365
FXUS63 KDTX 240014
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
814 PM EDT Thu May 23 2024

.KEY MESSAGES...

- Friday brings more nice weather to kick off the holiday weekend,
mostly sunny with highs in the lower 80s.

- Showers and thunderstorms move in Friday night (60-70%) and
continue into Saturday morning.

- Rain ends Saturday afternoon through Saturday night.

- Showers are likely again with a chance of thunderstorms Sunday
afternoon and Sunday night.

- The Memorial Day outlook calls for cool temperatures with showers
likely Monday and Monday night.

&&

.AVIATION...

Upper level confluence this evening will give way to geopotential
height rises Friday as mid to upper level ridging builds over Lower
Michigan. Forecast soundings show at least two distinct rounds of
active subsidence during the next 24 hours. Any remaining boundary
layer cumulus north of I 69 will fade the next hour or so loss of
daytime heating. Satellite trends do suggest some potential for
altocumulus/altostratus convective debris cloud from Wisconsin to
survive the trip into Southeast Michigan. Confidence remains
relatively low and will be monitored this evening. Significant
moisture advection is forecasted to hold off until Friday night
across Southeast Michigan.

DTW THRESHOLD PROBABILITIES...

*  None

&&

.PREV DISCUSSION...
Issued at 358 PM EDT Thu May 23 2024

DISCUSSION...

Ohio valley surface high pressure is demonstrating full control of
conditions today resulting in ideal mid to late May weather across
Lower Mi. Most locations enjoy full sun and breezy SW wind during
mid to late afternoon, both of which help lift temperatures to highs
near 80. Temperature trends follow a mostly clear sky with light and
variable wind tonight taking advantage of a low humidity air mass
and favorable radiational cooling. Lows in the lower 50s with a few
upper 40s in the usual cooler locations look good at the lower end
of the guidance range.

The low pressure system in the Rockies/High Plains tonight moves
toward the upper Midwest to start Friday. It helps build the mid
level short wave ridge downstream that in turn directs high pressure
into more of a south to north position across the central Great
Lakes for another day of full sun and low humidity in SE Mi.
Temperatures also reach about a category higher into the lower 80s
before high clouds thicken late in the day.

Thunderstorm trends become the forecast highlight for the Great
Lakes Friday night as multiple convective systems are likely to
occur upstream with the Plains to Midwest low pressure system. The
surface low is positioned with good model agreement in northern MN
by Friday evening and is connected to the primary warm frontal zone
that has been stalled across the Ohio valley. The system draws the
warm front northward Friday evening but only toward the southern Mi
border. Farther north progress is restricted by secondary low
pressure within the occlusion over WI thus setting up a sharp west
to east instability gradient shown best in the 12Z HREF mean MUCAPE
that holds sub 1000 J/kg across Lower Mi. The system continues to
pinch the surface based moisture/instability axis southward during
the night which helps explain a general weakening convective trend
in Hi-res solutions across the Great Lakes while remaining MCS
structures propagate into the OH/TN valleys toward the instability
axis. There is enough elevated instability to maintain a generous
coverage of showers with scattered ordinary storms across Lower Mi
judging by the corridor of 700-500 mb lapse rate averaging 7.5 C/km
that sweeps overhead and eastward during Saturday morning.

The rest of Saturday and Saturday night turn out Ok as a broad short
wave ridge and associated surface high pressure cover the Great
Lakes. However, the large scale mid and upper air pattern is zonal
and progressive which keeps short wave systems on the move through
the weekend. Consensus of extended range models projects the next
Plains low pressure system arriving late Sunday. It picks up the
Ohio valley front once again for another textbook low level jet
driven moisture transport scenario into Lower Mi Sunday night
through Memorial Day.

MARINE...

The central Great Lakes are positioned between a low pressure system
over southern Hudson Bay and a ridge of high pressure spreading
across the Ohio and Tennessee Valleys. Winds remain somewhat breezy
through the rest of the daylight period with gusts eventually
trending lower overnight. An upper level ridge works in aloft Friday
offering dry and stable conditions. Gradient winds veer northerly,
becoming variable, and eventually easterly with lower speeds.
Shortwave feature ejects across the Upper Midwest Friday night into
Saturday with a secondary surface low developing along the system`s
cold front. This offers opportunities for some thunderstorms and a
period of Small Craft Advisory conditions across Saginaw Bay during
the afternoon. An occluded low then tracks across Wisconsin and into
The UP Sunday night and Monday which drags an energetic LLJ across
the waterways. Expect a broader representation of Small Craft
Advisories marked by gusts approaching 30 knots.

&&

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

$$

AVIATION.....CB
DISCUSSION...BT
MARINE.......KGK


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