Expert Forecast Opinion

048
FXUS63 KDTX 231119
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
619 AM EST Sat Nov 23 2024

.KEY MESSAGES...

- Dry weather this weekend as weak high pressure builds in though
cloudy skies remain.

- Another low will develop over the region Monday bringing
additional rain chances and brief shot at milder air.

- Confidence is increasing in several days of below normal
temperatures Tuesday through next weekend.

&&

.AVIATION...

Moist low level conditions sustained within prevailing northwest
flow will remain firmly entrenched beneath a strong inversion this
taf period. This will maintain an extensive stratus deck, with a
fluctuating cloud base held largely in MVFR. Some improvement late
in the day may afford recovery into/near VFR. However, renewed
moisture advection near 925 mb as winds back with time toward the
west may help draw deeper low level moisture residing west of lake
Michigan back into the region overnight into Sunday morning. This
would solidify MVFR restrictions again during this time.

DTW THRESHOLD PROBABILITIES...

* High in ceilings at or below 5000 ft through tonight.

&&

.PREV DISCUSSION...
Issued at 330 AM EST Sat Nov 23 2024

DISCUSSION...

Upper troughing finally begins to dislodge east this morning as
ridging across the central CONUS expands into the Great Lakes.
Lingering spotty drizzle gradually diminishes as this occurs with
the region likely drying out by mid-late morning. Minimal warm
advection accompanies this ridge with the airmass largely remaining
unchanged thermally resulting in similar highs today that we seen
yesterday, ie mid to upper 40s. Stratus deck likely doesn`t go
anywhere today as no significant dry advection occurs beneath this
high with remnant low level moisture remaining trapped below the
developing subsidence inversion. Temperatures Sunday creep up into
the upper 40s as the ridge axis crosses the region during the
afternoon setting up warmer southwest flow below 800mb. This warm
advection becomes fully realized by Monday as 850mb temps reach 3-5C
Monday morning bringing highs back into the lower 50s.

Active weather also makes a return Monday as a northern stream mid-
level trough dropping out of the Canadian Prairie phases with
sheared a shortwave that broke off the Pacific NW trough and became
embedded with the jet over the central CONUS. This phasing looks to
occur over the western Great Lakes resulting into cyclogensis
directly over southern lower MI by late Monday morning. While the
GFS/GEFS remain the more aggressive solution family wrt to speed of
low deepening/maturation, they have trended more in line with the
ECMWF and Canadian with primary intensification occuring over Lake
Huron and southern Ontario. Main impact of this is on QPF with
lighter, more scattered showers occuring over SE MI Monday/Monday
night and heavier activity instead developing to our east. Colder air
wraps into the area by early Tuesday offering a shift towards rain-
snow or potentially all snow within lingering trailing precip. No
accumulation expected should this occur as intensities will be light
as well as there only being a brief few hour window before precip
peels away.

MARINE...

Small Craft Advisories continue this morning for most of the Lake
Huron shoreline. The pressure gradient gradually relaxes through the
day with flow backing just enough offshore (becoming WNW by tonight)
to push the elevated wave plume into the open waters. Quieter marine
conditions persist tonight and Sunday aside from waning pockets of
drizzle. The next system to impact the Great Lakes ejects from the
Plains Sunday evening, surging a jet of enhanced low level winds
over the Ohio Valley which will clip the southern marine areas. That
said, stable profiles over the water will keep these winds elevated.
The biggest change will be the southerly shift in wind direction
which holds on until a cold front tracks through late Monday. This
system will also bring widespread rain chances to the area Monday,
but cold advection behind the front draws a colder airmass into the
Great Lakes once again which will be conducive for both gusty winds
and wet snowflakes late Tuesday-Wednesday.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Small Craft Advisory until 4 PM EST this afternoon for LHZ421-
441>443.

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

$$

AVIATION.....MR
DISCUSSION...KDK
MARINE.......MV


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