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000
FXUS63 KDTX 161720
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
120 PM EDT Wed May 16 2018


.AVIATION...

VFR flying conditions will prevail through the period with high
pressure ridging at the surface remaining in control. Patchy cu
development will be possible this afternoon for most of the sites
with just enough boundary layer moisture coupled with the peak in
the diurnal heating cycle. Wispy cirrus will also filter in from the
south associated with a stationary boundary draped across the Ohio
River Valley. Light and variable winds will become northeast
Thursday at 6-12 knots as a weak cold front washes out over the
region.

For DTW...Light and variable flow will briefly become southeast
around 5-8 knots 20z-01z with Lake Erie lake breeze. Flow becomes
northeast at 7-10 knots after 12z with potential for northeast flow
runway operations.

.DTW THRESHOLD PROBABILITIES...

* None.

&&

.PREV DISCUSSION...
Issued at 334 AM EDT Wed May 16 2018

DISCUSSION...

Pretty quiet forecast with only a couple chances of precipitation as
a blocking pattern continues with an upper low stalled over the
Pacific northwest. This low is deflecting the jet well to the north
over Canada with a weak and segmented southern stream over the
conus. A second upper low over the SE conus will drift slowly north
and east over the coming days due to the lack of steering current.
Together these two upper lows, combined with a broad northern stream
trough over eastern Canada will produce confluent flow over the
Great Lakes through the end of the week. This stable pattern aloft
will be complimented by narrow ridge of surface high pressure across
the southern and central Great Lakes. The ridge is essentially
trapped between frontal boundaries to the north and south so it`s
not the strongest ridge, but it is dry and stable. Flow will be weak
as it varies in direction depending on where the ridge axis resides.
As was the case yesterday, expectations are for a good lake breeze
setup this afternoon. This will keep shoreline areas cool as the
interior part of the state rises into the upper 70s and a few 80s.

Much the same for Thursday as Wednesday with the exception of a
weakening cold front dropping into Mid MI. Increased northeasterly
flow will likely keep the north half of the CWA a few degrees cooler
than Wednesday with a push of cool air off the waters. Atmosphere
will still be on the dry side but could see a few clouds pop up as
the front washes out overhead. Stronger area of high pressure will
build across the northern Great Lakes behind this front, and will
reinforce the remnants of the previous high over southern MI.

Forecast for the weekend will be mostly dry but the aforementioned
upper low over the SE conus will lift northward up the east coast.
the northwest quadrant of the upper low will lift into the Ohio
Valley with models fluctuating on whether or not moisture will be
able to lift north into the ridge and produce some precip over SE
MI. We`ve been riding a low pop for a couple days Friday into
Saturday and see no reason to deviate from this forecast.

Best chance for precipitation will come Sunday as a strong northern
stream wave drops a trailing trough and cold front through the
region. Models are shifting focus from the front/trough itself to a
tail end wave in the southern stream that will get dragged across
southern MI through the day. Regardless, will continue to advertise
chance pops but have increased the likelihood of thunder as this
wave looks to pull the warm sector and instability up into southern
MI ahead of the wave.

MARINE...

A surface ridge axis will build in place over the central Great
Lakes today, leading to variable or light southerly winds today and
tonight. A strong upper level trough will pass through northern
Canada today, causing wind directions to switch to the north for the
beginning of the day Tuesday. Strongly stable lake environment will
push a shallow mesoscale cold frontal boundary down into the Lower
Peninsula. As a result, expect well organized, onshore northeast
winds Thursday and Thursday night. The onshore flow is expected to
range between 15 to 20 knots.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&

$$

AVIATION.....IRL
DISCUSSION...DRK
MARINE.......CB


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at www.weather.gov/detroit.