Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
FXUS63 KDTX 170355
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1155 PM EDT SUN OCT 16 2016
Moist low level environment will sustain a combination of low
stratus and fog through the early and mid morning period. Areas from
PTK northward already at or near LIFR conditions and expect these
locations to remain locked at these restrictions right through this
time. Trends not nearly as evident across the Detroit corridor, but
still favor a window for LIFR or near LIFR in stratus/fog during the
early morning period. Gradual improvement off these conditions by
late morning/early afternoon as a warm front lifts through. Light
southwest wind tonight will strengthen as mixing deepens behind the
warm front on Monday. Gusts reaching into the 25 knot range by
For DTW...Low stratus holds firm through at least mid morning,
before mixing out beyond 14z. Component of fog also expected to
emerge heading into the early morning period. However, confidence
in dense fog development resulting in visibility restrictions below
1 mile remains low given the presence of low stratus. Maintaining a
forecast of LIFR highlighting CIGS below 500 ft 09z-13z.
//DTW Threshold Probabilities...
* High in ceilings below 5000 ft through mid morning Monday, then
low thereafter through the afternoon.
* Low for ceilings below 200 feet or visibility below 1/2 mile
through Monday morning.
Issued at 312 PM EDT Sun OCT 16 2016
The remnants of this mornings rainfall have been exiting east of the
area this afternoon. It is apparent through the regional radar
mosaic that a short wave impulse was tied to this feature. Mid level
subsidence in the wake of this feature will linger across the
forecast area well into the evening. There is an abundance of low
level moisture as evident by the extent of low clouds covering much
of srn Lower Mi. The degree of moisture in the low levels does
suggest some possible drizzle during the evening. A weakening
frontal boundary will also inch its way into the Saginaw
Valley/Thumb from the north, possibly triggering a little heavier
This front will evolve into a warm front over srn Mi overnight, then
lift back north during the day Monday. This will occur in response
to strengthening low level sw flow across the upper Midwest and wrn
Great Lakes. While the better moisture transport will be focused
across nrn Wisconsin and wrn Upper Michigan late tonight, there will
be a ribbon of enhanced moist isentropic ascent that will traverse
the forecast area overnight. This will support a chance of late
night showers (into Monday morning across the tri cities and thumb).
There will be a brief window for destabilization in the mid levels,
supporting a chance of thunderstorms. The remnant sfc boundary will
support a little boundary layer convergence over portions of the
area tonight. Model soundings also suggest, aided by this
convergence, that the ample low level moisture will lead to some
build down of the stratus, causing persistent low clouds and/or fog
through much of the night (possibly well into the morning across the
Saginaw Valley and thumb).
Rapid warming in the 900 to 800mb layer on Monday will then cap the
atmosphere to further convection as Se Mi enters the warm sector.
925mb temps are forecast to rise to +21C during the afternoon within
good low level sw flow. While residual low level moisture may
support some degree of daytime cu, the well mixed boundary layer and
degree of low level warming will result in daytime highs from the
upper 70s to low 80s (well above normal).
A fast moving mid level short wave will eject out of the central
plains and race across the wrn Great Lakes Mon night. The 12Z model
suite all show deepening of this wave as it lifts northeast of Lake
Superior Tuesday, leading to a rapidly deepening sfc low. Se Mi will
remain capped in the warm sector Mon night and will remain within
the strong southwest gradient. This will support very mild nighttime
temps for mid October (mid to upper 60s). The associated cold front
will track across the forecast area on Tuesday. The rapid departure
of this system to the northeast keeps the better mid level height
falls north of the forecast area. Model soundings indicate a
persistent mid level cap and limited mid level moisture along the
front. So convection chances on Tuesday look to be very low. The
gusty prefrontal southwest winds will sustain mild and breezy
conditions through the first half of the day Tuesday, with a steady
drop in temps late afternoon into the evening. The better
isallobaric component will remain well north of the forecast area.
The post frontal west-northwest gradient will also weaken. So post
frontal winds on Tues are actually expected to decrease.
Focus on the middle to end of the week will be on the evolution of
a deepening upper trough and low-level baroclinic zone. Medium-range
models indicate a likelihood for an area of overrunning
precipitation developing along the cold side of the baroclinic zone
within the right entrance region of a strong upper jet. Where
exactly the favorable area for precipitation sets up is a question
mark. For instance, the ECMWF and CMC sharpen the upper trough just
upstream of SE MI, allowing us to get into the favorable right
entrance region. On the other hand, the GFS and a significant amount
of GEFS members do not consolidate the upper-level vorticity,
leaving a weaker and further east solution, keeping us mainly dry.
The play for now is a broad brush chance PoP favoring the southeast
half of the CWA until better agreement can be reached. Regardless,
temperatures will be on a downward trend into the end of the week,
with high temperatures reaching values AOB normal.
A warm front lifting north late Tonight into Tomorrow will allow for
increasing easterly winds over the north half of Lake Huron, topping
out around 30 knots near the Straights. As the warm front lifts
further north, southerly winds will take hold by Monday evening
across all marine areas, generally in the 15 to 20 knot range. Winds
will ramp up further as we head into Tuesday, as a rapidly deepening
low moving into Ontario drives a strong cold front through Central
Great Lakes. A gale watch has been issued for the northern two
thirds of Lake Huron on Tuesday, with even higher confidence in
Gales with the post frontal westerly winds across the northern third
of Lake Huron Tuesday afternoon. Winds quickly diminishing Tuesday
Night, and remaining light on Wednesday.
Lake Huron...Gale Watch Tuesday morning FOR LHZ363-421-441-462.
Gale Watch from Tuesday morning through Tuesday evening FOR LHZ361-
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
You can obtain your latest National Weather Service forecasts online