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434
FXUS63 KDTX 131904
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
304 PM EDT Sun Aug 13 2017

.DISCUSSION...

Surface high pressure and shortwave ridging over the area will
maintain quiet conditions through tonight, even as the high shifts
east. High/mid clouds will increase as the upper low over the
Dakotas moves into the western Great Lakes tonight, and a smaller
shortwave pivoting around the south side of it (now over MN/IA)
moves into Michigan. Partly to mostly cloudy skies will limit
radiational cooling to provide a milder night with min temps in the
upper 50s to low 60s. Weak southerly flow in advance of the
approaching low very late tonight and Monday will send a very weak
warm front up through the area, with isentropic ascent and moisture
just enough over the Saginaw Valley and Thumb to justify a low
chance for showers and thunderstorms throughout the day.

Dampening wave from ND/MN will meet up another shortwave pivoting
around the upper low over Hudson Bay Monday, before tracking across
Michigan Monday night into early Tuesday. Weak surface low pressure
ahead of this feature will track through central Michigan per latest
model consensus, but models are still divided on whether to drive a
cold front through Southeast Michigan Monday evening through Tuesday
morning (00Z Euro/GEM) or stall it over the area and ride additional
energy over the top of it on Tuesday (GFS/NAM). This leads to some
uncertainty with the POP forecast, and will retain chances for
showers/tstorms Monday night and Tuesday. Max temperatures Monday
will be fairly similar to today (upper 70s to low 80s) with only a
slight increase in humidity. Temps on Tuesday will be more dependent
on frontal position, and may see temps south of M-59 make a run for
the mid 80s.

Wednesday night into Thursday continues to look good regarding rain
and thunderstorm chances as low pressure from MN/WI pushes east into
northern lower MI/U.P. This will allows southerly winds to transport
enough heat and moisture to fuel storm chances through early
Thursday afternoon, before low pressure pushes east into Ontario.
Zonal flow aloft will then act to keep temperatures fairly
consistent Friday and into the weekend as daytime highs peak in the
lower 80s and overnight lows drop into the lower 60s. Precipitation
chances do not look all that impressive heading into the weekend,
however, spotty off and on showers and thunderstorms will not be out
of the question during daylight hours, as a series of short-waves in
conjunction with diurnal heating look to fuel some rain chances.
With forcing as weak as it is, PoP values will remain sub-35 percent
through the weekend.

&&

.MARINE...

High pressure centered over the region will maintain favorable
marine conditions under light south to southeast winds tonight and
Monday.  The development of weak instability will bring the low
potential for thunderstorms from Saginaw Bay into northern Lake
Huron late Monday into Monday night.  The existence of a weak
gradient will sustain this pattern of light winds through Tuesday. A
modest increase in easterly flow is forecast for Wednesday.

&&

.AVIATION...

High pressure centered over the region will sustain VFR conditions
through this forecast period.  Blossoming diurnal cu field will peak
with a period bkn coverage a possibility this afternoon. Standard
reduction in cumulus to accompanying sunset, leaving simply some
thicker high cloud for tonight.  Winds will remain generally light
and variable through tonight.

//DTW THRESHOLD PROBABILITIES...

* High for cigs aob 5000 ft this afternoon.

&&

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

$$

DISCUSSION...HLO/AM
MARINE.......MR
AVIATION.....MR


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