578
FXUS63 KDTX 140922
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
522 AM EDT Tue May 14 2024

.KEY MESSAGES...

- There is a chance of showers across all of southeast Michigan this
morning shifting toward the Ohio border this afternoon and tonight.
An isolated weak thunderstorm is possible.

- Notably cooler temperatures settle into the area today with highs
in the upper 50s to lower 60s after highs yesterday in the lower
80s.

- High pressure brings dry weather and a gradual temperature rebound
Wednesday and Thursday.

- The next low pressure system arrives with a chance of showers
Thursday night and Friday.

&&

.AVIATION...

Frontal boundary continuing to sag south through the region early
this morning, currently residing around PTK. This boundary pushes
through the remaining southern TAF sites this morning setting up
more uniform NE flow in its wake. Given morning observational and
model trends, raised ceilings to remain within VFR territory today.
Greatest low level tied to a low lifting into the Ohio Valley now
looks more likely to stall out near the Ohio border rather than
fully reach into the terminal corridor. Scattered shower activity
still expected towards FNT/PTK this morning before shifting towards
Detroit in the afternoon. Shower activity wanes by evening with some
further improvements in ceilings possible as the elevated portion
of the front fully vacates the area.

For DTW/D21 Convection... Little to no thunderstorm potential given
lack of instability behind the front. Sub 5kft ceilings possible
late morning into the afternoon as scattered shower activity drifts
south in the vicinity. While MVFR cigs can`t be completely ruled out
still, trends are greatly favoring VFR to hold through the day.

DTW THRESHOLD PROBABILITIES...

* Medium confidence in cigs aob 5000 feet late morning through
  this afternoon.

&&

.PREV DISCUSSION...
Issued at 357 AM EDT Tue May 14 2024

DISCUSSION...

Early morning observational trends and model analysis fields
indicate the cold front overhead and settling very slowly toward the
Ohio border leading up to sunrise. Slightly stronger high pressure
reaching down from northern Ontario combined with a slower/farther
south pace of mid MS valley low pressure is keeping the front slowly
on the move rather than completely stalled across southern Lower Mi.
Clusters of showers in progress are embedded in the west to east mid
level moisture axis extending north of the surface front up through
the Tri Cities and Thumb, and this is expected to continue during
the morning.

The temperature contrast will become the notable aspect of
conditions this afternoon as readings stall in the upper 50s to
lower 60s compared to highs in the lower 80s across all of SE Mi
yesterday. A shift toward surface based convective potential is
confined to along and near the cold front that will be very near the
Ohio border by mid afternoon, if not to the south when factoring in
the influence of Lake Erie. This will limit the chance of surface
based convection to Lenawee and Monroe counties during feeble peak
instability from mid afternoon to mid evening. HREF mean surface
based CAPE is only a few hundred J/kg after 18Z and almost non-
existent by 00Z this evening to go along with an impressively weak
wind profile featuring about 10 knots of flow at 500 mb. Scattered
afternoon and evening showers is the best way to describe the
result, with a rumble of thunder possible. A stray shower then
remains possible after midnight off the northern fringe of the low
pressure system as it moves slowly along the Ohio valley.

Clouds decrease north to south across Lower Mi during Wednesday as
surface high pressure builds down farther from northern Ontario.
Lingering NE boundary layer cold advection is balanced by breaks of
afternoon sunshine across interior locations making guidance highs
around 70 within reach. Given the NE wind, locations closer to the
shorelines will have much more of a temperature struggle where
readings end up stuck in the 50s near Lake Huron. Temperatures then
take a step upward Thursday as high pressure retreats into Quebec.
The Lake Huron shoreline remains the exception as easterly/onshore
wind continues, although on a weaker gradient compared to Wednesday.

For the late week and next weekend, extended/global model solutions
depict a less amplified long wave upper air pattern compared to
recent days/weeks. The relatively zonal flow carries the next short
wave system into central Canada during mid week with improved
agreement among solutions on Thursday night/Friday arrival timing in
the Great Lakes. The quick moving system brings our next chance of
showers and thunderstorms until exiting eastward Friday night. Model
consensus for the weekend maintains a progressive/zonal configuration
favoring mostly dry and mild weather this weekend.

MARINE...

The chance for showers will continue along a stationary front which
is currently positioned west-southwest to east-northeast, extending
from the basin of southern Lake Michigan into southern Lake Huron.
Some rumbles of thunder cannot be ruled out, but with limited
instability, mainly rain showers are expected. Shower chances remain
possible leading into the early afternoon, but will decrease as high
pressure builds into the northern Great Lakes, pushing the frontal
boundary south of the state line. Some renewed rain and some thunder
chances will build back in mainly across Lake Erie late tonight into
Wednesday as a low pressure fills in across the Ohio Valley. This
low pressure system will reinforce northeast flow across all of the
Great Lakes, building wave heights into Saginaw Bay and across the
Lake Huron shoreline. Small Craft Advisories will likely be needed
across the Bay and portions of the shorelines given wave heights
building to or slightly above the four feet. High pressure will
continue to settle in over the Great Lakes on Thursday, relaxing
wind speeds and subsequently wave heights.

&&

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

$$

AVIATION.....KDK
DISCUSSION...BT
MARINE.......AM


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