Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 141053
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
553 AM EST Tue Nov 14 2017

.AVIATION...

Narrow sliver of moisture residing within the 2000 to 3000 ft layer
will hold tough this morning under a strong inversion. This will
maintain the potential for a chaotic coverage of lower stratus to
persist or expand through the morning period. Cigs at high MVFR or
low VFR through this time. Diurnal mixing will work to diminish the
cloud coverage into the afternoon. Light southwest winds through the
daylight period.  Dry and stable conditions prevail tonight as flow
becomes southeasterly.  VFR with thickening high cloud with time
through the overnight period.

For DTW...Higher coverage of low stratus this morning as moisture
only slowly mixes out. Expected coverage to diminish through the
afternoon.

//DTW THRESHOLD PROBABILITIES...

* Moderate for cig aob 5kft this morning. Low this afternoon.

&&

.HYDROLOGY...

A strong cold front will advance across southeast Michigan on
Wednesday. This front will bring a period of widespread rainfall to
the region during the daylight period.  Average rainfall amounts
between 0.25" and 0.50" can be expected. This amount of rain is not
expected to leading to flooding issues.  Drier conditions will
develop by Wednesday evening.

&&

.PREV DISCUSSION...
Issued at 240 AM EST Tue Nov 14 2017

DISCUSSION...

Surface ridging with just enough low level drying this morning to
allow for partial clearing of the low clouds.  Light fog has also
developed in spots, but another round of mid/high clouds attempting
to work in from the northwest may be enough to prevent dense fog,
along with the lingering areas of low stratus around. Will continue
to monitor trends.

Continued drying looks to be occuring today as low level warm
advection ramps up, and continues into tonight. 925/850 MB temps
look to be both reaching around 5 C by 12z Wednesday. Yesterday`s
highs reached in the lower 40s with clouds, today temperatures
should have no problem making it into mid 40s with the increasing
southerly flow and developing sunshine, and probably even a few
upper 40s.

Consolidating upper level PV/strengthening upper level trough
impacting the Great Lakes Region Wednesday-Wednesday Night. Cold
front to track through during the afternoon, with good
dynamics/forcing to support showers/pops near 100 percent. In
agreement with SPC day 2 outlook, don`t think we will see any
thunderstorms as it appears to be too stable with showalter index
only falling to 3-4 C over southeast Michigan. Exception could be
over relatively warm waters of Lake Huron. Good shot of cold air
behind the front, as 850 mb temps drop to between -5 to -7 C by
Thursday morning. With the shortwave trough axis/700 MB cold pool of
-11 C tracking through late Wednesday Night, Lake Enhanced snow
 showers are possible, but boundary layer/surface temps still could
 be just warm enough for rain showers if any activity does in fact
 develop. Solid overcast on Thursday likely holding maxes around 40
 degrees with cold northwest flow, trending northerly.

Pronounced ridging at all levels to build into the Central Great
Lakes Thursday night. The trend for Friday and into the weekend is
to maintain upper level split flow a bit longer, with phasing and
rapidly deepening low taking a bit longer to get going, and thus the
strong low is more progressive and farther east for the second half
of the weekend, already over Quebec by Sunday morning. None-the-
less, better dynamics/moisture and instability with the cold front
Friday night-Saturday morning (compared to Wednesday), and will add
chance of thunderstorms for this period. Still plenty cold enough
for possible snow showers on Sunday, as 850 mb temps dip to around
-10 C/per euro vs -14 C/per GFS, with brisk northwest winds in
place.

MARINE...

A modest southwest wind this morning under lingering high pressure
will strengthen through the afternoon and evening as this high exits
to the east. Winds through the daylight period will remain at 20
knots or less. Winds will peak from the south to southwest tonight
and Wednesday as a cold front approaches the region. Winds
strengthen to 20 to 30 knots during this time, with waves reaching 8
to 10 feet. While a higher degree of stability will limit the gust
potential, this will bring the possibility for a period of low end
gales for central portions of Lake Huron early Wednesday.  A gale
watch is now in effect.  A period of showers will be likely as the
cold front pushes through on Wednesday before winds shift to the
west on Wednesday evening. Moderate northwest winds of 15 to 25
knots will then develop in the post-frontal environment Wednesday
night into Thursday allowing waves to grow to 6 to 8 feet across
southern Lake Huron on Thursday. This may lead to another short
period of low end gales across the Lake Huron open waters late
Wednesday night, with small craft advisory conditions likely for the
nearshore waters of Lake Huron on Thursday.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...Gale Watch from late tonight through Thursday afternoon for LHZ362-
     363-462-463.

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

$$

AVIATION.....MR
DISCUSSION...SF
MARINE.......MR
HYDROLOGY....MR

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at www.weather.gov/detroit.



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