Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 261124
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
724 AM EDT Thu Apr 26 2018


.AVIATION...

Overnight boundary layer decoupling has allowed surface dewpoint
depressions to decrease amidst some near-surface moisture to allow
for patchy ground fog to develop early in the TAF period. Brief
periods of MVFR/IFR visibilities will be possible through 14z,
mainly at KDTW and KYIP. Daytime heating will quickly erode any
linger ground fog thereafter with VFR and dry conditions prevailing
with SKC for most of the day. After 00z, high clouds will be on the
increase ahead of an approaching cold front that will bring
scattered rain showers after 12z Friday. West to southwest winds
will be less than 10 knots today, backing southerly after 00z.

For DTW...Ground fog will result in periods of MVFR/IFR visibility
through 13z-14z before dissipating with daytime heating. Outside of
the fog this morning, VFR conditions will prevail with light winds.

.DTW THRESHOLD PROBABILITIES...

* None.

&&

.PREV DISCUSSION...
Issued at 343 AM EDT Thu Apr 26 2018

DISCUSSION...

Skies have cleared across the Thumb where dry air continues to push
south and the trough moves further east of the area. This clearing is
allowing temperatures to drop into the lower 30s and a couple spots
into the upper 20s. Conditions at the surface look somewhat
favorable for some shallow fog development across portions of the
area with light to calm winds, clear skies and cooling temperatures.
Most favorable time frame for development will be between 6 to 8 am.
Confidence is low in reaching enough reduction in visibility or
coverage to add mention in the grids, so will leave it out at this
time.

Today will consist of a quick passing ridge and surface high
pressure that will result in dry conditions. Southeast Michigan will
see mostly clear skies through the day with only few scattered high
clouds moving in from the west. This will help bring temperatures
back up into the 60s for most locations. Winds will remain light and
westerly through the afternoon and evening before backing more out of
the southwest ahead of the next approaching system.

An upper trough will be digging through the Great Lakes and send a
cold front through Michigan on Friday. There will be a chance for
rain along the front, but resident dry airmass will keep any
precipitation on the lighter side late morning and early afternoon.
Brief break in rain chances late afternoon and evening as embedded
shortwaves begin to dive south on the back side of the broader
trough, which will form a closed mid level low over the central Great
Lakes. Rain chances will increase Friday night into Saturday morning
as a surface low with support of left exit region jet dynamics
swings through central and lower Michigan. The track of the surface
low pressure should keep higher rainfall amounts within the I-69 to
I-94 corridors and amounts of up to a quarter inch or less.

Cold pool consisting of 850mb temperatures around -5C will move
overhead during the afternoon. The cooler air moving in will result
in high temperatures dropping into the lower 50s and upper 40s for
Saturday. Dry northwesterly flow with a surface high pressure moving
into the western Great Lakes will bring any lingering showers to an
end in the afternoon and help clear out the clouds through the
evening. Clearing skies overnight Saturday will allow for favorable
radiational cooling to drop temperatures into the upper 20s and lower
30s.

Strong upper ridge building over the plains will slide east and take
hold of the region on Sunday into early next week. Dry conditions
and April insolation will lead to temperatures warming back up
during this time. Look for temperatures to climb back into the 60s
on Monday and then 70s for Tuesday and Wednesday. Rain chances
return on Wednesday as a closed low sets up over Ontario and allows
strong moist advection under southwesterly flow to be pulled
northward into Michigan along a frontal boundary.

MARINE...

High pressure will build across the region today with light winds
gradually backing from northwesterly to southerly as the day
progresses. A cold front will move across the region Thursday night
and continuing into Friday. Unsettled conditions will accompany the
frontal passage into Friday night as an upper-level disturbance
swings through and spawns low pressure development across lower
Ontario. Increased northwesterly winds associated with the front
will lead to gusts approaching 20 knots at times especially over
northern and central Lake Huron Friday. High pressure will then
build from the upper Midwest heading into the weekend, with a
tightening pressure gradient leading to frequent gusts of 20-30
knots across much of Lake Huron. Waves may become hazardous for
small craft across much of the Lake Huron nearshore waters this
weekend with the gusty winds and favorable northerly fetch.

&&

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

$$

AVIATION.....IRL
DISCUSSION...AA
MARINE.......IRL


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