012
FXUS63 KDTX 240917
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
517 AM EDT Mon Jun 24 2024

.KEY MESSAGES...

- High temperatures in the upper 70s to lower 80s today are right
around normal for mid to late June leading to a pleasant day with
low humidity.

- Showers and thunderstorms become active again early Tuesday
morning. These storms are not expected to reach severe intensity but
could produce locally heavy rainfall.

- An additional round of thunderstorms is possible Tuesday night
into early Wednesday, mainly south of I69. There is Marginal Risk of
severe thunderstorms during this time.

- Cooler and less humid air moves back into the area late Wednesday
and lasts through Thursday.

&&

.AVIATION...

Light northwest winds today with just a modest scattered VFR (4-
6kft) CU up expected. Low clouds dissipate by sunset, with light and
variable winds during the evening giving way to increasing south-
southwest winds tonight. Mid/high clouds will also be on the increase
after midnight, with the potential for elevated showers and
thunderstorms to arrive toward 12z Tuesday.

For DTW/D21 Convection...There is a good chance for thunderstorms
late Tuesday morning.

DTW THRESHOLD PROBABILITIES...

* Low for ceilings aob 5kt today, medium confidence Tuesday after
  12z.

* Medium confidence in thunderstorms late Tuesday morning.

&&

.PREV DISCUSSION...
Issued at 403 AM EDT Mon Jun 24 2024

DISCUSSION...

A stray shower remains possible until shortly after sunrise as the
overachieving mid level low pressure system exits into Ontario. It
is followed by a short wave ridge/surface high pressure combination
that takes over conditions for the rest of today through tonight
ensuring dry weather. Nearly full sun also helps lift temperatures
into the lower 80s across the area with the exception of cooler
readings near Lake Huron, still right around normal for late June
and with low humidity.

A mostly zonal long wave pattern keeps smaller scale wave structures
progressive across Canada and the northern tiers of states during
the mid week period. The first short wave system is already
organizing over the Canadian Prairie provinces today where ongoing
convection stays mostly north of the border as the low pressure
system reaches northern Ontario tonight. The system has a broad warm
front and warm sector extending southward into the upper Midwest
that will support a well organized low level jet focused into the
Great Lakes late tonight into Tuesday. Model projections are in good
agreement on 850 mb wind reaching 50 kts from the central Plains
into the warm frontal zone late tonight leading to strong mid level
moisture transport and destabilization. QPF fields from regional and
global models blossom as a result and are supported by MCS
development across the range of hi-res solutions. Consistent from
earlier forecast cycles is the pronounced south to north instability
axis feeding into the low pressure center which also sets up a sharp
gradient into Lower MI by sunrise Tuesday. Surface based CAPE is
almost nonexistent in SE MI Tuesday morning while MUCAPE drops off
below 1000 J/kg which leads to a pronounced weakening of any
organized convection while elevated moisture transport maintains
numerous to widespread coverage of showers and other thunderstorm
clusters across Lower MI until the low to mid level moisture axis
builds fully into the Great Lakes by afternoon. The SPC Day 1
outlook reflects these trends and the General Thunder outlook is in
good shape for SE MI.

A transition from nocturnal to surface based convective potential
occurs Tuesday afternoon as the warm sector of the system surges
into the Great Lakes. Afternoon temperatures reach the upper 80s as
surface Td returns to around 70 in SW flow ahead the initial cold
front/prefrontal trough. This boundary becomes the focus for round 2
of storms affecting Lower MI late Tuesday through Tuesday night. The
regional/global models help frame a wide range of hi-res CAM
solutions by suggesting surface based development is limited by
capping 700 mb temperatures until a new cycle of the low level jet
forcing occurs Tuesday night. The question then becomes how far north
into Lower MI will this activity be able to reach before the
trough/front sweeps the pattern south/east by Wednesday morning.
Probability is highest at the Ohio border and then tapers off toward
the I69 corridor. The potential for severe intensity drops off from
west to east across the southern Great Lakes reflecting the potential
for greater MCS-type organization earlier in the night.

A chance of showers and sub-severe storms lingers into Wednesday
morning until the primary cold front moves through SE MI by
afternoon. High pressure then builds in aggressively for Thursday
but the progressive larger scale pattern already has a very similar
low pressure system organizing in the Plains and Midwest. This
system is projected to bring a new thunderstorm pattern into the
Great Lakes by Friday.

MARINE...

A lingering trough draped along the long axis of Lake Huron will
pull away to the east today as high pressure builds across the
region. Northerly winds will persist today being on the eastern edge
of the high, but by this evening winds will go calm as the center of
the high passes overhead. The next low pressure system starts
developing upstream over the Plains/Midwest today and will pass
through the region Tuesday and Tuesday night. This will bring the
next chances of showers and thunderstorms and an uptick in southwest
winds Tuesday which may necessitate another Small Craft Advisory.

HYDROLOGY...

An active pattern of thunderstorms returns to Lower Michigan by
Tuesday morning as warm and humid air surges back into the region.
Most SE Michigan locations will see at least a period of showers
during the morning as thunderstorms decrease intensity while moving
in from the west. Rainfall totals average 0.25 to 0.5 inch with
localized amounts up to 1 inch possible.

The Tuesday morning activity is followed by a break in the afternoon
until the next round of storms becomes possible Tuesday night into
Wednesday morning. Current forecast trends suggest this round of
rainfall occurs mainly south of I69 across metro Detroit to the Ohio
border. Additional totals up to 1 inch are possible with this
activity until it exits the area by Wednesday afternoon.

The potential for flooding in each event is greater where repeated
rounds of storms occur over the same area making ponding of water on
roads and in prone low lying areas possible. The Tuesday and
Wednesday activity collectively could lead to a brief response in
the level of streams and rivers across the area.

&&

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

$$

AVIATION.....SF
DISCUSSION...BT
MARINE.......DRK
HYDROLOGY....BT


You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.