Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
FXUS63 KDTX 241632
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1232 PM EDT MON OCT 24 2016
Strong northwest flow between departing low and advancing high
pressure is producing lake effect enhanced diurnal bkn-ovc deck
generally in the 3-4k ft range. Sheared out vort max embedded in
mid level flow also helping in generating pockets of mainly sprinkles
mainly north of a DTw-FNT line. Clouds will dissipate towards evening
as diurnal heating ends. High pressure will maintain a northwest
flow through Tuesday with mostly clear skies tonight and some
scattered diurnal cu by early afternoon Tuesday.
//DTW Threshold Probabilities...
* High confidence in cigs aob 5kft through evening.
Issued at 315 AM EDT Mon OCT 24 2016
Temperatures on the colder/below normal side for the work week as
large and deep upper level low currently over Quebec is slow to
Considerable cloudiness expected today as solid shot of cold
advection takes place. 850 mb temps advertised to reside in the -1.5
to -3.5 C range, with boundary layer depths extending to that level,
per nam soundings. As such, looking at highs in the lower
50s, supported by 925 mb temps up around 5 C as well.
Northwest confluent upper level flow this evening leading to
strong subsidence and short lived warming at the 850 mb level, which
should scour out the daytime cloud cover, setting us up for a
favorable radiating night with temperatures falling toward freezing.
However, there still is a low risk enough moisture will be trapped
around 900mb level to maintain some clouds tonight, despite the
mostly clear/clear forecast. Either way, the growing season has
ended across southeast Michigan, and will not be issuing any
Strong Canadian High (1037 mb) becoming established over Ontario on
Tuesday, maintaining cold easterly flow across the Central Great
Lakes. Meanwhile, upper level energy off the West coast will be
tracking through the Rockies and into Midwest by Wednesday, with
consolidating upper level PV leading to cyclogensis/deepening
surface low, with the low then tracking along or close to the
southern Michigan border Wednesday Night, per model consensus
(GFS/Canadian/Euro). With the initial dry and cold airmass in
place to start the day on Wednesday, thermal profiles with the
lead isentropic ascent/moisture advection do get close to
supporting frozen precipitation (north of M-59), but ultimately
with 1000-850 mb thicknesses mainly above 1305 M and easterly flow
off mild waters of southern Lake Huron, likely will be just
dealing with a cold rain developing during the day, with
categorical rain Wednesday evening/night as the surface low tracks
through, working with the 1+ inch PW values along the southern
Another healthy shot of cold air to follow behind the low for
Thursday, as 850 mb temps fall into the -2 to -4 C range.
Shower/Graupel activity looks possible with the steep low level
lapse rates and cyclonic flow coming off lake Huron. Highs
forecasted to be near 50 degrees, but shower activity would likely
cause a quick temperature drop, potentially a good 10 degrees.
Yet another strong low forecasted to work through lower Michigan on
Saturday, but the 00z Euro has made significant deviation from
its 12z run, illustrating the sensitivity of the forecast. It
appears the shortwave currently over the Yukon is one significant
piece of the equation as it works through the Upper level low off
the Pacific Northwest Coast. The gfs/Canadian solutions offering
up deeper but faster solution, placing the best chance of rain
Friday Night. Winds may need to be ramped up from the outgoing
forecast on Saturday as we get closer to the Weekend and
Cold northwest flow will maintain unstable conditions across area
waterways today. Small craft advisory conditions will persist
during this time for all near shore waters of Lake Huron including
Saginaw Bay. Gusts of 25 to 30 knots will be common across the open
waters, but winds are expected to remain below gale force. Winds
and subsequently waves will gradually diminish tonight and Tuesday
as high pressure builds into the region. Winds will increase out of
the east Wednesday and Wednesday night as low pressure lifts toward
the region. The potential for a period of strong east winds to near
gales will be possible by Wednesday night and Thursday.
Lake Huron...Small Craft Advisory until 11 AM EDT Tuesday FOR LHZ421-441>443.
Small Craft Advisory until 10 PM EDT this evening FOR LHZ422.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
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