Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 301651

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1151 AM EST Wed Nov 30 2016


Dry cold front clearing southeast Michigan this afternoon, with
narrow Area of IFR/MVFR clouds tending to mix out/lift and slide off
to the east. Confidence in ceilings this afternoon across
southern taf sites is low. Post frontal Low level cold advection,
helped out by moisture off Lake Michigan, will assure low clouds
(low VFR to MVFR) will return to southeast Michigan, but timing of
this is uncertain, as mid level dry slot looks to be persisting
into early this evening. As cold pool settles over Lower Michigan
Tonight into Tomorrow, there will be increasing chance of rain
(possible snow mixed in) showers as low level lapse rates steepen
up, with trajectories off lake Michigan favoring MBS/FNT early
tomorrow morning, with low chance across the southern taf sites by
late morning.

For DTW... Upstream IFR ceilings/fog likely dissipating, not
advancing past the higher terrain of the Irish Hills. Any cigs below
5 kft ceilings at Metro this afternoon should be brief, as drier air
seen over northern Indiana works in from the southwest behind the
front. Targeting mid evening hours for low vfr ceilings arriving,
with MVFR ceiilngs settling in overnight, and persisting through
tomorrow. Chance of showers tomorrow too low to introduce in Taf at
this time.

//DTW Threshold Probabilities...

* Low for ceilings aob 5000 feet through early this evening, then
  high late evening through Tomorrow.


Issued at 303 AM EST Wed Nov 30 2016


WV and IR imagery reveal shear max of interest positioned along the
eastern flank of the broad trough centered over the central US.
Inflection point noted in the southern plains, and given away by
expanding clouds in TX/OK will be the focus of synoptic scale lift
as it lifts northeast into SE Michigan today. Relatively deep layer
of 925-700mb conditional instability will reside over the forecast
area, but the 00z progs all indicate that the weak northward
moisture surge associated with this wave will mainly take place to
the east. Trimmed pops back to chc over far eastern areas where
forcing, diurnal heating, and moisture will be most favorably
superpositioned. Steepening lapse rates west of US-23 beneath the
encroaching cold core aloft will be offset by lack of moisture. An
isolated shower possible, but nothing worth an explicit wx mention.
Cold front currently hung up along the Lake Michigan shoreline will
release east as large scale support translates over Lower Michigan
this aftn. Highs a few degrees colder than yesterday, near 50,
especially further west where cold fropa will occur in early/mid

Lake Michigan activates tonight 0-1km theta-e lapse rates fall to a
modest -3 to -5C/KM. Broad scale ascent and descent moisture quality
will support deepening convective depths emanating off the lake,
particularly as an embedded shortwave tracks across the area after
06z tonight. Deepening saturated layer during this time will favor
lake effect rain and snow showers becoming likely north of M59 late
tonight into Thursday morning. No accumulation. Cool cyclonic flow
and prevalence of lake clouds will ensure temps near average through
the end of the week.


Modest southerly flow will continue across the region through the
daylight period.  Winds will then increase from the southwest this
evening as cooler air begins to funnel over the lakes.  Gusty
southwest winds will persist tonight and Thursday.  While the gust
magnitude will largely remain just shy of cold season small craft
conditions /<30 kts/, a favorable trajectory across Saginaw Bay will
build waves sufficiently to warrant a small craft advisory across
the outer bay and along the tip of the thumb.  These conditions will
likely persist into early Thursday night before easing.


Lake Huron...Small Craft Advisory from 10 PM this evening to 10 PM EST Thursday
     FOR LHZ421-441.

Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.



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