conditions
expected just beyond this taf period. Mostly light winds will
continue through the period.

&&

.MARINE...
Issued at 315 AM EST Tue Jan 17 2017

Low pressure crosses srn lower Michigan today and then through the
eastern Great Lakes tonight with easterly winds turning northerly.
The easterly winds are expected to sneak into advisory levels over
Lakes Michigan and Huron today. Winds lighten up tonight as they
back SW into Wednesday morning. Winds increase through Wednesday
into Wednesday night with potential advisories over mainly Lake
Michigan.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...SMALL CRAFT ADVISORY until 5 PM EST this afternoon for LHZ345-
     347>349.
LM...SMALL CRAFT ADVISORY until 5 PM EST this afternoon for LMZ323-
     342-344>346.
LS...NONE.
&&

$$

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



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