683
FXUS63 KDTX 230339
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1139 PM EDT Sun Sep 22 2024

.KEY MESSAGES...

- Showers through the evening hours.

- More seasonable temperatures Monday through Wednesday with showers
likely once again on Tuesday.

&&

.AVIATION...

Area of rain associated with passing low pressure will continue to
work slowly east into the overnight with some degree of fog/drizzle
left in its wake into Sunday morning as IFR/possible LIFR stratus
spreads east/southeast into the area. Cigs will then increase into
Monday afternoon within slight drier northerly flow, but with some
potential of lower stratus/fog returning late Monday night.

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

 DTW THRESHOLD PROBABILITIES...

* High for ceilings at or below 5000 feet into Monday morning,
  medium by Monday afternoon/evening.

* Low for ceilings at or below 200 feet early Monday morning.

&&

.PREV DISCUSSION...
Issued at 300 PM EDT Sun Sep 22 2024

DISCUSSION...

Neutral to negative tilted upper level trough tracking through
Ontario/northern Great Lakes while a secondary, more subtle
shortwave, tracks through the Midwest. An attempt of a coupled jet
structure (right entrance/left exit region) over southeast Michigan.
Regardless, with the southern left exit region being the main driver
and with the good moisture axis (PW values of 1.5+"/700 MB dew pts
near 5 C/850 dew pts 12+ C) advancing through the CWA this evening,
widespread showers are expected with some modest instability
allowing for a slight chance of embedded thunderstorms.

Another round of showers likely for Tuesday as shortwave trough and
associated weak surface low tracks through Lower Michigan. 12z Euro
remains one of the more bullish solutions.

Strong upper level Jet (140 knots at 250 MB) tracking through
British Columbia on pace to dive south through the Plains on Monday.
Although there is some merger of heights with the upper level wave
coming out of the Four Corners region, the main height fall center
and subsequent closed 500 MB low looks to reach the southern
Mississippi River Valley Tuesday night-Wednesday, which will likely
capture the tropical system in the Gulf of Mexico. However, at this
time, it appears a blocking upper level ridge (588+ DAM at 500 MB)
will be building over the Great Lakes region to end the work week,
supporting dry weather into Friday.

MARINE...

A low pressure system and trailing cold front will bring widespread
rain showers and possibly some embedded thunderstorms through the
afternoon and evening hours. After the passage of the front, winds
will flip to the north and will increase up to 20 knots sustained,
with gusts to or just shy of 25 knots. These elevated winds will be
most likely across Lake Huron, and will push wave heights to around
4 ft around the tip of the Thumb. A Small Craft Advisory will be in
effect through tomorrow due to elevated wave heights.

High pressure then briefly fills in on Monday bringing lighter winds
and dry weather, but a second low pressure system will move right
over the central Great Lakes Tuesday afternoon into Wednesday
morning, bringing the likely chances for showers and embedded
thunderstorms.

HYDROLOGY...

Showers with a slight chance of embedded thunderstorms to move
through southeast Michigan this evening. Basin average rainfall
looks to be under half an inch. However, given PWATs greater than
1.50 inches, locally higher amounts to 1.00 inch can not be totally
ruled out.  No significant flooding is expected regardless.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Small Craft Advisory until 10 PM EDT Monday for LHZ421-441.

     Small Craft Advisory from 10 AM to 10 PM EDT Monday for LHZ442-443.

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

$$

AVIATION.....DG
DISCUSSION...SF
MARINE.......AM
HYDROLOGY....SF


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