Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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389
FXUS63 KDTX 290735
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
335 AM EDT Mon May 29 2017

.DISCUSSION...

Upper low centered just north of Lake Superior will broaden with the
addition of upper energy dropping through Central Canada and the
Northern Plains. This system will encompass the Great Lakes through
early Wednesday as it slowly wobbles east across Ontario.

Upper shortwave pivoting around the low center will swing across
Lower Michigan today, with a narrow ribbon of theta-e advection
streaming into Michigan ahead of it. Lapse rates will steepen with
daytime heating, and as upper cold pool associated with the low
slides in overhead. This looks to generate 500-1000 J/kg of SBCAPE
by afternoon, providing a chance for showers and thunderstorms.
Expecting just a scattered coverage with forecast soundings showing
saturation only between 800-600mb, and a boost from a strengthening
jet streak rounding the base of the upper low.

Breezy conditions will develop by this afternoon as southwesterly
gradient tightens between low pressure over Ontario and high
pressure over the Gulf States and Tennessee Valley. Gusts look to
reach between 25 and 30 knots by afternoon as the mixed layer
deepens and winds aloft strengthen slightly. Well-mixed boundary
layer and H925 temps rising to between 16-18C should boost max
temperatures into the mid 70s to near 80.

Chances for showers, or even a thunderstorm, tomorrow and Wednesday
look lower compared today as moist layer looks fairly shallow. Will
retain very low pops however as weak shortwaves look to continue
streaming over the area from around the upper low to our north. Cold
air advection will make for cooler temperatures, with max temps
reaching the mid 60s to near 70. Breezy conditions will also
continue as surface features remain fairly stagnant. Upper low will
finally lift out of the area Wednesday night, with high pressure
providing dry weather into Thursday.

Quite a bit of uncertainty then as we head into the end of the week
as an upper ridge builds through the Plains and into Central Canada,
and a strong upper low drops through Ontario and Quebec. Medium-
range models are still struggling with where to place the larger
features, making it difficult to pinpoint where an active frontal
zone will set up from late Thursday into the weekend. Model
solutions currently range from southern Michigan to the Southern
Ohio Valley. Latest GFS/Euro support better chance for
showers/tstorms on Friday, with at least some of the weekend under
high pressure as the frontal zone sinks to our south.

&&

.MARINE...

West to southwest winds will increase today as an upper level low
pressure system settles into the central Great lakes. Wind gusts
look to increase to around 20 knots for much of the marine areas.
The exception is over Saginaw Bay where a small craft advisory has
been issued for this morning through Tuesday evening as winds will
likely reach and exceed 25 knots This upper level low pressure
system is expected to become a persistent feature this week, possibly
reorganizing again late this week and upcoming weekend.

&&

.PREV DISCUSSION...
Issued at 1141 PM EDT Sun May 28 2017

AVIATION...

The slow eastward advancement of the sfc front and approaching upper
trough led to renewed convective development during the mid evening.
These thunderstorms have finally pushed east of the terminals. Post
frontal westerly flow overnight will sustain gradual low level
drying, eroding any remnant low clouds. Light westerly winds and
clear skies below 10k ft will then prevail through the morning.

For DTW...Daytime mixing late Mon morning will give way to gusty
southwest winds by afternoon, with peak gusts pushing 25 knots at
time.

//DTW THRESHOLD PROBABILITIES...

* None.


&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...Small Craft Advisory from 10 AM this morning to 10 PM EDT Tuesday
     for LHZ421-422.

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

$$

DISCUSSION...HLO
MARINE.......CB
AVIATION.....SC


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