Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 291049
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
649 AM EDT Wed Mar 29 2017

.NEAR TERM...(Today through Tonight)
Issued at 247 AM EDT Wed Mar 29 2017

High impact weather potential: None.

Pattern synopsis and forecast:

Early this morning, quiet outside with no concerns. Outside of some
low clouds that have worked into eastern upper from off Lake
Superior, skies were clear. Good radiational cooling has led to
temperatures in the middle 20s to lower 30s, already almost 30
degree spreads from yesterday`s highs. All the weather action was
well south and west of Michigan, in Texas and Oklahoma. A closed off
upper low and it`s associated sfc low and cold front were producing
showers and thunderstorms. Some of the storms were severe.

Pretty straightforward forecast. The upper low will lift into the
central plains through tonight with the sfc low and associated warm
front making it into the mid Mississippi valley. Mid level ridging
moves in overhead by tonight with ejected shortwave energy
increasing through tonight. This will result in a pretty sunny start
to the day, but skies will see an increase in higher level cloud.
Cloudy skies will develop into this evening in this scenario, with
saturation in the lower levels possibly occurring by daybreak,
especially the GTV Bay region. Here, the atmosphere will be cold
enough for the potential for a little snow and cold rain around
sunrise, with the arrival of stronger low to mid level warm
advection and possible upper level divergence.

A touch of cooling in the low level occurring right now due to
cooling from northerly winds just above the sfc. This will result in
cooler daytime temperatures than yesterday. The high almost  April
sun angle helped temperatures climb a little higher than yesterday,
and will go above guidance today. Readings in the middle 40s in
eastern upper, with upper 40s and lower 50s most areas of nrn lower.
Lows tonight in the lower half of the 30s.

&&

.SHORT TERM...(Thursday through Friday)
Issued at 247 AM EDT Wed Mar 29 2017

...Wintry mix expected Thursday - Thursday night...

High impact weather potential: Wintry mix of snow, sleet and
freezing rain arrives Thursday - Thursday night.

Pattern Forecast: Surface high pressure centered over Hudson Bay/NE
Ontario that`s responsible for today`s pleasant weather will
steadily move eastward, enabling developing low pressure across the
southern plains to eject toward the Great Lakes Thursday-Thursday
night before moving toward the Eastern Seaboard on Friday. This
feature will be the focus for the short term forecast period in what
has the potential to feature messy wintry weather Thursday into
Thursday night.

Primary Forecast Concerns: The main focus and challenges revolve
around the Thursday through Thursday night timeframe in terms of
timing of precip arrival, p-type, and amounts. What seems to be an
overly common theme with this system is the envelope of solutions
remains fairly wide at at this juncture. Model spread continues to
result in high confidence with respect to a storm system across the
Great Lakes region, but rather low confidence in the details as the
latest 24 hour trends have shifted the storm system back to the
north (vs. 48 hours ago, which featured a significant southward
trend). As was mentioned by the prior shift, the NAM remains the
outlier, at least in the upper level evolution of the system in
terms of overall phasing between a northern stream wave and the
parent low pressure system (in which the NAM features minimal
interaction). Will rely mainly on a blend of the ECMWF/GFS/GEM...all
of which are inclined to keep the system much more progressive.

Increasing isentropic ascent Thursday morning will gradually
overcome in-place dry air across the area from southwest to
northeast. Thus, a steady increase in PoPs throughout the day with
the steadiest/most widespread precip arriving during the mid-late
afternoon and evening hours before precip diminishes from west to
east overnight. In terms of p-type, this is where things become
awfully tricky. Expecting the bulk of precip to fall as rain during
the day Thursday as a lack of true cold air and late March diurnal
processes should help to sufficiently warm boundary layer temps
(high temps upper 30s to near 40). However, the expectation is for
rain to be sandwiched in between two periods of more wintry weather.
The intial threat Thursday morning continues to look fairly brief,
but may result in a bit of wet snow falling across far southwestern
areas. The more concerning window for mixed wintry precip will
arrive by mid-late afternoon into the evening for portions of north-
central and northeast Lower as precipitation continues to push
north, rates increase and a gradual loss of diurnal processes occur.
Expecting primarily snow for north-central/northeast Lower; however,
at the same time, a ~100-125 mb warm layer centered between roughly
925-800 mb will work its way into southern portions (generally along
and south of M-72) of the CWA during the evening, increasing
sleet/freezing rain chances across those locations. With low
pressure centered well off to our south, downsloping easterly winds
are expected to keep locations toward Manistee and Benzie counties a
couple of degrees warmer with rain continuing to be the predominant
p-type.

All in all, a fairly messy second half of Thursday looks to be on
tap for a portion of northern Michigan. Wet snow accumulations are
expected to remain on the minor side, ranging from an inch or two
across far northern/northeast Lower...to under an inch elsewhere.
See no glaring reason to remove mention of freezing rain and minor
(less than a tenth of an inch) ice accumulation for locations south
of M-72...primarily from Cadillac to Houghton Lake to Tawas.

Precip may diminish to lingering drizzle/freezing drizzle across
many areas after midnight Thursday night as mid-level moisture
begins to strip out before continuing to wane Friday
morning...pushing eastward by midday with partly sunny skies
prevailing eastern Upper and northwest Lower for the afternoon,
along with high temperatures topping out in the low 40s.

.LONG TERM...(Friday night through Tuesday)
Issued at 247 AM EDT Wed Mar 29 2017

Broad west-northwesterly flow takes hold across the Great Lakes over
the weekend with a weak wave or two sliding across southern Canada.
This may result in a scattered/light shower threat, primarily
Saturday night into early Sunday; however, most of the extended
period is expected to be dry with above normal temperatures
continuing. Beyond that, signals continue to suggest a more sizable
storm impacting a portion of the upper Midwest/Great Lakes during
the early to middle portion of next week. At this point, looks like
all rain with perhaps well above normal temperatures.

&&

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 646 AM EDT Wed Mar 29 2017

An area of low clouds and fog has progressively tracked south out
of PLN, heading for TVC for maybe a couple of hours at the start
of this TAF period. Otherwise, sunny skies will become
increasingly covered with higher level clouds through later today
and tonight in light wind environment. By late in the TAF period,
a little light rain or snow could begin in the GTV Bay region.
Confidence is not too high at this point.

&&

.MARINE...
Issued at 247 AM EDT Wed Mar 29 2017

Sfc high pressure nosing into the Great Lakes will gradually turn to
stronger easterly flow in tighter pressure gradient ahead of an
approaching low pressure system. These stronger easterly winds will
start late tonight and mainly through Thursday night as the low
crosses srn lower. As this system exits east, winds turn around out
of the northeast through Friday/Friday night. Small craft advisories
will be needed most everywhere in Lakes Michigan and Huron, while
it`s a little more iffy across Whitefish Bay/St. Mary`s. There, maybe
Thursday night into Friday morning.


&&

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

$$

NEAR TERM...SMD
SHORT TERM...MJG
LONG TERM...MJG
AVIATION...SMD
MARINE...SMD



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