263
FXUS63 KDTX 150935
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
535 AM EDT Tue Oct 15 2024

.KEY MESSAGES...

- Lake effect rain showers focused across the Thumb through today
  with an additional 1.00 to 1.50 inches of rainfall possible.

- Frost/freeze potential tonight and tomorrow night.

- Warming trend during the late week into the weekend as high
  pressure brings dry conditions.

&&

.AVIATION...

Cool northerly flow will continue to draw Lake Huron moisture
inland, bringing the chance for isolated to scattered shower
activity during the morning and low-end VFR cigs that will hold on
through daylight hours. There remains a low chance for sporadic MVFR
cigs through the morning hours, as has been periodically observed
across locations upstream. Otherwise, daytime mixing will again
support gust potential around 20 to 25 knots throughout the day. Both
gust potential and cloud coverage will wane after sunset.

For DTW/D21 Convection...Thunderstorms are not expected.

DTW THRESHOLD PROBABILITIES...

*  Medium in ceilings at or below 5000 ft this morning. Low this
   afternoon.

&&

.PREV DISCUSSION...
Issued at 405 AM EDT Tue Oct 15 2024

DISCUSSION...

Mid and upper level low with the associated cold thermal trough
resides over the Great Lakes and northeastern CONUS today. The 00Z
DTX RAOB from last evening sampled the 850 mb temperature at -2C and
the 500 mb temperature at -21C. These cold temperatures with a
steady northerly flow in the low levels has brought persistent lake
effect clouds and rain showers off Lake Huron since yesterday. The
greater focus of heavier precipitation through these overnight hours
has been along the east shoreline of the Thumb while the clouds have
helped hold low temperatures in the mid-upper 30s.

Another wave will drop south out of Ontario through today as
temperatures at 850 mb are expected to cool a couple degrees more by
mid morning. Expecting another diurnal uptick in lake effect shower
activity by late morning/early afternoon with the arrival of this
wave. Plenty of overlake instability will exist by early this
afternoon with plenty of CAPE up to 10kft within the 0C to -20C
layer to keep a chance for lighting and thunder in the forecast.
Trajectories off the lake through the first half of the day will keep
the likely PoPs confined to the northern and eastern portions of the
Thumb. Shoreline convergence with the added support of the wave will
bring potential for an additional 1 to 1.5 inches of rainfall
through this afternoon. Stronger lower level flow will develop late
this afternoon through early tonight. Some degree of boundary layer
mixing with help from the cold advection is expected during this time
leading to wind gusts mostly in the 30 to 35 mph range with some
gusts approaching 40 mph possible across the Thumb.

The passing of the wave will lead to winds backing slightly more to
the northwest this evening into tomorrow morning. This will help
gradually push lake effect shower activity off the Lake Huron
shoreline and focus the heavier east of Port Huron. Some clearing
may bring lead to frost development across western portions of the
CWA tonight as temperatures approach freezing. Encroaching ridge and
surface high pressure will bring an end to any precipitation chances
along the shorelines for Wednesday, though the western end of the
thermal trough will linger keeping daytime highs in the 50s. Coldest
morning of the week expected Thursday morning as clearing skies
should allow temperatures to plummet into the upper 20s across the
north and low 30s outside of the Detroit urban island.

Ridge axis will push further into the Great Lakes and bring a
warming trend in temperatures through the late week. Warm air
advection with the deeper southwest flow ushers in 850mb
temperatures above 10C by Saturday. This will bring daytime highs
back towards 70 degrees during the weekend as the high pressure
maintains dry conditions.

MARINE...

Extended period of Small Craft Advisories continues over Lake Huron
and Saginaw Bay today through Wednesday. Cold air advection will get
reinforced this morning as another cold frontal trough passes south
through Lake Huron. The increase mixed layer will briefly tap into
stronger winds which will bring higher gusts around 30 knots to the
basin. There remains a chance to see a few gusts to gales but
confidence is low so will continue to monitor at this time. The
northerly flow will continue to build wave heights along the Lake
Huron shoreline with significant wave heights of 8 to 10 feet
expected. Winds will settle back around 20 knots tonight into
Wednesday but the waves will remain elevated through the day. In
addition, the upper low overhead will maintain showery conditions
and waterspout potential over the next few days as well. High
pressure eventually fills in late week to bring an end to the
unsettled marine conditions.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Small Craft Advisory until 4 PM EDT Wednesday for LHZ421-422-
     441>443.

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

$$

AVIATION.....AM
DISCUSSION...AA
MARINE.......DRK


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