942
FXUS63 KDTX 291749
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
149 PM EDT Wed May 29 2024

.KEY MESSAGES...

- Light showers will carry through the morning near the Ohio border
  as a low pressure system passes to the south. Additional scattered
  showers and isolated thunderstorms continue early this afternoon
  along/south of I-94.

- Dry weather builds in later today which continues through late week.

- Temperatures drop below average throughout the mid week period
  before warming up again into the weekend.

&&

.AVIATION...

Axis of narrow showers, including some isolated lightning strikes,
continues to work south across the southern terminals early this
afternoon. Instability profiles are marginal (up to 500 J/kg of
MUCAPE) with limited effective shear (less than 15 knots), thus
pulse-type convective mode should persist a bit longer. Further
north, a SCT-BKN MVFR cumulus deck has thinned a bit while the main
clearing line is currently positioned near I-69 (and moving
southward). Expect VFR conditions across all TAF sites by 19Z with
clearing skies into the evening and overnight hours. SKC in-place
Thursday morning as surface high pressure centered over the WI/MI
border builds across the Great Lakes with lighter northwest flow
through the end of the TAF period.

For DTW/D21 Convection...Narrowed the window for additional
convection from the 1614Z amendment to end the TEMPO at 19Z as
storms remain sub-severe and exhibit a weakening trend with north-
south storm motions of 15-20 knots.

DTW THRESHOLD PROBABILITIES...

* Medium in ceiling at or below 5000 feet during convection through
  19Z today.

* Medium for additional thunderstorms through 19Z today.

&&

.PREV DISCUSSION...
Issued at 347 AM EDT Wed May 29 2024

DISCUSSION...

The broad trough over the Great Lakes will offer one more chance at
showers and isolated thunderstorms today as a mid level short wave,
surface low, and sinking cold front all work together in a way to
use the last of the moisture before it`s shunted to the south. Main
focus for early day showers will be the ongoing band stretching from
southern Lake MI to Cleveland on the deformation/moisture axis of a
surface low that will track along that same line. The compact mid
level wave and surface reflection will reach south of CLE by 12Z
this morning with the band of showers pivoting up into SE MI. These
showers will mostly affect locations south of I94 but there are some
isolated showers already developing up toward M59 as well. A cold
front will then push southward through the early afternoon which the
CAMs are mostly showing sparks up another round of showers and
possible some isolated thunderstorms. The residual moisture pool
with PWATs up near 1.0 inch and cooler air in the mid levels briefly
enhance the lapse rates and produce up to 500 J/kg of MUCAPE. This
is all while dry air advection is underway so expectation is for a
burst of diurnally driven cu that may develop into scattered showers
with an isolated thunderstorm that will fade quickly in the late
afternoon due to lack of greater forcing and moisture. Again this
will largely be south of I94 so most locations north of M59 should
stay dry through the day.

Expansive surface ridge will then begin to build into the area late
in the day and overnight. The high will be centered off to the west
keeping northerly flow persisting over SE MI overnight. Dry air with
dewpoints falling into the 30s with clear skies and decreasing winds
will offer fairly good radiational cooling conditions. Low
temperatures are forecast down to around 40 but would not be
surprised to see a few cooler spots come in with an upper 30. The
short nights this time of year along with any lingering moisture
being pushed out will both help minimize the extent of those sub 40
values.

Thursday and Friday will be dry with a gradual warming trend back
into the 70s as the surface low becomes centered over the Great
Lakes and amplified upper level ridge reaches the region. The ridge
axis passes east Friday evening opening the door for warmer
southwest flow into the region boosting temps further pushing 80 on
Saturday and into the 80s on Sunday. The next trough is already
pushing across central Canada at this time with an extension
southward through the Plains which will accompany the lead edge of
the warm advection push early Saturday. The pattern flattens out and
becomes progressive again which keeps us on the warmer side of the
jet into next week but also presents periodic opportunities for
precipitation next week.

MARINE...

Surface trough departs this morning in favor of high pressure moving
in from Canada this afternoon. Transition between these pressure
patterns results in a period of enhanced northerly flow through this
evening, with a combination of gusts to 25 knots and waves of 3 to 5
feet prompting additional Small Craft Advisories for today and
tonight. Drier conditions prevail to end the work week with winds
organizing out of the southwest by this weekend.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Small Craft Advisory until 10 PM EDT this evening for LHZ421-422-
     441>443.

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

$$

AVIATION.....KGK
DISCUSSION...DRK
MARINE.......MV


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