Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
FXUS63 KDTX 231634
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1234 PM EDT SUN OCT 23 2016
A dry 12z DTX sounding characterized by a dewpoint depression
pushing 45C near 7kft will guide the aviation forecast as a strong
waves dives out of Wisconsin. Clouds are prevalent along and north
of the surface low over WI and will expand eastward during the
mid/late as warm advection within SW wind increases. Forcing will be
sufficiently strong to produce a band of virga between about 23z and
midnight, but expect nothing more than brief light showers.
Confidence in tempo -shra impacting any one termal is low at this
time...most likely KFNT/KPTK but will wait for surface truth obs
before any TAF amendment. Regardless...any showers are unlikely to
be accompanied by a noteworthy vsby restriction. Passage of the low
will initially turn wind northerly before becoming gusty and backing
to the NW as cold air fills in. Borderline MVFR stratus expected by
predawn hours Monday.
For DTW...Clouds over northern Wisconsin and Lake Michigan will
expand southeast through this afternoon likely lowering cigs to 5kft
or less this afternoon. Northerly wind between 01-5z brings concerns
for noise abatement, especially after 03z. However, timing will be
sensitive to the exact track of the low since the center of the
low is currently forecast to pass directly over DTW.
//DTW Threshold Probabilities...
* Medium confidence in cigs aob 5kft this evening, then toward
sunrise Monday into Monday morning.
Issued at 348 AM EDT Sun OCT 23 2016
Compact shortwave currently lifting out of the northern plains will
accelerate east-southeast over the next 24 hours, placing this wave
near central Lake Erie by early Monday morning. This late
afternoon/evening timing locally will leave southeast Michigan
within a moderating pre-frontal environment for a good portion of
the daylight period, as a prevailing low level southwest gradient
works the ongoing weak mid level warm air advection down through the
lowest levels. A high degree of early day insolation will augment
this advective process, promoting a solid albeit brief warming trend
for today. Highs of lower to middle 60s, just a touch cooler in the
thumb /upper 50s/.
Dynamic wave transits the local area within the 21z-04z time window.
Defined cold front marking the edge of the inbound height falls
enters the Tri-Cities as early as mid afternoon, before sweeping
southeast in conjunction with the mid level feature through the
evening period. Overall looking at a healthy amount of low-mid
level forcing, most pronounced once trailing upper jet forcing/cva
works across the existing frontal boundary already positioned
locally. This will leave a window for a respectable fgen response
across a sliver of the forecast area. The degree of forcing
certainly provides a chance for shower development /mainly I-94
northward/ this evening, but limited moisture quality still
seemingly working against seeing a more widespread/higher coverage
of rainfall emerge with this system.
Early week period defined as cool and dry, conditions dictated by
gradually expanding high pressure tucked beneath confluent mid level
northwest flow. Deep column northwesterly flow for Monday, ongoing
cold air advection shifting 850 mb temperatures below freezing by
mid morning. Substantial component of low level moisture advection/
lake enhancement accompanies the advective process, favoring a more
pessimistic/cloudy forecast for the daylight period. A muted
diurnal temperature response given the environment, with highs back
down around 50 degrees. Similar profile heading into Tuesday,
little evidence for temperatures to really moderate despite the
increase in mid level heights.
Attention through the midweek period focuses on the evolution and
eventual downstream projection of a deepening wave that ejects
into the Plains by Wednesday. Setup exists for a solid low level
response with this system, leaving a classic mid latitude cyclone
evolution featuring a lead corridor of mid level moist isentropic
ascent/waa followed by strong cold frontal dynamics/convergence as
the surface low ejects into the Great Lakes. High end moisture
quality accompanies this system, with the level of dynamics
certainly pointing to a solid rainfall event within the late
Wednesday through Thursday period. Cool east flow with plenty of
cloud and eventually precipitation maintains below normal
temperatures through this time.
West to northwest winds will ease today, lowering to 15 knots or
less. A renewed surge of cold advection under northwest flow will
return Tonight into Monday however, as low pressure tracks across
southern Lower Michigan this evening. Frequent wind gusts of 25 to
30 knots can be expected over the open waters of Lake Huron. Small
Craft Advisories have been issued for nearshore zones of Lake Huron
during this time, as gusts hover near 25 knots and waves increase
above 4 feet. Winds will slowly diminish on Tuesday, but will be
coming from a northerly direction, which may help to sustain higher
waves along the nearshore waters a bit longer.
Lake Huron...Small Craft Advisory from 1 AM to 10 PM EDT Monday FOR LHZ421-
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
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