993
FXUS63 KDTX 280820
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
420 AM EDT Sun Apr 28 2024

.KEY MESSAGES...

- Showers and thunderstorms today and Monday before a cold front
  arrives Monday night bringing dry weather for Tuesday.

- Total rainfall amounts over the next two days to around 1.00" possible,
  particularly across the Tri-Cities and Thumb.

- Well above normal temperatures expected continue through this week.

&&

.DISCUSSION...

Showers and thunderstorms are gradually moving into the Tri-Cities
early this morning ahead of a slow moving frontal draped from
southern WI into northern lower Michigan. A secondary area of
showers and thunderstorms is lifting into Lower Michigan within a
zone of higher 850-500 mb theta-e-e advecting northward.
Mesoanalysis shows weakening MLCAPE throughout the morning hours
over the Tri-Cities along with weakening mid-level lapse rates which
should support continued weakening of these showers and
thunderstorms over the next few hours. The secondary area of showers
lifting in from Indiana and northwest Ohio will also be encountering
an unfavorable environment as they arrive in Michigan with mid-level
dry air and limited instability. This should result in mainly
showers with a few rumbles thunderstorms possible through 12Z across
Lower Michigan.

Persistent theta-e advection will carry through the morning with
greater large scale forcing holding largely to the west. The
presence of the stationary boundary will be enough to provide a
continued focus for convergence bringing more showers and
thunderstorms through the remainder of the morning into the
afternoon. A very warm airmass remains in place that supported high
temperatures yesterday in the low 80s at many locations. The mostly
cloudy skies with expected showers and thunderstorms will likely
tamper highs down slightly from yesterday. This is especially true
for northern portions of the CWA where scattered showers and
thunderstorms become more focused during the afternoon. Expecting a
15 to 20 degree temperature gradient from north to south. North of
the frontal boundary that settles roughly near the I-69 corridor
will see daytime highs in the 60 to 70 degree range. South of the
frontal boundary will see highs in the mid to upper 70s with some
spots near the OH border possibly reaching 80 degrees. These areas
look to remain mostly dry by 18Z and through the evening. Cannot
completely remove PoPs from the forecast for tonight across northern
portions of the CWA. The lingering boundary and persistent moist
southwest flow will continue to touch off mostly elevated scattered
showers and thunderstorms supported by weak instability and mid
level lapse rates of 6-7 C/km.

Stacked surface low and upper trough lifts into the upper Midwest
Monday morning putting southeast Michigan fully back in the warm
sector after the aforementioned stationary boundary is drawn
northward. The exiting boundary brings potential for a mostly dry
Monday morning. Increasing southwest gradient flow will bring an
uptick in winds on Monday. Flow at 850 mb increases to 30-40 knots,
though mixing depth will be limited. Gusts on Monday look top out
around 20 knots. Widespread rain chances return by Monday afternoon
ahead of a cold front that will sweep through southeast Michigan
Monday night. Thunderstorms will again be possible with increasing
daytime instability. Strong flow will increase shear and a few
hundred J/kg of MLCAPE look possible Monday afternoon.

Dry and slightly cooler conditions expected in the wake of the front
on Tuesday with highs down to around 70 and winds out of the west.
Uncertainty in synoptic features exists for Wednesday as several
wave interactions occur across the northern plains/Upper Midwest
into southern Canada. Regardless, an active pattern should set up
during the latter half of the week with warm advection returning
highs into the mid/upper 70s to low 80s.

&&

.MARINE...

A cold front will start to significantly slow down and stall across
central Michigan through the Saginaw Bay and central Lake Huron this
morning. This will be the focal point for showers and possible
thunderstorms, with increasing coverage for locations south through
the remaining morning hours as the frontal boundary very gradually
wavers to the south. The intrusion of shallow near surface cold air
behind the front will only reinforce stability over the lakes with
very warm air aloft, which will act to inhibit the stronger winds
aloft from mixing to the surface. Some isolated gusts around 25
knots cannot be ruled out with any thunderstorm activity. Shower and
some isolated thunderstorm activity will pivot back north into Lake
Huron through the afternoon and evening hours along the
wavering frontal boundary.

A very shallow mixing layer is expected to develop tomorrow morning
across north to north-central Lake Huron which will allow for some
localized higher wind gust potential with flow coming from the
northeast. Gusts around 30 knots will be probable through the first
half of the day on Monday, along with the continuation for rain
shower and thunderstorm potential. The mixing layer will shrink
through the evening, decreasing wind gust potential leading into
Tuesday.

&&

.HYDROLOGY...

A stalled frontal boundary will provide a focus for several rounds
of showers and thunderstorms this morning through tomorrow evening.
The first wave of rainfall will be throughout the course of today.
Showers and thunderstorms become more focus across northern portions
of the CWA by this afternoon with scattered activity continuing into
tonight. A break in widespread activity Monday morning before more
widespread showers and thunderstorms return Monday afternoon/evening.
Total rainfall amounts from 8 am this morning through 2 am Tuesday
will reach 0.75" to 1.00", mostly for areas along and north of I-69
and for portions of Oakland and Livingston County. Rainfall amounts
of 0.25" to 0.50" can be expected for the remaining areas. While
significant flooding is not expected at this time, expect minor
flooding in prone urban and poor drainage areas and possibly notable
rises in area rivers, especially to the north.

&&

.PREV DISCUSSION...
Issued at 1138 PM EDT Sat Apr 27 2024

AVIATION...

Current radar/satellite trends confirm a decrease in coverage and
intensity as the line of convection across northern Lower Mi sinks
southward over the next few hours. This will perhaps leave a chance
of convection at MBS for the first few hours of the TAF period.
Decoupling of the boundary layer tonight will lower sfc wind speeds,
however increasing winds just atop the nocturnal stable layer will
be supportive of some low level wind shear during the night. A
secondary influx of moisture and instability from the south
overnight will support another round of showers with a few embedded
thunderstorms late tonight through Sun morning. This added moisture
influx and showers will contribute to widespread MVFR and IFR based
clouds. Occasional showers, perhaps a few thunderstorms, will linger
through Sun afternoon along a slow moving cold front from FNT north
to MBS.

For DTW/D21 Convection...A subtle influx moisture and elevated
instability early Sun morning will drive scattered to numerous
showers across the area with some embedded thunderstorms. The risk
for thunderstorms to the airspace will be greatest in the 09Z to 15Z
time frame.

DTW THRESHOLD PROBABILITIES...

* Low in thunderstorms tonight. Moderate Sunday morning.

* High in ceilings aob 5000 feet overnight and Sunday morning.


&&

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

$$

DISCUSSION...AA
MARINE.......AA
HYDROLOGY....AA
AVIATION.....SC


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