253
FXUS63 KDTX 051909
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
309 PM EDT Sun May 5 2024

.KEY MESSAGES...

- Mostly sunny and mild Monday.

- Showers likely with a chance of thunderstorms Tuesday afternoon
  and evening.

- Marginal risk of strong to severe storms south of I-94 Tuesday.

&&

.DISCUSSION...

Skies will continue to clear from northwest to southeast across the
area this afternoon into early this evening as high pressure begins
to build into the area in the wake of an exiting cold front. Any
lingering isolated showers or patchy drizzle will dissipate during
the late afternoon/early evening. Clear skies and light winds during
the overnight will promote decent cooling with lows well into the
40s in most locations. This high pressure will remain in place
Monday with skies ranging from mostly sunny north to partly sunny
south as a weak mid level disturbance associated with today`s
convection well to the south brushes the area. Highs should reach
the upper 60s to around 70.

During this time frame, a much stronger upper level system will
emerge over the northern/central plains and lead to rapid surface
cyclogenesis over the western Dakotas with a cold front pivoting
quickly around the base of this low through the plains. A notable
severe weather outbreak is expected along this boundary over the
central plains. This front occludes as it then works east and
northeast into SE MI by late in the day Tuesday.

While a minor axis of instability does progress into/near the region
along this front, overall conditions still seem minimally supportive
for any notable strong/severe thunderstorms. (Even NAM has higher
CAPE environment subdued well south of the area over the Tennessee
Valley). That said, a marginal risk of severe weather has been
posted for the southern part of the forecast area as the northern
fringe of region of strongest shear and at least modest instability
does encroach on the Michigan and Ohio state line. So, perhaps a
strong storm or two will be possible on southern edge of what will
be a general area of showers/rumbles of thunder as the front arcs
northeast through the area.

Additional jet energy will race off the Pacific ocean around the
base of the occluded upper low over the northern plains. This will
provide another active weather day on Wednesday with showers and a
few thunderstorms. Once again, it appears the bulk of the severe
weather potential will remain south of the region on Wednesday with
just shower chances increasing from late in the day into Wednesday
night. Shower/isolated thunder chances actually persist into the day
Thursday as a northern stream shortwave pivots into the Great Lakes
from Canada.

This northern stream shortwave is the first of several which will
usher in a upper level pattern change that will bring cooler weather
to the region from late this week into next weekend as upper level
troughing becomes prevalent. So, the upper 60s to mid 70s common on
Tuesday and Wednesday will be replace by upper 50s to mid 60s.
Isolated to scattered showers will dot the area within this overall
unsettled pattern as well. Low temperatures will approach 40 in some
locations next weekend with some 30s not out of the question.

&&

.MARINE...

A weak cold front will finish pushing through the region this
afternoon. High pressure then centers itself over the region tonight
through Monday night which will result in winds generally under 15
knots with low wave heights. Next chance of showers and
thunderstorms comes Tuesday afternoon through Tuesday night as a
warm front gets pulled up through the Great Lakes. After a possible
lull on Wednesday, a low pressure system will then target the area
on Thursday bringing another chance for showers and thunderstorms.
At this time winds and waves are likely to remain below marine
headline criteria.

&&

.HYDROLOGY...

Showers and thunderstorms will move into the area along a warm front
Tuesday afternoon and persist into the evening. While a few of the
thunderstorms will produce locally heavy downpours, average rainfall
will remain below half an inch and in many cases well below that
threshold. No major flood concerns are expected at this time.

&&

.PREV DISCUSSION...
Issued at 124 PM EDT Sun May 5 2024

AVIATION...

Weak secondary cold front slowly sagging south through the TAF
corridor this afternoon maintaining MVFR cloud cover as well as
areas of drizzle. While clearing has already occurred over MBS,
satellite trends show lower cloud gradient has stubbornly held north
of FNT thus far. Based on these trends and forecast soundings, have
gone a bit more pessimistic on lifting/clearing timing for all TAF
sites (save for MBS) pushing it back to evening (~21-00Z). High
pressure becomes fully established over the region tonight setting
up lighter (10kt or less) flow as well as limiting any redevelopment
of lower cloud, once clearing occurs.

For DTW/D21 Convection... Low level moisture has held more
stubbornly even with drier air drawn into the area. Pushed
lifting/clearing timing to late evening-early tonight (~00-05Z)
though this still carries a fair degree of uncertainty.

DTW THRESHOLD PROBABILITIES...

* High for ceiling 5000 feet or less through this evening, turning
  low tonight (between ~03-06Z).


&&

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

$$

DISCUSSION...DG
MARINE.......DG
HYDROLOGY....DG
AVIATION.....KDK


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at www.weather.gov/detroit.