Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 202121 CCA
AFDAPX

Area Forecast Discussion...CORRECTED
National Weather Service Gaylord MI
421 PM EST Fri Jan 20 2017

.NEAR TERM...(Tonight and Saturday)
Issued at 409 PM EST Fri Jan 20 2017

...Periods of dense fog into Saturday...

High Impact Weather Potential...dense fog at times.

Pattern Synopsis/Forecast...Dampening mid level shortwave trough
continues to swing up through the state this afternoon with a
stretched out axis of precip lifting up through northern Michigan.
Precip really thinned/fell apart across this part of the state
over the last several hours producing only minor QPF. Precip is a
bit more robust just to our west across Lake Michigan and
Wisconsin where apparently stronger shortwave forcing resides and
some orographic lift may be helping the cause.

Meanwhile, we did manage to lose a good bit of the fog this
afternoon. But, there is still some rather dense fog across
eastern upper Michigan and parts of NE lower Michigan.

Primary Forecast Concerns...drizzle and fog. Shortwave trough and
axis of precip will continue to lift up through northern Michigan
this evening ending the main precip threat. Then, forecast
soundings show respectable drying aloft later in the evening and
overnight while low level saturated layer deepens to a few
thousand feet overnight through Saturday morning, a strong drizzle
and fog signal. Have trended the forecast to include more along
the lines of drizzle later tonight through Saturday, possibly a
little freezing drizzle in the higher terrain.

Fog concerns: Fog did manage to thin/clear over a good part of
northern lower Michigan today, still holding on across eastern
upper Michigan and NE lower Michigan. Fog likely to return again
tonight and plan on issuing another dense fog advisory for a good
portion of the CWA.

&&

.SHORT TERM...(Saturday night through Monday)
Issued at 409 PM EST Fri Jan 20 2017

...Continued cloudy and mild with rain chances...

High Impact Weather Potential...Minimal, but a brief period of
freezing rain can`t be ruled out late Sunday night into Monday
morning.

Pattern Synopsis/Forecast...A warm front over Lower Michigan
Saturday night will make it about as far north as our southern CWA
border by Sunday morning before it stalls out. Meanwhile an upper
low over northwest Wisconsin will shear out as it slowly wobbles to
north of Lake Superior on Sunday, and a strong surface low will move
eastward from the southern Plains, reaching the Mid-Atlantic Coast
on Monday. Ongoing WAA will persist across much of the area Sunday
into Monday, with isentropic lift and an inverted surface trough
leading to an increased chance of rain showers Sunday afternoon and
evening. Split upper level flow will develop over the Midwest Sunday
night into Monday as a blocking ridge becomes highly amplified off
the East Coast. This ridge will cause the sheared out upper low over
southern Ontario to lift further north while a deep cutoff low
meanders over the Mid-Atlantic. This will translate into continued
surface troughing over northern Michigan during the day on Monday,
providing continued rain chances.

Primary Forecast Concerns...Ongoing WAA and dewpoints in the mid to
upper 30s will allow for efficient melting of the snowpack through
the weekend, resulting in a rich supply of low level moisture and
persistent low level cloudiness. Also of concern will be the
potential for lingering fog across the area Saturday night into
Sunday morning. Southerly low level flow will back to easterly on
Sunday as the inverted surface trough noses into northern Michigan.
This will cause a westward propagation of isentropic lift during the
day on Sunday with rain chances increasing as the best lift arrives
during the afternoon and evening. Temperatures are expected to drop
to right around freezing over eastern Upper and higher elevations of
northern Lower late Sunday night into Monday morning. This may
result in a brief period of freezing rain for some, but NAM forecast
soundings show only a shallow saturated layer aloft suggestive of
drizzle. The GFS has a deeper, colder saturated layer more
supportive of light snow. The ECMWF and Canadian are more middle of
the road for temperatures aloft. This will bear watching, but
at this time impacts are expected to be minimal.

&&

.LONG TERM...(Monday night through Friday)
Issued at 409 PM EST Fri Jan 20 2017

The big picture in the extended period will be unsettled weather
with a general cooling trend from Tuesday to Friday.  The 500mb
pattern shows the conus dominated by broad troughing that begins in
the rockies and widens eastward by Thursday.

On Tuesday, a closed low develops in the central plains and sets it
sites on the great lakes. This low will move across Michigan on
Wednesday and of course it`s track will dictate exactly how Northern
Michigan is effected.  At present, The euro and GFS are tracking
this low through the straits of Mackinac. Of course that being day
5, this can still and likely will, change...but will remain the main
forecast challenge in the long term. The temperature regime and this
storm track would indicate we`ll be dealing with P-type issues...at
least across the lower peninsula.

Colder air begins to infiltrate on Thursday...at it`s looking like
it could be cold enough, with favorable wind fields and enough
moisture to generate some lake effect snow for Thursday and Friday.
It is still too far off to be confident in this call...but will
warrant chance pops at least.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 136 PM EST Fri Jan 20 2017

Some dense fog remains across northern lower Michigan this afternoon,
mainly NE lower Michigan and the tip of the mitt. Still anticipate
improvement at those terminal sites (PLN, APN) as we go through
the afternoon hours, although unclear over just how much
improvement occurs. VSBYs could return to VFR at those sites
although I have kept the terminal forecasts IFR for now and will
see how it goes. A different story at TVC and MBL where VSBYs and
CIGS have become VFR and will remain that way through the
afternoon. But, a return of lower cigs and fog happens again
tonight at all terminal sites.

Precip-wise, axis of decaying precip will slide up through
northern lower Michigan through 03Z or so bringing some light
rainfall. Drizzle may become more prevalent tonight into Saturday.


&&

.MARINE...
Issued at 409 PM EST Fri Jan 20 2017

Overall light winds and waves anticipated through the weekend. No
headlines anticipated.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...DENSE FOG ADVISORY until 6 PM EST this evening for MIZ015.
LH...NONE.
LM...NONE.
LS...NONE.
&&

$$

NEAR TERM...TBA
SHORT TERM...MEK
LONG TERM...KAB
AVIATION...TBA
MARINE...TBA



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