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fxus63 kdtx 242024 
afddtx

Area forecast discussion
National Weather Service Detroit/Pontiac Michigan
324 PM EST Sat Feb 24 2018

Discussion...

A high pressure will drift northeast of the Great Lakes this
afternoon resulting in a light easterly surface flow. Inversion has
kept low level moisture and clouds trapped with additional clouds
moving in from the southwest. This will keep mostly cloudy
conditions through this afternoon and evening. High temperatures
this afternoon remain on track to top out in the upper 30s and low
40s. A few light rain showers earlier today across the lower
portions of the area along the Ohio border have cleared out. There
will a brief break in rainfall during the early evening before the
next system tracks northeast into the Great Lakes and increases rain
chances after 0z tonight.

A dynamic mid level trough is ejecting out of The Rockies and into
the plains this afternoon. The trough will become negatively tilted
as it lifts northeastward into the Great Lakes. A surface low is set
to develop in association with the upper trough and strengthen
overnight as it reaches the western lower Great Lakes. The center of
the surface low is forecast to move across the Upper Peninsula by
around midnight. At the same time, the low and mid level jets will
strengthen around the base of the trough and bring with it favorable
lift across Southeast Michigan. Strong southwesterly flow will drive
some warm and moist advection up through the Ohio Valley. Some of
the higher dewpoints look to remain south of the Michigan border,
but there will be enough moisture available within the large scale
ascent and frontal convergence to produce widespread rainfall
tonight into tomorrow morning. Highest Theta-E may also stay south,
but mid level lapse rates of around 6 c/kg would support a chance of
a thunderstorms for the southern half of the County Warning Area. Even though the
better moisture may likely remain to the south, there will still be
potential to see pockets of localized heavy rainfall with the
passage of this system.

The low pressure system will send a cold front through Michigan
tomorrow morning. Deep dry air advection will get underway amidst
somewhat weak cold air advection. However, the presence of strong
winds just above the surface and strong isentropic decent in the
immediate wake of the front will result in strong winds reaching the
surface during the morning hours. The highest wind gust potential
should occur right behind the front within strong downward ascent
and last for a brief period. However, gusty southwest winds should
linger into the late morning and early afternoon as diurnal mixing
will begin to tap into those strong winds aloft. Peak wind gusts
residing in a narrow corridor behind the front will be nearing Wind
Advisory criteria in the 35 to 45 mph range.

High pressure will begin to build across the Ohio Valley Sunday
night. Winds will be on the lighter side for Monday and remain out
of the west. Weak ridge moving overhead will allow quite, dry
weather to start the work work. Low temperatures to start the day
will be slightly below freezing for the majority of Southeast
Michigan. High temperatures on Monday afternoon will remain above
normal in the mid to upper 40s, with a few locations across Metro
and the southern Michigan border reach 50 degrees.

Dry, mild conditions will continue on Tuesday with highs in the mid
to upper 50s while high pressure moves to the eastern Seaboard.
Return southwesterly flow will then advect increasing moisture to
the region late Tuesday while a weak frontal boundary sags southward
before stalling across lower Michigan on Wednesday. Along this
boundary, some light rain showers will be possible across Southeast
Michigan Tuesday night into Wednesday as mild temperatures continue
with highs in the low to mid 50s.

Low pressure developing in conjunction with a potent upper wave
ejecting out of the southwest US will then bring the next chance for
widespread precipitation to the region late next week. Model
guidance is in good agreement that low pressure will slowly track
into lower Michigan on Thursday before transferring energy to a
coastal low Thursday night into Friday. Widespread rain appears
likely on Thursday as temperatures again approach 50 across much of
Southeast Michigan. Cold air wrapping into the system Thursday night will
bring the chance for a rain/snow mix before precipitation gradually
tapers off on Friday.

&&

Marine...

Rapidly deepening low pressure tracking through the western Great
Lakes tonight will send a strong cold front through the central
Great Lakes around sunrise Sunday. Southwest gale force winds will
develop behind the front, persisting for much of Sunday as colder
air surges to the area. Strongest winds look to be near the
straights and across the Central Lake Huron, where they look to
slightly exceed 40 knots Sunday morning. Winds will drop below gales
Sunday evening and continue to diminish Sunday night into Monday as
high pressure ridges into the region from the southwest.

&&

Hydrology...

River levels continue to slowly come down, but moderate flooding was
still occuring along the Saginaw and Hamburg rivers. A strong low
pressure system will track northwest of the region, with widespread
rain showers developing late this evening, and continuing tonight.
Rainfall amounts look to range between a quarter of an inch to a
half of an inch. This rainfall is not expected to have any
significant impacts to Current River flooding. Dry weather then
expected tomorrow through at least Tuesday.

&&

Previous discussion...
issued at 1144 am EST Sat Feb 24 2018

Aviation...

MVFR stratus dissipated for a period late this morning, but has
since filled back in. Still can not rule out breaks/brief scattered
periods this afternoon, but a moisture surge coming up from the
south will allow more solid MVFR stratus to return early this
evening, with showers developing late this evening/around midnight.
Cigs expected to lower into IFR after midnight as showers continue
and deeper moisture arrives along with increasing frontal
convergence, and there is also a low chance of thunderstorms as well
as strong cold front crosses toward sunrise Sunday. Good wind pop
behind the frontal passage, with southwest (230-250) winds
frequently gusting between 30 and 35 knots Sunday morning. Good low
level drying and cold advection Sunday morning, but uncertainty on
the timing of when MVFR ceilings will scattered out.

For dtw...still could see variable MVFR ceilings this afternoon, but
then quickly lowering ceilings this evening as showers overspread
late in the evening. Low chance of thunderstorms, not included in
the taf, late tonight as cold front sweeps through, with wind shift
expected 10-12z Sunday. Southwest (240-250) gusts expected to reach
around 35 knots early in the day, with a slow diminishing trend
during the rest of the day.

/Dtw threshold probabilities...

* high for cigs below 5 kft through taf period.

* High for ptype as rain.

* Low for thunderstorm tonight.

* Medium for reaching crosswind threshold hold 11-16z Sunday.



&&

DTX watches/warnings/advisories...
Michigan...none.
Lake Huron...Gale Warning from 7 am to 7 PM EST Sunday for lhz363-421-422-
441>443-462>464.

Gale Warning from 10 PM this evening to 7 PM EST Sunday for lhz361-
362.

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

$$

Discussion...aa/jd
marine.......sf
hydrology....sf

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