Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 140250
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
950 PM EST Tue Feb 13 2018

.UPDATE...
Issued at 950 PM EST Tue Feb 13 2018

Subtle short wave trough continues to pass through northern
Michigan this evening...just behind a strong upper jet core that
stretches from the central Great Lakes into the Atlantic. Batch of
associated mid cloud cover has been streaming through the region
all afternoon and into this evening producing lots of mid level
radar returns. Mainly VIRGA...although probably a little bit of
something was getting to the ground in spots (ANJ and CYAM both
reported a little bit of light precip earlier in the day). Cloud
cover and mid level radar returns have been thinning out in recent
hours as the upper jet core continues to race eastward off the
coast.

Rest of tonight...mainly clear skies is the expectation. That
said...model RH forecasts/soundings continue to suggest develop of
low stratus from Wisconsin across northern Michigan
overnight...lingering into Wednesday...although 00Z NAM has
backed off some with that idea. Looking upstream...no hints of any
widespread stratus at the moment (should already be a good amount
of stratus across western Wisconsin into Minnesota per model
forecasts). It does remain a possibility however...as low level
flow ramps up and pulls increased low level dewpoint air into
region. But at the moment...will stay the course with mainly clear
skies overnight and a little bit of high cloud cover dropping in
on Wednesday. IF low cloud cover develops...high temps for
Wednesday will need adjusted.


&&

.NEAR TERM...(Tonight through Wednesday)
Issued at 312 PM EST Tue Feb 13 2018

...Mild weather arrives Wednesday...

High impact weather potential: Nothing.

Pattern synopsis/forecast: Mid level confluent axis laying out
across the region as strong surface high gets ready to slide off the
east coast. Passing shearing shortwave trough coming through with
little fanfare, other than plenty of high and mid level clouds.
Southerly flow ramping up on upstream side of that departing high
starting the upward temperature trend, with current readings
punching up well into the 20s, this despite those mostly cloudy
skies.

Today`s increasing temperatures just a sign of things to come as
southwest flow continues to strengthen through Wednesday. Coupled
and deep warm air advection between east Atlantic high pressure and
an approaching cold front will shoot temperatures to well above
normal levels for Wednesday.

Primary forecast concerns/challenges: Temperature and cloud trends.

Details: Tough temperature forecast tonight as clouds depart this
evening. Winds expected to never fully decouple for most areas,
allowing mixing to continue and preventing a strong nocturnal
temperature response. However, winds may go light enough across the
Ausable River Valley this evening to allow temperatures to drop
quickly into the teens before rising overnight. Forecast remains
trended in this direction, with colder readings across northeast
lower Michigan and temperatures barely responding at all along Lake
Michigan. Otherwise, some hints in guidance of stratus development
toward Wednesday morning. Those same progs seem to show unrealistic
moisture development in the near-surface layer, especially given no
substantial snow melt today. Will shy away form this idea for now.

Once again, not buying some of the aggressive low clouds during the
morning seen is some guidance. This forecast will definitely trend
to a much more sunnier scenario with a complete dearth of
appreciable moisture through the column. Warm air advection reaches
maturity by afternoon as H8 temperatures spike into the middle
single digits. Of course, full warming potential will not be
realized with maintenance of a very shallow inversion. With that
said, all warm-ups this winter have near or exceeded near-term
guidance numbers. Would expect the same Wednesday, with highs
punching into the lower and middle 40s over northern lower Michigan,
with just a bit cooler readings north of the big bridge. Gusty
southwest winds will make it feel a touch cooler of course.

&&

.SHORT TERM...(Wednesday night through Friday)
Issued at 312 PM EST Tue Feb 13 2018

...Drizzle/Freezing Drizzle Wednesday night?...

High Impact Weather Potential: Threat for drizzle Wednesday night
perhaps transitioning to patchy freezing drizzle, especially in the
typically cooler/interior spots by sunrise Thursday morning.

Pattern Forecast: Nearly zonal flow aloft on Wednesday night will
feature a pair of shortwaves trekking across the area. Deep layer
moisture remains next to nil, which is expected to keep measurable
precipitation out of the forecast; however, some drizzle and/or
freezing drizzle remains possible. A cold front will slide northwest
to southeast across northern Michigan Thursday morning with a return
to somewhat more wintry conditions expected through the start of the
weekend.

Primary Forecast Concerns/Challenges: Freezing drizzle threat
Wednesday night/early Thursday.

Primary focus revolved around light precip chances Wednesday night
into early Thursday ahead of a well-defined, but moisture starved
wave set to quickly race across the area. Latest model soundings
continue to suggest low level moisture increases Wednesday
evening...generally confined to the lowest 2-2.5 kft. As a result,
expecting any precip to fall in the form of drizzle, which by the
pre-dawn hours Thursday morning raises concern for the potential of
patchy freezing drizzle, especially across the typically
cooler/interior spots of both northern lower and eastern upper . The
threat window for freezing drizzle looks fairly brief, but worth
monitoring as even a little ice can cause travel headaches.

More winter-like air progressively spills back into northern Michigan
behind a cold front progged to be sliding northwest to southeast
across the forecast area early in the day Thursday. Moisture
gradually deepens throughout the day leading to increasing lake
effect snow chances in northwest flow lake belts Thursday night into
Friday; however, any accumulation is expected to be rather
scattered and minor.

High temperatures ranging from the low-mid 30s north to near 40 by
Saginaw Bay. Much cooler Friday with high in the teens to low 20s
area wide.

.LONG TERM...(Friday night through Tuesday)
Issued at 312 PM EST Tue Feb 13 2018

The upper level pattern is generally a dirty-zonal flow through the
first part of the extended period...but begins to transition with
the start of the new work week...as troughing begins to develop over
the western half of the conus.  Waves moving through the flow will
keep temperatures ever variable and with periodic chances for
precipitation.  But I think the big focus will be around Tuesday
when a substantial, slow moving frontal boundary will begin to press
into the Great Lakes.  This will bare watching closely, as the water
is very murky on what temperatures will be doing at that time.
There`s a chance that we could get a surge of warm air ahead of this
system...which could mean a relatively widespread rain event.  Then
again...if the aforementioned troughing shifts east, we could see
cold enough temperatures for mixed or more wintry precip.  Needless
to say...I have no confidence in making any deterministic calls 7
days out.  So bottom line...much (if not all) of Saturday should be
dry.  A brief chance for snow Saturday night/Sunday morning (but I`m
not impressed).  Warmer Sunday...so the next wave, late Sunday into
Monday could be rain/mixed.  Big weather maker for Tuesday and
beyond. Clear as mud? Yeah...welcome to my world.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 734 PM EST Tue Feb 13 2018

Batch of mid level cloud cover continues to pass through the
region this evening...but will thin out over the next few hours.
Solid VFR conditions are anticipated through the upcoming TAF
period. That said...some guidance sources/model data suggest the
development of low (MVFR) stratus across northern lower Michigan
later overnight and hanging around through the day Wednesday.
Thought is...raw model guidance is too aggressive and has been
largely discounted (MOS guidance keeps VFR CIGS through the
period). Nonetheless..the possibility is there.

Otherwise...strong winds develop off the surface this evening and
will lead to LLWS conditions at the terminal sites through
Wednesday morning.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
&&

$$

UPDATE...BA
NEAR TERM...MB
SHORT TERM...MG
LONG TERM...KB
AVIATION...BA



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