Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 280826
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
326 AM EST Tue Feb 28 2017

.NEAR TERM...(Today)
Issued at 326 AM EST Tue Feb 28 2017

...Wet...

High impact weather potential...could be a few spots that see a
wintry mix this morning. Better chances for mixed precip late
tonight.

Southerly low-level flow is increasing into the southern/central
Great Lakes region, between high pressure near the mid-Atlantic
coast and low pressure in the central plains. Warm front extends
across southern IA/central IL/southern IN. Precip is becoming more
extensive north of this front in the southern lakes. This shower
activity will impact northern MI today, transitioning to
fgen/deformation-related forcing tonight as the surface low cross
central/southern lower MI. Precip will mainly fall as rain. However,
will watch out for p-type concerns at precip onset today, and again
late tonight as cooler air filters back in.

Today...surface low will deepen as it moves east toward to IA/IL
border by 00z. Warm front will advance into southern lower MI.
Another unseasonably warm/moist airmass will invade the southern
lakes. This won`t be quite the push we saw last week, but still
rather impressive for the end of January. A few weak showers may
slip into southern portions of the forecast area by 12z/7am, but the
main invasion will clearly be after that. Surge of theta-e advection
aloft will allow showers to invade from sw to ne this morning.
Precip coverage will be more extensive and somewhat heavier this
afternoon. 0.10 to 0.40 rainfall totals will be common during the
daylight hours.

All sorts of warm air surging in aloft with the arrival of precip,
with 950-925mb temps in the +5c to 8c range. Excellent model
agreement that precip will be all liquid. But, given temps/dew
points are presently below freezing in much of northern MI, is
there a freezing rain (fzra) threat? Model guidance has also been
consistent that the fzra threat is small. Though warming surface
temps do (and will continue to) lag warming aloft, surface warming
is very much getting underway. Lake MI coast of nw lower MI,
aided by downsloping, is already zooming past freezing. Ne lower
coast is lagging by just a touch. This milder air will accelerate
nw-ward with time, and model soundings in most locales boost
surface temps above freezing 1-2 hours before precip begins, or
more. Will mention only a small chance of fzra in some areas this
morning, mainly around GLR and PLN, and in parts of Chippewa Co.

Differential temp/moisture advection will contribute to the
development of weak elevated instability late in the day south of M-
72. A slight chance for thunder will be mentioned here in the late
afternoon and evening hours.

Max temps will range from around 40f in the Sault, to around 50 at
MBL and Gladwin/Standish.

Tonight...as mentioned above, thunder mentioned in southern sections
in the evening. Rain will take on more of a banded/f-gen look in the
evening/early overnight (bands running from sw to ne), as the
surface low progresses into southern lower MI. Locally heavier
precip amounts will be seen at this time, with localized 0.50 to
1.00 inch QPF amounts at least feasible. Northern lower MI, closer
to the deepest moisture and outright (though weak) instability
aloft, has the best chance for this. Moisture starts to pull out
overnight above 600mb from nw to se. That still leaves moisture deep
enough to generate precip, but it will become lighter and less
expansive. This is just in time for precip to start to turn over to
snow, which will start around midnight in parts of eastern upper,
and will be approaching TVC/GLR/Rogers by daybreak. With precip
lightening up overnight, snow amounts will not be impressive,
perhaps pushing an inch near Whitefish Bay and less to the south.

Min temps from low/mid 20s eastern upper, to upper 30s near Saginaw
Bay.

&&

.SHORT TERM...(Wednesday and Wednesday night)
Issued at 326 AM EST Tue Feb 28 2017

...Accumulating snow possible Wednesday...

Yet another system that delves into the mixed precipitation realm.
This makes it tough to figure out what is actually going to fall
from the sky. There are lots of question marks as far as the details
of the likely change over to snow on Wednesday. This is in addition
to snow amounts and possible headlines are the biggest forecast
challenges facing this the midnight shift.

Wednesday into Wednesday evening...I wish this winter would just
make up its mind. Either stay mild or stay cold. This back and forth
stuff makes it extremely difficult to figure out the details
associated with the transitions. This is exactly what will be
happening once again. Models are in agreement that a deepening area
of low pressure moves across southern Lower Michigan then exits into
Lake Huron just south of the Thumb. Just how deep this system
becomes will ultimately determine how fast the cold air gets in here
as well as how much precipitation will fall and if what form it will
be in. As it stands now most models are in decent agreement in the
track but that`s about it. The GFS really cranks up the system. The
ECMWF is much more strung out but both models have a good deal of
QPF (between a half and three quarters of an inch across northern
Lower). The NAM is similar to the ECMWF as far as being strung out
and not as deep but it only has between a quarter and perhaps an inch
of QPF. All models it seems vary on how quickly the cold air advects
in from the northwest with the ECMWF seemingly the slowest with more
of a slow bleed in. Given all the uncertainty, will not be issuing
any winter weather headlines/watches. Expect a change over from rain
to snow from northwest to southeast. North central zones, especially
in the higher terrain stand the best chance at receiving several
inches of snow as they appear to get cold enough for snow while
likely receiving the most QPF. Elsewhere perhaps a couple to a few
inches of snow across eastern upper (not as much QPF) and across
southeast zones of northern Lower (later change over to all snow).
Snow should diminish from northwest to southeast during the evening
hours. Temperatures falling through the 30s into the 20s through the
day.

&&

.LONG TERM...(Thursday through Monday)
Issued at 326 AM EST Tue Feb 28 2017

Fairly decent but quick shot of arctic air moves into the region.
850 mb temperatures bottom out in the -20 C degree range Friday
morning. NNW/NW flow favored areas stand to see some lake effect
snow showers. The flow meanders around as a pair of short waves move
through the flow. Favored areas could see a few inches of snow. Much
colder with highs in the 20s Thursday and only the middle teens to
lower 20s Friday.

Friday night through Monday...Here we go again with rising
heights/warm advection kicking in. There could be some snow showers
Friday night and either rain or snow showers Saturday with the warm
advection, otherwise warming temperatures are expected through the
time period. Low pressure then tracks by to our north Monday
bringing a chance for mainly rain.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1219 AM EST Tue Feb 28 2017

...Widespread IFR conditions developing on Tuesday...

No problems tonight with gradually lowering mainly mid-high clouds
in advance of a warm front. Cloud deck will continue to lower on
Tuesday morning with areas of light rain/mist developing. VFR
cigs will quickly drop to MVFR and eventually IFR as the day
progresses. A borderline LLWS possibility for Tuesday morning at MBL
and TVC as winds aloft ramp up to 30 knots with still mainly light
surface winds.  Given marginal conditions and low confidence, did
not include in the 06z TAFs.  Widespread IFR cigs and vsbys expected
into Tuesday night with areas of LIFR possible.  Stronger winds
aloft over northeast lower Michigan near APN Tuesday evening may
result in a period of LLWS.   As colder air moves into the area late
Tuesday night, cigs and vsbys will slowly improve as the rain
transitions to wet snow.

&&

.MARINE...
Issued at 326 AM EST Tue Feb 28 2017

Southeast to south winds will increase today, in advance of low
pressure that will move into southern lower MI tonight. Some
advisories will be issued shortly. Northerly winds will be gusty
behind this low on Wednesday, and advisory conditions are expected
and gale force gusts are possible.

&&

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

$$

NEAR TERM...JZ
SHORT TERM...AJS
LONG TERM...AJS
AVIATION...JRK
MARINE...JZ


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