000
FXUS63 KDTX 260827
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
427 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.

&&

.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.

&&

.PREV DISCUSSION...
Issued at 1155 PM EDT Thu Apr 25 2024

AVIATION...

Surface high pressure will remain anchored across the eastern Great
Lakes tonight through early Fri morning and will maintain a very
light east wind, with the abundant dry air supporting clear skies.
An east-southeasterly gradient will increase during the day Friday
as the center of the sfc high drifts off the East Coast, with model
soundings supportive of wind speeds up around 10 knots. The
increased gradient flow will inhibit enhanced lake breeze
convergence like today, so the prospects for FEW-SCT diurnal cu is
expected to be less.

For DTW/D21 Convection...A warm front will approach late Friday
night/early Saturday morning. This will support numerous showers
toward the end of the TAF period. Increasing instability aloft will
also support a chance of thunderstorms, likely embedded within the
broader pattern of showers. Chances for thunderstorms will be during
the end of the TAF period (08-12Z Sat) and will be around 30
percent.

DTW THRESHOLD PROBABILITIES...

* Low in thunderstorms overnight Friday into early Saturday morning.

* High in ceilings aob 5000 feet overnight Friday into Saturday
  morning.


&&

.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.
&&

$$

DISCUSSION...KGK
MARINE.......BT
AVIATION.....SC


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