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400
FXUS63 KDTX 092311
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
711 PM EDT Thu May 9 2024

.KEY MESSAGES...

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- Cooler temperatures (50s to low 60s) hold through Saturday before
returning to at or above normal Sunday.

- Next chance of showers and thunderstorms comes Saturday with the
passage of a compact low pressure system. Severe weather is not
expected.

- Another chance of showers and thunderstorms comes Monday as a cold
front drops through the area..
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&&

.AVIATION...

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Remaining light showers with lower VFR cigs will gradually dissipate
and drop south of the area during the course of the evening with
northeast winds backing to the north. VFR conditions prevail into
Friday with sct-bkn diurnal cumulus expected. Winds will continue to
back to northwest into the end of the forecast period.

For DTW/D21 Convection...Thunderstorms are not expected for this
forecast period.

DTW THRESHOLD PROBABILITIES...

* Moderate in ceilings aob 5000 feet this evening, low Friday
  afternoon.
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&&

.PREV DISCUSSION...
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Issued at 353 PM EDT Thu May 9 2024

DISCUSSION...

Models continued to favor the deep layer of dry air north of the
elevated frontal surface, over the strength of the fgen aloft
resulting in drier conditions holding over much of the CWA through
the first half of the day. Latest runs offered weaker fgen and
focused it lower on the frontal surface (peaking around 700mb) which
has not be enough to overcome the dry layer between 900-600mb. SPC
meso analysis page shows the current showers paired perfectly with
the 700mb fgen band which is located over our southern 4 counties.
We`ll hold on to a chance POP up to around M59 as the moisture is
still pushing north with the low now passing directly south of us so
there is a chance for minor expansion northward albeit for light
showers or trace amounts of rain. Northeast flow will gain more
traction this evening as the low directly to our south this
afternoon pushes off to the east. The deformation axis will slide
through this evening across 00Z keeping some mention of POPs across
the far south til around 06Z.

Cool period continues Friday as the positively tilted trough axis
passes overhead. Cold air advection aloft will steepen low level
lapse rates allowing for an expanding coverage of stratocu Friday
with dry air advection and shortwave ridging helping to limit
duration of thicker clouds and potential for any isolated showers
to perk up during peak heating.  Highs will be muted in the low 60s
as the 850mb thermal trough around 2C slides southward out of the
area with cooler northerly flow off the lakes.

Next chance of showers and thunderstorms comes on Saturday as the
ridge quickly slides out and a clipper type low in the base of a
narrow northern stream trough drop southeast through the Great
Lakes. Attendant surface low spin up will track across far southern
MI with a trailing trough axis and theta e axis extending
north/northwest helping spread showers further north through Mid MI
as the low passes. Still looking at some embedded thunderstorms
being possible with steepening low/mid level lapse rates, a few
hundred joules of MUCAPE, and mid level support from the compact mid
level vort max. Severe weather is not expected as flow is very weak
through the column with winds under 20 knots through 20kft.

Stronger mid level ridge slides through Sunday with westerly warm
air advection boosted temps back up to at or above normal (which is
upper 60s for early/mid May). Next system comes quickly for Sunday
night and Monday as a northern stream trough pushes a cold front
through the region. Thunderstorms will be possible again with this
activity.

MARINE...

Northern edge of steady rainfall is just now approaching southern
Lake St. Clair, with limited additional northward expansion expected
this evening which will maintain dry conditions across Lake Huron.
Responsible surface low is currently over the Ohio Valley, with
prevailing northeast flow as a result. High pressure builds in
briefly for Friday resulting in just a subtle shift to northerly
flow and drier weather before the next low arrives on Saturday. The
low is forecast to track over central Michigan, lending to a brief
period of southwest flow Saturday morning ahead of a cold front
before returning to the northwest later in the day as the low/front
depart. Precipitation chances are once again in play for Saturday
especially south of Saginaw Bay before drier weather returns Sunday
in the wake of renewed high pressure. No wind/wave headlines are
expected through early next week.
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&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...None.
Lake St Clair...None.
Michigan waters of Lake Erie...Small Craft Advisory until 10 PM EDT this evening for LEZ444.

&&

$$

AVIATION.....DG
DISCUSSION...DRK
MARINE.......MV


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at www.weather.gov/detroit.