Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 152254
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
654 PM EDT Fri Mar 15 2024

.KEY MESSAGES...

- Breezy and mild Saturday as southwest wind gusts around 35 mph
help lift temperatures into the 50s, 10-15 degrees above normal for
mid March.

- There is also a chance of showers as a front moves through the
region; earlier in the day toward the Tri Cities, mid to late
afternoon toward metro Detroit.

- A surge of cold air follows Saturday night and Sunday which is
then reinforced Monday through Wednesday next week.

- Daytime temperatures drop into the 40s Sunday and then below
normal into the 30s Monday and Tuesday. The cold air also brings a
chance of snow showers for the early week period.

&&

.AVIATION...

Skies have cleared at the terminals as late day diurnal mixing and
expanding sfc high pressure have exerted their influence. The high
pressure will exit east of the area overnight as a strong cold front
approaches the region from the northwest. This front will advance
into Lower Mi on Saturday. Prefrontal southwest winds will
dramatically increase during the morning. Model soundings suggest
boundary layer growth through diurnal mixing will result in
southwest wind gusts up to or in excess of 30 knots by Saturday
afternoon. Moisture advection, beginning prior to daybreak Saturday
and into Saturday afternoon will mainly be in the mid levels. So
ceilings heights will be VFR. The front will slowly push across the
area Saturday afternoon and will provide a chance for a brief
interval of showers.

For DTW...The wind direction is forecast to veer slightly from
southwest to westerly late Saturday afternoon. With gusts expected
to remain over 25 knots, this could pose the chance for crosswind
concerns. Light showers may also accompany the front in the
afternoon. The chances look low so will refrain from mentioning in
the TAFs attm.

.DTW THRESHOLD PROBABILITIES...

* Low for ceilings at or below 5000 feet Saturday.

* Low for crosswind thresholds being exceeded Saturday afternoon.

&&

.PREV DISCUSSION...
Issued at 357 PM EDT Fri Mar 15 2024

DISCUSSION...

Mid afternoon observations show resilient low clouds holding on
across the Thumb over a lingering north surface wind, both of which
have temperatures locked in the upper 30s there. At the opposite end
of the spectrum, nearly full sun south of the M-59 corridor is
helping lift temperatures into the mid 50s. All locations should
expect a quick post sunset cooling trend as surface high pressure
slides eastward. This clears the remaining Thumb area clouds this
evening as wind becomes SW with just enough speed to hold
temperatures around freezing by sunrise.

The next low pressure system is well on its way through central
Canada this afternoon and will be on the doorstep of SE Mi Saturday
morning. It draws mild air into the region on breezy SW flow within
the warm sector of the system. Model soundings suggest gusts in the
30-40 mph range by late morning as daytime boundary layer growth
gets underway, and this helps lift temperatures into the 50s until
the initial cold front swings through from NW to SE mainly in the
afternoon. Today`s body of deterministic model solutions have
trended upward on the potential for rain showers along and ahead of
this leading frontal zone, and this potential is eased into the
forecast as concern remains regarding the moisture supply into the
system with Gulf moisture confined to the coast. At the same time,
the mid level wave and surface low amplify/deepen while tracking
toward Lake Superior which ramps up the wind field and thus
advection of Pacific moisture into Lower Mi. Model theta-e
depictions show an axis that is well defined but limited in
magnitude within the 850-700 mb layer but in line with the Pacific
origins. This is combined with the strength of the mid level wave
for chance POPs until the front exits south/east by Saturday
evening.

Saturday night and most of Sunday are dry slot dominated but with
plentiful cloud cover in strong low level cold advection.
Temperature guidance is solid with the trend toward the freezing
mark by Sunday morning followed by just a few degrees of recovery
during the day. Model soundings project convincingly cold low level
thermal profiles for snow flurries within steep boundary layer to
mid level lapse rates during the afternoon into Sunday night.

The larger scale mid level flow configuration continues to amplify
during Monday as part of the maturing rex block over the Rockies.
This leads to further deepening of the trough across the Great Lakes
and a reinforcing shot of cold air into Lower Mi. Model agreement
suggests increased predictability on a short wave circulation digging
into the region with a stronger forcing and deeper moisture profile
for snow showers. Today`s cloud pattern also proves that the cold but
unfrozen Great Lakes can still contribute moisture flux for a modest
lake effect component while northerly wind holds along and behind
the reinforcing cold front.

Deep northern stream NW flow is shown in the extended range model
consensus feeding several more embedded smaller scale systems into
the Great Lakes Monday night and Tuesday. This presents low
predictability on precipitation while below normal temperatures
continue into Wednesday. A moderating trend then appears as the
Rockies rex block releases eastward during the late week period.

MARINE...

High pressure has slide over the Great Lakes providing a temporary
break from wind and waves across the region. This will come to an
end Saturday as a strong low pressure system tracks out of central
Canada and across the northern Great Lakes. The low along with
several cold fronts will bring increasing winds and waves through
the weekend and into next week. Winds will increase Saturday morning
out of the southwest ahead of the first front with winds reaching 25
to 30 knots. Winds turn more northwesterly Saturday night and
through Sunday with gusts to around 25 knots behind the front with
cold advection resulting in increasing wave heights that will
continue to affect portions of the nearshore areas Sunday and
Monday. A Small Craft Advisory is in effect for all nearshore zones
for the 25+ knot southwest winds and additional Small Craft
Advisories will likely be needed Sunday and Monday for waves.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Small Craft Advisory from 5 AM to 10 PM EDT Saturday for LHZ421-422-
     441>443.

Lake St Clair...Small Craft Advisory from 10 AM to 10 PM EDT Saturday for LCZ460.

Michigan waters of Lake Erie...Small Craft Advisory from 10 AM to 10 PM EDT Saturday for LEZ444.

&&

$$

AVIATION.....SC
DISCUSSION...BT
MARINE.......DRK


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