Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 240737
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
337 AM EDT Wed May 24 2017

.NEAR TERM...(Today through Tonight)
Issued at 337 AM EDT Wed May 24 2017

...Unsettled weather continues...

High Impact Weather Potential...none.

Pattern Synopsis/Forecast: Blocky/slow moving flow pattern across
the CONUS with a deepening/pinching off upper low migrating down
through Iowa/Missouri, and broad surface low over the
Ohio/Tennessee Valleys. Weak-ish but persistent QG-forcing for
ascent associated with the upper low persists across the western
lakes region particularly from Wisconsin through lower Michigan
and into parts of Illinois/Indiana and Ohio. Strongest low level
moisture transport and corridor of the most persistent showers
currently stretches up through Lake Michigan and western lower
Michigan, before wrapping back into the upper low over Iowa along
the associated mid level deformation axis. Smaller pockets of
showers continue to percolate slowly up through the CWA.

Closed upper low will dig down into the Tennessee Valley during
the course of today, before swinging back into the Ohio Valley
tonight. As this occurs, ongoing weak-ish QG-forcing for ascent
across the western Great Lakes is expected to gradually fade in
time, refocusing down into the Tennessee Valley, then back into
the central Great Lakes tonight.

For today, with weakening QG-forcing, plan to have gradually
diminishing shower chances, although mid level deformation axis
sliding across the region along with the diurnal heating cycle
may once again help bubble-up showers across the inland higher
terrain, especially south of M-72 as forecast soundings reveal
some modest afternoon instability, particularly down around
Cadillac/Houghton Lake. In fact, wouldn`t be shocked to see a
little bit of thunder down that way this afternoon. Otherwise,
another mostly cloudy with temps continuing to run slightly below
normal.

Tonight: QG-forcing for ascent shifts back into the central Great
Lakes along with strengthening mid level deformation axis down
through the far eastern part of lower Michigan. Suspect we see
another batch of more widespread showers wrap back through SE
lower Michigan, Saginaw Bay and parts of NE lower Michigan as we
go through the night, and plan on having increasing E-W pops as we
go through the night.


&&

.SHORT TERM...(Thursday through Friday)
Issued at 337 AM EDT Wed May 24 2017

...Scattered showers...

High Impact Weather Potential...none.

Pattern Synopsis/Forecast...The 500 mb low slowly meanders to the
east during the day and overnight on Thursday. This produces
scattered showers through the day, especially in NE Lower as the
trough axis is just to the east over Lake Huron during the
afternoon. NW Lower looks to begin to dry out in the afternoon as a
500 mb ridge and dry air begins to push into the Upper Great Lakes.
AS the low goes east the rain looks to move out of NE Lower and
there is some drying in NE Lower overnight. Friday, it looks like
moisture and another 500 mb trough axis tries to push the ridge axis
out, the sfc flow looks rather weak with the sfc high over the
state. Not sure that the qpf that the models are producing will
materialize as the 500 mb ridge is over the area, but it looks like
a baroclinic zone is trying to form over the forecast area, so
scattered showers are possible. However, by the late afternoon
(21z), the 500 mb trough axis lifts NE and a 500 mb speed max
punches into the region with a dry air on the GFS.

Primary Forecast Concerns...The main concern is the coverage of the
showers and the duration of the low over the region, producing the
showers. The GFS clears things out quicker than the ECMWF, but even
the ECMWF does clear things out a bit Friday afternoon.

&&

.LONG TERM...(Friday night through Tuesday)
Issued at 337 AM EDT Wed May 24 2017

High Impact Weather Potential...Thunder Sunday, and Monday afternoon.

Extended (Saturday through Tuesday)...The blends on Saturday show
the rain moving into the forecast area, but thinning out until
Sunday. Sunday, a new more potent 500 mb low moves into the Upper
Great Lakes, during the day, with a sfc low and cold front. This may
have some thunder issues with the 500 mb speed maxes LFQ with winds
between 35-50 knots, mainly in NE Lower. At this point, it looks
like the 500 mb low moves through over about an 12-18 hour period.
The GEFS plumes of CAPE and shear show the best day for us on
Sunday, so will have to watch this day. However, Monday, the 500 mb
low slowly moves NE and allows for more rain showers and maybe some
thunder Monday afternoon. The trough moves through and clears out a
bit, but will expect that showers will be scattered Tuesday.


&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1153 PM EDT Tue May 23 2017

Weak low pressure was in SE Wisconsin, with an ill-defined frontal
boundary extending into lower Michigan, masked by very weak/near
calm wind flow. A more developed low pressure was in southern
Illinois, which will become the dominant sfc feature overnight,
which will help winds to become very light out of the east-
northeast. Minimal temp/dew point spreads, slow nocturnal cooling
under a blanket of clouds, and these very light winds coming in
off Lake Huron, will set the stage for MVFR to IFR CIGS and fog
for APN. Could see fog across the NW lower airports is the clouds
could thin a bit. Plus, better rains have fallen across this area,
and the wet ground will help in the development of fog. CIGS
remain difficult, as latest data still suggesting a period of
MVFR/IFR in NW lower as well. Not as confident in this however,
and have scaled back the length of time for these low clouds.

It may take awhile to get rid of the fog across APN Wednesday
morning. Confidence is somewhat low on how long VSBY restrictions
will last. The sfc low will only work very slowly east into
Indiana Wednesday, with additional scattered showers wrapping
around it`s nrn periphery, and into nrn Michigan for Wednesday and
Wednesday evening.


&&

.MARINE...
Issued at 337 AM EDT Wed May 24 2017

Northeasterly winds will increase a bit this afternoon into this evening
but are expected to remain blow small craft advisory conditions. Winds
diminish later tonight through Thursday. Scattered showers will
continue to impact most of our nearshore areas through thursday.

&&

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

$$

NEAR TERM...TBA
SHORT TERM...JSL
LONG TERM...JSL
AVIATION...SMD
MARINE...TBA


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