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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS63 KDTX 130800
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
400 AM EDT Sat Apr 13 2024

.KEY MESSAGES...

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- High pressure today supports plenty of sunshine with temperatures
near 60 degrees. Breezy northwest flow continues this morning with
peak gusts up to 35 mph before relaxing through the day.

- A cold front tracks through the region Sunday with a chance for
elevated showers and storms across the Thumb early in the morning
followed by a low chance for storms south of I-94 during the
afternoon. Temperatures will be in the low to mid 70s.

- Quieter conditions return early week amongst a warming trend with
temperatures well above normal in the upper 60s to low 70s.

- A strong low pressure system brings widespread shower and
thunderstorm chances to southeast Michigan middle of next week.
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&&

.DISCUSSION...

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Pattern shift is underway this morning as a sharp subsidence axis
migrates overhead, which coupled with lack of column moisture will
support clear skies today. The main forecast item to note is the
return of breezy conditions that develop shortly after sunrise as a
weak nocturnal inversion erodes. 850mb wind max will still be around
50 knots at 12z to support gusts of 30-35 mph this morning, but
relaxing through the day. Maximized solar insolation will boost
daytime highs to near 60 degrees even with strongest warm advection
holding off until this evening.

Rapid theta-e advection ensues this evening as winds shift southwest
ahead of a glancing low amplitude wave and frontal boundary set to
impact lower Michigan on Sunday. Coupled with a 55-60 knot LLJ,
elevated convection is expected to develop over the Upper Midwest
late tonight and dive toward Lake Huron and the Thumb early Sunday
morning. There is still a subset of guidance that keeps the complex
over the waters, but majority of guidance does clip the Tri Cities
and Thumb. Any storms could become organized in a region of steep
mid-level lapse rates and 60 knots mid level westerlies, but
elevated nature should keep impacts to frequent lightning and small
hail. The progressive upstream wave will displace low level jet
forcing into Lake Erie before 12z (8am local), bringing an end to
showers and elevated thunderstorms by daybreak.

As this wave continues to dive southeast, it encounters a strong
southeast CONUS ridge that effectively shears it east toward New
England. This slows southward progress of the cold front, with a
gradual drift toward the Ohio border through 20z (4pm local). Recent
suite of forecast soundings maintains enough static stability in the
850-700mb layer and weak frontal convergence to prevent widespread
convective initiation along the front. Still, there will be an
attempt at surface destabilization as surface temperatures rise into
the mid 70s and dewpoints into the 50s. Should at least see some
cumulus development across the area and breezy southwest flow (25 to
30 mph), with a low chance for a storm or two to break the cap south
of I-94. As mentioned in the previous discussion, any storms that do
develop will need to be monitored closely as other aspects of the
environment (steep mid level lapse rates, unidirectional shear)
could support storm organization. For most locations, however,
Sunday will be another quiet and mild day.

Seasonably warm temperatures continue into next week, with forecast
temperatures +10 degrees above normal per mid April standards. This
corresponds to daytime highs in the upper 60s to low 70s and
overnight lows in the mid-40s. Longwave upper level ridging pattern
holds through middle of next week, affording generally quiet weather
conditions. This will change mid-week, however, as a Pacific cutoff
low (already moving on shore the California coast this morning) will
migrate across the Four Corners and southern Plains before
negatively tilting toward the upper Midwest Tuesday night-Wednesday.
This will be the next system to watch for widespread rainfall and
thunderstorm chances mid-week.
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&&

.MARINE...

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Northwest winds will continue to slowly come down this morning as
the pressure gradient gradually weakens with weak surface high
pressure arriving this evening. Winds will be light tonight as a
result, before a much weaker low drops out of Canada into the
central Great Lakes on Sunday. This system brings chances for
additional showers and a few thunderstorms during the daytime hours
of Sunday, mainly over Lake St. Clair and Lake Erie. No wind
headlines are expected with this system as wind gusts generally top
out around 20kts.

Broad surface high pressure in place to start the work week will
provide light winds on Monday, with easterly winds increasing on
Tuesday ahead of the next low pressure system moving into the
Western Great Lakes.
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&&

.PREV DISCUSSION...
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Issued at 1205 AM EDT Sat Apr 13 2024

AVIATION...

Last bit of deep 925-850mb thetae/moisture advected through the
northern forecast area late this evening. Substantial drying is now
underway across the Southeast Michigan. With the subsidence, warmer
low-midlevel temperatures has resulted in higher stability and
lowering winds. Strong geostrophic/gradient wind will allow winds of
20 to 30 knots to persist tonight. Clearing is expected late tonight
and Saturday. West northwest winds Saturday of 20 to 30 knots.

DTW THRESHOLD PROBABILITIES...

*  None.
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&&

.DTX WATCHES/WARNINGS/ADVISORIES...
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MI...None.
Lake Huron...Gale Warning until 10 AM EDT this morning for LHZ421-422-441>443-
     462>464.

     Gale Warning until 4 PM EDT this afternoon for LHZ361>363.

Lake St Clair...Gale Warning until 10 AM EDT this morning for LCZ460.

Michigan waters of Lake Erie...Small Craft Advisory until 4 PM EDT this afternoon for LEZ444.
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&&

$$

DISCUSSION...MV
MARINE.......SF
AVIATION.....CB


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