Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 240650
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
250 AM EDT Thu May 24 2018

.DISCUSSION...

Upper level ridge axis sliding east and arriving over the Central
Great Lakes on Friday (582 DAM at 500 MB) will support a continued
warming trend and sunshine, as low level southwest winds also ramp
up, helping to limit lake breeze development during the afternoon
hours. Interestingly, the current average Lake Huron water
temperature is the coldest since 2014. Both northern and southern
Lake Huron buoys checking in with a chilly 37 degree water temp.

With the mild maxes yesterday, predominately in the 78-82 degree
range (all 3 climate sites hit 81 degrees), and some drying of the
boundary layer, coupled with the longer fall needed for temps to
reach dew pts, fog has not been an issue this morning, but still a
couple more hours to generate some patchy light fog before sunrise.
See no reason why highs will not climb into the 82-85 degree range
today, as 850 MB temps hit 14+ C and light southwest surface winds
attempt to develop. Deeper and greater low level southwest return
flow for Friday, and highs in the 85 to 88 degree range appears in
the offing, as 850 mb temps push toward 17 C.

Becoming humid (dew pts in 60s) and unsettled for the weekend, as
Euro indicated a weak shortwave trough already rolling through
Friday night, which will usher in higher moisture content, bringing
the first chance of showers and thunderstorms with showalter index
lowering to -1 to -3 C.  Moisture axis (PW values up to 1.50 inches)
in place on Saturday, with surface heating leading to MLCAPES of at
least 1 J/kg, but potentially higher depending on amount of
clouds/convective debris. Fortunately, 0-6 KM bulk shear looks weak,
under 20 knots, thus heavy rain producers will be main hazard, unless
capes reach toward 2000 J/kg, then pulse severe will be possible.

Main upper level wave/trough to track through the northern Great
Lakes on Sunday, with better 0-6 KM shear in place, 20 to 30 knots,
with MLCAPES again reaching at least around 1500 J/kg. Outgoing
forecast for Sunday may be too low with POPS.

Latest trends (00z Euro/GFS) suggests the surface cold front will be
reaching the southern Michigan border early Monday afternoon and
tending to wash out with no upper level support to work with, as 500
MB heights actually rise slightly. It looks doubtful there will be
any activity over southeast Michigan during Monday before the front
slips south, and large area of high pressure builds in for Monday
night/Tuesday, with return flow (increasing low level
moisture/humidity) and warmth for Wednesday.

&&

.MARINE...

High pressure will slowly push south from Lower Mi into Lake Erie
this morning. This will result in the development of light west-
southwest winds across northern Lake Huron. The resulting moisture
advection atop the cold lake waters is likely to result in some fog,
possibly affecting much of northern Lake Huron today. Otherwise, the
high pressure will sustain relatively light winds. The sfc high will
drift to the east coast by Friday. This will establish light south-
southwest winds across the lakes tonight into early Saturday. A slow
moving front will then slide into the northern Great Lakes from the
north on Saturday, resulting in light winds and providing a chance
for thunderstorms. The front will wash out over the region toward
the end of the weekend as high pressure expands back into the Great
Lakes.

&&

.PREV DISCUSSION...
Issued at 1154 PM EDT Wed May 23 2018

AVIATION...

High pressure will maintain mainly clear skies and light winds
throughout the forecast period with a trend to south/southwest
return flow around this high by midday Thursday. There remains some
chance of shallow, patchy fog early Thursday morning, but trends
late this evening suggest less of a chance than this morning as low
levels remain notably drier.

DTW THRESHOLD PROBABILITIES...

* None.


&&

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

$$

DISCUSSION...SF
MARINE.......SC
AVIATION.....DG


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