Expert Forecast Opinion

000
FXUS63 KDTX 252241
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
641 PM EDT Thu Apr 25 2024

.KEY MESSAGES...

- Dry conditions bring another cold night tonight and then a warming
trend with highs in the 60s on Friday.

- Showers are likely Friday night with a chance for a few embedded
thunderstorms through Saturday morning.

- Breezy southwest winds develop Saturday afternoon. Gusts up to 30
mph will be possible.

- There is a chance for additional thunderstorm development Saturday
afternoon and evening. A Marginal Risk for severe weather is in
place for northwest portions of the forecast area. An isolated storm
will be capable of producing hail to 1 inch in diameter and gusts up
to 60 mph with storm motion from southwest to northeast at 45 mph.

&&

.AVIATION...

Subtle moisture pooling across metro Detroit and enhanced low level
convergence off lake breeze boundaries was able to generate some cu
this afternoon. These will diminish around/shortly after 00Z as
daytime heating wanes. Surface high pressure will remain anchored
across the eastern Great Lakes tonight 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.

DTW THRESHOLD PROBABILITIES...

* None.

&&

.PREV DISCUSSION...
Issued by National Weather Service Grand Rapids MI

DISCUSSION...

We have issued a Freeze Warning for interior sections and a Frost
Advisory for the counties bordering Lake Huron for tonight. The
airmass will be modified a bit from last night and return flow begins
late tonight as the surface ridge begins to move east, but model
soundings still show an very dry airmass through 12Z Friday with
precipitable water down near 0.15 inches. This should allow
temperatures to drop quickly like last night. There could be some
wind picking up by 12Z...but we still expect temperatures to drop to
around 30 in the warning area and lower 30s in the advisory.

- Showers and Thunderstorms Arrive Friday Night

Return flow increases Friday but it will take a while to moisten
the column of the very dry atmosphere and showers will probably
hold off until Friday night although clouds will be in the increase
in the afternoon.

A large area of isentropic ascent and strong warm advection
pattern combine with the arrival of deep moisture to bring
increasing chances for rain Friday night and elevated instability
should be enough for isolated thunder and some heavier downpours
late Friday night.

Low confidence at present in convective trends for Later Saturday
Afternoon and Evening. A conditionally favorable environment for
organized convection will be present given MUCAPE values of over 1000
J/kg as moisture climbs in strong SW flow, and deep layer shear
values climbing to 35-45 knots thanks to favorable juxtaposition of
the low and mid-level jets. Threat is obviously dependent on whether
Convective Initiation (CI) occurs. Frontal forcing is not overly
impressive and the upper shortwave remains to the west; hence limited
synoptic/sub-synoptic forcing for upward vertical motion. If storms
can develop, they have some organization potential per the SPC
Marginal outlooks. That said, low-level shear will be mostly be
boundary-parallel which tends to favors rapid upscale growth into an
outflow dominant convective line. It therefore makes sense that a
somewhat greater risk will remain to the northwest where CI is more
likely to be. Regardless of convective outcome, it will be a breezy
day with gusts well into the 30 mph range.

For Sunday...the warm front is expected to be over Central Lower MI
and with it a second round of showers and storms is possible given
MUCAPE values north of 1000 J/kg.

Showers then expand across Lower MI Sunday Night into Monday as the
cold front drifts south before clearing the area Monday evening. CAPE
values on the ECMWF and GFS still look to be above 500 J/kg so
thunder continues to be possible.

Dry conditions expected for the Tuesday night timeframe as period of
surface ridging drifts over the area. After this, forecast
predictability for the finer details drops, but the general theme
seems to be mean troughing aloft with a relatively wet and unsettled
pattern for the rest of the work week.

For the weekend into early next week, 850mb temperatures climb into
the teens weekend, yielding surface temperatures in the 70s with even
80+ not out of the question in spots. into early next week causing
temperatures to climb into the 70s with low (around 10 percent)
chances that areas exceed 80 degrees.

MARINE...

High pressure will continue to maintain light flow with an easterly
component through Friday morning. The high shifts east Friday into
Friday night as strong low pressure moves from the central Plains to
the upper Midwest, eventually crossing Lake Superior on Saturday.
The strengthening pressure gradient between these features will
result in southeasterly flow ramping up late Friday, peaking late
Friday night into Saturday morning, then veering southerly on
Saturday while gradually weakening through the day. This will also
usher in a mild airmass, which will maintain very stable conditions
over the waters. Latest guidance suggests a brief window for gusts
approaching gale force roughly 09-15Z Saturday. There is also a
chance of thunderstorms Saturday into Saturday night.

&&

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

$$

AVIATION.....SC
DISCUSSION...TJT
MARINE.......DBT


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