Expert Forecast Opinion

760
FXUS63 KDTX 090739
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
339 AM EDT Fri May 9 2025

.KEY MESSAGES...

- A Freeze Warning is in effect through this morning for the Tri-
Cities and Thumb regions. A Frost Advisory is in effect for the rest
of southeast Michigan outside of Metro Detroit.

- High pressure brings sunny, dry weather today. An isolated shower
is possible on Saturday.

- Warmer temperatures prevail through the weekend and roughly remain
near normal for this time of year.

&&

.DISCUSSION...

Clear skies and light winds have led to a cold start this morning,
with pre-dawn temperatures in the upper 20s/around 30 up across the
Tri-Cities and Thumb regions. Given temperatures falling into the
upper 20s, did opt to expand the Freeze Warning into the Thumb
through the rest of the morning. Elsewhere, temperatures are
expected to fall into the low to upper 30s. No additional chances
were made to the Frost Advisory.

With a cloud-free start to the day, temperatures will quickly warm
into the 40s/50s through the mid to late morning hours. This
afternoon, temperatures will continue to warm under cloud-free
skies, with highs inland from Lake Huron reaching the mid to upper
60s. Communities immediately along the Lake Huron shoreline will
continue to see locally cooler temperatures given the north winds
coming in off of the cooler lake waters. Last evenings sounding
showed the impressive amount of dry air aloft, associated with the
area of high pressure over the region. Forecast soundings show
daytime heating and mixing tapping into this drier air aloft, thus
did mix down dewpoints quite a bit to bring afternoon RHs down
closer to 25%. Tonight will be another cool night, but we will see
an uptick in mid/high clouds overnight and into early Saturday
morning ahead of a shortwave tracking across the Upper Great Lakes.

As the above mentioned shortwave traverses the Upper Great Lakes, a
trailing cold front will drop south across the state on Saturday.
Saturday`s high temperatures will be highly dependent on the timing
of this front. There is some uncertainty in the timing of the front,
but the majority of models have the front clearing the Tri-
Cities/Thumb region by early to mid afternoon and then making it
further south during the late afternoon and evening hours. Did
adjust forecast temperatures and tried to time the arrival of
falling afternoon temperatures behind the cold front in the hourly
temperatures. Far southeast portions of Michigan, down into Metro
Detroit and further southwest, will see the warmest temperatures on
Saturday, with highs climbing into the 70s. The cold front will also
bring a chance for a few isolated showers as it moves through during
the day.

High pressure quickly drops southeast across Ontario and into the
Northeast through the end of the weekend, allowing southerly flow to
gradually return to the area. While southerly flow returns, an upper-
level low to our south looks to limit the return of better warm air
advection into the region. Given this pattern and these trends, the
latest NBM high temperatures for early next week have come in about
2 degrees cooler than the previous forecast. Given the large-scale
pattern, this cooling trend in daytime highs is headed in the right
direction for early next week. This slow moving upper low will also
bring occasional chances for showers and perhaps a few thunderstorms
through early/middle of next week. As we look ahead towards the end
of next week, confidence is higher that we will warmer temperatures
prevail as we get into the better warm air advection ahead of the
main upper-level trough.

&&

.MARINE...

High pressure will move southeast across the region through tonight,
with generally light winds. A cold front drops south across the
central Great Lakes on Saturday, bringing an uptick in north and
northeast winds. Right now, these gusty winds behind the cold front
look to remain below Small Craft Advisory criteria, but we will need
to keep an eye on winds/waves for Saturday afternoon/evening.
Outside of a low chance for a rain shower late tonight into Saturday
morning, dry weather prevails through the end of the weekend.
Lighter easterly winds prevail on Sunday, then become southerly as
we head into the first half of next week.

&&

.PREV DISCUSSION...
Issued at 1139 PM EDT Thu May 8 2025

AVIATION...

High pressure over the northern Great Lakes will make a gradual
southward expansion tonight and Friday. Very dry air associated with
this high will sustain clear skies tonight and Friday. Nighttime
cooling will support light northeast winds tonight. Winds will turn
northerly with the onset of daytime heating with speeds increasing to
near 10 knots.

For DTW/D21 Convection... No convection is forecast through the TAF
period.

THRESHOLD PROBABILITIES...

* None.


&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...Freeze Warning until 9 AM EDT this morning for MIZ047>049-054-055.

Frost Advisory until 9 AM EDT this morning for MIZ053-060>063-
068>070-075-082.

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

$$

DISCUSSION...JA
MARINE.......AM/JA
AVIATION.....SC


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