Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
FXUS63 KDTX 161940
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
340 PM EDT Sun Apr 16 2017
Zonal flow aloft and a low pressure system pulling east away from
the Great Lakes will lead to overall improving conditions across the
region with weak area of high pressure building in from the
southwest. There are some subtle features lingering over the state
that bear watching but mainly for a few hours of light rain chances.
First feature is the cold front sweeping across central lower MI.
Though not really showing much of a thermal gradient or convergence
signature, the nose of a moisture plume from the south is producing
low ceiling heights with dewpoints near 60F. Can`t rule out a stray
sprinkle or some drizzle but the area is capped so not expecting
much of anything through the early afternoon. The other feature is a
trailing secondary trough axis dropping slowly southward toward the
northern Thumb. There is a better surface convergence signature with
this trough and hints of afternoon heating to break the cap for a
few hours. Showers have recent initiated along this boundary and my
drift SE through the Thumb this afternoon. Thunder will be possible
with the weak instability.
On Monday high pressure over northern Ontario will sink south into
the Great Lakes which will sandwich the residual trough across Mid
MI between another weak area of high pressure over the Ohio Valley.
There will be a mid level shortwave tracking along the elevated
trough axis and pv filament which models are keying in on for
potential shower development Monday afternoon. Mid level ridging
will start building into the region in the evening which will help
put an end to any showers with this forcing. The dip in the jet
associated with this secondary front will allow some cooler air in
the area Monday night. With an expected clearing trend and this
trough of cool air, min temps Monday night will likely drop into the
30s for many locations.
Tuesday will remain dry and warm up into the mid/upper 60s with
ridging in place ahead of the next trough. A low pressure system
will track quickly northeast through the northern Great Lakes
Tuesday night which will pull a front through SE MI in that period.
A couple of low pressure systems look to move across the region for
the second half of the week. The low pressure on Wednesday over the
Northern Great Lakes region will continue to push east keeping
chances for precipitation in the forecast. The second low then moves
right in behind the departing first low, moving east across the
southern Great Lakes. Quieter conditions then finally move in on
Friday going into Saturday before unsettled weather returns to round
out the weekend as another low is advertised to move up from the
Light to moderate westerly wind will continue to diminish over
marine areas tonight and back to the north over Lake Huron. The
westerly flow will continue behind the initial cold front associated
with low pressure exiting southern Ontario while the primary cold
front with northerly wind settles southward over Lake Huron tonight
through Monday. Wind and waves will remain below advisory levels in
this pattern once conditions diminish this evening. High pressure
sliding through the northern Great Lakes Monday night will then give
way to the next low pressure system Tuesday. Increased southerly
wind ahead of this system will become a fresh to strong northeast
breeze behind the associated cold front Thursday. The front will be
tied to another low pressure center moving in from the Midwest that
will be strong enough for gale potential and high waves during this
Issued at 1253 PM EDT Sun Apr 16 2017
Late morning/early afternoon observations indicate abundant low
level moisture producing mostly MVFR ceiling over the area except
the DTW corridor. This air mass is along and ahead of the initial
cold front, associated with low pressure moving through southern
Ontario, that will move across Lower Michigan during late afternoon
and early evening. The boundary has a much greater moisture contrast
compared to temperature and its passage will push the low cloud
pattern eastward and out of SE Michigan. In the meantime, patches of
light rain/drizzle returned from radar have a chance to mix into
scattered showers as weak surface based instability develops.
Coverage and timing favor locations north and east of the terminals
which will be monitored while maintaining just a cloud mention in
the forecast. The evening clearing trend post front will last
through the night as the primary cold front with this system is
projected to remain over northern Lower Michigan until settling
toward the MBS region Monday afternoon.
For DTW... VFR ceiling below 5000 ft developing during the afternoon
possibly with a brief MVFR restriction. Clouds will be accompanied
by westerly wind gusting near 30 knots at times which could briefly
touch 25 knot crosswind threshold while turning toward 280 degrees
and then diminishing. The initial cold front passing by 00Z will
bring a clearing trend during the evening.
//DTW THRESHOLD PROBABILITIES...
* Medium for ceiling 5000 ft or less.
* Low for exceeding crosswind threshold for southwest traffic
Lake Huron...Small Craft Advisory until 10 PM EDT this evening for LHZ421-422-
Lake St Clair...Small Craft Advisory until 10 PM EDT this evening for LCZ460.
Michigan waters of Lake Erie...Small Craft Advisory until 10 PM EDT this evening for LEZ444.
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