FXUS63 KDTX 261136
AFDDTX
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
736 AM EDT Fri Apr 26 2024
.KEY MESSAGES...
- Dry conditions today with a warming trend lifts temperatures into
60s.
- Showers arrive overnight with a chance for a few embedded
thunderstorms through Saturday morning.
- Breezy southwest winds develop Saturday afternoon with gusts up to
30 mph.
- Some additional thunderstorms are possible Saturday evening with
an isolated severe storm possible northwest of Metro Detroit.
- Additional showers and a few storms are possible Sunday as above
normal temperatures continue through mid-week.
&&
.AVIATION...
VFR conditions are expected through today. Surface high pressure to
the east will influence weather conditions bringing southeast winds
at around 10 knots and dry conditions through the daylight hours. Low
pressure over the plains will send a warm front into the region
bringing increasing mid and high clouds late this afternoon into the
evening before scattered showers and possible thunderstorms arrive
tonight. Light rain showers move in around 03Z with the greater
thunderstorm by around 06Z and through the early morning hours. MVFR
ceilings will also accompany the better low level moisture tonight
through tomorrow morning while winds turn more southerly with gusts
to around 20 knots towards 12Z tomorrow morning.
For DTW/D21 Convection...A warm front will approach late
tonight/early Saturday morning with increasing instability aloft.
This will also support a chance of thunderstorms, likely embedded
within the broader pattern of scattered to numerous showers. Chances
for thunderstorms will be around 30 percent and focused
mainly between 08Z and 12Z.
DTW THRESHOLD PROBABILITIES...
* Low in thunderstorms tonight into early Saturday morning.
* High in ceilings aob 5000 feet tonight into Saturday morning.
&&
.PREV DISCUSSION...
Issued at 427 AM EDT Fri Apr 26 2024
DISCUSSION...
Unobstructed cooling and nearly clam winds through the overnight
period have sent temperatures into the low-mid 30s across much of
the CWA with light ESE flow. High cirrus streamers spilling
downstream of a potent shortwave trough closing off over eastern
Colorado will begin to interfere with outgoing longwave radiation.
This should limit further cooling to just a few more degrees (F)
until the diurnal rebound gets underway. Will allow the Frost/Freeze
headlines to run their course as dew points remain below freezing.
Minor height rises expected through midday as the resident southern
stream ridge builds into its northern stream equivalent. Stubborn
anticyclone flow then lingers to the east, offering sustained
stabilization that temporarily resists top-down saturation
processes. Once upper winds back westerly, clouds will work in aloft
while the low cloud fraction lags amidst longer duration
southeasterly flow. A very broad and highly confluent LLJ featuring
impressive latitudinal extent should fold/rotate into southern Lower
Michigan this evening providing a shift to southwest flow and
aggressive ThetaE convergence. Ultimately, this keeps conditions dry
through nearly the entire daylight hours before the sufficient
column moistening is achieved. Thermodynamic moderation also gets
underway with 850 mb temps increasing by at least 6C by 18Z
suggesting highs in the lower 60s, near climatological normals.
Cooler readings are anticipated along the coastal communities,
downwind of Lake Erie and Lake Huron from on-shore southeasterly
flow.
By nearly all accounts, showers should hold-off for Southeast
Michigan until after 00Z when isentropic ascent commences. This
leading arc of showers then transitions to more dynamically forced
activity packets of CVA stream through the perturbed mid-level flow
with the moistened environment. Forecast soundings reveal some
elevated instability above the warm frontal slope, therefore a few
rumbles of thunder are possible, late.
The mature low exhibits minor pressure rises Saturday as it tracks
across the Upper Midwest and merges with the central Canadian
trough. Current models suggest a delayed cold FROPA until late
Saturday night with a rather dry afternoon. Westerly flow trailing
the composite shortwave lends some degree of column drying as lapse
rates improve slightly. Did bring PoPs down quite a bit to reflect
this trend south of I-69. Main threat for broader coverage of
thunderstorms exists across the Tri-Cities INVOF the stalled frontal
boundary, higher dewpoints, and SBCAPE. Questions exist regarding
afternoon cap erosion per NAM3km/ARW, but a Marginal Risk for severe
weather persists. Much warmer conditions arise with highs in the mid-
upper 70s in addition to +25 mph gusts.
The active pattern continues Sunday as another wave ejects out of
the synoptic subtropical jet which reinforces southwesterly ThetaE
advection and continued warmth. Several more rounds of showers are
possible Saturday night and Sunday with the persistent forced ascent
and Gulf-augmented humidity. Some NWP drift now points to more
activity occurring over central Lower during the afternoon. Little
in the way of cooling mechanisms into Monday as the influence of the
departing ridge lingers until Tuesday. High pressure then anchors
over the coast of the southern Atlantic which maintains a component
of return flow into the midweek timeframe and warmer than normal
temperatures through the period.
MARINE...
Strong low pressure moves from the central Plains to the upper
Midwest today and then across Lake Superior on Saturday. The
strengthening pressure gradient ahead of this system results in
southeasterly flow ramping up today, peaking late Friday night into
Saturday morning. Wind veers southerly on Saturday with gusts
touching gale force during the morning before gradually weakening
through the day as much warmer air moves into the region to
stabilize flow over the cold lake water. The warm air also fuels
thunderstorm potential through Saturday and Saturday night, and
possibly even into Sunday as the associated cold front stalls over
the region. The front awaits yet another low pressure system moving
in from the Plains Sunday into Monday.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...Freeze Warning until 8 AM EDT this morning for MIZ047-053-054-
060>062-068-069-075.
Frost Advisory until 8 AM EDT this morning for MIZ048-049-055-063-
070-076-082-083.
Lake Huron...None.
Lake St Clair...None.
Michigan waters of Lake Erie...None.
&&
$$
AVIATION.....AA
DISCUSSION...KGK
MARINE.......BT
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