Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus63 kapx 160351 
afdapx

Area forecast discussion
National Weather Service Gaylord Michigan
1151 PM EDT sun Sep 15 2019

Update...
issued at 945 PM EDT sun Sep 15 2019

00z apx sounding was nearly saturated up thru 670mb, or 10k ft agl.
That is more than enough depth for warm rain processes to go work,
resulting in drizzle at times. Drizzle has been most frequent
over the high terrain of northern lower, but has been seen even
down into tvc. We are also seeing a few embedded showers,
especially over NW lower Michigan and Northern Lake Michigan. Cape values of
100-150j/kg are seen when lifting from 885mb. And there some lift
tonight, with shallow se sub-900mb winds ascending over a stalled
front downstate. Near-term cams allow showers to become more
prevalent tonight, mainly between M-32 and M-28. Will steer the
forecast wetter in that area.

Low-level moisture was mixed out today along the fringes of the
forecast area, especially in Chippewa co. With loss of heating,
and only weak se flow below 900mb, there is no further source of
dry air. Thus expect lower cloud to expand back out again tonight.
This could take the form of fog in some spots, especially over
the higher terrain, where stratus is already nearing ground level
(including here at apx).

Some fine-tuning of pops has been required, in general broadening
the area over which drizzle and/or showers are mentioned. Temps
have been tweaked slightly higher.

&&

Near term...(through tonight)
issued at 327 PM EDT sun Sep 15 2019

..cloudy with some fog and drizzle...

High impact weather potential: dense fog possible tonight into
Monday morning.

Pattern synopsis/forecast: afternoon composite analysis shows
broad northwesterly mid level flow aloft across the upper Midwest
and northern Great Lakes with an exiting short-wave sliding
through southeast Ontario. Weakly defined surface low pressure is
over Iowa into southern Wisconsin with a warm front that arcs into
the southwest part the forecast area and down toward Saginaw Bay.
Lots of low cloud cover is draped across lower Michigan but
clearing out north of The Straits. Despite this, and with the help
of a little sun, temperatures have been able to warm into the 70s
around tvc/fks/mbl area...60s elsewhere.

We've seen very little precip over the last several hours other
than just a hint of drizzle in the higher terrain and a couple
blips on radar toward tvc/cad/htl areas into Lake Michigan, in
the vicinity of the warm front.

Primary forecast concerns: dense fog possibilities tonight.

Weakly defined surface low circulation is expected to slide on
across Southern Lower Michigan tonight with low level flow across
northern Michigan eventually turning back into the north-
northeast, while reinforcing/deepening low level moisture/stratus
up through northern Michigan. With further heating, we may yet
see some isolated showers over the next few hours across the
southern/SW part of the County Warning Area in the vicinity of the front and where
temps have warmed some. Thus, I plan to retain our going low
chances for showers heading into the evening.

Meanwhile, with deepening moisture and increasing low level shear,
forecast soundings show a pretty good signal for fog/stratus/drizzle
potential, with drizzle most likely through the higher terrain
areas of northern lower Michigan. Temp/dewpoint spreads are
already pretty small in most areas. And with very limited daytime
mixing/cooling temps tonight and light winds, it's possible we see
some dense fog development as we go through the night. Not
planning any fog headlines at this juncture, but later shifts will
need to monitor conditions for possible fog headlines heading into
the Monday morning commute.

&&

Short term...(monday through wednesday)
issued at 327 PM EDT sun Sep 15 2019

High impact weather potential: none.

Pattern synopsis and forecast:

A large area of surface high pressure and anomalously strong upper
level ridge (582-588 dm heights at 500mb, about 1.5-2 Standard
deviations higher than normal) builds into the region to provide
warmer than normal temperatures and dry weather throughout the
period. The light winds and small dew point depressions during the
morning hours Monday and Tuesday may create some fog. This fog may
be a problem and hinder temperatures from rising as forecast Monday
and Tuesday. Also have concerns that the fog just rises as a stratus
deck and remains longer than forecast with the mid-September sun
angle taking longer to burn everything off. Light and variable winds
will be over the forecast area as aforementioned high pressure
remains overhead for at least Monday and Tuesday. Winds Wednesday
will become more southerly ahead of a tail end of a very weak cold
front associated with a low pressure system over Hudson Bay. These
winds will be stronger than the previous days...gusting 10-15 mph.
Temperatures will moderate a bit each day beginning in the low to
mid 70s Monday and reach into the mid 70s to near 80 by Wednesday.

Long term...(wednesday night through sunday)
issued at 327 PM EDT sun Sep 15 2019

High impact weather potential...minimal.

Ridging begins an eastward movement, putting northern Michigan on
the western periphery of the ridge. This will allow a few weak
disturbances to bring chances of rain showers. The first chance will
be Wednesday night as a tail end of a very weak cold front
associated with a low pressure system over Hudson Bay approaches the
Great Lakes region, bringing slight chances of warm air advection precip. This
pattern appears to remain throughout the long term period.
Southwesterly winds will prevail throughout as well. The ridging,
combined with expansive surface high pressure roaming the eastern
third of the Continental U.S. Will continue to yield above normal temps into
the upper 70s to 80 for much of the forecast area...some 10-15
degrees above the mid-upper 60 degree normal mid-September highs.

&&

Aviation...(for the 06z tafs through 06z Monday night)
issued at 1150 PM EDT sun Sep 15 2019

MVFR to IFR thru Monday morning.

Plenty of low level moisture in northern lower mi, north of a
stalled front in central/Southern Lower Michigan. Stratus/fog/drizzle
will produce MVFR to IFR conditions tonight into Monday morning,
with IFR most likely overnight into early Monday. Some showers
will also pass thru the region overnight, mainly impacting
pln/apn. Conditions are expected to gradually improve beginning
midday Monday.

Light and variable winds.

&&

Marine...
issued at 327 PM EDT sun Sep 15 2019

A little bit of gusty southeast winds will persist on Northern Lake
Huron into The Straits into the evening hours. Otherwise,
winds/waves will remain below marine headline criteria for the
next few days. However, marine fog may become an issue on Lake
Michigan tonight into Monday.



&&

Apx watches/warnings/advisories...
Michigan...none.
LH...none.
Lm...none.
Ls...none.
&&

$$

Update...jz

National Weather Service Glossary of Abbreviations